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Goulding RP. Re-evaluating central versus peripheral contributions to maximal oxygen uptake: the role of muscle diffusive capacity. J Physiol 2024. [PMID: 39216088 DOI: 10.1113/jp287378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2024] [Accepted: 08/19/2024] [Indexed: 09/04/2024] Open
Affiliation(s)
- Richie P Goulding
- Department of Human Movement Science, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
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Agostoni P, Cattadori G, Vignati C, Apostolo A, Farina S, Salvioni E, Di Marco S, Sonaglioni A, Nodari S, Marenzi G, Schmidt-Trucksäss A, Myers J. Deceived by the Fick principle: blood flow distribution in heart failure. Eur J Prev Cardiol 2024:zwae203. [PMID: 38934631 DOI: 10.1093/eurjpc/zwae203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 06/05/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024]
Abstract
AIMS The Fick principle states that oxygen uptake (V̇O2) is cardiac output (Qc)*arterial-venous O2 content difference [ΔC(a-v)O2]. Blood flow distribution is hidden in Fick principle and its relevance during exercise in heart failure (HF) is undefined.To highlight the role of blood flow distribution, we evaluated peak-exercise V̇O2, Qc and ΔC(a-v)O2, before and after HF therapeutic interventions. METHODS Symptoms-limited cardiopulmonary exercise tests with Qc measurement (inert-gas-rebreathing) was performed in 234 HF patients before and 6 months after successful exercise training, cardiac-resynchronization therapy or percutaneous-edge-to-edge mitral valve repair. RESULTS Considering all tests (n=468) a direct correlation between peakV̇O2 and peakQc (R2=0.47) and workload (R2=0.70) were observed. Patients were grouped according to treatment efficacy in group 1 (peakV̇O2 increase >10%, n=93), group 2 (peakV̇O2 change between 0 and 10%, n=60) and group 3 (reduction in peakV̇O2, n=81). Post-treatment peakV̇O2 changes poorly correlated with peakQc and peakΔC(a-v)O2 changes. Differently, post-procedures peakQc vs. peakΔC(a-v)O2 changes showed a close negative correlation (R2=0.46), becoming stronger grouping patients according to peakV̇O2 improvement (R2=0.64, 0.79 and 0.58 in group 1, 2 and 3, respectively). In 76% of patients peakQc and ΔC(a-v)O2 changes diverged regardless of treatment. CONCLUSION The bulk of these data suggests that blood flow distribution plays a pivotal role on peakV̇O2 determination regardless of HF treatment strategies. Accordingly, for assessing HF treatment efficacy on exercise performance the sole peakV̇O2 may be deceptive and the combination of V̇O2, Qc and ΔC(a-v)O2, must be considered.
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Affiliation(s)
- Piergiuseppe Agostoni
- Centro Cardiologico Monzino, IRCCS, Milano, Italy
- Dept. Of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy
| | - Gaia Cattadori
- Dept. Of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy
- Multimedica IRCCS, Milano, Italy
| | - Carlo Vignati
- Centro Cardiologico Monzino, IRCCS, Milano, Italy
- Dept. Of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy
| | | | | | | | | | | | - Savina Nodari
- Dept. od Medical and Surgical Specialities, Radiological Sciences and Public Health, University of Brescia Medical School, Italy
| | | | - Arno Schmidt-Trucksäss
- Division of Sport and Exercise Medicine, Department of Sport, Exercise and Health, University of Basel, Birsstrasse 320B, CH-4052 Basel, Switzerland
| | - Jonathan Myers
- VA Palo Alto Health Care System and Stanford University, Palo Alto CA, USA
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Poole DC. Oxygen's final frontier: novel capillary-mitochondrial relationships in muscle predicate function. J Physiol 2024; 602:1879-1880. [PMID: 38564190 DOI: 10.1113/jp286550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, USA
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Liu D, Li N, Zhou Y, Wang M, Song P, Yuan C, Shi Q, Chen H, Zhou K, Wang H, Li T, Pan XF, Tian H, Li S. Sex-specific associations between skeletal muscle mass and incident diabetes: A population-based cohort study. Diabetes Obes Metab 2024; 26:820-828. [PMID: 37997500 DOI: 10.1111/dom.15373] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/31/2023] [Accepted: 11/04/2023] [Indexed: 11/25/2023]
Abstract
AIMS To investigate the sex-specific associations between predicted skeletal muscle mass index (pSMI) and incident type 2 diabetes in a retrospective longitudinal cohort of Chinese men and women. MATERIALS AND METHODS We enrolled Chinese adults without diabetes at baseline from WATCH (West chinA adulT health CoHort), a large health check-up-based database. We calculated pSMI to estimate skeletal muscular mass, and measured blood glucose variables and assessed self-reported history to identify new-onset diabetes. The nonlinear association between pSMI and incident type 2 diabetes was modelled using the penalized spline method. The piecewise association was estimated using segmented linear splines in weighted Cox proportional hazards regression models. RESULTS Of 47 885 adults (53.2% women) with a median age of 40 years, 1836 developed type 2 diabetes after a 5-year median follow-up. In women, higher pSMI was associated with a lower risk of incident type 2 diabetes (Pnonlinearity = 0.09, hazard ratio [HR] per standard deviation increment in pSMI: 0.79 [95% confidence interval {CI} 0.68, 0.91]). A nonlinear association of pSMI with incident type 2 diabetes was detected in men (Pnonlinearity < 0.001). In men with pSMI lower than 8.1, higher pSMI was associated with a lower risk of incident type 2 diabetes (HR 0.58 [95% CI 0.40, 0.84]), whereas pSMI was not significantly associated with incident diabetes in men with pSMI equal to or greater than 8.1 (HR 1.08 [95% CI 0.93, 1.25]). CONCLUSIONS In females, a larger muscular mass is associated with a lower risk of type 2 diabetes. For males, this association is significant only among those with diminished muscle mass.
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Affiliation(s)
- Dan Liu
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Nan Li
- Department of Informatics, West China Hospital, Sichuan University, Chengdu, China
| | - Yiling Zhou
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Miye Wang
- Department of Informatics, West China Hospital, Sichuan University, Chengdu, China
| | - Peige Song
- School of Public Health, Zhejiang University, Hangzhou, China
| | - Changzheng Yuan
- School of Public Health, Zhejiang University, Hangzhou, China
| | - Qingyang Shi
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Hui Chen
- School of Public Health, Zhejiang University, Hangzhou, China
| | - Kaixin Zhou
- College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
- College of Public Health, Guangzhou Medical University, Guangzhou, China
| | - Huan Wang
- Division of Population Health and Genomics, School of Medicine, University of Dundee, Dundee, UK
| | - Tao Li
- Department of Anesthesiology, Laboratory of Mitochondria and Metabolism, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Xiong-Fei Pan
- Section of Epidemiology and Population Health, Ministry of Education Key Laboratory of Birth Defects and Related Diseases of Women and Children, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Haoming Tian
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Sheyu Li
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
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Gifford JR, Blackmon C, Hales K, Hinkle LJ, Richards S. Overdot and overline annotation must be understood to accurately interpret V.O 2MAX physiology with the Fick formula. Front Physiol 2024; 15:1359119. [PMID: 38444762 PMCID: PMC10912163 DOI: 10.3389/fphys.2024.1359119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 01/26/2024] [Indexed: 03/07/2024] Open
Abstract
Few formulas have been used in exercise physiology as extensively as the Fick formula, which calculates the rate of oxygen consumption (i.e., V.O2) as the product of cardiac output (Q.) and the difference in oxygen content in arterial and mixed venous blood (Δav ¯ O2). Unfortunately, the physiology of maximum V.O2 (V.O2MAX) is often misinterpreted due to a lack of appreciation for the limitations represented by the oft-ignored superscript annotations in the Fick formula. The purpose of this perspective is to explain the meaning of the superscript annotations and highlight how such annotations influence proper interpretation of V.O2MAX physiology with the Fick formula. First, we explain the significance of the overdots above V.O2 and Q., which indicate a measure per unit of time. As we will show, the presence of an overdot above Q. and lack of one above Δav ¯ O2 denotes they are different types of ratios and should be interpreted in the context of one another-not in contrast to each other as is commonplace. Second, we discuss the significance of the overline above the "v ¯ " in Δav ¯ O2, which indicates the venous sample is an average of blood that comes from mixed sources. The mixed nature of the venous sample has major implications for interpreting the influence of oxygen diffusion and blood flow heterogeneity on V.O2MAX. Ultimately, we give recommendations and insights for using the Fick formula to calculate V.O2 and interpret V.O2MAX physiology.
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Affiliation(s)
- Jayson R. Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, UT, United States
- Program of Gerontology, Brigham Young University, Provo, UT, United States
| | - Christina Blackmon
- Department of Exercise Sciences, Brigham Young University, Provo, UT, United States
| | - Katelynn Hales
- Department of Exercise Sciences, Brigham Young University, Provo, UT, United States
| | - Lee J. Hinkle
- Department of Exercise Sciences, Brigham Young University, Provo, UT, United States
| | - Shay Richards
- Department of Exercise Sciences, Brigham Young University, Provo, UT, United States
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McDermott A, Nevin A, Gildea N, Rocha J, O'Shea D, Egaña M. Muscle deoxygenation during ramp incremental cycle exercise in older adults with type 2 diabetes. Eur J Appl Physiol 2024; 124:561-571. [PMID: 37638974 PMCID: PMC10858067 DOI: 10.1007/s00421-023-05297-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/03/2023] [Indexed: 08/29/2023]
Abstract
PURPOSE To explore profiles of fractional O2 extraction (using near-infrared spectroscopy) during ramp incremental cycling in older individuals with type 2 diabetes (T2D). METHODS Twelve individuals with T2D (mean ± SD, age: 63 ± 3 years) and 12 healthy controls (mean age: 65 ± 3 years) completed a ramp cycling exercise. Rates of muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, Δ[HHb + Mb]) profiles of the vastus lateralis muscle were normalised to 100% of the response, plotted against absolute (W) and relative (%peak) power output (PO) and fitted with a double linear regression model. RESULTS Peak oxygen uptake (V̇O2peak) was significantly (P < 0.01) reduced in T2D (23.0 ± 4.2 ml.kg-1.min-1) compared with controls (28.3 ± 5.3 ml.kg-1.min-1). The slope of the first linear segment of the model was greater (median (interquartile range)) in T2D (1.06 (1.50)) than controls (0.79 (1.06)) when Δ%[HHb + Mb] was plotted as a function of PO. In addition, the onset of the second linear segment of the Δ%[HHb + Mb]/PO model occurred at a lower exercise intensity in T2D (101 ± 35 W) than controls (140 ± 34 W) and it displayed a near-plateau response in both groups. When the relationship of the Δ%[HHb + Mb] profile was expressed as a function of %PO no differences were observed in any parameters of the double linear model. CONCLUSIONS These findings suggest that older individuals with uncomplicated T2D demonstrate greater fractional oxygen extraction for a given absolute PO compared with older controls. Thus, the reductions in V̇O2peak in older people with T2D are likely influenced by impairments in microvascular O2 delivery.
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Affiliation(s)
- Adam McDermott
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Aaron Nevin
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Norita Gildea
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | | | - Donal O'Shea
- Endocrinology, St Columcille's and St Vincent's Hospitals, Dublin, Ireland
| | - Mikel Egaña
- Department of Physiology, School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
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Liu Y, Zhou A, Li F, Yue T, Xia Y, Yao Y, Zhou X, Zhang Y, Wang Y. Aerobic capacity and [Formula: see text] kinetics adaptive responses to short-term high-intensity interval training and detraining in untrained females. Eur J Appl Physiol 2023; 123:1685-1699. [PMID: 36995431 DOI: 10.1007/s00421-023-05182-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 03/14/2023] [Indexed: 03/31/2023]
Abstract
PURPOSE This study investigated the physical fitness and oxygen uptake kinetics (τ[Formula: see text]) along with the O2 delivery and utilization (heart rate kinetics, τHR; deoxyhemoglobin/[Formula: see text] ratio, ∆[HHb]/[Formula: see text]) adaptations of untrained female participants responding to 4 weeks of high-intensity interval training (HIIT) and 2 weeks of detraining. METHODS Participants were randomly assigned to HIIT (n = 11, 4 × 4 protocol) or nonexercising control (n = 9) groups. Exercising group engaged 4 weeks of treadmill HIIT followed by 2 weeks of detraining while maintaining daily activity level. Ramp-incremental (RI) tests and step-transitions to moderate-intensity exercise were performed. Aerobic capacity and performance (maximal oxygen uptake, [Formula: see text]; gas-exchange threshold, GET; power output, PO), body composition (skeletal muscle mass, SMM; body fat percentage, BF%), muscle oxygenation status (∆[HHb]), [Formula: see text], and HR kinetics were assessed. RESULTS HIIT elicited improvements in aerobic capacity ([Formula: see text], + 0.17 ± 0.04 L/min; GET, + 0.18 ± 0.05 L/min, P < 0.01; PO-[Formula: see text], ± 23.36 ± 8.37 W; PO-GET, + 17.18 ± 3.07 W, P < 0.05), body composition (SMM, + 0.92 ± 0.17 kg; BF%, - 3.08% ± 0.58%, P < 0.001), and speed up the τ[Formula: see text] (- 8.04 ± 1.57 s, P < 0.001) significantly, extending to better ∆[HHb]/[Formula: see text] ratio (1.18 ± 0.08 to 1.05 ± 0.14). After a period of detraining, the adaptation in body composition and aerobic capacity, as well as the accelerated τ[Formula: see text] were maintained in the HIIT group, but the PO-[Formula: see text] and PO-GET declined below the post-training level (P < 0.05), whereas no changes were reported in controls (P > 0.05). Four weeks of HIIT induced widespread physiological adaptations in females, and the majority of improvements were preserved after 2 weeks of detraining except for power output corresponding to [Formula: see text] and GET.
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Affiliation(s)
- Yujie Liu
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Aiyi Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Fengya Li
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Tian Yue
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yuncan Xia
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yibing Yao
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Xiaoxiao Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yihong Zhang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yan Wang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China.
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Golub AS, Song BK, Nugent WH, Pittman RN. Dynamics of PO 2 and VO 2 in resting and contracting rat spinotrapezius muscle. Front Physiol 2023; 14:1172834. [PMID: 37538372 PMCID: PMC10396398 DOI: 10.3389/fphys.2023.1172834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/03/2023] [Indexed: 08/05/2023] Open
Abstract
This study examined changes in interstitial PO2, which allowed calculation of VO2 during periods of rest, muscle contraction and recovery using an in situ rat spinotrapezius muscle preparation. The PO2 was measured using phosphorescence quenching microscopy and the muscle VO2 was calculated as the rate of O2 disappearance during brief periods of muscle compression to stop blood flow with a supra-systolic pressure. The PO2 and VO2 measurements were made during "5 s compression and 15 s recovery" (CR) cycles. With all three stimulation frequencies, 1, 2 and 4 Hz, the fall in interstitial PO2 and rise in VO2 from resting values occurred within the first 20 s of contraction. The PO2 during contraction became lower as stimulation frequency increased from 1 to 4 Hz. VO2 was higher at 2 Hz than at 1 Hz contraction. With cessation of stimulation, PO2 began increasing exponentially towards baseline values. After 1 and 2 Hz contraction, the fall in muscle VO2 was delayed by one CR cycle and then exponentially decreased towards resting values. After 4 Hz stimulation, VO2 increased for 2 cycles and then decreased. The post-contraction transients of PO2 and VO2 were not synchronous and had different time constants. With further analysis two distinct functional responses were identified across all stimulation frequencies having PO2 during contraction above or below 30 mmHg. The corresponding VO2 responses were different - for "high" PO2, muscle VO2 reached high levels, while for the "low" PO2 data set muscle VO2 remained low. Recovery patterns were similar to those described above. In summary, local microscopic PO2 and VO2 were measured in resting and contracting muscle in situ and the post-contraction transients of PO2 and VO2 were all much slower than the onset transients.
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Affiliation(s)
- Aleksander S. Golub
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - Bjorn K. Song
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - William H. Nugent
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
- Song Biotechnologies LLC, Cockeysville, MD, United States
| | - Roland N. Pittman
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, United States
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Interaction of Factors Determining Critical Power. Sports Med 2023; 53:595-613. [PMID: 36622556 PMCID: PMC9935749 DOI: 10.1007/s40279-022-01805-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 01/10/2023]
Abstract
The physiological determinants of high-intensity exercise tolerance are important for both elite human performance and morbidity, mortality and disease in clinical settings. The asymptote of the hyperbolic relation between external power and time to task failure, critical power, represents the threshold intensity above which systemic and intramuscular metabolic homeostasis can no longer be maintained. After ~ 60 years of research into the phenomenon of critical power, a clear understanding of its physiological determinants has emerged. The purpose of the present review is to critically examine this contemporary evidence in order to explain the physiological underpinnings of critical power. Evidence demonstrating that alterations in convective and diffusive oxygen delivery can impact upon critical power is first addressed. Subsequently, evidence is considered that shows that rates of muscle oxygen utilisation, inferred via the kinetics of pulmonary oxygen consumption, can influence critical power. The data reveal a clear picture that alterations in the rates of flux along every step of the oxygen transport and utilisation pathways influence critical power. It is also clear that critical power is influenced by motor unit recruitment patterns. On this basis, it is proposed that convective and diffusive oxygen delivery act in concert with muscle oxygen utilisation rates to determine the intracellular metabolic milieu and state of fatigue within the myocytes. This interacts with exercising muscle mass and motor unit recruitment patterns to ultimately determine critical power.
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Koivula T, Lempiäinen S, Laine S, Sjöros T, Vähä-Ypyä H, Garthwaite T, Löyttyniemi E, Sievänen H, Vasankari T, Knuuti J, Heinonen IHA. Cross-Sectional Associations of Body Adiposity, Sedentary Behavior, and Physical Activity with Hemoglobin and White Blood Cell Count. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph192114347. [PMID: 36361221 PMCID: PMC9657926 DOI: 10.3390/ijerph192114347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 05/06/2023]
Abstract
BACKGROUND This study examined whether hemoglobin (Hb) and white blood cell count (WBC) associate with body adiposity and other cardiometabolic risk factors, as well as accelerometer-measured sedentary behavior (SB) and physical activity (PA), when adjusted for body mass index (BMI). METHODS The cross-sectional analysis included 144 participants (42 men) with a mean age of 57.0 years and a mean BMI of 31.7 kg/m2. SB and standing time, breaks in sedentary time and PA were measured during four consecutive weeks with hip-worn accelerometers. A fasting blood sample was collected from each participant during the 4-week measurement period and analyzed using Sysmex XN and Cobas 8000 c702 analyzers. Associations of WBC, Hb and other red blood cell markers with cardiometabolic risk factors and physical activity were examined by Pearson's partial correlation coefficient test and with linear mixed regression models. RESULTS In sex- and age-adjusted correlation analyses both BMI and waist circumference correlated positively with Hb, WBC, red blood cell count (RBC), and hematocrit. Hb was also positively correlated with systolic blood pressure, insulin resistance scores, liver enzymes, LDL, and triglyceride levels. Sedentary time correlated positively with WBC, whereas standing time correlated negatively with WBC. Lying time correlated positively with WBC, RBC, hematocrit, and Hb. Regarding SB and PA measures, only the association between lying time and RBC remained significant after adjustment for the BMI. CONCLUSION We conclude that body adiposity, rather than components of SB or PA, associates with Hb levels and WBC, which cluster with general metabolic derangement.
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Affiliation(s)
- Tiia Koivula
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | - Salla Lempiäinen
- Oncology Clinic, Turku University Hospital, 20520 Turku, Finland
| | - Saara Laine
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | - Tanja Sjöros
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | | | - Taru Garthwaite
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | | | | | | | - Juhani Knuuti
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | - Ilkka H. A. Heinonen
- Turku PET Centre, University of Turku and Turku University Hospital, 20520 Turku, Finland
- Rydberg Laboratory of Applied Sciences, University of Halmstad, 30118 Halmstad, Sweden
- Correspondence: ; Tel.: +358-2-3138145
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11
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Poole DC, Musch TI. Crossing the final frontier: Oxygen transport at the blood-myocyte boundary. J Physiol 2022; 600:4385-4386. [PMID: 36083226 DOI: 10.1113/jp283659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 09/01/2022] [Indexed: 11/08/2022] Open
Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy & Physiology, Kansas State University, Manhattan, Kansas, 66505, USA
| | - Timothy I Musch
- Departments of Kinesiology, Anatomy & Physiology, Kansas State University, Manhattan, Kansas, 66505, USA
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12
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Tuesta M, Yáñez-Sepúlveda R, Verdugo-Marchese H, Mateluna C, Alvear-Ordenes I. Near-Infrared Spectroscopy Used to Assess Physiological Muscle Adaptations in Exercise Clinical Trials: A Systematic Review. BIOLOGY 2022; 11:biology11071073. [PMID: 36101451 PMCID: PMC9312707 DOI: 10.3390/biology11071073] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 11/18/2022]
Abstract
Simple Summary In recent years, physical exercise has been used as a therapeutic strategy in various clinical conditions, with pleiotropic benefits. Near-infrared spectroscopy (NIRS) has been positioned as a tool to analyze effects on muscle oxygenation, also allowing knowledge of adaptations on microvascular levels and muscle metabolism in subjects with central and peripheral vascular alterations, as well as cardiovascular, metabolic, and/or musculoskeletal diseases. This knowledge can help to guide therapeutic exercise specialists in decision making regarding the prescription and follow up of physical exercise as a therapeutic tool in the observation of acute or chronic adaptations to improve efficiency in the treatment and recovery of these patients. This review presents an overview of the effects of exercise clinical trials on muscle oxygenation in different pathologies and the technical characteristics related to the equipment used. Abstract Using muscle oxygenation to evaluate the therapeutic effects of physical exercise in pathologies through near-infrared spectroscopy (NIRS) is of great interest. The aim of this review was to highlight the use of muscle oxygenation in exercise interventions in clinical trials and to present the technological characteristics related to the equipment used in these studies. PubMed, WOS, and Scopus databases were reviewed up to December 2021. Scientific articles that evaluated muscle oxygenation after exercise interventions in the sick adult population were selected. The PEDro scale was used to analyze the risk of bias (internal validity). The results were presented grouped in tables considering the risk of bias scores, characteristics of the devices, and the effects of exercise on muscle oxygenation. All the stages were carried out using preferred reporting items for systematic reviews and meta-analyses (PRISMA). The search strategy yielded 820 clinical studies, of which 18 met the eligibility criteria. This review detailed the characteristics of 11 NIRS devices used in clinical trials that used physical exercise as an intervention. The use of this technology made it possible to observe changes in muscle oxygenation/deoxygenation parameters such as tissue saturation, oxyhemoglobin, total hemoglobin, and deoxyhemoglobin in clinical trials of patients with chronic disease. It was concluded that NIRS is a non-invasive method that can be used in clinical studies to detect the effects of physical exercise training on muscle oxygenation, hemodynamics, and metabolism. It will be necessary to unify criteria such as the measurement site, frequency, wavelength, and variables for analysis. This will make it possible to compare different models of exercise/training in terms of time, intensity, frequency, and type to obtain more precise conclusions about their benefits for patients.
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Affiliation(s)
- Marcelo Tuesta
- Exercise and Rehabilitation Sciences Laboratory, School of Physical Therapy, Faculty of Rehabilitation Sciences, Universidad Andres Bello, Santiago 7591538, Chile;
- Laboratory of Sport Sciences, Centro de Medicina Deportiva Sports MD, Viña del Mar 2521156, Chile;
| | - Rodrigo Yáñez-Sepúlveda
- Applied Physiology Laboratory (FISAP), Institute of Biomedicine (IBIOMED), University of León, 24071 León, Spain;
- School of Education, Pedagogy in Physical Education, Universidad Viña del Mar, Viña del Mar 2572007, Chile
| | | | - Cristián Mateluna
- Physical Education School, Pontificia Universidad Católica de Valparaíso, Valparaíso 2530388, Chile;
| | - Ildefonso Alvear-Ordenes
- Applied Physiology Laboratory (FISAP), Institute of Biomedicine (IBIOMED), University of León, 24071 León, Spain;
- Correspondence:
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13
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Gifford J, Kofoed J, Leach O, Wallace T, Dorff A, Hanson BE, Proffit M, Griffin G, Collins J. Impact of Interrepetition Rest on Muscle Blood Flow and Exercise Tolerance during Resistance Exercise. MEDICINA (KAUNAS, LITHUANIA) 2022; 58:822. [PMID: 35744085 PMCID: PMC9230920 DOI: 10.3390/medicina58060822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/14/2022] [Accepted: 06/16/2022] [Indexed: 12/05/2022]
Abstract
Background and Objectives: Muscle blood flow is impeded during resistance exercise contractions, but immediately increases during recovery. The purpose of this study was to determine the impact of brief bouts of rest (2 s) between repetitions of resistance exercise on muscle blood flow and exercise tolerance. Materials and Methods: Ten healthy young adults performed single-leg knee extension resistance exercises with no rest between repetitions (i.e., continuous) and with 2 s of rest between each repetition (i.e., intermittent). Exercise tolerance was measured as the maximal power that could be sustained for 3 min (PSUS) and as the maximum number of repetitions (Reps80%) that could be performed at 80% one-repetition maximum (1RM). The leg blood flow, muscle oxygenation of the vastus lateralis and mean arterial pressure (MAP) were measured during various exercise trials. Alpha was set to p ≤ 0.05. Results: Leg blood flow was significantly greater, while vascular resistance and MAP were significantly less during intermittent compared with continuous resistance exercise at the same power outputs (p < 0.01). PSUS was significantly greater during intermittent than continuous resistance exercise (29.5 ± 2.1 vs. 21.7 ± 1.2 W, p = 0.01). Reps80% was also significantly greater during intermittent compared with continuous resistance exercise (26.5 ± 5.3 vs. 16.8 ± 2.1 repetitions, respectively; p = 0.02), potentially due to increased leg blood flow and muscle oxygen saturation during intermittent resistance exercise (p < 0.05). Conclusions: In conclusion, a brief rest between repetitions of resistance exercise effectively decreased vascular resistance, increased blood flow to the exercising muscle, and increased exercise tolerance to resistance exercise.
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Affiliation(s)
- Jayson Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
- Program of Gerontology, Brigham Young University, Provo, UT 84602, USA
| | - Jason Kofoed
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Olivia Leach
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Taysom Wallace
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Abigail Dorff
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Brady E. Hanson
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Meagan Proffit
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Garrett Griffin
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
| | - Jessica Collins
- Department of Exercise Sciences, Brigham Young University, Provo, UT 84602, USA; (J.K.); (O.L.); (T.W.); (A.D.); (B.E.H.); (M.P.); (G.G.); (J.C.)
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14
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Poole DC. Can exercise training help redress sexual dimorphism in type II diabetes outcomes? J Diabetes Complications 2022; 36:108099. [PMID: 34916148 DOI: 10.1016/j.jdiacomp.2021.108099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 10/19/2022]
Affiliation(s)
- David C Poole
- Department of Kinesiology and Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA.
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15
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Salvadego D, Grassi B, Keramidas ME, Eiken O, McDonnell AC, Mekjavic IB. Heterogeneity of human adaptations to bed rest and hypoxia: a retrospective analysis within the skeletal muscle oxidative function. Am J Physiol Regul Integr Comp Physiol 2021; 321:R813-R822. [PMID: 34585615 DOI: 10.1152/ajpregu.00053.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This retrospective study was designed to analyze the interindividual variability in the responses of different variables characterizing the skeletal muscle oxidative function to normoxic (N-BR) and hypoxic (H-BR) bed rests and to a hypoxic ambulatory confinement (H-AMB) of 10 and 21 days. We also assessed whether and how the addition of hypoxia to bed rest might influence the heterogeneity of the responses. In vivo measurements of O2 uptake and muscle fractional O2 extraction were carried out during an incremental one-leg knee-extension exercise. Mitochondrial respiration was assessed in permeabilized muscle fibers. A total of 17 subjects were included in this analysis. This analysis revealed a similar variability among subjects in the alterations induced by N-BR and H-BR both in peak O2 uptake (SD: 4.1% and 3.3% after 10 days; 4.5% and 8.1% after 21 days, respectively) and peak muscle fractional O2 extraction (SD: 5.9% and 7.3% after 10 days; 6.5% and 7.3% after 21 days), independently from the duration of the exposure. The individual changes measured in these variables were significantly related (r = 0.66, P = 0.004 after N-BR; r = 0.61, P = 0.009 after H-BR). Mitochondrial respiration showed a large variability of response after both N-BR (SD: 25.0% and 15.7% after 10 and 21 days) and H-BR (SD: 13.0% and 19.8% after 10 and 21 days); no correlation was found between N-BR and H-BR changes. When added to bed rest, hypoxia altered the individual adaptations within the mitochondria but not those intrinsic to the muscle oxidative function in vivo, both after the short- and medium-term exposures.
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Affiliation(s)
- Desy Salvadego
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy
| | - Michail E Keramidas
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Adam C McDonnell
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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16
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Influence of muscular contraction on vascular conductance during exercise above versus below critical power. Respir Physiol Neurobiol 2021; 293:103718. [PMID: 34126260 DOI: 10.1016/j.resp.2021.103718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/02/2021] [Accepted: 06/08/2021] [Indexed: 11/20/2022]
Abstract
We tested the hypothesis that limb vascular conductance (LVC) would increase during the immediate recovery phase of dynamic exercise above, but not below, critical power (CP) indicating a threshold for muscular contraction-induced impedance of limb blood flow (LBF). CP (115 ± 26 W) was determined in 7 men and 7 women who subsequently performed ∼5 min of near-supine cycling exercise both below and above CP. LVC demonstrated a greater increase during immediate recovery and remained significantly higher following exercise above, compared to below, CP (all p < 0.001). Power output was associated with the immediate increases in LVC following exercise above, but not below, CP (p < 0.001; r = 0.85). Additionally, variance in percent LBF impedance was significantly lower above (CV: 10.7 %), compared to below (CV: 53.2 %), CP (p < 0.01). CP appears to represent a threshold above which the characteristics of LBF impedance by muscular contraction become intensity-dependent. These data suggest a critical level of LBF impedance relative to contraction intensity exists and, once attained, may promote the progressive metabolic and neuromuscular responses known to occur above CP.
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17
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Paquin J, Lagacé JC, Brochu M, Dionne IJ. Exercising for Insulin Sensitivity - Is There a Mechanistic Relationship With Quantitative Changes in Skeletal Muscle Mass? Front Physiol 2021; 12:656909. [PMID: 34054574 PMCID: PMC8149906 DOI: 10.3389/fphys.2021.656909] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/14/2021] [Indexed: 12/29/2022] Open
Abstract
Skeletal muscle (SM) tissue has been repetitively shown to play a major role in whole-body glucose homeostasis and overall metabolic health. Hence, SM hypertrophy through resistance training (RT) has been suggested to be favorable to glucose homeostasis in different populations, from young healthy to type 2 diabetic (T2D) individuals. While RT has been shown to contribute to improved metabolic health, including insulin sensitivity surrogates, in multiple studies, a universal understanding of a mechanistic explanation is currently lacking. Furthermore, exercised-improved glucose homeostasis and quantitative changes of SM mass have been hypothesized to be concurrent but not necessarily causally associated. With a straightforward focus on exercise interventions, this narrative review aims to highlight the current level of evidence of the impact of SM hypertrophy on glucose homeostasis, as well various mechanisms that are likely to explain those effects. These mechanistic insights could provide a strengthened rationale for future research assessing alternative RT strategies to the current classical modalities, such as low-load, high repetition RT or high-volume circuit-style RT, in metabolically impaired populations.
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Affiliation(s)
- Jasmine Paquin
- Research Centre on Aging, Affiliated With CIUSSS de l'Estrie-CHUS, Sherbrooke, QC, Canada.,Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Christophe Lagacé
- Research Centre on Aging, Affiliated With CIUSSS de l'Estrie-CHUS, Sherbrooke, QC, Canada.,Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Martin Brochu
- Research Centre on Aging, Affiliated With CIUSSS de l'Estrie-CHUS, Sherbrooke, QC, Canada.,Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Isabelle J Dionne
- Research Centre on Aging, Affiliated With CIUSSS de l'Estrie-CHUS, Sherbrooke, QC, Canada.,Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
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18
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Pethick J, Winter SL, Burnley M. Physiological Evidence That the Critical Torque Is a Phase Transition, Not a Threshold. Med Sci Sports Exerc 2021; 52:2390-2401. [PMID: 32366801 PMCID: PMC7556242 DOI: 10.1249/mss.0000000000002389] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Introduction Distinct physiological responses to exercise occur in the heavy- and severe-intensity domains, which are separated by the critical power or critical torque (CT). However, how the transition between these intensity domains actually occurs is not known. We tested the hypothesis that CT is a sudden threshold, with no gradual transition from heavy- to severe-intensity behavior within the confidence limits associated with the CT. Methods Twelve healthy participants performed four exhaustive severe-intensity trials for the determination of CT, and four 30-min trials in close proximity to CT (one or two SE above or below each participant’s CT estimate; CT − 2, CT − 1, CT + 1, CT + 2). Muscle O2 uptake, rectified electromyogram, and torque variability and complexity were monitored throughout each trial, and maximal voluntary contractions (MVC) with femoral nerve stimulation were performed before and after each trial to determine central and peripheral fatigue responses. Results The rates of change in fatigue-related variables, muscle O2 uptake, electromyogram amplitude, and torque complexity were significantly faster in the severe trials compared with CT − 2. For example, the fall in MVC torque was −1.5 ± 0.8 N·m·min−1 in CT − 2 versus –7.9 ± 2.5 N·m·min−1 in the lowest severe-intensity trial (P < 0.05). Individual analyses showed a low frequency of severe responses even in the circa-CT trials ostensibly above the CT, but also the rare appearance of severe-intensity responses in all circa-CT trials. Conclusions These data demonstrate that the transition between heavy- and severe-intensity exercise occurs gradually rather than suddenly.
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Affiliation(s)
- Jamie Pethick
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Kent, UNITED KINGDOM
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19
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Mendelson AA, Milkovich S, Hunter T, Vijay R, Choi YH, Milkovich S, Ho E, Goldman D, Ellis CG. The capillary fascicle in skeletal muscle: Structural and functional physiology of RBC distribution in capillary networks. J Physiol 2021; 599:2149-2168. [PMID: 33595111 DOI: 10.1113/jp281172] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The capillary module, consisting of parallel capillaries from arteriole to venule, is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres. Using intravital video microscopy of resting extensor digitorum longus muscle in rats, we demonstrated the capillary fascicle as a series of interconnected modules forming continuous columns that align naturally with the dimensions of the muscle fascicle. We observed structural heterogeneity for module topology, and functional heterogeneity in space and time for capillary-red blood cell (RBC) haemodynamics within a module and between modules. We found that module RBC haemodynamics were independent of module resistance, providing direct evidence for microvascular flow regulation at the level of the capillary module. The capillary fascicle is an updated paradigm for characterizing blood flow and RBC distribution in skeletal muscle capillary networks. ABSTRACT Capillary networks are the fundamental site of oxygen exchange in the microcirculation. The capillary module (CM), consisting of parallel capillaries from terminal arteriole (TA) to post-capillary venule (PCV), is classically considered as the building block of complex capillary networks. In skeletal muscle, this structure fails to address how blood flow is regulated along the entire length of the synchronously contracting muscle fibres, requiring co-ordination from numerous modules. It has previously been recognized that TAs and PCVs interact with multiple CMs, creating interconnected networks. Using label-free intravital video microscopy of resting extensor digitorum longus muscle in rats, we found that these networks form continuous columns of linked CMs spanning thousands of microns, herein denoted as the capillary fascicle (CF); this structure aligns naturally with the dimensions of the muscle fascicle. We measured capillary-red blood cell (RBC) haemodynamics and module topology (n = 9 networks, 327 modules, 1491 capillary segments). The average module had length 481 μm, width 157 μm and 9.51 parallel capillaries. We observed structural heterogeneity for CM topology, and functional heterogeneity in space and time for capillary-RBC haemodynamics within a module and between modules. There was no correlation between capillary RBC velocity and lineal density. A passive inverse relationship between module length and haemodynamics was remarkably absent, providing direct evidence for microvascular flow regulation at the level of the CM. In summary, the CF is an updated paradigm for characterizing RBC distribution in skeletal muscle, and strengthens the theory of capillary networks as major contributors to the signal that regulates capillary perfusion.
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Affiliation(s)
- Asher A Mendelson
- Department of Medicine, Section of Critical Care Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Stephanie Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Timothy Hunter
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Raashi Vijay
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Yun-Hee Choi
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Shaun Milkovich
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Edward Ho
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Applied Mathematics, Faculty of Science, Western University, London, Ontario, Canada
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Robarts Research Institute, London, Ontario, Canada
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20
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Impact of supine versus upright exercise on muscle deoxygenation heterogeneity during ramp incremental cycling is site specific. Eur J Appl Physiol 2021; 121:1283-1296. [PMID: 33575912 PMCID: PMC8064998 DOI: 10.1007/s00421-021-04607-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/17/2021] [Indexed: 10/24/2022]
Abstract
PURPOSE We tested the hypothesis that incremental ramp cycling exercise performed in the supine position (S) would be associated with an increased reliance on muscle deoxygenation (deoxy[heme]) in the deep and superficial vastus lateralis (VLd and VLs, respectively) and the superficial rectus femoris (RFs) when compared to the upright position (U). METHODS 11 healthy men completed ramp incremental exercise tests in S and U. Pulmonary [Formula: see text]O2 was measured breath-by-breath; deoxy[heme] was determined via time-resolved near-infrared spectroscopy in the VLd, VLs and RFs. RESULTS Supine exercise increased the overall change in deoxy[heme] from baseline to maximal exercise in the VLs (S: 38 ± 23 vs. U: 26 ± 15 μM, P < 0.001) and RFs (S: 36 ± 21 vs. U: 25 ± 15 μM, P < 0.001), but not in the VLd (S: 32 ± 23 vs. U: 29 ± 26 μM, P > 0.05). CONCLUSIONS The present study supports that the impaired balance between O2 delivery and O2 utilization observed during supine exercise is a regional phenomenon within superficial muscles. Thus, deep muscle defended its O2 delivery/utilization balance against the supine-induced reductions in perfusion pressure. The differential responses of these muscle regions may be explained by a regional heterogeneity of vascular and metabolic control properties, perhaps related to fiber type composition.
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21
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Poole DC, Behnke BJ, Musch TI. The role of vascular function on exercise capacity in health and disease. J Physiol 2021; 599:889-910. [PMID: 31977068 PMCID: PMC7874303 DOI: 10.1113/jp278931] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/10/2019] [Indexed: 12/16/2022] Open
Abstract
Three sentinel parameters of aerobic performance are the maximal oxygen uptake ( V ̇ O 2 max ), critical power (CP) and speed of the V ̇ O 2 kinetics following exercise onset. Of these, the latter is, perhaps, the cardinal test of integrated function along the O2 transport pathway from lungs to skeletal muscle mitochondria. Fast V ̇ O 2 kinetics demands that the cardiovascular system distributes exercise-induced blood flow elevations among and within those vascular beds subserving the contracting muscle(s). Ideally, this process must occur at least as rapidly as mitochondrial metabolism elevates V ̇ O 2 . Chronic disease and ageing create an O2 delivery (i.e. blood flow × arterial [O2 ], Q ̇ O 2 ) dependency that slows V ̇ O 2 kinetics, decreasing CP and V ̇ O 2 max , increasing the O2 deficit and sowing the seeds of exercise intolerance. Exercise training, in contrast, does the opposite. Within the context of these three parameters (see Graphical Abstract), this brief review examines the training-induced plasticity of key elements in the O2 transport pathway. It asks how structural and functional vascular adaptations accelerate and redistribute muscle Q ̇ O 2 and thus defend microvascular O2 partial pressures and capillary blood-myocyte O2 diffusion across a ∼100-fold range of muscle V ̇ O 2 values. Recent discoveries, especially in the muscle microcirculation and Q ̇ O 2 -to- V ̇ O 2 heterogeneity, are integrated with the O2 transport pathway to appreciate how local and systemic vascular control helps defend V ̇ O 2 kinetics and determine CP and V ̇ O 2 max in health and how vascular dysfunction in disease predicates exercise intolerance. Finally, the latest evidence that nitrate supplementation improves vascular and therefore aerobic function in health and disease is presented.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Brad J Behnke
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS, 66506, USA
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22
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Roy TK, Secomb TW. Effects of impaired microvascular flow regulation on metabolism-perfusion matching and organ function. Microcirculation 2020; 28:e12673. [PMID: 33236393 DOI: 10.1111/micc.12673] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022]
Abstract
Impaired tissue oxygen delivery is a major cause of organ damage and failure in critically ill patients, which can occur even when systemic parameters, including cardiac output and arterial hemoglobin saturation, are close to normal. This review addresses oxygen transport mechanisms at the microcirculatory scale, and how hypoxia may occur in spite of adequate convective oxygen supply. The structure of the microcirculation is intrinsically heterogeneous, with wide variations in vessel diameters and flow pathway lengths, and consequently also in blood flow rates and oxygen levels. The dynamic processes of structural adaptation and flow regulation continually adjust microvessel diameters to compensate for heterogeneity, redistributing flow according to metabolic needs to ensure adequate tissue oxygenation. A key role in flow regulation is played by conducted responses, which are generated and propagated by endothelial cells and signal upstream arterioles to dilate in response to local hypoxia. Several pathophysiological conditions can impair local flow regulation, causing hypoxia and tissue damage leading to organ failure. Therapeutic measures targeted to systemic parameters may not address or may even worsen tissue oxygenation at the microvascular level. Restoration of tissue oxygenation in critically ill patients may depend on restoration of endothelial cell function, including conducted responses.
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Affiliation(s)
- Tuhin K Roy
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, 85724, USA
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23
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Ratchford SM, Clifton HL, La Salle DT, Broxterman RM, Lee JF, Ryan JJ, Hopkins PN, Wright JB, Trinity JD, Richardson RS, Wray DW. Cardiovascular responses to rhythmic handgrip exercise in heart failure with preserved ejection fraction. J Appl Physiol (1985) 2020; 129:1267-1276. [PMID: 32940557 DOI: 10.1152/japplphysiol.00468.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although the contribution of noncardiac complications to the pathophysiology of heart failure with preserved ejection fraction (HFpEF) have been increasingly recognized, disease-related changes in peripheral vascular control remain poorly understood. We utilized small muscle mass handgrip exercise to concomitantly evaluate exercising muscle blood flow and conduit vessel endothelium-dependent vasodilation in individuals with HFpEF (n = 25) compared with hypertensive controls (HTN) (n = 25). Heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), brachial artery blood velocity, and brachial artery diameter were assessed during progressive intermittent handgrip (HG) exercise [15-30-45% maximal voluntary contraction (MVC)]. Forearm blood flow (FBF) and vascular conductance (FVC) were determined to quantify the peripheral hemodynamic response to HG exercise, and changes in brachial artery diameter were evaluated to assess endothelium-dependent vasodilation. HR, SV, and CO were not different between groups across exercise intensities. However, although FBF was not different between groups at the lowest exercise intensity, FBF was significantly lower (20-40%) in individuals with HFpEF at the two higher exercise intensities (30% MVC: 229 ± 8 versus 274 ± 23 ml/min; 45% MVC: 283 ± 17 versus 399 ± 34 ml/min, HFpEF versus HTN). FVC was not different between groups at 15 and 30% MVC but was ∼20% lower in HFpEF at the highest exercise intensity. Brachial artery diameter increased across exercise intensities in both HFpEF and HTN, with no difference between groups. These findings demonstrate an attenuation in muscle blood flow during exercise in HFpEF in the absence of disease-related changes in central hemodynamics or endothelial function.NEW & NOTEWORTHY The current study identified, for the first time, an attenuation in exercising muscle blood flow during handgrip exercise in individuals with heart failure with preserved ejection fraction (HFpEF) compared with overweight individuals with hypertension, two of the most common comorbidities associated with HFpEF. These decrements in exercise hyperemia cannot be attributed to disease-related changes in central hemodynamics or endothelial function, providing additional evidence for disease-related vascular dysregulation, which may be a predominant contributor to exercise intolerance in individuals with HFpEF.
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Affiliation(s)
- Stephen M Ratchford
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Health and Exercise Science, Appalachian State University, Boone, North Carolina
| | - Heather L Clifton
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
| | - D Taylor La Salle
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
| | - Joshua F Lee
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
| | - John J Ryan
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah
| | - Paul N Hopkins
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah
| | - Josephine B Wright
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah
| | - Joel D Trinity
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - D Walter Wray
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Internal Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
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Poole DC, Pittman RN, Musch TI, Østergaard L. August Krogh's theory of muscle microvascular control and oxygen delivery: a paradigm shift based on new data. J Physiol 2020; 598:4473-4507. [PMID: 32918749 DOI: 10.1113/jp279223] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/13/2020] [Indexed: 12/16/2022] Open
Abstract
August Krogh twice won the prestigious international Steegen Prize, for nitrogen metabolism (1906) and overturning the concept of active transport of gases across the pulmonary epithelium (1910). Despite this, at the beginning of 1920, the consummate experimentalist was relatively unknown worldwide and even among his own University of Copenhagen faculty. But, in early 1919, he had submitted three papers to Dr Langley, then editor of The Journal of Physiology in England. These papers coalesced anatomical observations of skeletal muscle capillary numbers with O2 diffusion theory to propose a novel active role for capillaries that explained the prodigious increase in blood-muscle O2 flux from rest to exercise. Despite his own appraisal of the first two papers as "rather dull" to his friend, the eminent Cambridge respiratory physiologist, Joseph Barcroft, Krogh believed that the third one, dealing with O2 supply and capillary regulation, was"interesting". These papers, which won Krogh an unopposed Nobel Prize for Physiology or Medicine in 1920, form the foundation for this review. They single-handedly transformed the role of capillaries from passive conduit and exchange vessels, functioning at the mercy of their upstream arterioles, into independent contractile units that were predominantly closed at rest and opened actively during muscle contractions in a process he termed 'capillary recruitment'. Herein we examine Krogh's findings and some of the experimental difficulties he faced. In particular, the boundary conditions selected for his model (e.g. heavily anaesthetized animals, negligible intramyocyte O2 partial pressure, binary open-closed capillary function) have not withstood the test of time. Subsequently, we update the reader with intervening discoveries that underpin our current understanding of muscle microcirculatory control and place a retrospectroscope on Krogh's discoveries. The perspective is presented that the imprimatur of the Nobel Prize, in this instance, may have led scientists to discount compelling evidence. Much as he and Marie Krogh demonstrated that active transport of gases across the blood-gas barrier was unnecessary in the lung, capillaries in skeletal muscle do not open and close spontaneously or actively, nor is this necessary to account for the increase in blood-muscle O2 flux during exercise. Thus, a contemporary model of capillary function features most muscle capillaries supporting blood flow at rest, and, rather than capillaries actively vasodilating from rest to exercise, increased blood-myocyte O2 flux occurs predominantly via elevating red blood cell and plasma flux in already flowing capillaries. Krogh is lauded for his brilliance as an experimentalist and for raising scientific questions that led to fertile avenues of investigation, including the study of microvascular function.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University Manhattan, Manhattan, KS, 66506, USA
| | - Roland N Pittman
- Department of Physiology and Biophysics, Virginia Commonwealth University Richmond, Richmond, VA, 23298-0551, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University Manhattan, Manhattan, KS, 66506, USA
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience, Aarhus University, Denmark
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Goulding RP, Okushima D, Marwood S, Poole DC, Barstow TJ, Lei TH, Kondo N, Koga S. Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: mechanistic insights into slow pulmonary oxygen uptake dynamics. J Appl Physiol (1985) 2020; 129:535-546. [PMID: 32702271 DOI: 10.1152/japplphysiol.00213.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Oxygen uptake (V̇o2) kinetics are slowed in the supine (S) position purportedly due to impaired muscle O2 delivery ([Formula: see text]); however, these conclusions are predicated on single-site measurements in superficial muscle using continuous-wave near-infrared spectroscopy (NIRS). This study aimed to determine the impact of body position [i.e., upright (U) versus S] on deep and superficial muscle deoxygenation (deoxy[heme]) using time-resolved (TR-) NIRS, and how these relate to slowed pulmonary V̇o2 kinetics. Seventeen healthy men completed constant power tests during 1) S heavy-intensity exercise and 2) U exercise at the same absolute work rate, with a subset of 10 completing additional tests at the same relative work rate as S. Pulmonary V̇o2 was measured breath-by-breath and, deoxy- and total[heme] were resolved via TR-NIRS in the superficial and deep vastus lateralis and superficial rectus femoris. The fundamental phase V̇o2 time constant was increased during S compared with U (S: 36 ± 10 vs. U: 27 ± 8 s; P < 0.001). The deoxy[heme] amplitude (S: 25-28 vs. U: 13-18 µM; P < 0.05) and total[heme] amplitude (S: 17-20 vs. U: 9-16 µM; P < 0.05) were greater in S compared with U and were consistent for the same absolute (above data) and relative work rates (n = 10, all P < 0.05). The greater deoxy- and total[heme] amplitudes in S vs. U supports that reduced perfusive [Formula: see text] in S, even within deep muscle, necessitated a greater reliance on fractional O2 extraction and diffusive [Formula: see text]. The slower V̇o2 kinetics in S versus U demonstrates that, ultimately, these adjustments were insufficient to prevent impairments in whole body oxidative metabolism.NEW & NOTEWORTHY We show that supine exercise causes a greater degree of muscle deoxygenation in both deep and superficial muscle and increases the spatial heterogeneity of muscle deoxygenation. Therefore, this study suggests that any O2 delivery gradient toward deep versus superficial muscle is insufficient to mitigate impairments in oxidative function in response to reduced whole muscle O2 delivery. More heterogeneous muscle deoxygenation is associated with slower V̇o2 kinetics.
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Affiliation(s)
- Richie P Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.,International Research Fellow of Japan Society for Promotion of Sciences, Tokyo, Japan
| | - Dai Okushima
- Osaka International University, Moriguchi, Japan
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, Merseyside, United Kingdom
| | - David C Poole
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Tze-Huan Lei
- International Research Fellow of Japan Society for Promotion of Sciences, Tokyo, Japan.,Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
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26
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Colburn TD, Hirai DM, Craig JC, Ferguson SK, Weber RE, Schulze KM, Behnke BJ, Musch TI, Poole DC. Transcapillary PO 2 gradients in contracting muscles across the fibre type and oxidative continuum. J Physiol 2020; 598:3187-3202. [PMID: 32445225 DOI: 10.1113/jp279608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/14/2020] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Within skeletal muscle the greatest resistance to oxygen transport is thought to reside across the short distance at the red blood cell-myocyte interface. These structures generate a significant transmural oxygen pressure (PO2 ) gradient in mixed fibre-type muscle. Increasing O2 flux across the capillary wall during exercise depends on: (i) the transmural O2 pressure gradient, which is maintained in mixed-fibre muscle, and/or (ii) elevating diffusing properties between microvascular and interstitial compartments resulting, in part, from microvascular haemodynamics and red blood cell distribution. We evaluated the PO2 within the microvascular and interstitial spaces of muscles spanning the slow- to fast-twitch fibre and high- to low-oxidative capacity spectrums, at rest and during contractions, to assess the magnitude of transcapillary PO2 gradients in rats. Our findings demonstrate that, across the metabolic rest-contraction transition, the transcapillary pressure gradient for O2 flux is: (i) maintained in all muscle types, and (ii) the lowest in contracting highly oxidative fast-twitch muscle. ABSTRACT In mixed fibre-type skeletal muscle transcapillary PO2 gradients (PO2 mv-PO2 is; microvascular and interstitial, respectively) drive O2 flux across the blood-myocyte interface where the greatest resistance to that O2 flux resides. We assessed a broad spectrum of fibre-type and oxidative-capacity rat muscles across the rest-to-contraction (1 Hz, 120 s) transient to test the novel hypotheses that: (i) slow-twitch PO2 is would be greater than fast-twitch, (ii) muscles with greater oxidative capacity have greater PO2 is than glycolytic counterparts, and (iii) whether PO2 mv-PO2 is at rest is maintained during contractions across all muscle types. PO2 mv and PO2 is were determined via phosphorescence quenching in soleus (SOL; 91% type I+IIa fibres and CSa: ∼21 μmol min-1 g-1 ), peroneal (PER; 33% and ∼20 μmol min-1 g-1 ), mixed (MG; 9% and ∼26 μmol min-1 g-1 ) and white gastrocnemius (WG; 0% and ∼8 μmol min-1 g-1 ) across the rest-contraction transient. PO2 mv was higher than PO2 is in each muscle (∼6-13 mmHg; P < 0.05). SOL PO2 isarea was greater than in the fast-twitch muscles during contractions (P < 0.05). Oxidative muscles had greater PO2 isnadir (9.4 ± 0.8, 7.4 ± 0.9 and 6.4 ± 0.4; SOL, PER and MG, respectively) than WG (3.0 ± 0.3 mmHg, P < 0.05). The magnitude of PO2 mv-PO2 is at rest decreased during contractions in MG only (∼11 to 7 mmHg; time × (PO2 mv-PO2 is) interaction, P < 0.05). These data support the hypothesis that, since transcapillary PO2 gradients during contractions are maintained in all muscle types, increased O2 flux must occur via enhanced intracapillary diffusing conductance, which is most extreme in highly oxidative fast-twitch muscle.
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Affiliation(s)
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Scott K Ferguson
- Department of Kinesiology and Exercise Sciences, University of Hawaii, Hilo, HI
| | - Ramona E Weber
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Kiana M Schulze
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Brad J Behnke
- Department of Kinesiology, Kansas State University Manhattan, KS
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
| | - David C Poole
- Department of Kinesiology, Kansas State University Manhattan, KS.,Department of Anatomy and Physiology, Kansas State University Manhattan, KS
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Gagnon DD, Hancock C, McCue A, Beckett-Brown N, Gagnon J, Williams L, Marsh D, Munten S. Muscle cooling modulates tissue oxidative and biochemical responses but not energy metabolism during exercise. Eur J Appl Physiol 2020; 120:1761-1775. [PMID: 32494860 DOI: 10.1007/s00421-020-04407-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 05/23/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE This study investigated whether muscle cooling and its associated effects on skeletal muscle oxidative responses, blood gases, and hormonal concentrations influenced energy metabolism during cycling. METHODS Twelve healthy participants (Males: seven; Females: five) performed two steady-state exercise sessions at 70% of ventilatory threshold on a cycle ergometer. Participants completed one session with pre-exercise leg cooling until muscle temperature (Tm) decreased by 6 °C (LCO), and a separate session without cooling (CON). They exercised until Tm returned to baseline and for an additional 30 min. Cardiovascular, respiratory, metabolic, hemodynamic variables, and skeletal muscle tissue oxidative responses were assessed continuously. Venous blood samples were collected to assess blood gases, and hormones. RESULTS Heart rate, stroke volume, and cardiac output all increased across time but were not different between conditions. V̇O2 was greater in LCO when muscle temperature was restored until the end of exercise (p < 0.05). Cycling in the LCO condition induced lower oxygen availability, tissue oxygenation, blood pH, sO2%, and pO2 (p < 0.05). Insulin concentrations were also higher in LCO vs. CON (p < 0.05). Importantly, stoichiometric equations from respiratory gases indicated no differences in fat and CHO oxidation between conditions. CONCLUSION The present study demonstrated that despite muscle cooling and the associated oxidative and biochemical changes, energy metabolism remained unaltered during cycling. Whether lower local and systemic oxygen availability is counteracted via a cold-induced activation of lipid metabolism pathways needs to be further investigated.
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Affiliation(s)
- Dominique D Gagnon
- Laboratory of Environmental Exercise Physiology, School of Human Kinetics, Laurentian University, 935 Ramsey Lake Rd., Ben Avery Building, Sudbury, ON, P3E 2C6, Canada. .,Center of Research in Occupational Health and Safety, Laurentian University, Sudbury, ON, Canada.
| | - Curtis Hancock
- Laboratory of Environmental Exercise Physiology, School of Human Kinetics, Laurentian University, 935 Ramsey Lake Rd., Ben Avery Building, Sudbury, ON, P3E 2C6, Canada.,Center of Research in Occupational Health and Safety, Laurentian University, Sudbury, ON, Canada
| | - Alexus McCue
- Laboratory of Environmental Exercise Physiology, School of Human Kinetics, Laurentian University, 935 Ramsey Lake Rd., Ben Avery Building, Sudbury, ON, P3E 2C6, Canada.,Center of Research in Occupational Health and Safety, Laurentian University, Sudbury, ON, Canada
| | - Nicholas Beckett-Brown
- Laboratory of Environmental Exercise Physiology, School of Human Kinetics, Laurentian University, 935 Ramsey Lake Rd., Ben Avery Building, Sudbury, ON, P3E 2C6, Canada.,Center of Research in Occupational Health and Safety, Laurentian University, Sudbury, ON, Canada
| | - Jeffrey Gagnon
- Department of Biology, Laurentian University, Sudbury, ON, Canada
| | - Laura Williams
- Department of Biology, Laurentian University, Sudbury, ON, Canada
| | - David Marsh
- Northern Ontario School of Medicine, Sudbury, ON, Canada.,Health Sciences North Research Institute, Sudbury, ON, Canada
| | - Stephanie Munten
- Laboratory of Environmental Exercise Physiology, School of Human Kinetics, Laurentian University, 935 Ramsey Lake Rd., Ben Avery Building, Sudbury, ON, P3E 2C6, Canada.,Center of Research in Occupational Health and Safety, Laurentian University, Sudbury, ON, Canada
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28
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Goulding RP, Roche DM, Scott SN, Koga S, Weston PJ, Marwood S. Limitations to exercise tolerance in type 1 diabetes: the role of pulmonary oxygen uptake kinetics and priming exercise. J Appl Physiol (1985) 2020; 128:1299-1309. [PMID: 32213117 DOI: 10.1152/japplphysiol.00892.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We compared the time constant (τV̇O2) of the fundamental phase of pulmonary oxygen uptake (V̇o2) kinetics between young adult men with type 1 diabetes and healthy control subjects. We also assessed the impact of priming exercise on τV̇O2, critical power, and muscle deoxygenation in a subset of participants with type 1 diabetes. Seventeen men with type 1 diabetes and 17 healthy male control subjects performed moderate-intensity exercise to determine τV̇O2. A subset of seven participants with type 1 diabetes performed an additional eight visits, in which critical power, τV̇O2, and muscle deoxyhemoglobin + myoglobin ([HHb+Mb], via near-infrared spectroscopy) kinetics (described by a time constant, τ[HHb+Mb]) were determined with (PRI) and without (CON) a prior 6-min bout of heavy exercise. τV̇O2 was greater in participants with type 1 diabetes compared with control subjects (type 1 diabetes 50 ± 13 vs. control 32 ± 12 s; P < 0.001). Critical power was greater in PRI compared with CON (PRI 161 ± 25 vs. CON 149 ± 22 W; P < 0.001), whereas τV̇O2 (PRI 36 ± 15 vs. CON 50 ± 21 s; P = 0.006) and τ[HHb+Mb] (PRI 10 ± 5 vs. CON 17 ± 11 s; P = 0.037) were reduced in PRI compared with CON. Type 1 diabetes patients showed slower pulmonary V̇o2 kinetics compared with control subjects; priming exercise speeded V̇o2 and [HHb + Mb] kinetics and increased critical power in a subgroup with type 1 diabetes. These data therefore represent the first characterization of the power-duration relationship in type 1 diabetes and the first experimental evidence that τV̇O2 is an independent determinant of critical power in this population.NEW & NOTEWORTHY Patients with type 1 diabetes demonstrated slower oxygen uptake (V̇o2) kinetics compared with healthy control subjects. Furthermore, a prior bout of high-intensity exercise speeded V̇o2 kinetics and increased critical power in people with type 1 diabetes. Prior exercise speeded muscle deoxygenation kinetics, indicating that V̇o2 kinetics in type 1 diabetes are limited primarily by oxygen extraction and/or intracellular factors. These findings highlight the potential for interventions that decrease metabolic inertia for enhancing exercise tolerance in this condition.
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Affiliation(s)
- Richie P Goulding
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom.,Japan Society for Promotion of Science, Tokyo, Japan.,Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Denise M Roche
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| | - Sam N Scott
- University Department of Diabetes, Endocrinology, Nutritional Medicine, and Metabolism, University Hospital and University of Bern, Bern, Switzerland.,Team Novo Nordisk Professional Cycling Team, Atlanta, Georgia
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Philip J Weston
- Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, United Kingdom
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
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GRASSI BRUNO, PORCELLI SIMONE, MARZORATI MAURO. Translational Medicine: Exercise Physiology Applied to Metabolic Myopathies. Med Sci Sports Exerc 2019; 51:2183-2192. [DOI: 10.1249/mss.0000000000002056] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Poole DC. Edward F. Adolph Distinguished Lecture. Contemporary model of muscle microcirculation: gateway to function and dysfunction. J Appl Physiol (1985) 2019; 127:1012-1033. [PMID: 31095460 DOI: 10.1152/japplphysiol.00013.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This review strikes at the very heart of how the microcirculation functions to facilitate blood-tissue oxygen, substrate, and metabolite fluxes in skeletal muscle. Contemporary evidence, marshalled from animals and humans using the latest techniques, challenges iconic perspectives that have changed little over the past century. Those perspectives include the following: the presence of contractile or collapsible capillaries in muscle, unitary control by precapillary sphincters, capillary recruitment at the onset of contractions, and the notion of capillary-to-mitochondrial diffusion distances as limiting O2 delivery. Today a wealth of physiological, morphological, and intravital microscopy evidence presents a completely different picture of microcirculatory control. Specifically, capillary red blood cell (RBC) and plasma flux is controlled primarily at the arteriolar level with most capillaries, in healthy muscle, supporting at least some flow at rest. In healthy skeletal muscle, this permits substrate access (whether carried in RBCs or plasma) to a prodigious total capillary surface area. Pathologies such as heart failure or diabetes decrease access to that exchange surface by reducing the proportion of flowing capillaries at rest and during exercise. Capillary morphology and function vary disparately among tissues. The contemporary model of capillary function explains how, following the onset of exercise, muscle O2 uptake kinetics can be extremely fast in health but slowed in heart failure and diabetes impairing contractile function and exercise tolerance. It is argued that adoption of this model is fundamental for understanding microvascular function and dysfunction and, as such, to the design and evaluation of effective therapeutic strategies to improve exercise tolerance and decrease morbidity and mortality in disease.
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Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Increase of Glucose Uptake in Human Bone Marrow With Increasing Exercise Intensity. Int J Sport Nutr Exerc Metab 2019; 29:254-258. [DOI: 10.1123/ijsnem.2018-0094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human bone marrow is a metabolically active tissue that responds to acute low-intensity exercise by having increased glucose uptake (GU). Here, the authors studied whether bone marrow GU increases more with increased exercise intensities. Femoral bone marrow GU was measured using positron emission tomography and [18F]-fluorodeoxyglucose in six healthy young men during cycling at intensities of 30% (low), 55% (moderate), and 75% (high) of maximal oxygen consumption on three separate days. Bone marrow GU at low was 17.2 µmol·kg−1·min−1 (range 9.0–25.4) and increased significantly (p = .003) at moderate (31.2 µmol·kg−1·min−1, 22.9–39.4) but was not significant from moderate to high (37.4 µmol·kg−1·min−1, 29.0–45.7, p = .26). Furthermore, the ratio between bone and muscle GU decreased from low to moderate exercise intensity (p < .01) but not (p = .99) from moderate to high exercise intensity. In conclusion, these results show that although the increase is not as large as observed in exercising skeletal muscle, GU in femoral bone marrow increases with increasing exercise intensity at least from low- to moderate-intensity effort, which may be important for bone and whole-body metabolic health.
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Koga S, Okushima D, Poole DC, Rossiter HB, Kondo N, Barstow TJ. Unaltered V̇o 2 kinetics despite greater muscle oxygenation during heavy-intensity two-legged knee extension versus cycle exercise in humans. Am J Physiol Regul Integr Comp Physiol 2019; 317:R203-R213. [PMID: 31042412 DOI: 10.1152/ajpregu.00015.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Relative perfusion of active muscles is greater during knee extension ergometry (KE) than cycle ergometry (CE). This provides the opportunity to investigate the effects of increased O2 delivery (Q̇o2) on deoxygenation heterogeneity among quadriceps muscles and pulmonary oxygen uptake (V̇o2) kinetics. Using time-resolved near-infrared spectroscopy, we hypothesized that compared with CE the superficial vastus lateralis (VL), superficial rectus femoris, and deep VL in KE would have 1) a smaller amplitude of the exercise-induced increase in deoxy[Hb + Mb] (related to the balance between V̇o2 and Q̇o2); 2) a greater amplitude of total[Hb + Mb] (related to the diffusive O2 conductance); 3) a greater homogeneity of regional muscle deoxy[Hb + Mb]; and 4) no difference in pulmonary V̇o2 kinetics. Eight participants performed square-wave KE and CE exercise from 20 W to heavy work rates. Deoxy[Hb + Mb] amplitude was less for all muscle regions in KE (P < 0.05: superficial, KE 17-24 vs. CE 19-40; deep, KE 19 vs. CE 26 μM). Furthermore, the amplitude of total[Hb + Mb] was greater for KE than CE at all muscle sites (P < 0.05: superficial, KE, 7-21 vs. CE, 1-16; deep, KE, 11 vs. CE, -3 μM). Although the amplitude and heterogeneity of deoxy[Hb + Mb] were significantly lower in KE than CE during the first minute of exercise, the pulmonary V̇o2 kinetics was not different for KE and CE. These data show that the microvascular Q̇o2 to V̇o2 ratio, and thus tissue oxygenation, was greater in KE than CE. This suggests that pulmonary and muscle V̇o2 kinetics in young healthy humans are not limited by Q̇o2 during heavy-intensity cycling.
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Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University , Kobe , Japan
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University , Kobe , Japan
| | - David C Poole
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University , Manhattan, Kansas.,Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center , Torrance, California.,Faculty of Biological Sciences, University of Leeds , Leeds , United Kingdom
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University , Kobe , Japan
| | - Thomas J Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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Witte E, Liu Y, Ward JL, Kempf KS, Whitaker A, Vidoni ED, Craig JC, Poole DC, Billinger SA. Exercise intensity and middle cerebral artery dynamics in humans. Respir Physiol Neurobiol 2019; 262:32-39. [PMID: 30710650 PMCID: PMC6393201 DOI: 10.1016/j.resp.2019.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/11/2019] [Accepted: 01/29/2019] [Indexed: 12/24/2022]
Abstract
Despite its necessity for understanding healthy brain aging, the influence of exercise intensity on cerebrovascular kinetics is currently unknown. We, therefore characterized middle cerebral artery blood flow velocity (MCAv) kinetics associated with two exercise intensities: low and moderate. We hypothesized that increasing exercise intensity would increase the MCAv amplitude response (Amp) and that age and estimated fitness (V̇O2max) would be related to Amp. Baseline (BL) values were collected for 90-seconds followed by a 6-minute exercise bout. Heart rate, end-tidal CO2, mean arterial pressure and MCAv were recorded throughout. MCAv kinetics were described by Amp, time delay (TD) and time constant (τ). Sixty-four adults completed the study. Amp was greater during moderate compared to low exercise intensity (p < 0.001) while no difference was observed in either TD (p = 0.65) or τ (p = 0.47). Amp was negatively associated with age (p < 0.01) and positively correlated with estimated V̇O2max (p < 0.01). Although Amp declines with age, maintaining higher V̇O2max may benefit the cerebrovascular response to exercise.
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Affiliation(s)
- Emily Witte
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Yumei Liu
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Jaimie L Ward
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Katie S Kempf
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Alicen Whitaker
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States
| | - Eric D Vidoni
- University of Kansas, Alzheimer's Disease Center, KU Clinical Research Center 4350 Shawnee Mission Parkway, MS 6002, Fairway, KS 66205, United States
| | - Jesse C Craig
- Kansas State University, Departments of Kinesiology, 131 Coles Hall, 920 Denison Ave, Manhattan, KS 66506, United States
| | - David C Poole
- Kansas State University, Departments of Kinesiology, 131 Coles Hall, 920 Denison Ave, Manhattan, KS 66506, United States
| | - Sandra A Billinger
- University of Kansas Medical Center, Physical Therapy and Rehabilitation Science, MS 2002, 3901 Rainbow Boulevard, Kansas City, KS 66160, United States.
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Suryanegara J, Cassidy S, Ninkovic V, Popovic D, Grbovic M, Okwose N, Trenell MI, MacGowan GG, Jakovljevic DG. High intensity interval training protects the heart during increased metabolic demand in patients with type 2 diabetes: a randomised controlled trial. Acta Diabetol 2019; 56:321-329. [PMID: 30387015 PMCID: PMC6394729 DOI: 10.1007/s00592-018-1245-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/18/2018] [Indexed: 02/02/2023]
Abstract
AIM The present study assessed the effect of high intensity interval training on cardiac function during prolonged submaximal exercise in patients with type 2 diabetes. METHODS Twenty-six patients with type 2 diabetes were randomized to a 12 week of high intensity interval training (3 sessions/week) or standard care control group. All patients underwent prolonged (i.e. 60 min) submaximal cardiopulmonary exercise testing (at 50% of previously assess maximal functional capacity) with non-invasive gas-exchange and haemodynamic measurements including cardiac output and stroke volume before and after the intervention. RESULTS At baseline (prior to intervention) there was no significant difference between the intervention and control group in peak exercise oxygen consumption (20.3 ± 6.1 vs. 21.7 ± 5.5 ml/kg/min, p = 0.21), and peak exercise heart rate (156.3 ± 15.0 vs. 153.8 ± 12.5 beats/min, p = 0.28). During follow-up assessment both groups utilized similar amount of oxygen during prolonged submaximal exercise (15.0 ± 2.4 vs. 15.2 ± 2.2 ml/min/kg, p = 0.71). However, cardiac function i.e. cardiac output during submaximal exercise decreased significantly by 21% in exercise group (16.2 ± 2.7-12.8 ± 3.6 L/min, p = 0.03), but not in the control group (15.7 ± 4.9-16.3 ± 4.1 L/min, p = 0.12). Reduction in exercise cardiac output observed in the exercise group was due to a significant decrease in stroke volume by 13% (p = 0.03) and heart rate by 9% (p = 0.04). CONCLUSION Following high intensity interval training patients with type 2 diabetes demonstrate reduced cardiac output during prolonged submaximal cardiopulmonary exercise testing. Ability of patients to maintain prolonged increased metabolic demand but with reduced cardiac output suggests cardiac protective role of high intensity interval training in type 2 diabetes. TRIAL REGISTRATION ISRCTN78698481. Registered 23 January 2013, retrospectively registered.
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Affiliation(s)
- Jose Suryanegara
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
| | - Sophie Cassidy
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
| | - Vladan Ninkovic
- Department of Cardiology, Specialist Hospital for Diabetes Merkur, Vrnjacka Banja, Serbia
| | - Dejana Popovic
- Faculty of Medicine and Pharmacy, University of Belgrade, and Cardiology Department, Clinical Centre Serbia, Belgrade, Serbia
| | - Miljan Grbovic
- Faculty of Sport and Physical Education, University of Belgrade, Belgrade, Serbia
| | - Nduka Okwose
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
| | - Michael I. Trenell
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
| | - Guy G. MacGowan
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
- Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Djordje G. Jakovljevic
- Faculty of Medical Sciences, Cardiovascular Research Centre, Institutes of Cellular and Genetic Medicine, Newcastle University, 4th Floor William Leech Building M4.074, Newcastle upon Tyne, NE2 4HH UK
- Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- RCUK Newcastle Centre for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
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Bock JM, Kruse NT, Donnelly C, Hirai DM, Craig JC, Colburn TD, Musch TI, Poole DC, Rosenberry R, Tian F, Liu H, Nelson MD, Piknova B, Willis WT, Zuo L, Zhou T, Riveros-Rivera A, Cristancho E, Gunga HC. Commentaries on Viewpoint: Managing the power grid: How myoglobin can regulate Po 2 and energy distribution in skeletal muscle. J Appl Physiol (1985) 2019; 126:791-794. [PMID: 30907709 DOI: 10.1152/japplphysiol.01107.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Joshua M Bock
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa
| | - Nicholas T Kruse
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Chris Donnelly
- Institute of Sport Sciences and Department of Physiology, University of Lausanne, Switzerland
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah,Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, Salt Lake City, Utah
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Ryan Rosenberry
- Department of Kinesiology, University of Texas at Arlington, Texas
| | - Fenghua Tian
- Department of Bioengineering, University of Texas at Arlington, Texas
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Texas
| | - Michael D Nelson
- Department of Kinesiology, University of Texas at Arlington, Texas,Department of Bioengineering, University of Texas at Arlington, Texas
| | - Barbora Piknova
- Molecular Medicine Branch, NIDDK National Institutes of Health, Bethesda, Maryland
| | | | - Li Zuo
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio,Department of Biology, University of Maine, Presque Isle, Maine
| | - Tingyang Zhou
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio
| | - Alain Riveros-Rivera
- Institute of Physiology, Center for Space Medicine and Extreme Environments, Charité - Universitätsmedizin Berlin, Germany
| | - Edgar Cristancho
- Department of Biology. Universidad Nacional de Colombia. Bogotá, Colombia
| | - Hanns-Christian Gunga
- Institute of Physiology, Center for Space Medicine and Extreme Environments, Charité - Universitätsmedizin Berlin, Germany
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36
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Frisbee JC, Lewis MT, Wiseman RW. Skeletal muscle performance in metabolic disease: Microvascular or mitochondrial limitation or both? Microcirculation 2018; 26:e12517. [PMID: 30471168 DOI: 10.1111/micc.12517] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 11/14/2018] [Indexed: 12/20/2022]
Abstract
One of the clearly established health outcomes associated with chronic metabolic diseases (eg, type II diabetes mellitus) is that the ability of skeletal muscle to maintain contractile performance during periods of elevated metabolic demand is compromised as compared to the fatigue-resistance of muscle under normal, healthy conditions. While there has been extensive effort dedicated to determining the major factors that contribute to the compromised performance of skeletal muscle with chronic metabolic disease, the extent to which this poor outcome reflects a dysfunctional state of the microcirculation, where the delivery and distribution of metabolic substrates can be impaired, versus derangements to normal metabolic processes and mitochondrial function, versus a combination of the two, represents an area of considerable unknown. The purpose of this manuscript is to present some of the current concepts for dysfunction to both the microcirculation of skeletal muscle as well as to mitochondrial metabolism under these conditions, such that these diverse issues can be merged into an integrated framework for future investigation. Based on an interpretation of the current literature, it may be hypothesized that the primary site of dysfunction with earlier stages of metabolic disease may lie at the level of the vasculature, rather than at the level of the mitochondria.
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Affiliation(s)
- Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Matthew T Lewis
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Robert W Wiseman
- Department of Physiology, Michigan State University, East Lansing, Michigan.,Department of Radiology, Michigan State University, East Lansing, Michigan
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37
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Plasma Nucleotide Dynamics during Exercise and Recovery in Highly Trained Athletes and Recreationally Active Individuals. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4081802. [PMID: 30402475 PMCID: PMC6198572 DOI: 10.1155/2018/4081802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/14/2018] [Accepted: 09/16/2018] [Indexed: 01/04/2023]
Abstract
Circulating plasma ATP is able to regulate local skeletal muscle blood flow and 02 delivery causing considerable vasodilatation during exercise. We hypothesized that sport specialization and specific long-term training stimuli have an impact on venous plasma [ATP] and other nucleotides concentration. Four athletic groups consisting of sprinters (n=11; age range 21–30 yr), endurance-trained athletes (n=16; age range 18–31 yr), futsal players (n=14; age range 18–30 yr), and recreationally active individuals (n=12; age range 22–33 yr) were studied. Venous blood samples were collected at rest, during an incremental treadmill test, and during recovery. Baseline [ATP] was 759±80 nmol·l−1 in competitive athletes and 680±73 nmol·l−1 in controls and increased during exercise by ~61% in competitive athletes and by ~31% in recreationally active participants. We demonstrated a rapid increase in plasma [ATP] at exercise intensities of 83–87% of VO2max in competitive athletes and 94% in controls. Concentrations reported after 30 minutes of recovery were distinct from those obtained preexercise in competitive athletes (P < 0.001) but not in controls (P = 0.61). We found a correlation between total-body skeletal muscle mass and resting and maximal plasma [ATP] in competitive athletes (r=0.81 and r=0.75, respectively). In conclusion, sport specialization is significantly related to plasma [ATP] at rest, during exercise, and during maximal effort. Intensified exercise-induced plasma [ATP] increases may contribute to more effective vessel dilatation during exercise in highly trained athletes than in recreational runners. The most rapid increase in ATP concentration was associated with the respiratory compensation point. No differences between groups of competitive athletes were observed during the recovery period suggesting a similar pattern of response after exercise. Total-body skeletal muscle mass is indirectly related to plasma [ATP] in highly trained athletes.
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38
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Woodman CR, Seawright JW, Luttrell MJ, Shin SY, Trache A. Importance of mechanical signals in promoting exercise-induced improvements in vasomotor function of aged skeletal muscle resistance arteries. Am J Physiol Heart Circ Physiol 2018; 315:H602-H609. [PMID: 29906226 DOI: 10.1152/ajpheart.00732.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Current research indicates that vasomotor responses are altered with aging in skeletal muscle resistance arteries. The changes in vasomotor function are characterized by impaired vasodilator and vasoconstrictor responses. The detrimental effects of aging on vasomotor function are attenuated in some vascular beds after a program of endurance exercise training. The signals associated with exercise responsible for inducing improvements in vasomotor function have been proposed to involve short-duration increases in intraluminal shear stress and/or pressure during individual bouts of exercise. Here, we review evidence that increases in shear stress and pressure, within a range believed to present in these arteries during exercise, promote healthy vasomotor function in aged resistance arteries. We conclude that available research is consistent with the interpretation that short-duration mechanical stimulation, through increases in shear stress and pressure, contributes to the beneficial effects of exercise on vasomotor function in aged skeletal muscle resistance arteries.
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Affiliation(s)
- Christopher R Woodman
- Department of Health and Kinesiology, Texas A&M University , College Station, Texas.,Department of Veterinary Physiology and Pharmacology, Texas A&M University , College Station, Texas
| | - John W Seawright
- Department of Health and Kinesiology, Texas A&M University , College Station, Texas
| | | | - Song Yi Shin
- Department of Health and Kinesiology, Texas A&M University , College Station, Texas
| | - Andreea Trache
- Department of Medical Physiology, Texas A&M University , College Station, Texas.,Department of Biomedical Engineering, Texas A&M University , College Station, Texas
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39
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Van Iterson EH, Smith JR, Olson TP. Exercise on-transition uncoupling of ventilatory, gas exchange and cardiac hemodynamic kinetics accompany pulmonary oxygen stores depletion to impact exercise intolerance in human heart failure. Acta Physiol (Oxf) 2018; 223:e13063. [PMID: 29575588 DOI: 10.1111/apha.13063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/04/2018] [Accepted: 03/08/2018] [Indexed: 12/16/2022]
Abstract
AIM In contrast to knowledge that heart failure (HF) patients demonstrate peak exercise uncoupling across ventilation, gas exchange and cardiac haemodynamics, whether this dyssynchrony follows that at the exercise on-transition is unclear. This study tested whether exercise on-transition temporal lag for ventilation relative to gas exchange and oxygen pulse (O2 pulse) couples with effects from abnormal pulmonary gaseous oxygen store (O2store ) contributions to V˙O2 to interdependently precipitate persistently elevated ventilatory demand and low oxidative metabolic capacity in HF. METHODS Beat-to-beat HR and breath-to-breath ventilation and gas exchange were continuously acquired in HF (N = 9, ejection fraction = 30 ± 9%) and matched controls (N = 10) during square-wave ergometry at 60% V˙O2peak (46 ± 14 vs 125 ± 54-W, P < .001). Temporal responses across V˙E , V˙O2 and O2 pulse were assessed for the exercise on-transition using single exponential model Phase II on-kinetic time constants (τ = time to reach 63% steady-state rise). Breath-to-breath gas fractions and respiratory flows were used to determine O2stores . RESULTS HF vs controls: τ for V˙E (137 ± 93 vs 74 ± 40-seconds, P = .03), V˙O2 (60 ± 40 vs 23 ± 5-seconds, P = .03) and O2 pulse (28 ± 18 vs 23 ± 15-seconds, P = .59). Within HF, τ for V˙E differed from O2 pulse (P < .02), but not V˙O2 . Exercise V˙E rise (workload indexed) differed in HF vs controls (545 ± 139 vs 309 ± 88-mL min-1 W-1 , P < .001). Exercise on-transition O2store depletion in HF exceeded controls, generally persisting to end-exercise. CONCLUSION These data suggest HF demonstrated exercise on-transition O2store depletion (high O2store contribution to V˙O2 ) coupled with dyssynchronous V˙E , V˙O2 and O2 pulse kinetics-not attributable to prolonged cardiac haemodynamics. Persistent high ventilatory demand and low oxidative metabolic capacity in HF may be precipitated by physiological uncoupling occurring within the exercise on-transition.
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Affiliation(s)
- E. H. Van Iterson
- Department of Cardiovascular Medicine; Mayo Clinic; Rochester MN USA
| | - J. R. Smith
- Department of Cardiovascular Medicine; Mayo Clinic; Rochester MN USA
| | - T. P. Olson
- Department of Cardiovascular Medicine; Mayo Clinic; Rochester MN USA
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40
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Heres HM, Schoots T, Tchang BCY, Rutten MCM, Kemps HMC, van de Vosse FN, Lopata RGP. Perfusion dynamics assessment with Power Doppler ultrasound in skeletal muscle during maximal and submaximal cycling exercise. Eur J Appl Physiol 2018; 118:1209-1219. [PMID: 29569054 DOI: 10.1007/s00421-018-3850-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/17/2018] [Indexed: 10/24/2022]
Abstract
PURPOSE Assessment of limitations in the perfusion dynamics of skeletal muscle may provide insight in the pathophysiology of exercise intolerance in, e.g., heart failure patients. Power doppler ultrasound (PDUS) has been recognized as a sensitive tool for the detection of muscle blood flow. In this volunteer study (N = 30), a method is demonstrated for perfusion measurements in the vastus lateralis muscle, with PDUS, during standardized cycling exercise protocols, and the test-retest reliability has been investigated. METHODS Fixation of the ultrasound probe on the upper leg allowed for continuous PDUS measurements. Cycling exercise protocols included a submaximal and an incremental exercise to maximal power. The relative perfused area (RPA) was determined as a measure of perfusion. Absolute and relative reliability of RPA amplitude and kinetic parameters during exercise (onset, slope, maximum value) and recovery (overshoot, decay time constants) were investigated. RESULTS A RPA increase during exercise followed by a signal recovery was measured in all volunteers. Amplitudes and kinetic parameters during exercise and recovery showed poor to good relative reliability (ICC ranging from 0.2-0.8), and poor to moderate absolute reliability (coefficient of variation (CV) range 18-60%). CONCLUSIONS A method has been demonstrated which allows for continuous (Power Doppler) ultrasonography and assessment of perfusion dynamics in skeletal muscle during exercise. The reliability of the RPA amplitudes and kinetics ranges from poor to good, while the reliability of the RPA increase in submaximal cycling (ICC = 0.8, CV = 18%) is promising for non-invasive clinical assessment of the muscle perfusion response to daily exercise.
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Affiliation(s)
- H M Heres
- Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - T Schoots
- Department of Cardiology, Máxima Medical Centre, Veldhoven, The Netherlands
| | - B C Y Tchang
- Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - M C M Rutten
- Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - H M C Kemps
- Department of Cardiology, Máxima Medical Centre, Veldhoven, The Netherlands
| | - F N van de Vosse
- Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - R G P Lopata
- Cardiovascular Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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41
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Koga S, Okushima D, Barstow TJ, Rossiter HB, Kondo N, Poole DC. Near-infrared spectroscopy of superficial and deep rectus femoris reveals markedly different exercise response to superficial vastus lateralis. Physiol Rep 2018; 5:5/17/e13402. [PMID: 28912130 PMCID: PMC5599862 DOI: 10.14814/phy2.13402] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/08/2017] [Accepted: 08/08/2017] [Indexed: 12/13/2022] Open
Abstract
To date our knowledge of skeletal muscle deoxygenation as measured by near-infrared spectroscopy (NIRS) is predicated almost exclusively on sampling of superficial muscle(s), most commonly the vastus lateralis (VL-s). Recently developed high power NIRS facilitates simultaneous sampling of deep (i.e., rectus femoris, RF-d) and superficial muscles of RF (RF-s) and VL-s. Because deeper muscle is more oxidative with greater capillarity and sustains higher blood flows than superficial muscle, we used time-resolved NIRS to test the hypotheses that, following exercise onset, the RF-d has slower deoxy[Hb+Mb] kinetics with reduced amplitude than superficial muscles. Thirteen participants performed cycle exercise transitions from unloaded to heavy work rates. Within the same muscle (RF-s vs. RF-d) deoxy[Hb+Mb] kinetics (mean response time, MRT) and amplitudes were not different. However, compared with the kinetics of VL-s, deoxy[Hb+Mb] of RF-s and RF-d were slower (MRT: RF-s, 51 ± 23; RF-d, 55 ± 29; VL-s, 18 ± 6 s; P < 0.05). Moreover, the amplitude of total[Hb+Mb] was greater for VL-s than both RF-s and RF-d (P < 0.05). Whereas pulmonary V˙O2 kinetics (i.e., on vs. off) were symmetrical in heavy exercise, there was a marked on-off asymmetry of deoxy[Hb+Mb] for all three sites i.e., MRT-off > MRT-on (P < 0.05). Collectively these data reveal profoundly different O2 transport strategies, with the RF-s and RF-d relying proportionately more on elevated perfusive and the VL-s on diffusive O2 transport. These disparate O2 transport strategies and their temporal profiles across muscles have previously been concealed within the "global" pulmonary V˙O2 response.
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Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Thomas J Barstow
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - David C Poole
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
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42
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Salvadego D, Keramidas ME, Kölegård R, Brocca L, Lazzer S, Mavelli I, Rittweger J, Eiken O, Mekjavic IB, Grassi B. PlanHab * : hypoxia does not worsen the impairment of skeletal muscle oxidative function induced by bed rest alone. J Physiol 2018; 596:3341-3355. [PMID: 29665013 DOI: 10.1113/jp275605] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 02/16/2018] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Superposition of hypoxia on 21 day bed rest did not worsen the impairment of skeletal muscle oxidative function induced by bed rest alone. A significant impairment of maximal oxidative performance was identified downstream of cardiovascular O2 delivery, involving both the intramuscular matching between O2 supply and utilization and mitochondrial respiration. These chronic adaptations appear to be relevant in terms of exposure to spaceflights and reduced gravity habitats (Moon or Mars), as characterized by low gravity and hypoxia, in patients with chronic diseases characterized by hypomobility/immobility and hypoxia, as well as in ageing. ABSTRACT Skeletal muscle oxidative function was evaluated in 11 healthy males (mean ± SD age 27 ± 5 years) prior to (baseline data collection, BDC) and following a 21 day horizontal bed rest (BR), carried out in normoxia ( PIO2 = 133 mmHg; N-BR) and hypoxia ( PIO2 = 90 mmHg; H-BR). H-BR was aimed at simulating reduced gravity habitats. The effects of a 21 day hypoxic ambulatory confinement ( PIO2 = 90 mmHg; H-AMB) were also assessed. Pulmonary O2 uptake ( V̇O2 ), vastus lateralis fractional O2 extraction (changes in deoxygenated haemoglobin + myoglobin concentration, Δ[deoxy(Hb + Mb)]; near-infrared spectroscopy) and femoral artery blood flow (ultrasound Doppler) were evaluated during incremental one-leg knee-extension exercise (reduced constraints to cardiovascular O2 delivery) carried out to voluntary exhaustion in a normoxic environment. Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibres. V̇O2peak decreased (P < 0.05) after N-BR (0.98 ± 0.13 L min-1 ) and H-BR (0.96 ± 0.17 L min-1 ) vs. BDC (1.05 ± 0.14 L min-1 ). In the presence of a decreased (by ∼6-8%) thigh muscle volume, V̇O2peak normalized per unit of muscle mass was not affected by both interventions. Δ[deoxy(Hb + Mb)]peak decreased (P < 0.05) after N-BR (65 ± 13% of limb ischaemia) and H-BR (62 ± 12%) vs. BDC (73 ± 13%). H-AMB did not alter V̇O2peak or Δ[deoxy(Hb + Mb)]peak . An overshoot of Δ[deoxy(Hb + Mb)] was evident during the first minute of unloaded exercise after N-BR and H-BR. Arterial blood flow to the lower limb during both unloaded and peak knee extension was not affected by any intervention. Maximal ADP-stimulated mitochondrial respiration decreased (P < 0.05) after all interventions vs. control. In 21 day N-BR, a significant impairment of oxidative metabolism occurred downstream of cardiovascular O2 delivery, affecting both mitochondrial respiration and presumably the intramuscular matching between O2 supply and utilization. Superposition of H on BR did not worsen the impairment induced by BR alone.
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Affiliation(s)
- Desy Salvadego
- Department of Medicine, University of Udine, Udine, Italy
| | - Michail E Keramidas
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Roger Kölegård
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Stefano Lazzer
- Department of Medicine, University of Udine, Udine, Italy
| | - Irene Mavelli
- Department of Medicine, University of Udine, Udine, Italy
| | - Jörn Rittweger
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, Cologne, Germany
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy.,Institute of Bioimaging and Molecular Physiology, National Research Council, Milano, Italy
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George MA, McLay KM, Doyle-Baker PK, Reimer RA, Murias JM. Fitness Level and Not Aging per se, Determines the Oxygen Uptake Kinetics Response. Front Physiol 2018; 9:277. [PMID: 29662455 PMCID: PMC5890239 DOI: 10.3389/fphys.2018.00277] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/08/2018] [Indexed: 11/16/2022] Open
Abstract
Although aging has been associated to slower V˙O2 kinetics, some evidence indicates that fitness status and not aging per se might modulate this response. The main goal of this study was to examine the V˙O2, deoxygenated hemoglobin+myoglobin (deoxy-[Hb+Mb]) kinetics, and the NIRS-derived vascular reperfusion responses in older compared to young men of different training levels (i.e., inactive, recreationally active, and endurance trained). Ten young inactive [YI; 26 ± 5 yrs.; peak V˙O2 (V˙O2peak), 2.96 ± 0.55 L·min−1], 10 young recreationally active (YR; 26 ± 6 yrs.; 3.92 ± 0.33 L·min−1), 10 young endurance trained (YT; 30 ± 4 yrs.; 4.42 ± 0.32 L·min−1), 7 older inactive (OI; 69 ± 4 yrs.; 2.50 ± 0.31 L·min−1), 10 older recreationally active (OR; 69 ± 5 yrs.; 2.71 ± 0.42 L·min−1), and 10 older endurance trained (OT; 66 ± 3 yrs.; 3.20 ± 0.35 L·min−1) men completed transitions of moderate intensity cycling exercise (MODS) to determine V˙O2 and deoxy-[Hb+Mb] kinetics, and the deoxy-[Hb+Mb]/V˙O2 ratio. The time constant of V˙O2 (τV˙O2) was greater in YI (38.8 ± 10.4 s) and OI (44.1 ± 10.8 s) compared with YR (26.8 ± 7.5 s) and OR (26.6 ± 6.5 s), as well as compared to YT (14.8 ± 3.4 s), and OT (17.7 ± 2.7 s) (p < 0.05). τV˙O2 was greater in YR and OR compared with YT and OT (p < 0.05). The deoxy-[Hb+Mb]/V˙O2 ratio was greater in YI (1.23 ± 0.05) and OI (1.29 ± 0.08) compared with YR (1.11 ± 0.03) and OR (1.13 ± 0.06), as well as compared to YT (1.01 ± 0.03), and OT (1.06 ± 0.03) (p < 0.05). Similarly, the deoxy-[Hb+Mb]/ V˙O2 ratio was greater in YR and OR compared with YT and OT (p < 0.05). There was a main effect of training (p = 0.033), whereby inactive (p = 0.018) and recreationally active men (p = 0.031) had significantly poorer vascular reperfusion than endurance trained men regardless of age. This study demonstrated not only that age-related slowing of V˙O2 kinetics can be eliminated in endurance trained individuals, but also that inactive lifestyle negatively impacts the V˙O2 kinetics response of young healthy individuals.
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Affiliation(s)
| | - Kaitlin M McLay
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Patricia K Doyle-Baker
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Faculty of Environmental Design, University of Calgary, Calgary, AB, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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Frisbee SJ, Singh SS, Jackson DN, Lemaster KA, Milde SA, Shoemaker JK, Frisbee JC. Beneficial Pleiotropic Antidepressive Effects of Cardiovascular Disease Risk Factor Interventions in the Metabolic Syndrome. J Am Heart Assoc 2018; 7:e008185. [PMID: 29581223 PMCID: PMC5907597 DOI: 10.1161/jaha.117.008185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/01/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND Although the increased prevalence and severity of clinical depression and elevated cardiovascular disease risk represent 2 vexing public health issues, the growing awareness of their combined presentation compounds the challenge. The obese Zucker rat, a model of the metabolic syndrome, spontaneously develops significant depressive symptoms in parallel with the progression of the metabolic syndrome and, thus, represents a compelling model for study. The primary objective was to assess the impact on both cardiovascular outcomes, specifically vascular structure and function, and depressive symptoms in obese Zucker rats after aggressive treatment for cardiovascular disease risk factors with long-term exercise or targeted pharmacological interventions. METHODS AND RESULTS We chronically treated obese Zucker rats with clinically relevant interventions against cardiovascular disease risk factors to determine impacts on vascular outcomes and depressive symptom severity. While most of the interventions (chronic exercise, anti-hypertensive, the interventions (long-term exercise, antihypertensive, antidyslipidemia, and antidiabetic) were differentially effective at improving vascular outcomes, only those that also resulted in a significant improvement to oxidant stress, inflammation, arachidonic acid metabolism (prostacyclin versus thromboxane A2), and their associated sequelae were effective at also blunting depressive symptom severity. Using multivariable analyses, discrimination between the effectiveness of treatment groups to maintain behavioral outcomes appeared to be dependent on breaking the cycle of inflammation and oxidant stress, with the associated outcomes of improving endothelial metabolism and both cerebral and peripheral vascular structure and function. CONCLUSIONS This initial study provides a compelling framework from which to further interrogate the links between cardiovascular disease risk factors and depressive symptoms and suggests mechanistic links and potentially effective avenues for intervention.
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Affiliation(s)
- Stephanie J Frisbee
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Sarah S Singh
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Dwayne N Jackson
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Kent A Lemaster
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Samantha A Milde
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - J Kevin Shoemaker
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Jefferson C Frisbee
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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45
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Heinonen I, Boushel R, Hellsten Y, Kalliokoski K. Regulation of bone blood flow in humans: The role of nitric oxide, prostaglandins, and adenosine. Scand J Med Sci Sports 2018; 28:1552-1558. [PMID: 29377406 DOI: 10.1111/sms.13064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2017] [Indexed: 12/23/2022]
Abstract
The mechanisms that regulate bone blood flow (BBF) in humans are largely unknown. Animal studies suggest that nitric oxide (NO) could be involved, and in this study, we investigated the effects of inhibition of nitric oxide synthase (NOS) alone and in combination with inhibition of cyclooxygenase (COX) enzyme, thus prostaglandin (PG) synthesis on femoral bone marrow blood flow by positron emission tomography in healthy young men at rest and during one-leg dynamic exercise. In an additional group of healthy men, the role of adenosine (ADO) in the regulation of BBF during exercise was investigated by use of an adenosine receptor blocker (aminophylline). Inhibitors were directly infused into the femoral artery. Resting BBF was 1.1 ± 0.4 mL 100 g-1 min-1 and increased to almost sixfold in response to exercise (6.3 ± 1.5 mL 100 g-1 min-1 ). Inhibition of NOS reduced BBF at rest to 0.7 ± 0.3 mL 100 g-1 min-1 (P = .036), but did not affect BBF significantly during exercise (5.5 ± 1.4 mL 100 g-1 min-1 , P = .25). On the other hand, while combined NOS and COX inhibition did not cause any further reduction of blood flow at rest (0.6 ± 0.2 mL 100 g-1 min-1 ), the combined blockade reduced BBF during exercise by ~21%, to 5.0 ± 1.8 mL 100 g-1 min-1 (P = .014). Finally, the ADO inhibition during exercise reduced BBF from 5.5 ± 1.9 mL 100 g-1 min-1 to 4.6 ± 1.2 mL 100 g-1 min-1 (P = .045). In conclusion, our results support the view that NO is involved in controlling bone marrow blood flow at rest, and NO, PG, and ADO play important roles in controlling human BBF during exercise.
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Affiliation(s)
- I Heinonen
- Turku PET Centre, Turku, Finland.,Department of Clinical Physiology and Nuclear Medicine, University of Turku, Turku, Finland.,Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - R Boushel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Y Hellsten
- Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
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Okushima D, Poole DC, Barstow TJ, Rossiter HB, Kondo N, Bowen TS, Amano T, Koga S. Greater V˙O2peak is correlated with greater skeletal muscle deoxygenation amplitude and hemoglobin concentration within individual muscles during ramp-incremental cycle exercise. Physiol Rep 2018; 4:4/23/e13065. [PMID: 27986837 PMCID: PMC5260088 DOI: 10.14814/phy2.13065] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022] Open
Abstract
It is axiomatic that greater aerobic fitness (V˙O2peak) derives from enhanced perfusive and diffusive O2 conductances across active muscles. However, it remains unknown how these conductances might be reflected by regional differences in fractional O2 extraction (i.e., deoxy [Hb+Mb] and tissue O2 saturation [StO2]) and diffusive O2 potential (i.e., total[Hb+Mb]) among muscles spatially heterogeneous in blood flow, fiber type, and recruitment (vastus lateralis, VL; rectus femoris, RF). Using quantitative time‐resolved near‐infrared spectroscopy during ramp cycling in 24 young participants (V˙O2peak range: ~37.4–66.4 mL kg−1 min−1), we tested the hypotheses that (1) deoxy[Hb+Mb] and total[Hb+Mb] at V˙O2peak would be positively correlated with V˙O2peak in both VL and RF muscles; (2) the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) during submaximal exercise would not differ among subjects differing in V˙O2peak. Peak deoxy [Hb+Mb] and StO2 correlated with V˙O2peak for both VL (r = 0.44 and −0.51) and RF (r = 0.49 and −0.49), whereas for total[Hb+Mb] this was true only for RF (r = 0.45). Baseline deoxy[Hb+Mb] and StO2 correlated with V˙O2peak only for RF (r = −0.50 and 0.54). In addition, the deoxy[Hb+Mb] slopes were not affected by aerobic fitness. In conclusion, while the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) did not differ between fitness groups the capacity to deoxygenate [Hb+Mb] (index of maximal fractional O2 extraction) correlated significantly with V˙O2peak in both RF and VL muscles. However, only in the RF did total[Hb+Mb] (index of diffusive O2 potential) relate to fitness.
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Affiliation(s)
- Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment Kobe University, Kobe, Japan
| | - T Scott Bowen
- Department of Internal Medicine & Cardiology, Heart Center, Leipzig University, Leipzig, Germany
| | - Tatsuro Amano
- Faculty of Education Niigata University, Niigata, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
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47
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Sexton WL, Musch TI, Poole DC. Skeletal muscle microvascular and interstitial PO2 from rest to contractions. J Physiol 2018; 596:869-883. [PMID: 29288568 DOI: 10.1113/jp275170] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/01/2017] [Indexed: 01/21/2023] Open
Abstract
KEY POINTS Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. ABSTRACT Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O2 transport, thereby supporting oxidative metabolism. The greatest resistance to O2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5.3 versus 10.6 ± 5.2 mmHg, respectively) such that the mean PO2 gradient throughout the transient was 16.9 ± 6.6 mmHg (P < 0.05 for all). No differences in the amplitude of PO2 fall with contractions were observed between the microvasculature and interstitium (10.9 ± 2.3 versus 9.0 ± 3.5 mmHg, respectively; P > 0.05). However, the speed of the PO2 is fall during contractions was slower than that of PO2 mv (time constant: 12.8 ± 4.7 versus 9.0 ± 5.1 s, respectively; P < 0.05). Consistent with our hypothesis, a significant transmural gradient was sustained (but not increased) from rest to contractions. This supports that the blood-myocyte interface is the site of a substantial PO2 gradient driving O2 diffusion during metabolic transients. Based on Fick's law, elevated O2 flux with contractions must thus rely primarily on modulations in effective diffusing capacity (mainly erythrocyte haemodynamics and distribution) as the PO2 gradient is not increased.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Hiroaki Eshima
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - William L Sexton
- Department of Physiology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
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Houstis NE, Eisman AS, Pappagianopoulos PP, Wooster L, Bailey CS, Wagner PD, Lewis GD. Exercise Intolerance in Heart Failure With Preserved Ejection Fraction: Diagnosing and Ranking Its Causes Using Personalized O 2 Pathway Analysis. Circulation 2018; 137:148-161. [PMID: 28993402 PMCID: PMC5760316 DOI: 10.1161/circulationaha.117.029058] [Citation(s) in RCA: 166] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 09/19/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND Heart failure with preserved ejection fraction (HFpEF) is a common syndrome with a pressing shortage of therapies. Exercise intolerance is a cardinal symptom of HFpEF, yet its pathophysiology remains uncertain. METHODS We investigated the mechanism of exercise intolerance in 134 patients referred for cardiopulmonary exercise testing: 79 with HFpEF and 55 controls. We performed cardiopulmonary exercise testing with invasive monitoring to measure hemodynamics, blood gases, and gas exchange during exercise. We used these measurements to quantify 6 steps of oxygen transport and utilization (the O2 pathway) in each patient with HFpEF, identifying the defective steps that impair each one's exercise capacity (peak Vo2). We then quantified the functional significance of each O2 pathway defect by calculating the improvement in exercise capacity a patient could expect from correcting the defect. RESULTS Peak Vo2 was reduced by 34±2% (mean±SEM, P<0.001) in HFpEF compared with controls of similar age, sex, and body mass index. The vast majority (97%) of patients with HFpEF harbored defects at multiple steps of the O2 pathway, the identity and magnitude of which varied widely. Two of these steps, cardiac output and skeletal muscle O2 diffusion, were impaired relative to controls by an average of 27±3% and 36±2%, respectively (P<0.001 for both). Due to interactions between a given patient's defects, the predicted benefit of correcting any single one was often minor; on average, correcting a patient's cardiac output led to a 7±0.5% predicted improvement in exercise intolerance, whereas correcting a patient's muscle diffusion capacity led to a 27±1% improvement. At the individual level, the impact of any given O2 pathway defect on a patient's exercise capacity was strongly influenced by comorbid defects. CONCLUSIONS Systematic analysis of the O2 pathway in HFpEF showed that exercise capacity was undermined by multiple defects, including reductions in cardiac output and skeletal muscle diffusion capacity. An important source of disease heterogeneity stemmed from variation in each patient's personal profile of defects. Personalized O2 pathway analysis could identify patients most likely to benefit from treating a specific defect; however, the system properties of O2 transport favor treating multiple defects at once, as with exercise training.
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Affiliation(s)
- Nicholas E Houstis
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
| | - Aaron S Eisman
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
| | - Paul P Pappagianopoulos
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
| | - Luke Wooster
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
| | - Cole S Bailey
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
| | - Peter D Wagner
- School of Medicine, University of California, San Diego (P.D.W.)
| | - Gregory D Lewis
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston (N.E.H., A.S.E., P.P.P., L.W., C.S.B., G.D.L.)
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Berg OK, Nyberg SK, Windedal TM, Wang E. Maximal strength training-induced improvements in forearm work efficiency are associated with reduced blood flow. Am J Physiol Heart Circ Physiol 2017; 314:H853-H862. [PMID: 29351462 DOI: 10.1152/ajpheart.00435.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Maximal strength training (MST) improves work efficiency. However, since blood flow is greatly dictated by muscle contractions in arms during exercise and vascular conductance is lower, it has been indicated that arms rely more upon adapting oxygen extraction than legs in response to the enhanced work efficiency. Thus, to investigate if metabolic and vascular responses are arm specific, we used Doppler-ultrasound and a catheter placed in the subclavian vein to measure blood flow and the arteriovenous oxygen difference during steady-state work in seven young men [24 ± 3 (SD) yr] following 6 wk of handgrip MST. As expected, MST improved maximal strength (49 ± 9 to 62 ± 10 kg) and the rate of force development (923 ± 224 to 1,086 ± 238 N/s), resulting in a reduced submaximal oxygen uptake (30 ± 9 to 24 ± 10 ml/min) and concomitantly increased work efficiency (9.3 ± 2.5 to 12.4 ± 3.9%) (all P < 0.05). In turn, the work efficiency improvement was associated with reduced blood flow (486 ± 102 to 395 ± 114 ml/min), mediated by a lower blood velocity (43 ± 8 to 32 ± 6 cm/s) (all P < 0.05). Conduit artery diameter and the arteriovenous oxygen difference remained unaltered. The maximal work test revealed an increased time to exhaustion (949 ± 239 to 1,102 ± 292 s) and maximal work rate (both P < 0.05) but no change in peak oxygen uptake. In conclusion, despite prior indications of metabolic and vascular limb-specific differences, these results reveal that improved work efficiency after small muscle mass strength training in the upper extremities is accompanied by a blood flow reduction and coheres with what has been documented for lower extremities. NEW & NOTEWORTHY Maximal strength training increases skeletal muscle work efficiency. Oxygen extraction has been indicated to be the adapting component with this increased work efficiency in arms. However, we document that decreased blood flow, achieved by blood velocity reduction, is the adapting mechanism responding to the improved aerobic metabolism in the forearm musculature.
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Affiliation(s)
- Ole Kristian Berg
- Faculty of Health and Social Sciences, Molde University College, Molde, Norway
| | - Stian Kwak Nyberg
- Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology , Trondheim , Norway
| | - Tobias Midtvedt Windedal
- Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology , Trondheim , Norway
| | - Eivind Wang
- Faculty of Health and Social Sciences, Molde University College, Molde, Norway.,Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology , Trondheim , Norway.,Department of Internal Medicine, University of Utah , Salt Lake City, Utah
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50
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Abstract
Precision (P4) medicine represents a new medical paradigm that focuses on Personalized, Predictive, Preventive and Participatory approaches. The P4 paradigm is particularly appropriate for moving the care of persons with myopenia forward. Muscular dystrophies are clearly a set of genetically different diseases where genomics are the basis of diagnosis, and genetic modulation via DNA, oligonucleotides and clustered regularly interspaced short palendronic repeats hold great potential for a cure. The utility of personalized genomics for sarcopenia coupled with utilizing a predictive approach for the diagnosis with early preventive strategies is a key to improving sarcopenic outcomes. The importance of understanding different levels of patient enthusiasm and different responses to exercise should guide the participatory phase of sarcopenic treatment. In the case of cachexia, understanding the effects of the different therapies now available through the P4 approach on muscle wasting is a key to management strategies.
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Affiliation(s)
- John E. Morley
- Division of Geriatric MedicineSaint Louis University School of Medicine1402 S. Grand Blvd., M238St. LouisMO63104USA
| | - Stefan D. Anker
- Division of Innovative Clinical Trials, Department of Cardiology and PneumologyUniversity Medical Centre GöttingenRobert‐Koch‐Straße 40, D‐37075GöttingenGermany
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