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Katagiri M, Nakabayashi M, Matsuda Y, Ono Y, Ichinose M. Differential changes in blood flow and oxygen utilization in active muscles between voluntary exercise and electrical muscle stimulation in young adults. J Appl Physiol (1985) 2024; 136:1053-1064. [PMID: 38482573 DOI: 10.1152/japplphysiol.00863.2023] [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: 11/30/2023] [Revised: 02/22/2024] [Accepted: 03/05/2024] [Indexed: 04/24/2024] Open
Abstract
The physiological effects on blood flow and oxygen utilization in active muscles during and after involuntary contraction triggered by electrical muscle stimulation (EMS) remain unclear, particularly compared with those elicited by voluntary (VOL) contractions. Therefore, we used diffuse correlation and near-infrared spectroscopy (DCS-NIRS) to compare changes in local muscle blood flow and oxygen consumption during and after these two types of muscle contractions in humans. Overall, 24 healthy young adults participated in the study, and data were successfully obtained from 17 of them. Intermittent (2-s contraction, 2-s relaxation) isometric ankle dorsiflexion with a target tension of 20% of maximal VOL contraction was performed by EMS or VOL for 2 min, followed by a 6-min recovery period. DCS-NIRS probes were placed on the tibialis anterior muscle, and relative changes in local tissue blood flow index (rBFI), oxygen extraction fraction (rOEF), and metabolic rate of oxygen (rMRO2) were continuously derived. EMS induced more significant increases in rOEF and rMRO2 than VOL exercise but a comparable increase in rBFI. After EMS, rBFI and rMRO2 decreased more slowly than after VOL and remained significantly higher until the end of the recovery period. We concluded that EMS augments oxygen consumption in contracting muscles by enhancing oxygen extraction while increasing oxygen delivery at a rate similar to the VOL exercise. Under the conditions examined in this study, EMS demonstrated a more pronounced and/or prolonged enhancement in local muscle perfusion and aerobic metabolism compared with VOL exercise in healthy participants.NEW & NOTEWORTHY This is the first study to visualize continuous changes in blood flow and oxygen utilization within contracted muscles during and after electrical muscle stimulation (EMS) using combined diffuse correlation and near-infrared spectroscopy. We found that initiating EMS increases blood flow at a rate comparable to that during voluntary (VOL) exercise but enhances oxygen extraction, resulting in higher oxygen consumption. Furthermore, EMS increased postexercise muscle perfusion and oxygen consumption compared with that after VOL exercise.
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Affiliation(s)
- Makoto Katagiri
- Electrical Engineering Program, Graduate School of Science and Technology, Meiji University, Kanagawa, Japan
| | - Mikie Nakabayashi
- Electrical Engineering Program, Graduate School of Science and Technology, Meiji University, Kanagawa, Japan
| | - Yasuhiro Matsuda
- Faculty of Medical Science, Nippon Sport Science University, Kanagawa, Japan
| | - Yumie Ono
- Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University, Kanagawa, Japan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
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Rios M, Becker KM, Monteiro AS, Fonseca P, Pyne DB, Reis VM, Moreira-Gonçalves D, Fernandes RJ. Effect of the Fran CrossFit Workout on Oxygen Uptake Kinetics, Energetics, and Postexercise Muscle Function in Trained CrossFitters. Int J Sports Physiol Perform 2024; 19:299-306. [PMID: 38194958 DOI: 10.1123/ijspp.2023-0201] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 10/30/2023] [Accepted: 11/19/2023] [Indexed: 01/11/2024]
Abstract
PURPOSE Fran is one of the most popular CrossFit benchmark workouts used to control CrossFitters' improvements. Detailed physiological characterization of Fran is needed for a more specific evaluation of CrossFitters' training performance improvements. The aim of the study was to analyze the oxygen uptake (V˙O2) kinetics and characterize the energy system contributions and the degree of postexercise fatigue of the unbroken Fran. METHODS Twenty trained CrossFitters performed Fran at maximal exertion. V˙O2 and heart-rate kinetics were assessed at baseline and during and post-Fran. Blood lactate and glucose concentrations and muscular fatigue were measured at baseline and in the recovery period. RESULTS A marked increase in V˙O2 kinetics was observed at the beginning of Fran, remaining elevated until the end (V˙O2peak: 49.2 [3.7] mL·kg-1·min-1, V˙O2 amplitude: 35.8 [5.2] mL·kg-1·min-1, time delay: 4.7 [2.5] s and time constant: 23.7 [11.1] s; mean [SD]). Aerobic, anaerobic lactic, and alactic pathways accounted for 62% (4%), 26% (4%), and 12% (2%) of energy contribution. Reduction in muscle function in jumping ability (jump height: 8% [6%], peak force: 6% [4%], and maximum velocity: 4% [2%]) and plank prone test (46% [20%]) was observed in the recovery period. CONCLUSIONS The Fran unbroken workout is a high-intensity effort associated with an elevated metabolic response. This pattern of energy response highlights the primary contribution of aerobic energy metabolism, even during short and very intense CrossFit workouts, and that recovery can take >24 hours due to cumulative fatigue.
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Affiliation(s)
- Manoel Rios
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
- Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, Porto, Portugal
| | - Klaus Magno Becker
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
- Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, Porto, Portugal
| | - Ana Sofia Monteiro
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
- Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, Porto, Portugal
| | - Pedro Fonseca
- Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, Porto, Portugal
| | - David B Pyne
- Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| | - Victor Machado Reis
- Department of Sport Sciences, Exercise and Health, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal
- Research Center in Sports Sciences, Health Sciences and Human Development, Vila Real, Portugal
| | - Daniel Moreira-Gonçalves
- Research Center in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal
- Laboratory for Integrative and Translational Research in Population Health, Porto, Portugal
| | - Ricardo J Fernandes
- Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
- Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, Porto, Portugal
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Ozkaya O, Jones AM, Burnley M, As H, Balci GA. Different categories of VO 2 kinetics in the 'extreme' exercise intensity domain. J Sports Sci 2023; 41:2144-2152. [PMID: 38380593 DOI: 10.1080/02640414.2024.2316504] [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: 08/06/2023] [Accepted: 02/01/2024] [Indexed: 02/22/2024]
Abstract
The aim of this study was to classify potential sub-zones within the extreme exercise domain. Eight well-trained male cyclists participated in this study. The upper boundary of the severe exercise domain (Pupper-bound) was estimated by constant-work-rate tests. Then three further extreme-work-rate tests were performed in discrete regions within the extreme domain: extreme-1) at a work-rate greater than the Pupper-bound providing an 80-110-s time to task failure; extreme-2) a 30-s maximal sprint; and extreme-3) a 4-s maximal sprint. Different functions were used to describe the behaviour of the V ˙ O 2 kinetics over time. V ˙ O 2 on-kinetics during extreme-1 exercise was best described by a single-exponential model (R2 ≥ 0.97; SEE ≤ 0.10; p < 0.001), and recovery V ˙ O 2 decreased immediately after the termination of exercise. In contrast, V ˙ O 2 on-kinetics during extreme-2 exercise was best fitted by a linear function (R2 ≥ 0.96; SEE ≤ 0.16; p < 0.001), and V ˙ O 2 responses continued to increase during the first 10-20 s of recovery. During the extreme-3 exercise, V ˙ O 2 could not be modelled due to inadequate data, and there was an M-shape recovery V ˙ O 2 response with an exponential decay at the end. The V ˙ O 2 response to exercise across the extreme exercise domain has distinct features and must therefore be characterised with different fitting strategies in order to describe the responses accurately.
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Affiliation(s)
- Ozgur Ozkaya
- Department of Coaching Education, Faculty of Sports Sciences, Ege University, Izmir, Turkiye
| | - Andrew M Jones
- Faculty of Health and Life Sciences, University of Exeter Medical School, Exeter, UK
| | - Mark Burnley
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Hakan As
- Department of Sports Health Sciences, Institution of Health Sciences, Ege University, Izmir, Turkiye
| | - Gorkem A Balci
- Department of Coaching Education, Faculty of Sports Sciences, Ege University, Izmir, Turkiye
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Jessup LN, Kelly LA, Cresswell AG, Lichtwark GA. It is not just the work you do, but how you do it: the metabolic cost of walking uphill and downhill with varying grades. J Appl Physiol (1985) 2023; 135:1263-1267. [PMID: 37855031 DOI: 10.1152/japplphysiol.00349.2023] [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: 06/01/2023] [Revised: 10/03/2023] [Accepted: 10/16/2023] [Indexed: 10/20/2023] Open
Abstract
The cost of walking and running on uneven terrain is not directly explained by external mechanical work. Although metabolic cost of transport increases linearly with gradient at uphill and downhill gradients exceeding 15%, at shallower gradients, the relationship is nonlinear, with the minimum cost occurring at ∼10% downhill grade. Given these nonlinear relationships between grade and metabolic cost, we projected a significant difference in the total metabolic cost of two walking conditions that required the same total external mechanical work be performed over the same total period of time; in one condition, time was spent walking to gradients that were fixed at +10.5% and -10.5% and in the other condition time was spent walking to gradients that varied from 0 to +21% and from -21 to 0%. We compared these two conditions experimentally, using an approach to quantify nonsteady-state oxidative energy expenditure. In line with our projection, the "variable" grade condition resulted in an 8.3 ± 2.2% higher total cumulative oxidative energy expenditure (J·kg-1) compared with the "fixed" grade condition (P < 0.001). Future work should aim to apply our approach across different gradients, speeds, and forms of locomotion; especially those that might provide insight into how humans optimize locomotion on variable grade routes.NEW & NOTEWORTHY We use a method for quantifying nonsteady-state energetics to show that regardless of whether the same total gain and loss in elevation (i.e., same total external mechanical work) is achieved over the same period of time, the total energy expenditure of different graded walking conditions can vary depending on the grades that are walked at and for how long they are walked at.
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Affiliation(s)
- Luke N Jessup
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Luke A Kelly
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Andrew G Cresswell
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Glen A Lichtwark
- School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
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Korzeniewski B. Mechanisms of slowed V̇O 2 on-kinetics in second step of two-step-incremental exercise in skeletal muscle. Respir Physiol Neurobiol 2023:104084. [PMID: 37230211 DOI: 10.1016/j.resp.2023.104084] [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: 02/16/2023] [Revised: 05/03/2023] [Accepted: 05/20/2023] [Indexed: 05/27/2023]
Abstract
Simulations using a computer model of the skeletal muscle bioenergetic system demonstrate that the slowed V̇O2 on-kinetics of the second step in two-step incremental exercise (exercise initiated from elevated baseline metabolic rate) can be accounted for by a decrease in the stimulation of oxidative phosphorylation (OXPHOS) and/or increase in the stimulation of glycolysis through each-step activation (ESA) in working skeletal muscle. This effect can be caused by either a recruitment of more glycolytic type IIa, IIx and IIb fibers or metabolic regulation in already recruited fibers, or both. The elevated-glycolysis-stimulation mechanism predicts that the end-second-step pH in two-step-incremental exercise is lower than the end-exercise pH in constant-power exercise with the same work intensity (power output). The lowered-OXPHOS-stimulation mechanism predicts higher end-exercise ADP and Pi, and lower PCr in the second step of two-step-incremental than in constant-power exercise. These predictions/mechanisms can be verified or falsified in the experimental way. DATA AVAILABILITY STATEMENT: There are no additional data available.
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Korzeniewski B. V̇O 2 (non-)linear increase in ramp-incremental exercise vs. V̇O 2 slow component in constant-power exercise: Underlying mechanisms. Respir Physiol Neurobiol 2023; 311:104023. [PMID: 36731708 DOI: 10.1016/j.resp.2023.104023] [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: 10/09/2022] [Revised: 12/31/2022] [Accepted: 01/28/2023] [Indexed: 02/01/2023]
Abstract
A computer model of the skeletal muscle bioenergetic system involving the Pi double-threshold mechanism of muscle fatigue was used to study the V̇O2 (non-)linear increase in time in ramp-incremental exercise as compared to the V̇O2 slow component in constant-power exercise. The Pi double-threshold mechanism applies to both constant-power and ramp-incremental exercise. The additional ATP usage is initiated at a significantly higher ATP usage activity (power output), determining the moderate/heavy exercise border, in ramp-incremental, than in constant-power exercise. A significantly lowered additional ATP usage activity or elevated glycolysis stimulation at the highest power outputs in ramp-incremental exercise in relation to constant-power exercise can additionally explain the much smaller (or zero) V̇O2 non-linearity in ramp-incremental exercise, than V̇O2 slow component in constant-power exercise. The V̇O2 (non-)linearity in ramp-incremental exercise and V̇O2 slow component in constant-power exercise is a derivative of a balance between the additional ATP usage and ATP production by anaerobic glycolysis.
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Goulding RP, Burnley M, Wüst RCI. How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance. Sports Med 2023; 53:959-976. [PMID: 37010782 PMCID: PMC10115720 DOI: 10.1007/s40279-023-01832-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/04/2023]
Abstract
The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ([Formula: see text]O2) kinetics, termed the "priming effect", has garnered significant research attention and its underpinning mechanisms have been hotly debated. In the first part of this review, the evidence for and against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns and (5) enhanced intracellular O2 utilisation in underpinning the priming effect is discussed. Lactic acidosis and increased muscle temperature are most likely not key determinants of the priming effect. Whilst priming increases muscle O2 delivery, many studies have demonstrated that an increased muscle O2 delivery is not a prerequisite for the priming effect. Motor unit recruitment patterns are altered by prior exercise, and these alterations are consistent with some of the observed changes in [Formula: see text]O2 kinetics in humans. Enhancements in intracellular O2 utilisation likely play a central role in mediating the priming effect, probably related to elevated mitochondrial calcium levels and parallel activation of mitochondrial enzymes at the onset of the second bout. In the latter portion of the review, the implications of priming on the parameters of the power-duration relationship are discussed. The effect of priming on subsequent endurance performance depends critically upon which phases of the [Formula: see text]O2 response are altered. A reduced [Formula: see text]O2 slow component or increased fundamental phase amplitude tend to increase the work performable above critical power (i.e. W´), whereas a reduction in the fundamental phase time constant following priming results in an increased critical power.
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Affiliation(s)
- Richie P Goulding
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
| | - Mark Burnley
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Rob C I Wüst
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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Michel CP, Bendahan D, Giannesini B, Vilmen C, Le Fur Y, Messonnier LA. Effects of hydroxyurea on skeletal muscle energetics and force production in a sickle cell disease murine model. J Appl Physiol (1985) 2023; 134:415-425. [PMID: 36603048 DOI: 10.1152/japplphysiol.00333.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hydroxyurea (HU) is commonly used as a treatment for patients with sickle cell disease (SCD) to enhance fetal hemoglobin production. This increased production is expected to reduce anemia (which depresses oxygen transport) and abnormal Hb content alleviating clinical symptoms such as vaso-occlusive crisis and acute chest syndrome. The effects of HU on skeletal muscle bioenergetics in vivo are still unknown. Due to the beneficial effects of HU upon oxygen delivery, improved skeletal muscle energetics and function in response to a HU treatment have been hypothesized. Muscle energetics and function were analyzed during a standardized rest-exercise-recovery protocol, using 31P-magnetic resonance spectroscopy in Townes SCD mice. Measurements were performed in three groups of mice: one group of 2-mo-old mice (SCD2m, n = 8), another one of 4-mo-old mice (SCD4m, n = 8), and a last group of 4-mo-old mice that have been treated from 2 mo of age with HU at 50 mg/kg/day (SCD4m-HU, n = 8). As compared with SCD2m mice, SCD4m mice were heavier and displayed a lower acidosis. As lower specific forces were developed by SCD4m compared with SCD2m, greater force-normalized phosphocreatine consumption and oxidative and nonoxidative costs of contraction were also reported. HU-treated mice (SCD4m-HU) displayed a significantly higher specific force production as compared with untreated mice (SCD4m), whereas muscle energetics was unchanged. Overall, our results support a beneficial effect of HU on muscle function.NEW & NOTEWORTHY Our results highlighted that force production decreases between 2 and 4 mo of age in SCD mice thereby indicating a decrease of muscle function during this period. Of interest, HU treatment seemed to blunt the observed age effect given that SCD4m-HU mice displayed a higher specific force production as compared with SCD4m mice. In that respect, HU treatment would help to maintain a higher capacity of force production during aging in SCD.
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Affiliation(s)
| | - David Bendahan
- CNRS, CRMBM, Aix-Marseille Université, Marseille, France
| | | | | | - Yann Le Fur
- CNRS, CRMBM, Aix-Marseille Université, Marseille, France
| | - Laurent A Messonnier
- Laboratoire Interuniversitaire de Biologie de la Motricité EA7424, Université Savoie Mont Blanc, Chambéry, France
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Rowland SN, Da Boit M, Tan R, Robinson GP, O’Donnell E, James LJ, Bailey SJ. Dietary Nitrate Supplementation Enhances Performance and Speeds Muscle Deoxyhaemoglobin Kinetics during an End-Sprint after Prolonged Moderate-Intensity Exercise. Antioxidants (Basel) 2022; 12:antiox12010025. [PMID: 36670889 PMCID: PMC9854517 DOI: 10.3390/antiox12010025] [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: 11/30/2022] [Revised: 12/18/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
Short-term dietary nitrate (NO3−) supplementation has the potential to enhance performance during submaximal endurance, and short-duration, maximal-intensity exercise. However, it has yet to be determined whether NO3− supplementation before and during submaximal endurance exercise can improve performance during a short-duration, maximal-intensity end-sprint. In a randomised, double-blind, crossover study, 9 recreationally active men ingested NO3−-rich (BR: 8 mmol NO3−/day) and NO3−-depleted (PL: 0.75 mmol NO3−/day) beetroot powder for 7 days. On day 7, participants completed 2 h of moderate-intensity cycling, which immediately transitioned into a 60 s maximal-intensity end-sprint, with supplements ingested 2 h before and 1 h into the moderate-intensity exercise bout. Plasma [NO3−] and [NO2−] were higher in BR compared to PL pre- and post-exercise (p < 0.05). Post-exercise plasma [NO3−] was higher than pre-exercise (562 ± 89 µM vs. 300 ± 73 µM; p < 0.05) and plasma [NO2−] was not significantly different pre- (280 ± 58 nM) and post-exercise (228 ± 63 nM) in the BR condition (p > 0.05). Mean power output during the final 30 s of the end-sprint was greater after BR (390 ± 38 W) compared to PL (365 ± 41 W; p < 0.05). There were no differences between BR and PL in any muscle oxygenation variables during moderate-intensity cycling (p > 0.05), but muscle [deoxyhaemoglobin] kinetics was faster during the end-sprint in BR (6.5 ± 1.4 s) compared to PL (7.3 ± 1.4 s; p < 0.05). These findings suggest that NO3− supplementation has the potential to improve end-sprint performance in endurance events when ingested prior to and during exercise.
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Affiliation(s)
- Samantha N. Rowland
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK
| | - Mariasole Da Boit
- Health and Life Sciences, School of Allied Health Sciences, De Montfort University, Leicester LE1 9BH, UK
| | - Rachel Tan
- Department of Sports Medicine, Pepperdine University, Malibu, CA 90263, USA
| | - George P. Robinson
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK
| | - Emma O’Donnell
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK
| | - Lewis J. James
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK
| | - Stephen J. Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK
- Correspondence:
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Hovorka M, Prinz B, Simon D, Zöger M, Rumpl C, Nimmerichter A. Longitudinal alterations of pulmonary V.O2 on-kinetics during moderate-intensity exercise in competitive youth cyclists are related to alterations in the balance between microvascular O2 distribution and muscular O2 utilization. Front Sports Act Living 2022; 4:982548. [DOI: 10.3389/fspor.2022.982548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
PurposeThe main purpose of the current study was to investigate the dynamic adjustment of pulmonary oxygen uptake (V.O2) in response to moderate-intensity cycling on three occasions within 15 months in competitive youth cyclists. Furthermore, the muscle Δdeoxy[heme] on-kinetics and the Δdeoxy[heme]-to-V.O2 ratio were modeled to examine possible mechanistic basis regulating pulmonary V.O2 on-kinetics.MethodsEleven cyclists (initial age, 14.3 ± 1.6 y; peak V.O2, 62.2 ± 4.5 mL.min−1.kg−1) with a training history of 2–5 years and a training volume of ~10 h per week participated in this investigation. V.O2 and Δdeoxy[heme] responses during workrate-transitions to moderate-intensity cycling were measured with breath-by-breath spirometry and near-infrared spectroscopy, respectively, and subsequently modeled with mono-exponential models to derive parameter estimates. Additionally, a normalized Δdeoxy[heme]-to-V.O2 ratio was calculated for each participant. One-way repeated-measures ANOVA was used to assess effects of time on the dependent variables of the responses.ResultsThe V.O2 time constant remained unchanged between the first (~24 s) and second visit (~22 s, P > 0.05), whereas it was significantly improved through the third visit (~13 s, P = 0.006–0.013). No significant effects of time were revealed for the parameter estimates of the Δdeoxy[heme] response (P > 0.05). A significant Δdeoxy[heme]-to-V.O2 ratio “overshoot” was evident on the first (1.09 ± 0.10, P = 0.006) and second (1.05 ± 0.09, P = 0.047), though not the third (0.97 ± 0.10, P > 0.05), occasion. These “overshoots” showed strong positive relationships with the V.O2 time constant during the first (r = 0.66, P = 0.028) and second visit (r = 0.76, P = 0.007). Further, strong positive relationships have been observed between the individual changes of the fundamental phase τp and the Δdeoxy[heme]-to-V.O2 ratio “overshoot” from occasion one to two (r = 0.70, P = 0.017), and two to three (r = 0.74, P = 0.009).ConclusionThis suggests that improvements in muscle oxygen provision and utilization capacity both occurred, and each may have contributed to enhancing the dynamic adjustment of the oxidative “machinery” in competitive youth cyclists. Furthermore, it indicates a strong link between an oxygen maldistribution within the tissue of interrogation and the V.O2 time constant.
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Electromyography as a surrogate for estimating metabolic energy expenditure during locomotion. Med Eng Phys 2022; 109:103899. [DOI: 10.1016/j.medengphy.2022.103899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 07/21/2022] [Accepted: 09/27/2022] [Indexed: 11/11/2022]
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Hori A, Saito R, Suijo K, Kushnick MR, Hasegawa D, Ishida K, Hotta N. Blood flow restriction accelerates aerobic training-induced adaptation of [Formula: see text] kinetics at the onset of moderate-intensity exercise. Sci Rep 2022; 12:18160. [PMID: 36307460 PMCID: PMC9616915 DOI: 10.1038/s41598-022-22852-3] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 10/20/2022] [Indexed: 12/31/2022] Open
Abstract
It is unclear whether blood flow restriction (BFR) accelerates the adaptation of the time constant (τ) of phase II oxygen uptake ([Formula: see text]) kinetics in the moderate-intensity exercise domain via moderate-intensity aerobic training. Therefore, healthy participants underwent moderate-intensity [45-60% [Formula: see text] Reserve] aerobic cycle training with or without BFR (BFR group, n = 9; CON group, n = 9) for 8 weeks to evaluate [Formula: see text] kinetics during moderate-intensity cycle exercise before (Pre) and after 4 (Mid) and 8 (Post) weeks of training. Both groups trained for 30 min, 3 days weekly. BFR was performed for 5 min every 10 min by applying cuffs to the upper thighs. The τ significantly decreased by Mid in the BFR group (23.7 ± 2.9 s [Pre], 15.3 ± 1.8 s [Mid], 15.5 ± 1.4 s [Post], P < 0.01) and by Post in the CON group (27.5 ± 2.0 s [Pre], 22.1 ± 0.7 s [Mid], 18.5 ± 1.9 s [Post], P < 0.01). Notably, the BFR group's τ was significantly lower than that of the CON group at Mid (P < 0.01) but not at Post. In conclusion, BFR accelerates the adaptation of the [Formula: see text] kinetics of phase II by moderate-intensity aerobic training.
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Affiliation(s)
- Amane Hori
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ryuji Saito
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Kenichi Suijo
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Michael R. Kushnick
- College of Health and Human Sciences, Northern Illinois University, DeKalb, IL USA
| | - Daisuke Hasegawa
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
| | - Koji Ishida
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
| | - Norio Hotta
- Graduate School of Life and Health Sciences, Chubu University, Kasugai, Japan
- College of Life and Health Sciences, Chubu University, Kasugai, Japan
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13
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Age-Related Changes in Skeletal Muscle Oxygen Utilization. J Funct Morphol Kinesiol 2022; 7:jfmk7040087. [PMID: 36278748 PMCID: PMC9590092 DOI: 10.3390/jfmk7040087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022] Open
Abstract
The cardiovascular and skeletal muscle systems are intrinsically interconnected, sharing the goal of delivering oxygen to metabolically active tissue. Deficiencies within those systems that affect oxygen delivery to working tissues are a hallmark of advancing age. Oxygen delivery and utilization are reflected as muscle oxygen saturation (SmO2) and are assessed using near-infrared resonance spectroscopy (NIRS). SmO2 has been observed to be reduced by ~38% at rest, ~24% during submaximal exercise, and ~59% during maximal exercise with aging (>65 y). Furthermore, aging prolongs restoration of SmO2 back to baseline by >50% after intense exercise. Regulatory factors that contribute to reduced SmO2 with age include blood flow, capillarization, endothelial cells, nitric oxide, and mitochondrial function. These mechanisms are governed by reactive oxygen species (ROS) at the cellular level. However, mishandling of ROS with age ultimately leads to alterations in structure and function of the regulatory factors tasked with maintaining SmO2. The purpose of this review is to provide an update on the current state of the literature regarding age-related effects in SmO2. Furthermore, we attempt to bridge the gap between SmO2 and associated underlying mechanisms affected by aging.
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14
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Skeletal Muscle Biochemical Origin of Exercise Intensity Domains and their Relation to Whole-Body V̇O2 Kinetics. Biosci Rep 2022; 42:231600. [PMID: 35880531 PMCID: PMC9366749 DOI: 10.1042/bsr20220798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/16/2022] [Accepted: 06/29/2022] [Indexed: 11/17/2022] Open
Abstract
This article presents the biochemical intra-skeletal-muscle basis of exercise intensity domains: moderate (M), heavy (H), very heavy (VH) and severe (S). Threshold origins are mediated by a "Pi double-threshold" mechanism of muscle fatigue, which assumes: (1) additional ATP usage, underlying muscle V̇O2 and metabolite slow components, is initiated when inorganic phosphate (Pi) exceeds a critical value (Picrit); (2) exercise is terminated because of fatigue, when Pi reaches a peak value (Pipeak); (3) the Pi increase and additional ATP usage increase mutually stimulate each other forming a positive feedback. M/H and H/VH borders are defined by Pi on-kinetics in relation to Picrit and Pipeak. The values of the ATP usage activity, proportional to power output (PO), for the M/H, H/VH and VH/S borders are lowest in untrained muscle and highest in well-trained muscle. The metabolic range between the M/H and H/VH border (or "H space") decreases with muscle training, while the difference between the H/VH and VH/S border (or "VH space") is only weakly dependent on training status. The absolute magnitude of the muscle V̇O2 slow-component, absent in M exercise, rises gradually with PO to a maximal value in H exercise, and then decreases with PO in VH and S exercise. Simulations of untrained, physically-active and well-trained muscle demonstrate that the muscle M/H border need not be identical to the whole-body M/H border determined from pulmonary V̇O2 on-kinetics and blood lactate, while suggesting that the biochemical origins of the H/VH border reside within skeletal muscle and correspond to whole-body critical power.
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15
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Gløersen Ø, Colosio AL, Boone J, Dysthe DK, Malthe-Sørenssen A, Capelli C, Pogliaghi S. Modeling VO 2 on-kinetics based on intensity-dependent Delayed Adjustment and Loss of Efficiency (DALE). J Appl Physiol (1985) 2022; 132:1480-1488. [PMID: 35482330 DOI: 10.1152/japplphysiol.00570.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study presents and evaluates a new mathematical model of V̇O2 on-kinetics, with the following properties: (i) a progressively slower primary phase following the size-principle of motor unit recruitment, explaining the delayed V̇O2 steady state seen in the heavy exercise intensity domain, and (ii) a severe-domain slow component modelled as a time-dependent decrease in efficiency. Breath-by-breath V̇O2 measurements from eight subjects performing step cycling transitions, in the moderate, heavy and severe exercise domains, were fitted to the conventional 3-phase model and the new model. Model performance was evaluated with a residual analysis and by comparing Bayesian (BIC) and corrected Akaike (AICc) information criteria. The residual analysis showed no systematic deviations, except perhaps for the initial part of the primary phase. BIC favored the new model, being 9.3 (SD 7.1) lower than the conventional model while AICc was similar between models. Compared to the conventional 3-phase model, the proposed model distinguishes between the kinetic adaptations in the heavy and severe domains by predicting a delayed steady state V̇O2 in the heavy and no steady state V̇O2 in the severe domain. This allows to determine when stable oxygen costs of exercise are attainable and it also represents a first step in defining time-dependent oxygen costs when stable energy conversion efficiency is not attainable.
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Affiliation(s)
- Øyvind Gløersen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Department of Physics, University of Oslo, Oslo, Norway.,Smart Sensors and Microsystems, SINTEF Digital, Oslo, Norway
| | - Alessandro L Colosio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | | | | | - Carlo Capelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Silvia Pogliaghi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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16
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Tan R, Wylie LJ, Wilkerson DP, Vanhatalo A, Jones AM. Effects of dietary nitrate on the O 2 cost of submaximal exercise: Accounting for "noise" in pulmonary gas exchange measurements. J Sports Sci 2022; 40:1149-1157. [PMID: 35301929 DOI: 10.1080/02640414.2022.2052471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dietary nitrate (NO3-) supplementation can reduce the oxygen cost of submaximal exercise, but this has not been reported consistently. We hypothesised that the number of step transitions to moderate-intensity exercise, and corresponding effects on the signal-to-noise ratio for pulmonary V˙ O2, may be important in this regard. Twelve recreationally active participants were assigned in a randomised, double-blind, crossover design to supplement for 4 days in three conditions: 1) control (CON; water); 2); PL (NO3--depleted beetroot juice); and 3) BR (NO3--rich beetroot juice). On days 3 and 4, participants completed two 6-min step transitions to moderate-intensity cycle exercise. Breath-by-breath V˙ O2 data were collected and V˙ O2 kinetic responses were determined for a single transition and when the responses to 2, 3 and 4 transitions were ensemble-averaged. Steady-state V˙ O2 was not different between PL and BR when the V˙ O2 response to one-, two- or three-step transition was compared but was significantly lower in BR compared to PL when four-step transitions was considered (PL: 1.33 ± 0.34 vs. BR: 1.31 ± 0.34 L·min-1, P < 0.05). There were no differences in pulmonary V˙ O2 responses between CON and PL (P > 0.05). Multiple step transitions may be required to detect the influence of NO3- supplementation on steady-state V˙ O2.
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Affiliation(s)
- Rachel Tan
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, UK
| | - Lee J Wylie
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, UK
| | - Daryl P Wilkerson
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, UK
| | - Anni Vanhatalo
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, UK
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, UK
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17
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de Aguiar RA, Turnes T, Borszcz FK, Raimundo JAG, Caputo F. NIRS-derived muscle V̇O 2 kinetics after moderate running exercise in healthy males: reliability and associations with parameters of aerobic fitness. Exp Physiol 2022; 107:476-488. [PMID: 35244956 DOI: 10.1113/ep090105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 03/01/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? In vivo muscle oxidative capacity has been evaluated through the mV̇O2 kinetics following single joint exercise using NIRS system. Here, we demonstrated its utility following running exercise. What is the main finding and its importance? We demonstrated that time constant of mV̇O2 kinetics in gastrocnemius following moderate running exercise presents good to excellent reliability. In addition, it was well correlated with parameters of aerobic fitness, such as maximal speed of the incremental test, ventilatory threshold and pulmonary V̇O2 on-kinetics. Therefore, NIRS-derived muscle oxidative capacity together with other physiological measurements may allow a concomitant local and systemic analysis of the components of the oxidative system. ABSTRACT NIRS-derived muscle oxygen uptake (mV̇O2 ) kinetics following single-joint exercise has been used to assess muscle oxidative capacity. However, little evidence is available on the use of this technique following whole-body exercises. Therefore, this study aimed to assess the reliability of the NIRS-derived mV̇O2 kinetics following running exercise and to investigate the relationship between the time constant of mV̇O2 off-kinetics (τmV̇O2 ) with parameters of aerobic fitness. After an incremental test to determine V̇O2 max, first (VT1 ) and second (VT2 ) ventilatory thresholds, and maximal speed (Smax), thirteen males (age = 21 ± 4 years; V̇O2 max = 55.9 ± 3.4 mlꞏkg-1ꞏmin-1) performed three sets (two in the first day and one on a subsequent day) of two repetitions of 6-min running exercise at 90%VT1 . The pulmonary V̇O2 on-kinetics (pV̇O2 ) and mV̇O2 off-kinetics in gastrocnemius were assessed. τmV̇O2 presented no systematic change and satisfactory reliability (SEM and ICC of 4.21 s and 0.49 for between transitions; and 2.65 s and 0.74 averaging τmV̇O2 within each time-set), with no difference (p > 0.3) between the within- (SEM = 2.92 s) and between-day variability (SEM = 2.78 s and 2.19 s between first vs. third set, and second vs. third set, respectively). τmV̇O2 (28.5 ± 4.17 s) correlated significantly (p < 0.05) with Smax (r = -0.66), VT1 (r = -0.64) and time constant of the pV̇O2 on-kinetics (r = 0.69). These findings indicate that NIRS-derived mV̇O2 kinetics in the gastrocnemius following moderate running exercise is a useful and reliable method to assess muscle oxidative capacity. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Rafael A de Aguiar
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianópolis, Brazil
| | - Tiago Turnes
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianópolis, Brazil.,Physical Effort Laboratory, Sports Centre, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Fernando K Borszcz
- Physical Effort Laboratory, Sports Centre, Federal University of Santa Catarina, Florianópolis, Brazil
| | - João A G Raimundo
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianópolis, Brazil
| | - Fabrizio Caputo
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianópolis, Brazil
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18
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Antunes A, Domingos C, Diniz L, Monteiro CP, Espada MC, Alves FB, Reis JF. The Relationship between VO 2 and Muscle Deoxygenation Kinetics and Upper Body Repeated Sprint Performance in Trained Judokas and Healthy Individuals. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19020861. [PMID: 35055684 PMCID: PMC8776052 DOI: 10.3390/ijerph19020861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 01/10/2023]
Abstract
The present study sought to investigate if faster upper body oxygen uptake (VO2) and hemoglobin/myoglobin deoxygenation ([HHb]) kinetics during heavy intensity exercise were associated with a greater upper body repeated-sprint ability (RSA) performance in a group of judokas and in a group of individuals of heterogenous fitness level. Eight judokas (JT) and seven untrained healthy participants (UT) completed an incremental step test, two heavy intensity square-wave transitions and an upper body RSA test consisting of four 15 s sprints, with 45 s rest, from which the experimental data were obtained. In the JT group, VO2 kinetics, [HHb] kinetics and the parameters determined in the incremental test were not associated with RSA. However, when the two groups were combined, the amplitude of the primary phase VO2 and [HHb] were positively associated with the accumulated work in the four sprints (ΣWork). Additionally, maximal aerobic power (MAP), peak VO2 and the first ventilatory threshold (VT1) showed a positive correlation with ΣWork and an inverse correlation with the decrease in peak power output (Dec-PPO) between the first and fourth sprints. Faster VO2 and [HHb] kinetics do not seem to be associated with an increased upper body RSA in JT. However, other variables of aerobic fitness seem to be associated with an increased upper body RSA performance in a group of individuals with heterogeneous fitness level.
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Affiliation(s)
- André Antunes
- Laboratory of Physiology and Biochemistry of Exercise, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal; (A.A.); (L.D.); (C.P.M.); (F.B.A.)
| | - Christophe Domingos
- Life Quality Research Centre, 2040-413 Rio Maior, Portugal; (C.D.); (M.C.E.)
| | - Luísa Diniz
- Laboratory of Physiology and Biochemistry of Exercise, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal; (A.A.); (L.D.); (C.P.M.); (F.B.A.)
| | - Cristina P. Monteiro
- Laboratory of Physiology and Biochemistry of Exercise, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal; (A.A.); (L.D.); (C.P.M.); (F.B.A.)
- Interdisciplinary Centre for Human Performance Research (CIPER), Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal
| | - Mário C. Espada
- Life Quality Research Centre, 2040-413 Rio Maior, Portugal; (C.D.); (M.C.E.)
- Polytechnic Institute of Setúbal, School of Education, 2914-514 Setúbal, Portugal
| | - Francisco B. Alves
- Laboratory of Physiology and Biochemistry of Exercise, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal; (A.A.); (L.D.); (C.P.M.); (F.B.A.)
- Interdisciplinary Centre for Human Performance Research (CIPER), Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal
| | - Joana F. Reis
- Laboratory of Physiology and Biochemistry of Exercise, Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal; (A.A.); (L.D.); (C.P.M.); (F.B.A.)
- Interdisciplinary Centre for Human Performance Research (CIPER), Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz Quebrada-Dafundo, 1495-761 Lisboa, Portugal
- Correspondence:
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19
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Reuveny R, Luboshitz J, Wilkerson D, Bar-Dayan A, DiMenna FJ, Jones AM, Segel MJ. Oxygen Uptake Kinetics during Exercise Reveal Central and Peripheral Limitation in Patients with Ilio-Femoral Venous Obstruction. J Vasc Surg Venous Lymphat Disord 2021; 10:697-704.e4. [PMID: 34958976 DOI: 10.1016/j.jvsv.2021.12.006] [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: 08/25/2021] [Accepted: 12/01/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Pulmonary oxygen uptake (V̇O2) kinetics measured during initiation of exercise mirror energetic transition during daily activity. The aim of this study was to elucidate the pathophysiological mechanisms of exercise limitation of patients with chronic ilio-femoral vein obstruction after deep vein thrombosis by measuring V̇O2 kinetics compared to patients with peripheral arterial disease (PAD) and healthy individuals. METHODS Eleven patients with ilio-femoral vein obstruction (7 man, age 20-65 yrs.), seven patients with PAD (all men, age 44-60 yrs.) and eight healthy participants (5 men, age 28-58 yrs.) were studied. Participants performed upper and lower-limb symptom-limited cardiopulmonary exercise tests on cycle ergometers; and four repeat lower-limb tests at a constant work-rate (WR) corresponding to 90% of the gas exchange threshold for determining V̇O2 kinetics. RESULTS Phase I V̇O2 amplitude in the constant WR tests (% increase over resting V̇O2), representing the initial surge in cardiac output caused by the emptying of leg veins, was 59±19% in the ilio-femoral vein obstruction group, 73±22% in peripheral arterial disease and 85±26% in healthy participants (p=0.055 for ilio-femoral vein obstruction vs. healthy). Phase II V̇O2 kinetics, which largely reflect the kinetics of O2 consumption in the exercising muscles, were slower in ilio-femoral vein obstruction (tau = 42±6 s), and PAD (tau = 49±19 s), compared to healthy participants (23±4 s; p<0.01) CONCLUSIONS: Slow phase II V̇O2 kinetics reflect a slow onset of muscular aerobic metabolism in both ilio-femoral vein obstruction and PAD. Low amplitude phase I of V̇O2 kinetics observed in ilio-femoral vein obstruction suggests a damped cardio-dynamic phase, consistent with reduced venous return from the obstructed veins. These abnormalities of V̇O2 kinetics may contribute to exercise intolerance in ilio-femoral vein obstruction and PAD.
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Affiliation(s)
- Ronen Reuveny
- Pulmonary Institute, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; Physical Therapy Department, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel.
| | - Jacob Luboshitz
- Israeli National Hemophilia Center, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel
| | - Daryl Wilkerson
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Avner Bar-Dayan
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; Vascular Surgery Department, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel
| | - Fred J DiMenna
- Division of Endocrinology, Diabetes and Bone, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Michael J Segel
- Pulmonary Institute, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
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20
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Love LK, Hodgson MD, Keir DA, Kowalchuk JM. Data analysis technique influences blood flow kinetics parameter estimates for moderate- and heavy-intensity exercise transitions. Exp Physiol 2021; 107:82-93. [PMID: 34731518 DOI: 10.1113/ep089834] [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: 06/16/2021] [Accepted: 10/22/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? During exercise, there are fluctuations in conduit artery blood flow (BF) caused by both cardiac and muscle contraction-relaxation cycles. What is the optimal method to process Doppler ultrasound-measured BF for the purpose of characterizing the dynamic response of BF during step-transitions in exercise? What is the main finding and its importance? Continuous BF data were processed in relation to either cardiac or muscle contraction-relaxation cycles and computed based on 'binned' or 'rolling' averages over one, two or five consecutive cycles. Kinetics characterization revealed no data processing technique-specific differences in steady-state BF, but variability in the rapidity at which BF attained steady-state (i.e., mean response time) was observed. ABSTRACT The overall rate of blood flow (BF) adjustment (i.e., kinetics) from the onset of an exercise transition can be quantified by the mean response time (MRT). However, the BF response profile can be distorted during rhythmic, dynamic exercise consequent to variations caused by the cardiac cycle (HR) and the muscle contraction-relaxation (CR) cycle. We examined the extent to which distortions imposed by HR and CR cycles affected BF kinetics. Eight healthy, young men (27 (4) years; mean (SD)) performed transitions of alternate-leg knee-extension exercise from 3 W to either a moderate- (MOD) or heavy-intensity (HVY) power output. Femoral artery BF was continuously measured by Doppler ultrasound and averaged over one, two or five 'binned' (e.g., HR2b, etc.) or 'rolling' (e.g., CR5r, etc.) HR and CR cycles. Among analysis techniques, there were no differences for steady-state BF values at the 3 W baseline. In MOD, MRT using contraction-relaxation cycle (CR1) was smaller than most other analysis techniques. For both MOD and HVY, the 95% confidence interval for MRT was generally larger when using HR- compared to CR-related methods, and monoexponential fits based on 'rolling' averages (HR2r, HR5r, CR2r, CR5r) had a poorer ability to estimate the true end-exercise BF in HVY than in MOD. When modelling BF kinetics, we conclude that the CR1 method is a good option because of its ability to accurately estimate the 'data-determined' end-exercise BF value from the 'model-derived' response, maintain a relatively high density of data points during the transition and yield a relatively small 95% CI.
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Affiliation(s)
- Lorenzo K Love
- Canadian Centre for Activity and Aging, University of Western Ontario, London, Ontario, Canada.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Department of Kinesiology and Physical Education, Redeemer University, Ancaster, Ontario, Canada
| | - Michael D Hodgson
- Canadian Centre for Activity and Aging, University of Western Ontario, London, Ontario, Canada.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Daniel A Keir
- Canadian Centre for Activity and Aging, University of Western Ontario, London, Ontario, Canada.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, University of Western Ontario, London, Ontario, Canada.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Faculty of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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21
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Nyberg M, Christensen PM, Blackwell JR, Hostrup M, Jones AM, Bangsbo J. Nitrate-rich beetroot juice ingestion reduces skeletal muscle O 2 uptake and blood flow during exercise in sedentary men. J Physiol 2021; 599:5203-5214. [PMID: 34587650 DOI: 10.1113/jp281995] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 09/22/2021] [Indexed: 12/21/2022] Open
Abstract
Dietary nitrate supplementation has been shown to reduce pulmonary O2 uptake during submaximal exercise and enhance exercise performance. However, the effects of nitrate supplementation on local metabolic and haemodynamic regulation in contracting human skeletal muscle remain unclear. To address this, eight healthy young male sedentary subjects were assigned in a randomized, double-blind, crossover design to receive nitrate-rich beetroot juice (NO3, 9 mmol) and placebo (PLA) 2.5 h prior to the completion of a double-step knee-extensor exercise protocol that included a transition from unloaded to moderate-intensity exercise (MOD) followed immediately by a transition to intense exercise (HIGH). Compared with PLA, NO3 increased plasma levels of nitrate and nitrite. During MOD, leg V ̇ O 2 and leg blood flow (LBF) were reduced to a similar extent (∼9%-15%) in NO3. During HIGH, leg V ̇ O 2 was reduced by ∼6%-10% and LBF by ∼5%-9% (did not reach significance) in NO3. Leg V ̇ O 2 kinetics was markedly faster in the transition from passive to MOD compared with the transition from MOD to HIGH both in NO3 and PLA with no difference between PLA and NO3. In NO3, a reduction in nitrate and nitrite concentration was detected between arterial and venous samples. No difference in the time to exhaustion was observed between conditions. In conclusion, elevation of plasma nitrate and nitrate reduces leg skeletal muscle V ̇ O 2 and blood flow during exercise. However, nitrate supplementation does not enhance muscle V ̇ O 2 kinetics during exercise, nor does it improve time to exhaustion when exercising with a small muscle mass. KEY POINTS: Dietary nitrate supplementation has been shown to reduce systemic O2 uptake during exercise and improve exercise performance. The effects of nitrate supplementation on local metabolism and blood flow regulation in contracting human skeletal muscle remain unclear. By using leg exercise engaging a small muscle mass, we show that O2 uptake and blood flow are similarly reduced in contracting skeletal muscle of humans during exercise. Despite slower V ̇ O 2 kinetics in the transition from moderate to intense exercise, no effects of nitrate supplementation were observed for V ̇ O 2 kinetics and time to exhaustion. Nitrate and nitrite concentrations are reduced across the exercising leg, suggesting that these ions are extracted from the arterial blood by contracting skeletal muscle.
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Affiliation(s)
- Michael Nyberg
- Department of Nutrition, Exercise and Sports, Integrative Physiology Section, Cardiovascular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Peter M Christensen
- Department of Nutrition, Exercise and Sports, Integrative Physiology Section, Cardiovascular Physiology, University of Copenhagen, Copenhagen, Denmark.,Team Danmark (Danish Elite Sports Organization), Copenhagen, Denmark
| | - Jamie R Blackwell
- Department of Sport and Health Sciences, University of Exeter St Luke's Campus, Exeter, UK
| | - Morten Hostrup
- Department of Nutrition, Exercise and Sports, Integrative Physiology Section, Cardiovascular Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Andrew M Jones
- Department of Sport and Health Sciences, University of Exeter St Luke's Campus, Exeter, UK
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Integrative Physiology Section, Cardiovascular Physiology, University of Copenhagen, Copenhagen, Denmark
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22
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Nixon RJ, Kranen SH, Vanhatalo A, Jones AM. Steady-state [Formula: see text] above MLSS: evidence that critical speed better represents maximal metabolic steady state in well-trained runners. Eur J Appl Physiol 2021; 121:3133-3144. [PMID: 34351531 PMCID: PMC8505327 DOI: 10.1007/s00421-021-04780-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/26/2021] [Indexed: 11/26/2022]
Abstract
The metabolic boundary separating the heavy-intensity and severe-intensity exercise domains is of scientific and practical interest but there is controversy concerning whether the maximal lactate steady state (MLSS) or critical power (synonymous with critical speed, CS) better represents this boundary. We measured the running speeds at MLSS and CS and investigated their ability to discriminate speeds at which \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2 could not be established. Ten well-trained male distance runners completed 9–12 constant-speed treadmill tests, including 3–5 runs of up to 30-min duration for the assessment of MLSS and at least 4 runs performed to the limit of tolerance for assessment of CS. The running speeds at CS and MLSS were significantly different (16.4 ± 1.3 vs. 15.2 ± 0.9 km/h, respectively; P < 0.001). Blood lactate concentration was higher and increased with time at a speed 0.5 km/h higher than MLSS compared to MLSS (P < 0.01); however, pulmonary \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2 did not change significantly between 10 and 30 min at either MLSS or MLSS + 0.5 km/h. In contrast, \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2 increased significantly over time and reached \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2\,\,\max }$$\end{document}V˙O2max at end-exercise at a speed ~ 0.4 km/h above CS (P < 0.05) but remained stable at a speed ~ 0.5 km/h below CS. The stability of \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2 at a speed exceeding MLSS suggests that MLSS underestimates the maximal metabolic steady state. These results indicate that CS more closely represents the maximal metabolic steady state when the latter is appropriately defined according to the ability to stabilise pulmonary \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2.
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Affiliation(s)
- Rebekah J Nixon
- Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX12LU, UK
| | - Sascha H Kranen
- Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX12LU, UK
| | - Anni Vanhatalo
- Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX12LU, UK
| | - Andrew M Jones
- Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter, EX12LU, UK.
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23
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Korzeniewski B. Mechanisms of the effect of oxidative phosphorylation deficiencies on the skeletal muscle bioenergetic system in patients with mitochondrial myopathies. J Appl Physiol (1985) 2021; 131:768-777. [PMID: 34197225 DOI: 10.1152/japplphysiol.00196.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Simulations carried out using a previously developed model of the skeletal muscle bioenergetic system, involving the "inorganic phosphate (Pi) double-threshold" mechanism of muscle fatigue, lead to the conclusion that a decrease in the oxidative phosphorylation (OXPHOS) activity, caused by mutations in mitochondrial or nuclear DNA, is the main mechanism underlying the changes in the kinetic properties of the system in mitochondrial myopathies (MM). These changes generally involve the very-heavy-exercise-like behavior and exercise termination because of fatigue at low work intensities. In particular, a sufficiently large (at a given work intensity) decrease in OXPHOS activity leads to slowing of the primary phase II of the oxygen uptake (V̇o2) on-kinetics, decrease in maximal V̇o2 (V̇o2max), appearance of the slow component of the V̇o2 on-kinetics, exercise intolerance, and lactic acidosis at relatively low power outputs encountered in experimental studies in patients with MM. Thus, the "Pi double-threshold" mechanism of muscle fatigue is able to account, at least semiquantitatively, for various kinetic effects of inborn OXPHOS deficiencies of the skeletal muscle bioenergetic system. Exercise can be potentially lengthened and V̇o2max elevated in patients with MM through an increase in peak Pi (Pipeak), at which exercise is terminated because of fatigue. Generally, a mechanism underlying the kinetic effects of OXPHOS deficiencies on the skeletal muscle bioenergetic system in MM is proposed that was absent in the literature.NEW & NOTEWORTHY A mechanism of the OXPHOS deficiencies-induced changes of the skeletal muscle bioenergetic system in patients with mitochondrial myopathies (MM), namely, appearance of the slow component of the V̇o2 on-kinetics at relatively low work intensities, slowed primary phase II of the V̇o2 on-kinetics, lowered V̇o2max, and lactic acidosis is proposed. It involves a decrease in OXPHOS activity acting through the "Pi double-threshold" mechanism of muscle fatigue comprising initiation of the additional ATP usage and termination of exercise.
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24
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Slade P, Kochenderfer MJ, Delp SL, Collins SH. Sensing leg movement enhances wearable monitoring of energy expenditure. Nat Commun 2021; 12:4312. [PMID: 34257310 PMCID: PMC8277831 DOI: 10.1038/s41467-021-24173-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 06/07/2021] [Indexed: 12/31/2022] Open
Abstract
Physical inactivity is the fourth leading cause of global mortality. Health organizations have requested a tool to objectively measure physical activity. Respirometry and doubly labeled water accurately estimate energy expenditure, but are infeasible for everyday use. Smartwatches are portable, but have significant errors. Existing wearable methods poorly estimate time-varying activity, which comprises 40% of daily steps. Here, we present a Wearable System that estimates metabolic energy expenditure in real-time during common steady-state and time-varying activities with substantially lower error than state-of-the-art methods. We perform experiments to select sensors, collect training data, and validate the Wearable System with new subjects and new conditions for walking, running, stair climbing, and biking. The Wearable System uses inertial measurement units worn on the shank and thigh as they distinguish lower-limb activity better than wrist or trunk kinematics and converge more quickly than physiological signals. When evaluated with a diverse group of new subjects, the Wearable System has a cumulative error of 13% across common activities, significantly less than 42% for a smartwatch and 44% for an activity-specific smartwatch. This approach enables accurate physical activity monitoring which could enable new energy balance systems for weight management or large-scale activity monitoring.
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Affiliation(s)
- Patrick Slade
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
| | - Mykel J Kochenderfer
- Department of Aeronautics and Astronautics, Stanford University, Stanford, CA, USA
| | - Scott L Delp
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
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25
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Combret Y, Medrinal C, Prieur G, Robledo Quesada A, Gillot T, Gravier FE, Bonnevie T, Lamia B, Le Roux P, Reychler G. Oxygen uptake kinetics during treadmill walking in adolescents with clinically stable cystic fibrosis. Physiother Theory Pract 2021; 38:1389-1397. [PMID: 33390080 DOI: 10.1080/09593985.2020.1868029] [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: 12/14/2022]
Abstract
Background: Oxygen uptake (V̇O2) kinetics have been shown to be slowed in adolescents with cystic fibrosis (CF) during heavy-intensity cycling and maximal exercise testing.Objectives: This study investigated V̇O2 kinetics in adolescents with CF compared to control adolescents (CON) during a treadmill-walking exercise.Methods: Eight adolescents with CF and mild-to-moderate pulmonary obstruction (5 girls; 13.1 ± 2.5 years; FEV1 67.8 ± 21.4%) and 18 CON adolescents (10 girls; 13.8 ± 1.8 years) were recruited. Pulmonary gas exchange and ventilation were measured during a single transition of 10 min of treadmill walking and a 5 min seated recovery period. Participant's walking speed was determined during a one-minute self-paced walking task along a 50-m corridor. A six-parameter, non-linear regression model was used to describe the changes in V̇O2 function during the treadmill walking and recovery, with monoexponential curve fitting used to describe the mean response time (MRT1) at the onset of exercise, and the half-life (T1/2V̇O2) at the offset of exercise. V̇O2 baseline and amplitude, minute ventilation and respiratory equivalents were recorded.Results: V̇O2 kinetics were slower in CF group compared to CON group during the treadmill walking with a greater MRT1 (32 ± 14 s vs 21 ± 16 s; p = .04, effect size = 0.75). The T1/2V̇O2 was prolonged during recovery in CF group compared to CON group (86 ± 24 s vs 56 ± 22 s; p = .04, effect size = 1.31). The mean VE/V̇CO2 during exercise was the only parameter significantly greater in CF group compared to CON group (32.9 ± 2.3 vs 29.0 ± 2.4; p < .01, effect size = 1.66). Conclusion: V̇O2 kinetics were found to be slowed in adolescents with CF during treadmill walking.
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Affiliation(s)
- Yann Combret
- Physiotherapy Department, Le Havre Hospital, Montivilliers, France.,Institut De Recherche Et d'Expérimentation Clinique (IREC), Pôle De Pneumologie, ORL and Dermatologie, Université Catholique De Louvain, Brussels, Belgium
| | - Clément Medrinal
- Physiotherapy Department, Le Havre Hospital, Montivilliers, France.,Erphan, Paris-Saclay University, UVSQ, Versailles, France.,Saint Michel School of Physiotherapy, Paris, France
| | - Guillaume Prieur
- Physiotherapy Department, Le Havre Hospital, Montivilliers, France.,Institut De Recherche Et d'Expérimentation Clinique (IREC), Pôle De Pneumologie, ORL and Dermatologie, Université Catholique De Louvain, Brussels, Belgium.,UPRES EA3830 - GRHV, Normandie University, UNIROUEN, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France
| | | | - Timothée Gillot
- Cetaps, EA3832, Rouen University, Mont Saint Aignan, France.,School of Physiotherapy, Rouen University Hospital, Rouen, France
| | - Francis-Edouard Gravier
- UPRES EA3830 - GRHV, Normandie University, UNIROUEN, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France.,ADIR Association, Rouen University Hospital, Bois-Guillaume, France
| | - Tristan Bonnevie
- UPRES EA3830 - GRHV, Normandie University, UNIROUEN, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France.,ADIR Association, Rouen University Hospital, Bois-Guillaume, France
| | - Bouchra Lamia
- UPRES EA3830 - GRHV, Normandie University, UNIROUEN, Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France.,Pulmonology Department, Le Havre Hospital, Montivilliers, France.,Intensive Care Unit, Respiratory Department, Rouen University Hospital, Rouen, France
| | - Pascal Le Roux
- Pediatric Department, Le Havre Hospital, Montivilliers, France
| | - Grégory Reychler
- Institut De Recherche Et d'Expérimentation Clinique (IREC), Pôle De Pneumologie, ORL and Dermatologie, Université Catholique De Louvain, Brussels, Belgium.,Department of Physical Medicine and Rehabilitation, Saint-Luc University Clinics, Brussels, Belgium
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26
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Stucky F, Aliverti A, Kayser B, Uva B. Priming the cardiodynamic phase of pulmonary oxygen uptake through voluntary modulations of the respiratory pump at the onset of exercise. Exp Physiol 2020; 106:555-566. [PMID: 33369778 DOI: 10.1113/ep089180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/11/2020] [Indexed: 01/15/2023]
Abstract
NEW FINDINGS What is the central question of this study? The initial increase in oxygen uptake ( V ̇ O 2 ) at exercise onset results from pulmonary perfusion changes secondary to an increased venous return. Breathing mechanics contribute to venous return through abdominal and intrathoracic pressures variation. Can voluntary breathing techniques (abdominal or rib cage breathing) increase venous return and improve V ̇ O 2 at exercise onset? What is the main finding and its importance? Abdominal and rib cage breathing increase venous return and V ̇ O 2 at exercise onset. This mechanism could be clinically relevant in patients with impaired cardiac function limiting oxygen transport. ABSTRACT We examined how different breathing patterns can modulate venous return and alveolar gas transfer during exercise transients in humans. Ten healthy men transitioned from rest to moderate cycling while breathing spontaneously (SP) or with voluntary increases in abdominal (AB) or intrathoracic (RC) pressure swings. We used double body plethysmography to determine blood displacements between the trunk and the extremities (Vbs ). From continuous signals of airflow and O2 fraction, we calculated breath-by-breath oxygen uptake at the mouth and used optoelectronic plethysmography to correct for lung O2 store changes and calculate alveolar O2 transfer ( V ̇ O 2 A ). Oesophageal (Poes ) and gastric (Pga ) pressures were monitored using balloon-tipped catheters. Cardiac stroke volume was measured using impedance cardiography. During the cardiodynamic phase (Φ1) of V ̇ O 2 A -on kinetics (20 s following exercise onset), AB and RC increased total alveolar oxygen transfer compared to SP (227 ± 32, P = 0.019 vs. 235 ± 27, P = 0.001 vs. 206 ± 20 ml, mean ± SD). Pga and Poes swings increased with AB (by 24.4 ± 9.6 cmH2 O, P < 0.001) and RC (by 14.5 ± 5.7 cmH2 O, P < 0.001), respectively. AB yielded a greater increase in intra-breath Vbs swings compared with RC and SP (+0.30 ± 0.14 vs. +0.16 ± 0.11, P < 0.001 vs. +0.10 ± 0.05 ml, P = 0.006) and increased the sum of stroke volumes compared to SP (4.47 ± 1.28 vs. 3.89 ± 0.96 litres, P = 0.053), while RC produced significant central blood translocation from the extremities compared with SP (by 493 ± 311 ml, P < 0.001). Our findings indicate that combining exercise onset with AB or RC increases venous return, thus increasing mass oxygen transport above metabolic consumption during Φ1 and limiting the oxygen deficit incurred.
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Affiliation(s)
- Frédéric Stucky
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Andrea Aliverti
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Bengt Kayser
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Barbara Uva
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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27
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Sigmoidal VO 2 on-kinetics: A new pattern in VO 2 responses at the lower district of extreme exercise domain. Respir Physiol Neurobiol 2020; 281:103507. [PMID: 32726644 DOI: 10.1016/j.resp.2020.103507] [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] [Received: 02/04/2020] [Revised: 07/06/2020] [Accepted: 07/23/2020] [Indexed: 11/21/2022]
Abstract
The aim of the study was to analyse the VO2 on-kinetics belonging to the work rates within the lower district of extreme exercise domain. Maximal O2 utilisation and peak power outputs of eight well-trained cyclists were revealed by multisession trails. Critical threshold (CT) as the lower boundary of severe domain and aerobic limit power (ALP) as the upper boundary of severe domain were determined by multisession constant-load exercises. VO2 on-kinetics over time were best fitted by multicomponent exponential models described by an initial concave-up response known as cardio-dynamic phase (τ = 18.2 ± 2.88 s; a = 1.56 ± 0.39 L·min-1) before a primary concave-up phase (τ = 35.4 ± 12.4 s; a = 1.53 ± 0.36 L·min-1), and then a slow component in two of the participants (τ = 80.8 ± 37 s; a = 0.47 ± 0.05 L·min-1) or without a slow component in six of the participants during exercises performed at 50 W above the CT (R2≥0.96; SEE ≤ 0.24; p < 0.001). However, VO2 on-kinetics over time belonging to exercises performed at 50 W above the ALP were best fitted by sigmoidal model (R2≥0.98; SEE ≤ 0.14; p < 0.001) in comparison with linear (R2 = 0.37-0.66; SEE = 0.46-0.64; p < 0.01), or exponential functions (p> 0.05). Indeed, during those exercises, a short period of convex-up response (τ = 16.8 ± 3.1 s; a = 1.72 ± 0.39 L·min-1) was determined just before a concave-up primary phase in VO2 over time (τ = 24.6 ± 5.86 s; a = 1.31 ± 0.20 L·min-1). It was shown that multicomponent exponential trend in VO2 transformed into a sigmoidal shape, once the work rate exceeded the upper boundary of severe exercise domain.
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28
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Zuccarelli L, do Nascimento Salvador PC, Del Torto A, Fiorentino R, Grassi B. Skeletal muscle V̇o2 kinetics by the NIRS repeated occlusions method during the recovery from cycle ergometer exercise. J Appl Physiol (1985) 2020; 128:534-544. [DOI: 10.1152/japplphysiol.00580.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) has been utilized as a noninvasive method to evaluate skeletal muscle mitochondrial function in humans, by calculating muscle V̇o2 (V̇o2 m) recovery (off-) kinetics following short light-intensity plantar flexion exercise. The aim of the present study was to determine V̇o2 m off- kinetics following standard cycle ergometer exercise of different intensities. Fifteen young physically active healthy men performed an incremental exercise (INCR) up to exhaustion and two repetitions of constant work-rate (CWR) exercises at 80% of gas exchange threshold (GET; MODERATE) and at 40% of the difference between GET and peak pulmonary V̇o2 (V̇o2 p; HEAVY). V̇o2 p and vastus lateralis muscle fractional O2 extraction by NIRS (Δ[deoxy(Hb+Mb)]) were recorded continuously. Transient arterial occlusions were carried out at rest and during the recovery for V̇o2 m calculation. All subjects tolerated the repeated occlusions protocol without problems. The quality of the monoexponential fitting for V̇o2 m off-kinetics analysis was excellent (0.93≤ r2≤0.99). According to interclass correlation coefficient, the test-retest reliability was moderate to good. V̇o2 m values at the onset of recovery were ~27, ~38, and ~35 times higher (in MODERATE, HEAVY, and INCR, respectively) than at rest. The time constants (τ) of V̇o2 m off-kinetics were lower ( P < 0.001) following MODERATE (29.1 ± 6.8 s) vs. HEAVY (40.8 ± 10.9) or INCR (42.9 ± 10.9), suggesting an exercise intensity dependency of V̇o2 m off-kinetics. Only following MODERATE the V̇o2 m off-kinetics were faster than the V̇o2 p off-kinetics. V̇o2 m off-kinetics, determined noninvasively by the NIRS repeated occlusions technique, can be utilized as a functional evaluation tool of skeletal muscle oxidative metabolism also following conventional cycle ergometer exercise. NEW & NOTEWORTHY This is the first study in which muscle V̇o2 recovery kinetics, determined noninvasively by near-infrared spectroscopy (NIRS) by utilizing the repeated occlusions method, was applied following standard cycle ergometer exercise of different intensities. The results demonstrate that muscle V̇o2 recovery kinetics, determined noninvasively by the NIRS repeated occlusions technique, can be utilized as a functional evaluation tool of skeletal muscle oxidative metabolism also following conventional cycle ergometer exercise, overcoming significant limitations associated with the traditionally proposed protocol.
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Affiliation(s)
| | | | | | | | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy
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Breese BC, Saynor ZL, Barker AR, Armstrong N, Williams CA. Relationship between (non)linear phase II pulmonary oxygen uptake kinetics with skeletal muscle oxygenation and age in 11-15 year olds. Exp Physiol 2019; 104:1929-1941. [PMID: 31512297 DOI: 10.1113/ep087979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/09/2019] [Indexed: 12/28/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do the phase II parameters of pulmonary oxygen uptake ( V ̇ O 2 ) kinetics display linear, first-order behaviour in association with alterations in skeletal muscle oxygenation during step cycling of different intensities or when exercise is initiated from an elevated work rate in youths. What is the main finding and its importance? Both linear and non-linear features of phase II V ̇ O 2 kinetics may be determined by alterations in the dynamic balance between microvascular O2 delivery and utilization in 11-15 year olds. The recruitment of higher-order (i.e. type II) muscle fibres during 'work-to-work' cycling might be responsible for modulating V ̇ O 2 kinetics with chronological age. ABSTRACT This study investigated in 19 male youths (mean age: 13.6 ± 1.1 years, range: 11.7-15.7 years) the relationship between pulmonary oxygen uptake ( V ̇ O 2 ) and muscle deoxygenation kinetics during moderate- and very heavy-intensity 'step' cycling initiated from unloaded pedalling (i.e. U → M and U → VH) and moderate to very heavy-intensity step cycling (i.e. M → VH). Pulmonary V ̇ O 2 was measured breath-by-breath along with the tissue oxygenation index (TOI) of the vastus lateralis using near-infrared spectroscopy. There were no significant differences in the phase II time constant ( τ V ̇ O 2 p ) between U → M and U → VH (23 ± 6 vs. 25 ± 7 s; P = 0.36); however, the τ V ̇ O 2 p was slower during M → VH (42 ± 16 s) compared to other conditions (P < 0.001). Quadriceps TOI decreased with a faster (P < 0.01) mean response time (MRT; i.e. time delay + τ) during U → VH (14 ± 2 s) compared to U → M (22 ± 4 s) and M → VH (20 ± 6 s). The difference (Δ) between the τ V ̇ O 2 p and MRT-TOI was greater during U → VH compared to U → M (12 ± 7 vs. 2 ± 7 s, P < 0.001) and during M → VH (23 ± 15 s) compared to other conditions (P < 0.02), suggesting an increased proportional speeding of fractional O2 extraction. The slowing of the τ V ̇ O 2 p during M → VH relative to U → M and U → VH correlated positively with chronological age (r = 0.68 and 0.57, respectively, P < 0.01). In youths, 'work-to-work' transitions slowed microvascular O2 delivery-to-O2 utilization with alterations in phase II V ̇ O 2 dynamics accentuated between the ages of 11 and 15 years.
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Affiliation(s)
- Brynmor C Breese
- School of Biomedical Sciences, Faculty of Medicine and Dentistry, University of Plymouth, Plymouth, UK
| | - Zoe L Saynor
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, UK
| | - Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Neil Armstrong
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Craig A Williams
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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30
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial Po 2 kinetics during recovery from contractions. J Appl Physiol (1985) 2019; 127:930-939. [PMID: 31369325 DOI: 10.1152/japplphysiol.00297.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The oxygen partial pressure in the interstitial space (Po2 is) drives O2 into the myocyte via diffusion, thus supporting oxidative phosphorylation. Although crucial for metabolic recovery and the capacity to perform repetitive tasks, the time course of skeletal muscle Po2 is during recovery from contractions remains unknown. We tested the hypothesis that Po2 is would recover to resting values and display considerable on-off asymmetry (fast on-, slow off-kinetics), reflective of asymmetric capillary hemodynamics. Microvascular Po2 (Po2 mv) was also evaluated to test the hypothesis that a significant transcapillary gradient (ΔPo2 = Po2 mv - Po2 is) would be sustained during recovery. Po2 mv and Po2 is (expressed in mmHg) were determined via phosphorescence quenching in the exposed rat spinotrapezius muscle during and after submaximal twitch contractions (n = 12). Po2 is rose exponentially (P < 0.05) from end-contraction (11.1 ± 5.1), such that the end-recovery value (17.9 ± 7.9) was not different from resting Po2 is (18.5 ± 8.1; P > 0.05). Po2 is off-kinetics were slower than on-kinetics (mean response time: 53.1 ± 38.3 versus 18.5 ± 7.3 s; P < 0.05). A significant transcapillary ΔPo2 observed at end-contraction (16.6 ± 7.4) was maintained throughout recovery (end-recovery: 18.8 ± 9.6; P > 0.05). Consistent with our hypotheses, muscle Po2 is recovered to resting values with slower off-kinetics compared with the on-transient in line with the on-off asymmetry for capillary hemodynamics. Maintenance of a substantial transcapillary ΔPo2 during recovery supports that the microvascular-interstitium interface provides considerable resistance to O2 transport. As dictated by Fick's law (V̇o2 = Do2 × ΔPo2), modulation of O2 flux (V̇o2) during recovery must be achieved via corresponding changes in effective diffusing capacity (Do2; mainly capillary red blood cell hemodynamics and distribution) in the face of unaltered ΔPo2.NEW & NOTEWORTHY Capillary blood-myocyte O2 flux (V̇o2) is determined by effective diffusing capacity (Do2; mainly erythrocyte hemodynamics and distribution) and microvascular-interstitial Po2 gradients (ΔPo2 = Po2 mv - Po2 is). We show that Po2 is demonstrates on-off asymmetry consistent with Po2 mv and erythrocyte kinetics during metabolic transitions. A substantial transcapillary ΔPo2 was preserved during recovery from contractions, indicative of considerable resistance to O2 diffusion at the microvascular-interstitium interface. This reveals that effective Do2 declines in step with V̇o2 during recovery, as per Fick's law.
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Affiliation(s)
- Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana.,Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Hiroaki Eshima
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - 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
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Slade P, Troutman R, Kochenderfer MJ, Collins SH, Delp SL. Rapid energy expenditure estimation for ankle assisted and inclined loaded walking. J Neuroeng Rehabil 2019; 16:67. [PMID: 31171003 PMCID: PMC6555733 DOI: 10.1186/s12984-019-0535-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 05/14/2019] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Estimating energy expenditure with indirect calorimetry requires expensive equipment and several minutes of data collection for each condition of interest. While several methods estimate energy expenditure using correlation to data from wearable sensors, such as heart rate monitors or accelerometers, their accuracy has not been evaluated for activity conditions or subjects not included in the correlation process. The goal of our study was to develop data-driven models to estimate energy expenditure at intervals of approximately one second and demonstrate their ability to predict energetic cost for new conditions and subjects. Model inputs were muscle activity and vertical ground reaction forces, which are measurable by wearable electromyography electrodes and pressure sensing insoles. METHODS We developed models that estimated energy expenditure while walking (1) with ankle exoskeleton assistance and (2) while carrying various loads and walking on inclines. Estimates were made each gait cycle or four second interval. We evaluated the performance of the models for three use cases. The first estimated energy expenditure (in Watts) during walking conditions for subjects with some subject specific training data available. The second estimated all conditions in the dataset for a new subject not included in the training data. The third estimated new conditions for a new subject. RESULTS The mean absolute percent errors in estimated energy expenditure during assisted walking conditions were 4.4%, 8.0%, and 8.1% for the three use cases, respectively. The average errors in energy expenditure estimation during inclined and loaded walking conditions were 6.1%, 9.7%, and 11.7% for the three use cases. For models not using subject-specific data, we evaluated the ability to order the magnitude of energy expenditure across conditions. The average percentage of correctly ordered conditions was 63% for assisted walking and 87% for incline and loaded walking. CONCLUSIONS We have determined the accuracy of estimating energy expenditure with data-driven models that rely on ground reaction forces and muscle activity for three use cases. For experimental use cases where the accuracy of a data-driven model is sufficient and similar training data is available, standard indirect calorimetry could be replaced. The models, code, and datasets are provided for reproduction and extension of our results.
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Affiliation(s)
- Patrick Slade
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
| | - Rachel Troutman
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Mykel J Kochenderfer
- Department of Aeronautics and Astronautics, Stanford University, Stanford, CA, USA
| | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Scott L Delp
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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Onslev J, Jensen J, Bangsbo J, Wojtaszewski J, Hostrup M. β2-Agonist Induces Net Leg Glucose Uptake and Free Fatty Acid Release at Rest but Not During Exercise in Young Men. J Clin Endocrinol Metab 2019; 104:647-657. [PMID: 30285125 DOI: 10.1210/jc.2018-01349] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/28/2018] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The role of selective β2-adrenergic stimulation in regulation of leg glucose uptake and free fatty acid (FFA) balance is inadequately explored in humans. The objective of this study was to investigate β2-adrenergic effects on net leg glucose uptake and clearance, as well as FFA balance at rest and during exercise. DESIGN The study was a randomized, placebo-controlled crossover trial where 10 healthy men received either infusion of β2-agonist terbutaline (0.2 to 0.4 mg) or placebo. Net leg glucose uptake and clearance and FFA balance were determined at rest and during 8 minutes of knee extensor exercise using Fick's principle. Vastus lateralis muscle biopsies were collected at rest and at cessation of exercise. The primary outcome measure was net leg glucose uptake. RESULTS At rest, net leg glucose uptake and clearance were 0.35 (±0.16) mmol/min and 41 (±17) mL/min (mean ± 95% CI) higher (P < 0.001) for terbutaline than placebo, corresponding to increases of 84% and 70%. During exercise, no treatment differences were observed in net leg glucose uptake, whereas clearance was 101 (±86) mL/min lower (P < 0.05) for terbutaline than placebo. At rest, terbutaline induced a net leg FFA release of 21 (±14) µmol/min, being different from placebo (P = 0.04). During exercise, net leg FFA uptake was not different between the treatments. CONCLUSIONS These observations indicate that β2-agonist alters net leg glucose uptake and clearance, as well as FFA balance in humans, which is associated with myocellular β2-adrenergic and insulin-dependent signaling. Furthermore, the study shows that exercise confounds the β2-adrenergic effect on net leg glucose uptake and FFA balance.
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Affiliation(s)
- Johan Onslev
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Wojtaszewski
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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Korzeniewski B. Muscle V˙O2-power output nonlinearity in constant-power, step-incremental, and ramp-incremental exercise: magnitude and underlying mechanisms. Physiol Rep 2018. [PMCID: PMC6234149 DOI: 10.14814/phy2.13915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A computer model of the skeletal muscle bioenergetic system was used to simulate time courses of muscle oxygen consumption (V˙O2), cytosolic metabolite (ADP, PCr, Pi, and ATP) concentrations, and pH during whole‐body constant‐power exercise (CPE) (6 min), step‐incremental exercise (SIE) (30 W/3 min), and slow (10 W/min), medium (30 W/min), and fast (50 W/min) ramp‐incremental exercise (RIE). Different ESA (each‐step activation) of oxidative phosphorylation (OXPHOS) intensity‐ATP usage activity relationships, representing different muscle fibers recruitment patterns, gave best agreement with experimental data for CPE, and for SIE and RIE. It was assumed that the muscle V˙O2‐power output (PO) nonlinearity is related to a time‐ and PO‐dependent increase in the additional ATP usage underlying the slow component of the V˙O2 on‐kinetics minus the increase in ATP supply by anaerobic glycolysis leading to a decrease in V˙O2. The muscle V˙O2‐PO relationship deviated upward (+) or downward (−) from linearity above critical power (CP), and the nonlinearity equaled +16% (CPE),+12% (SIE), +8% (slow RIE), +1% (moderate RIE), and −2% (fast RIE) at the end of exercise, in agreement with experimental data. During SIE and RIE, changes in PCr and Pi accelerated moderately above CP, while changes in ADP and pH accelerated significantly with time and PO. It is postulated that the intensity of the additional ATP usage minus ATP supply by anaerobic glycolysis determines the size of the muscle V˙O2‐PO nonlinearity. It is proposed that the extent of the additional ATP usage is proportional to the time integral of PO ‐ CP above CP.
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Effects of ischemic preconditioning on economy, VO2 kinetics and cycling performance in endurance athletes. Eur J Appl Physiol 2018; 118:2541-2549. [DOI: 10.1007/s00421-018-3979-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/25/2018] [Indexed: 01/01/2023]
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Drescher U. Impact of venous return on pulmonary oxygen uptake kinetics during dynamic exercise: in silico time series analyses from muscles to lungs. J Appl Physiol (1985) 2018; 125:1150-1164. [DOI: 10.1152/japplphysiol.01058.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of the present study was to investigate whether a single-compartment (SCM) and a multi-compartment (MCM) venous return model will produce significantly different time-delaying and distortive effects on pulmonary oxygen uptake (V̇o2pulm) responses with equal cardiac outputs (Q̇) and muscle oxygen uptake (V̇o2musc) inputs. For each model, 64 data sets were simulated with alternating Q̇ and V̇o2musc kinetics—time constants (τ) ranging from 10 to 80 s—as responses to pseudorandom binary sequence work rate (WR) changes. Kinetic analyses were performed by using cross-correlation functions (CCFs) between WR with V̇o2pulm and V̇o2musc. Higher maxima of the CCF courses indicate faster system responses—equal to smaller τ values of the variables of interest (e.g., τV̇o2musc). The models demonstrated a highly significant relationship for the resulting V̇o2pulm responses ( r = 0.976, P < 0.001, n = 64). Both models showed significant differences between V̇o2pulm and V̇o2musc kinetics for τV̇o2musc ranging from 10 to 30 s ( P < 0.05 each). In addition, a significant difference in V̇o2pulm kinetics ( P < 0.05) between the models was observed for very fast V̇o2musc kinetics (τ = 10 s). The combinations of fast Q̇ dynamics and slow V̇o2musc kinetics yield distinct deviations in the resultant V̇o2pulm responses compared with V̇o2musc kinetics. Therefore, the venous return models should be used with care and caution if the aim is to infer V̇o2musc by means of V̇o2pulm kinetics. Finally, the resultant V̇o2pulm responses seem to be complex and most likely unpredictable if no cardiodynamic measurements are available in vivo. NEW & NOTEWORTHY A single-compartment and a multi-compartment venous return model were tested to see whether they result in different pulmonary oxygen uptake (V̇o2pulm) kinetics from equal cardiac output and muscle oxygen uptake (V̇o2musc) kinetics. To infer V̇o2musc kinetics by means of V̇o2pulm kinetics, both models should only be used for V̇o2musc time constants ranging from 40 to 80 s. The resultant V̇o2pulm responses seem to be complex and most likely unpredictable if no cardiodynamic measurements are available.
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Affiliation(s)
- Uwe Drescher
- Institute of Physiology and Anatomy, German Sport University Cologne, Cologne, Germany
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Pornsuriyasak P, Rambod M, Effros RM, Casaburi R, Porszasz J. Oxygen Uptake and Lactate Kinetics in Patients with Chronic Obstructive Pulmonary Disease during Heavy Intensity Exercise: Role of Pedaling Cadence. COPD 2018; 15:283-293. [PMID: 30156941 DOI: 10.1080/15412555.2018.1487391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Oxygen uptake slow component ([Formula: see text]sc) is associated with lactate accumulation, likely a contribution of poorly oxidative muscle fibers. We aimed to test the hypothesis that higher muscle tension during slow pedaling rates would yield more prominent [Formula: see text]sc in healthy subjects, but not in COPD patients. Eight severe COPD patients and 8 age-matched healthy individuals performed 4 rest-heavy exercise transitions at 40 and 80 RPM. Work rates at the two cadences were balanced. Venous blood was sampled for measurement of lactate concentration at rest and every 2 minutes until the end of exercise. [Formula: see text] kinetics were analyzed utilizing nonlinear regression. [Formula: see text] phase II amplitudes at the two cadences were similar in both groups. In healthy individuals, [Formula: see text]sc was steeper at 40 than 80 RPM (46.6 ± 12.0 vs. 29.5 ± 11.7 mL/min2, p = 0.002) but not in COPD patients (16.2 ± 14.7 vs. 13.3 ± 7.6 mL/min2). End-exercise lactate concentration did not differ between cadences in either group. In healthy individuals, greater slow-cadence [Formula: see text]sc seems likely related to oxidative muscle fiber recruitment at higher muscular tension. COPD patients, known to have fast-twitch fiber predominance, might be unable to recruit oxidative fibers at high muscle tension, blunting [Formula: see text]sc response.
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Affiliation(s)
- Prapaporn Pornsuriyasak
- a Division of Pulmonary and Critical Care, Faculty of Medicine , Ramathibodi Hospital, Mahidol University , Bangkok , Thailand
| | - Mehdi Rambod
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA.,c Division of Cardiology , University of Vermont College of Medicine , Burlington , Vermont , USA
| | - Richard M Effros
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
| | - Richard Casaburi
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
| | - Janos Porszasz
- b Rehabilitation Clinical Trials Center , Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance , California , USA
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Temporal dissociation between muscle and pulmonary oxygen uptake kinetics: influences of perfusion dynamics and arteriovenous oxygen concentration differences in muscles and lungs. Eur J Appl Physiol 2018; 118:1845-1856. [PMID: 29934765 DOI: 10.1007/s00421-018-3916-x] [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: 02/13/2018] [Accepted: 06/08/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE The aim of the study was to test whether or not the arteriovenous oxygen concentration difference (avDO2) kinetics at the pulmonary (avDO2pulm) and muscle (avDO2musc) levels is significantly different during dynamic exercise. METHODS A re-analysis involving six publications dealing with kinetic analysis was utilized with an overall sample size of 69 participants. All studies comprised an identical pseudorandom binary sequence work rate (WR) protocol-WR changes between 30 and 80 W-to analyze the kinetic responses of pulmonary ([Formula: see text]) and muscle ([Formula: see text]) oxygen uptake kinetics as well as those of avDO2pulm and avDO2musc. RESULTS A significant difference between [Formula: see text] (0.395 ± 0.079) and [Formula: see text] kinetics (0.330 ± 0.078) was observed (p < 0.001), where the variables showed a significant relationship (rSP = 0.744, p < 0.001). There were no significant differences between avDO2musc (0.446 ± 0.077) and avDO2pulm kinetics (0.451 ± 0.075), which are highly correlated (r = 0.929, p < 0.001). CONCLUSION It is suggested that neither avDO2pulm nor avDO2musc kinetic responses seem to be responsible for the differences between estimated [Formula: see text] and measured [Formula: see text] kinetics. Obviously, the conflation of avDO2 and perfusion ([Formula: see text] ) at different points in time and at different physiological levels drive potential differences in [Formula: see text] and [Formula: see text] kinetics. Therefore, [Formula: see text] should, in general, be considered whenever oxygen uptake kinetics are analyzed or discussed.
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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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Korzeniewski B. Regulation of oxidative phosphorylation is different in electrically- and cortically-stimulated skeletal muscle. PLoS One 2018; 13:e0195620. [PMID: 29698403 PMCID: PMC5919680 DOI: 10.1371/journal.pone.0195620] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/26/2018] [Indexed: 01/09/2023] Open
Abstract
A computer model of the skeletal muscle bioenergetic system was used to study the regulation of oxidative phosphorylation (OXPHOS) in electrically-stimulated and cortically-stimulated skeletal muscle. Two types of the dependence of the intensity of each-step activation (ESA) of OXPHOS complexes on ATP usage activity were tested: power-type dependence and saturating-type dependence. The dependence of muscle oxygen consumption ([Formula: see text]), phosphocreatine (PCr), cytosolic ADP, ATP, inorganic phosphate (Pi), pH and τp (characteristic transition time) of the principal component of the muscle [Formula: see text] on-kinetics on the ATP usage activity was simulated for both types of the ESA intensity-ATP usage activity dependence. Computer simulations involving the power-type dependence predict system properties that agree well with experimental data for electrically-stimulated muscle. On the other hand, model predictions for the saturating-type dependence in the presence of the 'additional' ATP usage (postulated previously to underlie the slow component of the VO2 on-kinetics) reproduce well system properties encountered in human skeletal muscle during voluntary exercise. It is postulated that the difference between the regulation and kinetic properties of the system in electrically- and cortically-stimulated muscle is mostly due to the different muscle fibers recruitment pattern. In the former, all fiber types are recruited in parallel already at low power output (PO) values, while in the latter type I fibers (with higher ESA intensity) are stimulated at low PO values, while type II fibers (especially type II b and IIx fibers) with low ESA intensity are recruited predominantly at high PO values.
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Affiliation(s)
- Bernard Korzeniewski
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
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Piil P, Jørgensen TS, Egelund J, Rytter N, Gliemann L, Bangsbo J, Hellsten Y, Nyberg M. Effects of aging and exercise training on leg hemodynamics and oxidative metabolism in the transition from rest to steady-state exercise: role of cGMP signaling. Am J Physiol Regul Integr Comp Physiol 2018; 315:R274-R283. [PMID: 29668326 DOI: 10.1152/ajpregu.00446.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging is associated with slower skeletal muscle O2 uptake (V̇o2) kinetics; however, the mechanisms underlying this effect of age are unclear. Also, the effects of exercise training in elderly on the initial vascular and metabolic response to exercise remain to be elucidated. We measured leg hemodynamics and oxidative metabolism in the transition from rest to steady-state exercise engaging the knee-extensor muscles in young ( n = 15, 25 ± 1 yr) and older ( n = 15, 72 ± 1 yr) subjects before and after a period of aerobic high-intensity exercise training. To enhance cGMP signaling, pharmacological inhibition of phosphodiesterase 5 (PDE5) was performed. Before training, the older group had a slower ( P <0.05) increase in femoral arterial blood flow and leg vascular conductance in the transition from rest to steady-state exercise at low- and moderate-intensity compared with the young group. The rate of increase in leg V̇o2 was, however, similar in the two groups as a result of higher ( P < 0.05) arteriovenous O2 difference in the older group. Potentiation of cGMP signaling did not affect the rate of increase in blood flow or V̇o2 in either group. Exercise training augmented ( P < 0.05) the increase in leg vascular conductance and blood flow during the onset of moderate-intensity exercise in both groups without altering V̇o2. These findings suggest that an age-related reduction in the initial vascular response to low- and moderate-intensity knee-extensor exercise is not limiting for V̇o2 in older individuals. A lower blood flow response in aging does not appear to be a result of reduced cGMP signaling.
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Affiliation(s)
- Peter Piil
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Tue Smith Jørgensen
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark.,Department of Orthopedics, Herlev and Gentofte Hospital, Herlev, Denmark
| | - Jon Egelund
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Nicolai Rytter
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Michael Nyberg
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
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Improvement of Oxygen-Uptake Kinetics and Cycling Performance With Combined Prior Exercise and Fast Start. Int J Sports Physiol Perform 2018; 13:305-312. [DOI: 10.1123/ijspp.2016-0557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Purpose: To investigate whether oxygen-uptake () kinetics and simulated 4-km cycling performance are synergistically improved by prior “priming” exercise and an all-out starting strategy. Methods: Nine men completed 4 target work trials (114 ± 17 kJ) to assess kinetics and cycling performance in a repeated-measures, crossover experimental design. Trials were initiated with either a 12-s all-out start or a self-selected start and preceded by prior severe-intensity (70%Δ) priming exercise or no priming exercise. Results: The mean response time (MRT) was lower (indicative of faster kinetics) in the all-out primed condition (20 ± 6 s) than in the all-out unprimed (23 ± 6 s), self-paced-unprimed (42 ± 13 s), and self-paced-primed (42 ± 11 s) trials (P < .05), with the MRT also lower in the all-out unprimed than the self-paced unprimed and self-paced primed trials (P < .05). Trial-completion time was shorter (performance was enhanced) in the all-out primed trial (402 ± 14 s) than in the all-out unprimed (408 ± 14 s), self-paced unprimed (411 ± 16 s), and self-paced primed (411 ± 19 s) trials (P < .05), with no differences between the latter 3 trials. Conclusions: The findings from this study suggest that combining severe-intensity priming exercise with a short-duration all-out starting strategy can expedite the adjustment of and lower completion time during a cycling performance trial to a greater extent than either intervention administered independently. These results might have implications for optimizing performance in short-duration high-intensity competitive events such as a 4-km cycling time trial.
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Non-invasive estimation of muscle oxygen uptake kinetics with pseudorandom binary sequence and step exercise responses. Eur J Appl Physiol 2017; 118:429-438. [DOI: 10.1007/s00421-017-3785-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/08/2017] [Indexed: 10/18/2022]
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Goulding RP, Roche DM, Marwood S. Prior exercise speeds pulmonary oxygen uptake kinetics and increases critical power during supine but not upright cycling. Exp Physiol 2017. [PMID: 28627041 DOI: 10.1113/ep086304] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
NEW FINDINGS What is the central question of this study? Critical power (CP) represents the highest work rate for which a metabolic steady state is attainable. The physiological determinants of CP are unclear, but research suggests that CP might be related to the time constant of phase II oxygen uptake kinetics (τV̇O2). What is the main finding and its importance? We provide the first evidence that τV̇O2 is mechanistically related to CP. A reduction of τV̇O2 in the supine position was observed alongside a concomitant increase in CP. This effect may be contingent on measures of oxygen availability derived from near-infrared spectroscopy. Critical power (CP) is a fundamental parameter defining high-intensity exercise tolerance and is related to the time constant of phase II pulmonary oxygen uptake kinetics (τV̇O2). To test the hypothesis that this relationship is causal, we determined the impact of prior exercise ('priming') on CP and τV̇O2 in the upright and supine positions. Seventeen healthy men were assigned to either upright or supine exercise groups, whereby CP, τV̇O2 and muscle deoxyhaemoglobin kinetics (τ[HHb] ) were determined via constant-power tests to exhaustion at four work rates with (primed) and without (control) priming exercise at ∼31%Δ. During supine exercise, priming reduced τV̇O2 (control 54 ± 18 s versus primed 39 ± 11 s; P < 0.001), increased τ[HHb] (control 8 ± 4 s versus primed 12 ± 4 s; P = 0.003) and increased CP (control 177 ± 31 W versus primed 185 ± 30 W, P = 0.006) compared with control conditions. However, priming exercise had no effect on τV̇O2 (control 37 ± 12 s versus primed 35 ± 8 s; P = 0.82), τ[HHb] (control 10 ± 5 s versus primed 14 ± 10 s; P = 0.10) or CP (control 235 ± 42 W versus primed 232 ± 35 W; P = 0.57) during upright exercise. The concomitant reduction of τV̇O2 and increased CP following priming in the supine group, effects that were absent in the upright group, provide the first experimental evidence that τV̇O2 is mechanistically related to critical power. The increased τ[HHb+Mb] suggests that this effect was mediated, at least in part, by improved oxygen availability.
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Affiliation(s)
- Richie P Goulding
- School of Health Sciences, Liverpool Hope University, Hope Park Campus, Liverpool, Merseyside, L16 9JD, UK
| | - Denise M Roche
- School of Health Sciences, Liverpool Hope University, Hope Park Campus, Liverpool, Merseyside, L16 9JD, UK
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Hope Park Campus, Liverpool, Merseyside, L16 9JD, UK
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Layec G, Hart CR, Trinity JD, Kwon OS, Rossman MJ, Broxterman RM, Le Fur Y, Jeong EK, Richardson RS. Oxygen delivery and the restoration of the muscle energetic balance following exercise: implications for delayed muscle recovery in patients with COPD. Am J Physiol Endocrinol Metab 2017; 313:E94-E104. [PMID: 28292763 PMCID: PMC6109703 DOI: 10.1152/ajpendo.00462.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/03/2017] [Accepted: 03/13/2017] [Indexed: 11/22/2022]
Abstract
Patients with chronic obstructive pulmonary disease (COPD) experience a delayed recovery from skeletal muscle fatigue following exhaustive exercise that likely contributes to their progressive loss of mobility. As this phenomenon is not well understood, this study sought to examine postexercise peripheral oxygen (O2) transport and muscle metabolism dynamics in patients with COPD, two important determinants of muscle recovery. Twenty-four subjects, 12 nonhypoxemic patients with COPD and 12 healthy subjects with a sedentary lifestyle, performed dynamic plantar flexion exercise at 40% of the maximal work rate (WRmax) with phosphorus magnetic resonance spectroscopy (31P-MRS), near-infrared spectroscopy (NIRS), and vascular Doppler ultrasound assessments. The mean response time of limb blood flow at the offset of exercise was significantly prolonged in patients with COPD (controls: 56 ± 27 s; COPD: 120 ± 87 s; P < 0.05). In contrast, the postexercise time constant for capillary blood flow was not significantly different between groups (controls: 49 ± 23 s; COPD: 51 ± 21 s; P > 0.05). The initial postexercise convective O2 delivery (controls: 0.15 ± 0.06 l/min; COPD: 0.15 ± 0.06 l/min) and the corresponding oxidative adenosine triphosphate (ATP) demand (controls: 14 ± 6 mM/min; COPD: 14 ± 6 mM/min) in the calf were not significantly different between controls and patients with COPD (P > 0.05). The phosphocreatine resynthesis time constant (controls: 46 ± 20 s; COPD: 49 ± 21 s), peak mitochondrial phosphorylation rate, and initial proton efflux were also not significantly different between groups (P > 0.05). Therefore, despite perturbed peripheral hemodynamics, intracellular O2 availability, proton efflux, and aerobic metabolism recovery in the skeletal muscle of nonhypoxemic patients with COPD are preserved following plantar flexion exercise and thus are unlikely to contribute to the delayed recovery from exercise in this population.
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Affiliation(s)
- Gwenael Layec
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah;
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Corey R Hart
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Joel D Trinity
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Oh-Sung Kwon
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Matthew J Rossman
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Ryan M Broxterman
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Yann Le Fur
- Centre de Résonance Magnétique Biologique et Médicale, Aix-Marseille Universite, Centre National de la Recherche Scientifique, Marseille, France; and
| | - Eun-Kee Jeong
- Department of Radiology and Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
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45
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Regulation of oxidative phosphorylation through each-step activation (ESA): Evidences from computer modeling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 125:1-23. [DOI: 10.1016/j.pbiomolbio.2016.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/06/2016] [Indexed: 01/20/2023]
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Barclay CJ. Energy demand and supply in human skeletal muscle. J Muscle Res Cell Motil 2017; 38:143-155. [PMID: 28286928 DOI: 10.1007/s10974-017-9467-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 02/14/2017] [Indexed: 12/18/2022]
Abstract
The energy required for muscle contraction is provided by the breakdown of ATP but the amount of ATP in muscles cells is sufficient to power only a short duration of contraction. Buffering of ATP by phosphocreatine, a reaction catalysed by creatine kinase, extends the duration of activity possible but sustained activity depends on continual regeneration of PCr. This is achieved using ATP generated by oxidative processes and, during intense activity, by anaerobic glycolysis. The rate of ATP breakdown ranges from 70 to 140 mM min-1 during isometric contractions of various intensity to as much as 400 mM min-1 during intense, dynamic activity. The maximum rate of oxidative energy supply in untrained people is ~50 mM min-1 which, if the contraction duty cycle is 0.5 as is often the case in cyclic activity, is sufficient to match an ATP breakdown rate during contraction of 100 mM min-1. During brief, intense activity the rate of ATP turnover can exceed the rates of PCr regeneration by combined oxidative and glycolytic energy supply, resulting in a net decrease in PCr concentration. Glycolysis has the capacity to produce between 30 and 50 mM of ATP so that, for example, anaerobic glycolysis could provide ATP at an average of 100 mM min-1 over 30 s of exhausting activity. The creatine kinase reaction plays an important role not only in buffering ATP but also in communicating energy demand from sites of ATP breakdown to the mitochondria. In that role, creatine kinases acts to slow and attenuate the response of mitochondria to changes in energy demand.
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Affiliation(s)
- C J Barclay
- School of Allied Health Sciences, Griffith University, Gold Coast, QLD, 4222, Australia.
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47
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Drescher U, Mookerjee S, Steegmanns A, Knicker A, Hoffmann U. Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise. Respir Physiol Neurobiol 2017; 240:53-60. [PMID: 28215595 DOI: 10.1016/j.resp.2017.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To evaluate the effects of exercise velocity (60, 150, 240deg∙s-1) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. METHODS Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E). RESULTS Significant differences of the t1/2 values were identified between 60 and 150deg∙s-1. Significant differences in the t1/2 values were observed between V˙O2pulm and V˙CO2pulm and between V˙CO2pulm and V˙E. The time to attain the first avDO2-peak showed significant differences between arm and leg exercise. CONCLUSIONS The present study illustrates, that V˙O2pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O2pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases.
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Affiliation(s)
- U Drescher
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany.
| | - S Mookerjee
- Department of Exercise Science, 400 E. 2nd St, Bloomsburg University, Bloomsburg, PA, 17815, USA
| | - A Steegmanns
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
| | - A Knicker
- Institute of Movement and Neuroscience, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
| | - U Hoffmann
- Institute of Physiology and Anatomy, Am Sportpark Müngersdorf 6, German Sport University Cologne, Cologne, 50933, Germany
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48
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SAYNOR ZOELOUISE, BARKER ALANROBERT, OADES PATRICKJOHN, WILLIAMS CRAIGANTHONY. Impaired Pulmonary V˙O2 Kinetics in Cystic Fibrosis Depend on Exercise Intensity. Med Sci Sports Exerc 2016; 48:2090-2099. [DOI: 10.1249/mss.0000000000001004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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49
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Keir DA, Robertson TC, Benson AP, Rossiter HB, Kowalchuk JM. The influence of metabolic and circulatory heterogeneity on the expression of pulmonary oxygen uptake kinetics in humans. Exp Physiol 2016; 101:176-92. [PMID: 26537768 DOI: 10.1113/ep085338] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 10/30/2015] [Indexed: 11/08/2022]
Abstract
We examined the relationship amongst baseline work rate (WR), phase II pulmonary oxygen uptake (V̇(O2p)) time constant (τV̇(O2p)) and functional gain (G(P)=ΔV̇(O2p)/ΔWR) during moderate-intensity exercise. Transitions were initiated from a constant or variable baseline WR. A validated circulatory model was used to examine the role of heterogeneity in muscle metabolism (V̇(O2m)) and blood flow (Q̇(m)) in determining V̇(O2p) kinetics. We hypothesized that τV̇(O2p) and G(P) would be invariant in the constant baseline condition but would increase linearly with increased baseline WR. Fourteen men completed three to five repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100 and 120 W on a cycle ergometer. The ∆40 W step transitions from 60, 80, 100 and 120 W were preceded by 6 min of 20 W cycling, from which the progressive ΔWR transitions (constant baseline condition) were examined. The V̇(O2p) was measured breath by breath using mass spectrometry and a volume turbine. For a given ΔWR, both τV̇(O2p) (22-35 s) and G(P) (8.7-10.5 ml min(-1) W(-1)) increased (P < 0.05) linearly as a function of baseline WR (20-120 W). The τV̇(O2p) was invariant (P < 0.05) in transitions initiated from 20 W, but G(P) increased with ΔWR (P < 0.05). Modelling the summed influence of multiple muscle compartments revealed that τV̇(O2p) could appear fast (24 s), and similar to in vivo measurements (22 ± 6 s), despite being derived from τV̇(O2p) values with a range of 15-40 s and τQ̇(m) with a range of 20-45 s, suggesting that within the moderate-intensity domain phase II V̇(O2p) kinetics are slowed dependent on the pretransition WR and are strongly influenced by muscle metabolic and circulatory heterogeneity.
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Affiliation(s)
- Daniel A Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Taylor C Robertson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Alan P Benson
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - 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, CA, USA
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada.,School of Kinesiology, The University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada
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50
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Richardson RS, Wary C, Wray DW, Hoff J, Rossiter HB, Layec G, Carlier PG. MRS Evidence of Adequate O₂ Supply in Human Skeletal Muscle at the Onset of Exercise. Med Sci Sports Exerc 2016; 47:2299-307. [PMID: 25830362 DOI: 10.1249/mss.0000000000000675] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE At exercise onset, intramuscular oxidative energy production responds relatively slowly in comparison with the change in adenosine triphosphate demand. To determine whether the slow kinetics of oxidative adenosine triphosphate production is due to inadequate O2 supply or metabolic inertia, we studied the kinetics of intramyocellular deoxygenation (deoxy-myoglobin (Mb)) and metabolism (phosphocreatine (PCr)) using proton (1H) and phosphorus (31P) magnetic resonance spectroscopy in six healthy subjects (33 ± 5 yr). METHODS Specifically, using dynamic plantarflexion exercise, rest to exercise and recovery were assessed at both 60% of maximum work rate (moderate intensity) and 80% of maximum work rate (heavy intensity). RESULTS At exercise onset, [PCr] fell without delay and with a similar time constant (τ) at both exercise intensities (approximately 33 s). In contrast, the increase in deoxy-Mb was delayed at exercise onset by 5-7 s, after which it increased with kinetics (moderate τ = 37 ± 9 s; heavy τ = 29 ± 6 s) that was not different from τPCr (P > 0.05). At cessation, deoxy-Mb recovered without time delay and more rapidly (τ = ∼20 s) than PCr (τ = ∼33 s) (P < 0.05). CONCLUSIONS Using a unique combination of in vivo magnetic resonance spectroscopy techniques with high time resolution, this study revealed a delay in intramuscular deoxygenation at the onset of exercise and rapid reoxygenation kinetics upon cessation. Together, these data imply that intramuscular substrate-enzyme interactions, and not O2 availability, determine the exercise onset kinetics of oxidative metabolism in healthy human skeletal muscles.
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Affiliation(s)
- Russell S Richardson
- 1Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, UT; 2Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT; 3Geriatric Research, Education and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, UT; 4Institute of Myology, Paris, FRANCE; 5CEA, I2BM, MIRcen, IdM NMR Laboratory, Paris, FRANCE; 6Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, NORWAY; and 7Department of Medicine, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA
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