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Physiological determinants of mechanical efficiency during advanced ageing and disuse. J Physiol 2024; 602:355-372. [PMID: 38165402 DOI: 10.1113/jp285639] [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: 09/05/2023] [Accepted: 12/20/2023] [Indexed: 01/03/2024] Open
Abstract
This study aimed to determine which physiological factors impact net efficiency (ηnet) in oldest-old individuals at different stages of skeletal muscle disuse. To this aim, we examined ηnet, central haemodynamics, peripheral circulation, and peripheral factors (skeletal muscle fibre type, capillarization and concentration of mitochondrial DNA [mtDNA]). Twelve young (YG; 25 ± 2 years), 12 oldest-old mobile (OM; 87 ± 3 years), and 12 oldest-old immobile (OI; 88 ± 4 years) subjects performed dynamic knee extensor (KE) and elbow flexors (EF) exercise. Pulmonary oxygen uptake, photoplethysmography, Doppler ultrasound and muscle biopsies of the vastus lateralis and biceps brachii were used to assess central and peripheral adaptations to advanced ageing and disuse. Compared to the YG (12.1 ± 2.4%), the ηnet of lower-limb muscle was higher in the OM (17.6 ± 3.5%, P < 0.001), and lower in the OI (8.9 ± 1.9%, P < 0.001). These changes in ηnet during KE were coupled with significant peripheral adaptations, revealing strong correlations between ηnet and the proportion of type I muscle fibres (r = 0.82), as well as [mtDNA] (r = 0.77). No differences in ηnet were evident in the upper-limb muscles between YG, OM and OI. In view of the differences in limb-specific activity across the lifespan, these findings suggest that ηnet is reduced by skeletal muscle inactivity and not by chronological age, per se. Likewise, this study revealed that the age-related changes in ηnet are not a consequence of central or peripheral haemodynamic adaptations, but are likely a product of peripheral changes related to skeletal muscle fibre type and mitochondrial density. KEY POINTS: Although the effects of ageing and muscle disuse deeply impact the cardiovascular and skeletal muscle function, the combination of these factors on the mechanical efficiency are still a matter of debate. By measuring both upper- and lower-limb muscle function, which experience differing levels of disuse, we examined the influence of central and peripheral haemodynamics, and skeletal muscle factors linked to mechanical efficiency. Across the ages and degree of disuse, upper-limb muscles exhibited a preserved work economy. In the legs the oldest-old without mobility limitations exhibited an augmented mechanical efficiency, which was reduced in those with an impairment in ambulation. These changes in mechanical efficiency were associated with the proportion of type I muscle fibres. Recognition that the mechanical efficiency is not simply age-dependent, but the consequence of inactivity and subsequent skeletal muscle changes, highlights the importance of maintaining physical activity across the lifespan.
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The relationship between hemoglobin and [Formula: see text]: A systematic review and meta-analysis. PLoS One 2023; 18:e0292835. [PMID: 37824583 PMCID: PMC10569622 DOI: 10.1371/journal.pone.0292835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 09/29/2023] [Indexed: 10/14/2023] Open
Abstract
OBJECTIVE There is widespread agreement about the key role of hemoglobin for oxygen transport. Both observational and interventional studies have examined the relationship between hemoglobin levels and maximal oxygen uptake ([Formula: see text]) in humans. However, there exists considerable variability in the scientific literature regarding the potential relationship between hemoglobin and [Formula: see text]. Thus, we aimed to provide a comprehensive analysis of the diverse literature and examine the relationship between hemoglobin levels (hemoglobin concentration and mass) and [Formula: see text] (absolute and relative [Formula: see text]) among both observational and interventional studies. METHODS A systematic search was performed on December 6th, 2021. The study procedures and reporting of findings followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Article selection and data abstraction were performed in duplicate by two independent reviewers. Primary outcomes were hemoglobin levels and [Formula: see text] values (absolute and relative). For observational studies, meta-regression models were performed to examine the relationship between hemoglobin levels and [Formula: see text] values. For interventional studies, meta-analysis models were performed to determine the change in [Formula: see text] values (standard paired difference) associated with interventions designed to modify hemoglobin levels or [Formula: see text]. Meta-regression models were then performed to determine the relationship between a change in hemoglobin levels and the change in [Formula: see text] values. RESULTS Data from 384 studies (226 observational studies and 158 interventional studies) were examined. For observational data, there was a positive association between absolute [Formula: see text] and hemoglobin levels (hemoglobin concentration, hemoglobin mass, and hematocrit (P<0.001 for all)). Prespecified subgroup analyses demonstrated no apparent sex-related differences among these relationships. For interventional data, there was a positive association between the change of absolute [Formula: see text] (standard paired difference) and the change in hemoglobin levels (hemoglobin concentration (P<0.0001) and hemoglobin mass (P = 0.006)). CONCLUSION These findings suggest that [Formula: see text] values are closely associated with hemoglobin levels among both observational and interventional studies. Although our findings suggest a lack of sex differences in these relationships, there were limited studies incorporating females or stratifying results by biological sex.
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Effect of Exercise Training on Arterial Stiffness in Overweight or Obese Populations. Int J Sports Med 2022; 43:996-1012. [PMID: 35468651 PMCID: PMC9622304 DOI: 10.1055/a-1795-2940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose was to analyze the effects of exercise training (ET) on arterial
stiffness in all-age overweight or obese individuals. Sixty-one trials were
included with ET improving flow-mediated dilation (FMD), pulse wave velocity
(PWV), and intima-media thickness (IMT). In the subgroup analysis: (i) ET
improved FMD in overweight or obese children and adolescents with a large effect
size (SMD=0.83, 95% CI 0.42–1.25). PWV was decreased
after ET regardless of age. IMT was decreased by ET in participants younger than
60, (ii) ET improved FMD, PWV, and IMT in participants whose BMI were smaller
than 30 kg/m
2
, but ET only improved PWV of
participants whose BMI were larger than 30 kg/m
2
.
(iii) AE improved FMD, PWV, and IMT. High-intensity interval training (HIIT)
decreased IMT. (iv) The increase of FMD only happened when training duration was
longer than eight weeks. However, ET decreased PWV when the training duration
was no longer than 12 weeks. IMT was decreased when the training duration was
longer than eight weeks. ET instigated an improvement in endothelial function
and arterial stiffness in overweight or obese populations, but depending on the
different characteristics of exercise intervention and participants’
demographics.
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Similar Adaptations to 10 Weeks Concurrent Training on Metabolic Markers and Physical Performance in Young, Adult, and Older Adult Women. J Clin Med 2021; 10:jcm10235582. [PMID: 34884282 PMCID: PMC8658306 DOI: 10.3390/jcm10235582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/01/2021] [Accepted: 11/10/2021] [Indexed: 11/16/2022] Open
Abstract
It has been proposed that the combination of high-intensity aerobic exercises and resistance training (RT) known as concurrent training (CT) could improve metabolic syndrome (MetS) markers, and that the exercise mixture in CT could dampen muscle anaerobic pathways, a result known as the interference effect. However, there is scarce evidence on its effects in women across different ages. Therefore, we sought to determine the effects of a 10-week CT intervention on MetS markers and endurance performance in adult women and compared age-related differences between young, adult, and older participants. A total of 112 women with >1 MetS risk factors were included in the study. Participants were allocated to different groups according to the following cutoff age ranges: 20-29years (y), n = 25; 30-39y, n = 35; 40-49y, n = 43; and 50-59y, n = 53. Participants performed 10 weeks of CT, including resistance training (RT), involving six major muscle groups, and high-intensity interval training (HIIT) in a cycle ergometer. Anthropometric, cardiovascular, metabolic, and performance outcomes were assessed before and after the intervention. The CT induced significant improvements in waist circumference (WC) (20-29y: -2.5; 30-39y: -4.1; 40-49y: -4.2; 50-59y: -2.8 Δcm) and the distance achieved in the six-minute walking test (6Mwt) (20-29y: +47.6; 30-39y: +66.0; 40-49y: +43.0; 50-59y: +58.6 Δm) across all age groups, without significant differences between groups. In addition, a significant correlation was found between 6Mwt and WC, independent of age. In conclusion, our results showed that a 10-week CT intervention improved MetS risk factors in women, suggesting that the beneficial effects promoted by CT are independent of age and confirming CT as an effective, age-independent training regimen to improve metabolic health in women.
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Exercise training in COPD: muscle O 2 transport plasticity. Eur Respir J 2021; 58:13993003.04146-2020. [PMID: 33446612 DOI: 10.1183/13993003.04146-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/05/2021] [Indexed: 11/05/2022]
Abstract
Both convective oxygen (O2) transport to, and diffusive transport within, skeletal muscle are markedly diminished in patients with COPD. However, it is unknown how these determinants of peak muscle O2 uptake (V'mO2peak) respond to exercise training in patients with COPD. Therefore, the purpose of this study was to assess the plasticity of skeletal muscle O2 transport determinants of V'mO2peak in patients with COPD.Adaptations to 8 weeks of single-leg knee-extensor exercise training were measured in eight patients with severe COPD (mean±sem forced expiratory volume in 1 s (FEV1) 0.9±0.1 L) and eight healthy, well-matched controls. Femoral arterial and venous blood samples, and thermodilution-assessed leg blood flow were used to determine muscle O2 transport and utilisation at maximal exercise pre- and post-training.Training increased V'mO2peak in both COPD (by ∼26% from 271±29 to 342±35 mL·min-1) and controls (by ∼32% from 418±37 to 553±41 mL·min-1), restoring V'mO2peak in COPD to only ∼80% of pre-training control V'mO2peak Muscle diffusive O2 transport increased similarly in both COPD (by ∼38% from 6.6±0.9 to 9.1±0.9 mL·min-1·mmHg-1) and controls (by ∼36% from 10.4±0.7 to 14.1±0.8 mL·min-1·mmHg-1), with the patients reaching ∼90% of pre-training control values. In contrast, muscle convective O2 transport increased significantly only in controls (by ∼26% from 688±57 to 865±69 mL·min-1), leaving patients with COPD (438±45 versus 491±51 mL·min-1) at ∼70% of pre-training control values.While muscle diffusive O2 transport in COPD was largely restored by exercise training, V'mO2peak remained constrained by limited plasticity in muscle convective O2 transport.
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Examining Arm Vascular Function and Blood Flow Regulation in Row-trained Males. Med Sci Sports Exerc 2019; 51:2058-2066. [PMID: 31009422 DOI: 10.1249/mss.0000000000002014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vascular function and blood flow responses to upper limb exercise are differentially altered in response to different exercise training modalities. Rowing is a unique exercise modality that incorporates the upper limbs and can significantly augment upper limb endurance, strength, and power capacity. PURPOSE This study sought to determine whether vascular function and blood flow regulation during handgrip exercise are altered in row-trained males. METHODS Nine young row-trained males (ROW, 20 ± 1 yr; V˙O2peak = 51 ± 2 mL·kg·min) and 14 recreationally active male controls (C: 22 ± 1 yr; V˙O2peak = 37 ± 2 mL·kg·min) were recruited for this study. Subjects performed multiple bouts of progressive rhythmic handgrip exercise. Brachial artery (BA) diameter, blood flow, shear rate, and mean arterial pressure were measured at rest and during the last minute of each exercise workload. RESULTS Resting values for BA diameter, blood flow, shear rate, and mean arterial pressure were not different between groups. During handgrip exercise, the ROW group reported significantly lower BA blood flow (ROW vs C: 4 kg [146 ± 21 vs 243 ± 13 mL·min], 8 kg [248 ± 29 vs 375 ± 17 mL·min], 12 kg [352 ± 43 vs 490 ± 22 mL·min]) across all workloads when compared with controls. The examination of BA dilation, when controlled for the shear rate stimulus and evaluated across all workloads, was revealed to be significantly greater in ROW group versus controls. CONCLUSION This study revealed that vascular function and blood flow regulation were significantly different in row-trained males when compared with untrained controls evidenced by greater shear-induced BA dilation and lower arm blood flow during progressive handgrip exercise.
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The Role of Muscle Perfusion in the Age-Associated Decline of Mitochondrial Function in Healthy Individuals. Front Physiol 2019; 10:427. [PMID: 31031645 PMCID: PMC6473080 DOI: 10.3389/fphys.2019.00427] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/27/2019] [Indexed: 12/25/2022] Open
Abstract
Maximum oxidative capacity of skeletal muscle measured by in vivo phosphorus magnetic resonance spectroscopy (31P-MRS) declines with age, and negatively affects whole-body aerobic capacity. However, it remains unclear whether the loss of oxidative capacity is caused by reduced volume and function of mitochondria or limited substrate availability secondary to impaired muscle perfusion. Therefore, we sought to elucidate the role of muscle perfusion on the age-related decline of muscle oxidative capacity and ultimately whole-body aerobic capacity. Muscle oxidative capacity was assessed by 31P-MRS post-exercise phosphocreatine recovery time (τPCr), with higher τPCr reflecting lower oxidative capacity, in 75 healthy participants (48 men, 22–89 years) of the Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing study. Muscle perfusion was characterized as an index of blood volume at rest using a customized diffusion-weighted MRI technique and analysis method developed in our laboratory. Aerobic capacity (peak-VO2) was also measured during a graded treadmill exercise test in the same visit. Muscle oxidative capacity, peak-VO2, and resting muscle perfusion were significantly lower at older ages independent of sex, race, and body mass index (BMI). τPCr was significantly associated with resting muscle perfusion independent of age, sex, race, and BMI (p-value = 0.004, β = −0.34). τPCr was also a significant independent predictor of peak-VO2 and, in a mediation analysis, significantly attenuated the association between muscle perfusion and peak-VO2 (34% reduction for β in perfusion). These findings suggest that the age-associated decline in muscle oxidative capacity is partly due to impaired muscle perfusion and not mitochondrial dysfunction alone. Furthermore, our findings show that part of the decline in whole-body aerobic capacity observed with aging is also due to reduced microvascular blood volume at rest, representing a basal capacity of the microvascular system, which is mediated by muscle oxidative capacity. This finding suggests potential benefit of interventions that target an overall increase in muscle perfusion for the restoration of energetic capacity and mitochondrial function with aging.
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Overweight in the Elderly Induces a Switch in Energy Metabolism that Undermines Muscle Integrity. Aging Dis 2019; 10:217-230. [PMID: 31011474 PMCID: PMC6457058 DOI: 10.14336/ad.2018.0430] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 04/30/2018] [Indexed: 12/19/2022] Open
Abstract
Aging is characterized by a progressive loss of skeletal muscle mass and function (sarcopenia). Obesity exacerbates age-related decline and lead to frailty. Skeletal muscle fat infiltration increases with aging and seems to be crucial for the progression of sarcopenia. Additionally, skeletal muscle plasticity modulates metabolic adaptation to different pathophysiological situations. Thus, cellular bioenergetics and mitochondrial profile were studied in the skeletal muscle of overweight aged people without reaching obesity to prevent this extreme situation. Overweight aged muscle lacked ATP production, as indicated by defects in the phosphagen system, glycolysis and especially mostly by oxidative phosphorylation metabolic pathway. Overweight subjects exhibited an inhibition of mitophagy that was linked to an increase in mitochondrial biogenesis that underlies the accumulation of dysfunctional mitochondria and encourages the onset of sarcopenia. As a strategy to maintain cellular homeostasis, overweight subjects experienced a metabolic switch from oxidative to lactic acid fermentation metabolism, which allows continued ATP production under mitochondrial dysfunction, but without reaching physiological aged basal levels. This ATP depletion induced early signs of impaired contractile function and a decline in skeletal muscle structural integrity, evidenced by lower levels of filamin C. Our findings reveal the main effector pathways at an early stage of obesity and highlight the importance of mitochondrial metabolism in overweight and obese individuals. Exploiting mitochondrial profiles for therapeutic purposes in humans is an ambitious strategy for treating muscle impairment diseases.
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Acute and chronic exercise in patients with heart failure with reduced ejection fraction: evidence of structural and functional plasticity and intact angiogenic signalling in skeletal muscle. J Physiol 2018; 596:5149-5161. [PMID: 30192995 DOI: 10.1113/jp276678] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/04/2018] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS The vascular endothelial growth factor (VEGF) responses to acute submaximal exercise and training effects in patients with heart failure with reduced ejection fraction (HFrEF) were investigated. Six patients and six healthy matched controls performed knee-extensor exercise (KE) at 50% of maximum work rate before and after (only patients) KE training. Muscle biopsies were taken to assess skeletal muscle structure and the angiogenic response. Before training, during this submaximal KE exercise, patients with HFrEF exhibited higher leg vascular resistance and greater noradrenaline spillover. Skeletal muscle structure and VEGF response were generally not different between groups. Following training, resistance was no longer elevated and noradrenaline spillover was curtailed in the patients. Although, in the trained state, VEGF did not respond to acute exercise, capillarity was augmented. Muscle fibre cross-sectional area and percentage area of type I fibres increased and mitochondrial volume density exceeded that of controls. Structural/functional plasticity and appropriate angiogenic signalling were observed in skeletal muscle of patients with HFrEF. ABSTRACT This study examined the response to acute submaximal exercise and the effect of training in patients with heart failure with reduced ejection fraction (HFrEF). The acute angiogenic response to submaximal exercise in HFrEF after small muscle mass training is debated. The direct Fick method, with vascular pressures, was performed across the leg during knee-extensor exercise (KE) at 50% of maximum work rate (WRmax ) in patients (n = 6) and controls (n = 6) and then after KE training in patients. Muscle biopsies facilitated the assessment of skeletal muscle structure and vascular endothelial growth factor (VEGF) mRNA levels. Prior to training, HFrEF exhibited significantly higher leg vascular resistance (LVR) (≈15%) and significantly greater noradrenaline spillover (≈385%). Apart from mitochondrial volume density, which was significantly lower (≈22%) in HFrEF, initial skeletal muscle structure, including capillarity, was not different between groups. Resting VEGF mRNA levels, and the increase with exercise, was not different between patients and controls. Following training, LVR was no longer elevated and noradrenaline spillover was curtailed. Skeletal muscle capillarity increased with training, as assessed by capillary-to-fibre ratio (≈13%) and number of capillaries around a fibre (NCAF ) (≈19%). VEGF mRNA was now not significantly increased by acute exercise. Muscle fibre cross-sectional area and percentage area of type I fibres both increased significantly with training (≈18% and ≈21%, respectively), while the percentage area of type II fibres fell significantly (≈11%), and mitochondrial volume density now exceeded that of controls. These data reveal structural and functional plasticity and appropriate angiogenic signalling in skeletal muscle of HFrEF patients.
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Skeletal muscle homeostasis and plasticity in youth and ageing: impact of nutrition and exercise. Acta Physiol (Oxf) 2016; 216:15-41. [PMID: 26010896 PMCID: PMC4843955 DOI: 10.1111/apha.12532] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/10/2014] [Accepted: 05/18/2015] [Indexed: 12/18/2022]
Abstract
Skeletal muscles comprise a substantial portion of whole body mass and are integral for locomotion and metabolic health. Increasing age is associated with declines in both muscle mass and function (e.g. strength‐related performance, power) with declines in muscle function quantitatively outweighing those in muscle volume. The mechanisms behind these declines are multi‐faceted involving both intrinsic age‐related metabolic dysregulation and environmental influences such as nutritional and physical activity. Ageing is associated with a degree of ‘anabolic resistance’ to these key environmental inputs, which likely accelerates the intrinsic processes driving ageing. On this basis, strategies to sensitize and/or promote anabolic responses to nutrition and physical activity are likely to be imperative in alleviating the progression and trajectory of sarcopenia. Both resistance‐ and aerobic‐type exercises are likely to confer functional and health benefits in older age, and a clutch of research suggests that enhancement of anabolic responsiveness to exercise and/or nutrition may be achieved by optimizing modifications of muscle‐loading paradigms (workload, volume, blood flow restriction) or nutritional support (e.g. essential amino acid/leucine) patterns. Nonetheless, more work is needed in which a more holistic view in ageing studies is taken into account. This should include improved characterization of older study recruits, that is physical activity/nutritional behaviours, to limit confounding variables influencing whether findings are attributable to age, or other environmental influences. Nonetheless, on balance, ageing is associated with declines in muscle mass and function and a partially related decline in aerobic capacity. There is also good evidence that metabolic flexibility is impaired in older age.
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Arterial dilator function in athletes: present and future perspectives. Front Physiol 2015; 6:163. [PMID: 26042052 PMCID: PMC4436563 DOI: 10.3389/fphys.2015.00163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/06/2015] [Indexed: 01/23/2023] Open
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Acute ascorbic acid ingestion increases skeletal muscle blood flow and oxygen consumption via local vasodilation during graded handgrip exercise in older adults. Am J Physiol Heart Circ Physiol 2015; 309:H360-8. [PMID: 25980023 DOI: 10.1152/ajpheart.00209.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 05/12/2015] [Indexed: 02/07/2023]
Abstract
Human aging is associated with reduced skeletal muscle perfusion during exercise, which may be a result of impaired endothelium-dependent dilation and/or attenuated ability to blunt sympathetically mediated vasoconstriction. Intra-arterial infusion of ascorbic acid (AA) increases nitric oxide-mediated vasodilation and forearm blood flow (FBF) during handgrip exercise in older adults, yet it remains unknown whether an acute oral dose can similarly improve FBF or enhance the ability to blunt sympathetic vasoconstriction during exercise. We hypothesized that 1) acute oral AA would improve FBF (Doppler ultrasound) and oxygen consumption (V̇o2) via local vasodilation during graded rhythmic handgrip exercise in older adults (protocol 1), and 2) AA ingestion would not enhance sympatholysis in older adults during handgrip exercise (protocol 2). In protocol 1 (n = 8; 65 ± 3 yr), AA did not influence FBF or V̇o2 during rest or 5% maximal voluntary contraction (MVC) exercise, but increased FBF (199 ± 13 vs. 248 ± 16 ml/min and 343 ± 24 vs. 403 ± 33 ml/min; P < 0.05) and V̇o2 (26 ± 2 vs. 34 ± 3 ml/min and 43 ± 4 vs. 50 ± 5 ml/min; P < 0.05) at both 15 and 25% MVC, respectively. The increased FBF was due to elevations in forearm vascular conductance (FVC). In protocol 2 (n = 10; 63 ± 2 yr), following AA, FBF was similarly elevated during 15% MVC (∼ 20%); however, vasoconstriction to reflex increases in sympathetic activity during -40 mmHg lower-body negative pressure at rest (ΔFVC: -16 ± 3 vs. -16 ± 2%) or during 15% MVC (ΔFVC: -12 ± 2 vs. -11 ± 4%) was unchanged. Our collective results indicate that acute oral ingestion of AA improves muscle blood flow and V̇o2 during exercise in older adults via local vasodilation.
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'Fine-tuning' blood flow to the exercising muscle with advancing age: an update. Exp Physiol 2015; 100:589-602. [PMID: 25858164 DOI: 10.1113/ep085076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 04/08/2015] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review focuses on age-related changes in the regulatory pathways that exist at the unique interface between the vascular smooth muscle and the endothelium of the skeletal muscle vasculature, and how these changes contribute to impairments in exercising skeletal muscle blood flow in the elderly. What advances does it highlight? Several recent in vivo human studies from our group and others are highlighted that have examined age-related changes in nitric oxide, endothelin-1, alpha adrenergic, and renin-angiotensin-aldosterone (RAAS) signaling. During dynamic exercise, oxygen demand from the exercising muscle is dramatically elevated, requiring a marked increase in skeletal muscle blood flow that is accomplished through a combination of systemic sympathoexcitation and local metabolic vasodilatation. With advancing age, the balance between these factors appears to be disrupted in favour of vasoconstriction, leading to an impairment in exercising skeletal muscle blood flow in the elderly. This 'hot topic' review aims to provide an update to our current knowledge of age-related changes in the neural and local mechanisms that contribute to this 'fine-tuning' of blood flow during exercise. The focus is on results from recent human studies that have adopted a reductionist approach to explore how age-related changes in both vasodilators (nitric oxide) and vasoconstrictors (endothelin-1, α-adrenergic agonists and angiotensin II) interact and how these changes impact blood flow to the exercising skeletal muscle with advancing age.
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Role of α-adrenergic vasoconstriction in regulating skeletal muscle blood flow and vascular conductance during forearm exercise in ageing humans. J Physiol 2014; 592:4775-88. [PMID: 25194040 DOI: 10.1113/jphysiol.2014.278358] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In healthy humans, ageing is typically associated with reduced skeletal muscle blood flow and vascular conductance during exercise. Further, there is a marked increase in resting sympathetic nervous system (SNS) activity with age, yet whether augmented SNS-mediated α-adrenergic vasoconstriction contributes to the age-associated impairment in exercising muscle blood flow and vascular tone in humans is unknown. We tested the hypothesis that SNS-mediated vasoconstriction is greater in older than young adults and limits muscle (forearm) blood flow (FBF) during graded handgrip exercise (5, 15, 25% maximal voluntary contraction (MVC)). FBF was measured (Doppler ultrasound) and forearm vascular conductance (FVC) was calculated in 11 young (21 ± 1 years) and 12 older (62 ± 2 years) adults in control conditions and during combined local α- and β-adrenoreceptor blockade via intra-arterial infusions of phentolamine and propranolol, respectively. Under control conditions, older adults exhibited significantly lower FBF and FVC at 15% MVC exercise (22.6 ± 1.3 vs. 29 ± 3.3 ml min(-1) 100 g forearm fat-free mass (FFM)(-1) and 21.7 ± 1.2 vs. 33.6 ± 4.0 ml min(-1) 100 g FFM(-1) 100 mmHg(-1); P < 0.05) and 25% MVC exercise (37.4 ± 1.4 vs. 46.0 ± 4.9 ml min(-1) 100 g FFM(-1) and 33.7 ± 1.4 vs. 49.0 ± 5.7 ml min(-1) 100 g FFM(-1) 100 mmHg(-1); P < 0.05), whereas there was no age group difference at 5% MVC exercise. Local adrenoreceptor blockade increased FBF and FVC at rest and during exercise in both groups, although the increase in FBF and FVC from rest to steady-state exercise was similar in young and older adults across exercise intensities, and thus the age-associated impairment in FBF and FVC persisted. Our data indicate that during graded intensity handgrip exercise, the reduced FVC and subsequently lower skeletal muscle blood flow in older healthy adults is not due to augmented sympathetic vasoconstriction, but rather due to impairments in local signalling or structural limitations in the peripheral vasculature with advancing age.
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Two weeks of one-leg immobilization decreases skeletal muscle respiratory capacity equally in young and elderly men. Exp Gerontol 2014; 58:269-78. [PMID: 25193555 DOI: 10.1016/j.exger.2014.08.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/18/2014] [Accepted: 08/26/2014] [Indexed: 12/19/2022]
Abstract
Physical inactivity affects human skeletal muscle mitochondrial oxidative capacity but the influence of aging combined with physical inactivity is not known. This study investigates the effect of two weeks of immobilization followed by six weeks of supervised cycle training on muscle oxidative capacity in 17 young (23±1years) and 15 elderly (68±1years) healthy men. We applied high-resolution respirometry in permeabilized fibers from muscle biopsies at inclusion after immobilization and training. Furthermore, protein content of mitochondrial complexes I-V, mitochondrial heat shock protein 70 (mtHSP70) and voltage dependent anion channel (VDAC) were measured in skeletal muscle by Western blotting. The elderly men had lower content of complexes I-V and mtHSP70 but similar respiratory capacity and content of VDAC compared to the young. In both groups the respiratory capacity and protein content of VDAC, mtHSP70 and complexes I, II, IV and V decreased with immobilization and increased with retraining. Moreover, there was no overall difference in the response between the groups. When the intrinsic mitochondrial capacity was evaluated by normalizing respiration to citrate synthase activity, the respiratory differences with immobilization and training disappeared. In conclusion, aging is not associated with a decrease in muscle respiratory capacity in spite of lower complexes I-V and mtHSP70 protein content. Furthermore, immobilization decreased and aerobic training increased the respiratory capacity and protein contents of complexes I-V, mtHSP70 and VDAC similarly in the two groups. This suggests that inactivity and training alter mitochondrial biogenesis equally in young and elderly men.
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Endothelin-A-mediated vasoconstriction during exercise with advancing age. J Gerontol A Biol Sci Med Sci 2014; 70:554-65. [PMID: 24821105 DOI: 10.1093/gerona/glu065] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 03/31/2014] [Indexed: 11/14/2022] Open
Abstract
The endothelin-1 vasoconstrictor pathway contributes to age-related elevations in resting peripheral vascular tone primarily through activation of the endothelin subtype A (ET(A)) receptor. However, the regulatory influence of ET(A)-mediated vasoconstriction during exercise in the elderly is unknown. Thus, in 17 healthy volunteers (n = 8 young, 24±2 years; n = 9 old, 70±2 years), we examined leg blood flow, mean arterial pressure, leg arterial-venous oxygen (O2) difference, and leg O2 consumption (VO2) at rest and during knee-extensor exercise before and after intra-arterial administration of the ET(A) antagonist BQ-123. During exercise, BQ-123 administration increased leg blood flow to a greater degree in the old (+29±5 mL/min/W) compared with the young (+16±3 mL/min/W). The increase in leg blood flow with BQ-123 was accompanied by an increase in leg VO2 in both groups, suggesting a reduced efficiency following ET(A) receptor blockade. Together, these findings have identified an age-related increase in ET(A)-mediated vasoconstrictor activity that persists during exercise, suggesting an important role of this pathway in the regulation of exercising skeletal muscle blood flow and maintenance of arterial blood pressure in the elderly.
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Exercise-training-induced changes in metabolic capacity with age: the role of central cardiovascular plasticity. AGE (DORDRECHT, NETHERLANDS) 2014; 36:665-676. [PMID: 24243396 PMCID: PMC4039249 DOI: 10.1007/s11357-013-9596-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 10/23/2013] [Indexed: 06/01/2023]
Abstract
Although aging is typically associated with a decline in maximal oxygen consumption (VO2max), young and old subjects, of similar initial muscle metabolic capacity, increased quadriceps VO2max equally when this small muscle mass was trained in isolation. As it is unclear if this preserved exercise-induced plasticity with age is still evident with centrally challenging whole body exercise, we assessed maximal exercise responses in 13 young (24 ± 2 years) and 13 old (60 ± 3 years) males, matched for cycling VO2max (3.82 ± 0.66 and 3.69 ± 0.30 L min(-1), respectively), both before and after 8 weeks of high aerobic intensity cycle exercise training. As a consequence of the training both young and old significantly improved VO2max (13 ± 6 vs. 6 ± 7 %) and maximal power output (20 ± 6 vs. 10 ± 6 %, respectively) from baseline, however, the young exhibited a significantly larger increase than the old. Similarly, independently assessed maximal cardiac output (Q max) tended to increase more in the young (16 ± 14 %) than in the old (11 ± 12 %), with no change in a-vO2 difference in either group. Further examination of the components of Q max provided additional evidence of reduced exercise-induced plasticity in both maximal heart rate (young -3 %, old 0 %) and stroke volume (young 19 ± 15, old 11 ± 11 %) in the old. In combination, these findings imply that limited central cardiovascular plasticity may be responsible, at least in part, for the attenuated response to whole body exercise training with increasing age.
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In vivo evidence of an age-related increase in ATP cost of contraction in the plantar flexor muscles. Clin Sci (Lond) 2014; 126:581-92. [PMID: 24224517 DOI: 10.1042/cs20130442] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Impaired skeletal muscle efficiency potentially contributes to the age-related decline in exercise capacity and may explain the altered haemodynamic response to exercise in the elderly. Thus we examined whether (i) the ATP cost of contraction increases with age, and (ii) this results in altered convective O(2) delivery to maintain microvascular oxygenation in the calf muscle. To this aim, we used an integrative experimental approach combining (31)P-MRS (magnetic resonance spectroscopy), Doppler ultrasound imaging and NIRS (near-IR spectroscopy) during dynamic plantar flexion exercise at 40% of WR(max) (maximal power output) in 20 healthy young and 20 older subjects matched for physical activity. The ATP cost of contraction was significantly higher in the old (7.2±4.1 mM/min per W) compared with the young (2.4±1.9 mM/min per W; P<0.05) and this was only significantly correlated with the plantar flexion WR(max) value in the old subjects (r=-0.52; P<0.05). Even when differences in power output were taken into account, end-exercise blood flow (old, 259±168 ml/min per W and young, 134±40 ml/min per W; P<0.05) and convective O(2) delivery (old, 0.048±0.031 l/min per W and young, 0.026±0.008 l/min per W; P<0.05) were greater in the old in comparison with the young subjects. In contrast, the NIRS oxyhaemoglobin, deoxyhaemoglobin and microvascular oxygenation indices were not significantly different between the groups (P>0.05). Therefore the present study reveals that, although the peripheral haemodynamic responses to plantar flexion exercise appear to be appropriate, the elevated energy cost of contraction and associated reduction in the WR(max) value in this muscle group may play a role in limiting exercise capacity with age.
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Environmental enrichment induces neuroplastic changes in middle age female BalbC mice and increases the hippocampal levels of BDNF, p-Akt and p-MAPK1/2. Neuroscience 2014; 260:158-70. [DOI: 10.1016/j.neuroscience.2013.12.026] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/09/2013] [Accepted: 12/11/2013] [Indexed: 12/21/2022]
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Abstract
Blood flow (BF) increases with increasing exercise intensity in skeletal, respiratory, and cardiac muscle. In humans during maximal exercise intensities, 85% to 90% of total cardiac output is distributed to skeletal and cardiac muscle. During exercise BF increases modestly and heterogeneously to brain and decreases in gastrointestinal, reproductive, and renal tissues and shows little to no change in skin. If the duration of exercise is sufficient to increase body/core temperature, skin BF is also increased in humans. Because blood pressure changes little during exercise, changes in distribution of BF with incremental exercise result from changes in vascular conductance. These changes in distribution of BF throughout the body contribute to decreases in mixed venous oxygen content, serve to supply adequate oxygen to the active skeletal muscles, and support metabolism of other tissues while maintaining homeostasis. This review discusses the response of the peripheral circulation of humans to acute and chronic dynamic exercise and mechanisms responsible for these responses. This is accomplished in the context of leading the reader on a tour through the peripheral circulation during dynamic exercise. During this tour, we consider what is known about how each vascular bed controls BF during exercise and how these control mechanisms are modified by chronic physical activity/exercise training. The tour ends by comparing responses of the systemic circulation to those of the pulmonary circulation relative to the effects of exercise on the regional distribution of BF and mechanisms responsible for control of resistance/conductance in the systemic and pulmonary circulations.
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The effect of Bikram yoga on arterial stiffness in young and older adults. J Altern Complement Med 2013; 19:930-4. [PMID: 23738677 DOI: 10.1089/acm.2012.0709] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Bikram yoga is the most popular form of hot yoga, despite the limited information available on its cardiovascular benefits. This study sought to determine the effect of Bikram yoga on arterial stiffness and insulin resistance in young and older adults. METHODS Twenty-four young (mean age±standard deviation, 30±1 years) and 18 middle-aged and older (mean age, 53±2 years) adults completed an 8-week Bikram yoga intervention. Bikram yoga classes were performed for 90 minutes per session, three times per week, in a room heated to 40.5°C with 40%--60% relative humidity. RESULTS Body mass, body fat percentage, blood pressure, and fasting blood glucose and triglyceride concentrations did not significantly change as a result of the intervention in either the young or the older group. Trunk flexibility, as measured by the sit-and-reach test, increased in both groups (p<0.01). Total (p<0.05) and low-density lipoprotein cholesterol (p<0.05) levels, plasma insulin concentrations (p<0.01), and scores on the homeostatic model of the assessment of insulin resistance (p<0.01) decreased in older adults, whereas total and high-density lipoprotein cholesterol concentrations were reduced in young adults (all p<0.05). Carotid artery compliance (p<0.05) was increased and β-stiffness index decreased in young (p<0.05) but not in older adults. Carotid pulse pressure did not significantly change in either group. CONCLUSION A relatively short-term Bikram yoga intervention improved arterial stiffness in young but not older adults and significantly reduced insulin resistance index in older but not young adults.
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Abstract
Aging is characterized by increased sympatho-excitation, expressed through both the α-adrenergic and RAAS (renin-angiotensin-aldosterone) pathways. Although the independent contribution of these two pathways to elevated vasoconstriction with age may be substantial, significant cross-talk exists that could produce potentiating effects. To examine this interaction, 14 subjects (n=8 young, n=6 old) underwent brachial artery catheterization for administration of AngII (angiotensin II; 0.8-25.6 ng/dl per min), NE [noradrenaline (norepinephrine); 2.5-80 ng/dl per min] and AngII with concomitant α-adrenergic antagonism [PHEN (phentolamine); 10 μg/dl per min]. Ultrasound Doppler was utilized to determine blood flow, and therefore vasoconstriction, in both infused and contralateral (control) limbs. Arterial blood pressure was measured directly, and sympathetic nervous system activity was assessed via microneurography and plasma NE analysis. AngII sensitivity was significantly greater in the old, indicated by both greater maximal vasoconstriction (-59±4% in old against -48±3% in young) and a decreased EC50 (half-maximal effective concentration) (1.4±0.2 ng/dl per min in old against 2.6±0.7 μg/dl per min in young), whereas the maximal NE-mediated vasoconstriction was similar between these groups (-58±9% in old and -62±5% in young). AngII also increased venous NE in the old group, but was unchanged in the young group. In the presence of α-adrenergic blockade (PHEN), maximal AngII-mediated vasoconstriction in the old was restored to that of the young (-43±8% in old and -39±6% in young). These findings indicate that, with healthy aging, the increased AngII-mediated vasoconstriction may be attributed, in part, to potentiation of the α-adrenergic pathway, and suggest that cross-talk between the RAAS and adrenergic systems may be an important consideration in therapeutic strategies targeting these two pathways.
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Influence of α-adrenergic vasoconstriction on the blunted skeletal muscle contraction-induced rapid vasodilation with aging. J Appl Physiol (1985) 2012; 113:1201-12. [PMID: 22961267 DOI: 10.1152/japplphysiol.00734.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that elevated sympathetic tone is responsible for lower peak vasodilation after single muscle contractions in older adults. Young (n = 13, 7 men and 6 women, age: 27 ± 1 yr) and older (n = 13, 7 men and 6 women, age: 69 ± 2 yr) adults performed single forearm contractions at 10%, 20%, and 40% of maximum during 1) control, 2) sympathetic activation via lower body negative pressure (LBNP; -20 mmHg), and 3) intra-arterial infusion of phentolamine (α-adrenergic antagonist). Brachial artery diameter and velocities were measured via Doppler ultrasound, and forearm vascular conductance (FVC; in ml·min(-1)·100 mmHg(-1)) was calculated from blood flow (in ml/min) and blood pressure (in mmHg). Peak vasodilator responses [change in (Δ) FVC from baseline] were attenuated in older adults at 20% and 40% of maximum (P < 0.05). LBNP reduced peak ΔFVC at 10% (98 ± 17 vs. 70 ± 12 ml·min(-1)·100 mmHg(-1)), 20% (144 ± 12 vs. 98 ± 3 ml·min(-1)·100 mmHg(-1)), and 40% (209 ± 20 vs. 161 ± 21 ml·min(-1)·100 mmHg(-1), P < 0.01 vs. control) in younger adults but not in older adults (71 ± 11 vs. 68 ± 11, 107 ± 13 vs. 106 ± 16, and 161 ± 22 vs. 144 ± 22 ml·min(-1)·100 mmHg(-1), respectively, P = 0.22-0.99). With phentolamine, peak ΔFVC was enhanced in older adults at each contraction intensity (100 ± 14, 147 ± 22, and 200 ± 26 ml·min(-1)·100 mmHg(-1), respectively, P < 0.01 vs. control) but not in younger adults (94 ± 13, 153 ± 13, and 224 ± 27 ml·min(-1)·100 mmHg(-1), respectively, P = 0.30-0.81 vs. control). Our data indicate that α-adrenergic vasoconstriction and/or blunted functional sympatholysis might contribute to the age-related decreases in skeletal muscle contraction-induced rapid vasodilation in humans.
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Adjustments of pulmonary O2 uptake and muscle deoxygenation during ramp incremental exercise and constant-load moderate-intensity exercise in young and older adults. J Appl Physiol (1985) 2012; 113:1466-75. [PMID: 22961268 DOI: 10.1152/japplphysiol.00884.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The matching of muscle O(2) delivery to O(2) utilization can be inferred from the adjustments in muscle deoxygenation (Δ[HHb]) and pulmonary O(2) uptake (Vo(2p)). This study examined the adjustments of Vo(2p) and Δ[HHb] during ramp incremental (RI) and constant-load (CL) exercise in adult males. Ten young adults (YA; age: 25 ± 5 yr) and nine older adults (OA; age: 70 ± 3 yr) completed two RI tests and six CL step transitions to a work rate (WR) corresponding to 1) 80% of the estimated lactate threshold (same relative WR) and 2) 50 W (same absolute WR). Vo(2p) was measured breath by breath, and Δ[HHb] of the vastus lateralis was measured using near-infrared spectroscopy. Δ[HHb]-WR profiles were normalized from baseline (0%) to peak Δ[HHb] (100%) and fit using a sigmoid function. The sigmoid slope (d) was greater (P < 0.05) in OA (0.027 ± 0.01%/W) compared with YA (0.017 ± 0.01%/W), and the c/d value (a value corresponding to 50% of the amplitude) was smaller (P < 0.05) for OA (133 ± 40 W) than for YA (195 ± 51 W). No age-related differences in the sigmoid parameters were reported when WR was expressed as a percentage of peak WR. Vo(2p) kinetics compared with Δ[HHb] kinetics for the 50-W transition were similar between YA and OA; however, Δ[HHb] kinetics during the transition to 80% of the lactate threshold were faster than Vo(2p) kinetics in both groups. The greater reliance on O(2) extraction displayed in OA during RI exercise suggests a lower O(2) delivery-to-O(2) utilization relationship at a given absolute WR compared with YA.
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Isolated quadriceps training increases maximal exercise capacity in chronic heart failure: the role of skeletal muscle convective and diffusive oxygen transport. J Am Coll Cardiol 2011; 58:1353-62. [PMID: 21920265 DOI: 10.1016/j.jacc.2011.06.025] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 06/23/2011] [Accepted: 06/27/2011] [Indexed: 01/08/2023]
Abstract
OBJECTIVES This study sought to elucidate the mechanisms responsible for the benefits of small muscle mass exercise training in patients with chronic heart failure (CHF). BACKGROUND How central cardiorespiratory and/or peripheral skeletal muscle factors are altered with small muscle mass training in CHF is unknown. METHODS We studied muscle structure, and oxygen (O(2)) transport and metabolism at maximal cycle (whole-body) and knee-extensor exercise (KE) (small muscle mass) in 6 healthy controls and 6 patients with CHF who then performed 8 weeks of KE training (both legs, separately) and repeated these assessments. RESULTS Pre-training cycling and KE peak leg O(2) uptake (Vo(2peak)) were ~17% and ~15% lower, respectively, in the patients compared with controls. Structurally, KE training increased quadriceps muscle capillarity and mitochondrial density by ~21% and ~25%, respectively. Functionally, despite not altering maximal cardiac output, KE training increased maximal O(2) delivery (~54%), arterial-venous O(2) difference (~10%), and muscle O(2) diffusive conductance (D(M)O(2)) (~39%) (assessed during KE), thereby increasing single-leg Vo(2peak) by ~53%, to a level exceeding that of the untrained controls. Post-training, during maximal cycling, O(2) delivery (~40%), arterial-venous O(2) difference (~15%), and D(M)O(2) (~52%) all increased, yielding an increase in Vo(2peak) of ~40%, matching the controls. CONCLUSIONS In the face of continued central limitations, clear improvements in muscle structure, peripheral convective and diffusive O(2) transport, and subsequently, O(2) utilization support the efficacy of local skeletal muscle training as a powerful approach to combat exercise intolerance in CHF.
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Ageing reduces the compensatory vasodilatation during hypoxic exercise: the role of nitric oxide. J Physiol 2011; 589:1477-88. [PMID: 21282292 DOI: 10.1113/jphysiol.2010.203539] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We tested the hypotheses that (1) the compensatory vasodilatation in skeletal muscle during hypoxic exercise is attenuated in ageing humans and (2) local inhibition of nitric oxide (NO) synthesis in the forearm of ageing humans will have less impact on the compensatory dilatation during rhythmic exercise with hypoxia, due to a smaller compensatory dilator response. Eleven healthy older subjects (61 ± 2 years) performed forearm exercise (10% and 20% of maximum) during saline infusion (control) and NO synthase inhibition (NG-monomethyl-L-arginine; L-NMMA) under normoxic and normocapnic hypoxic (80% arterial O2 saturation) conditions. Forearm vascular conductance (FVC; ml min⁻¹ (100 mmHg)⁻¹) was calculated from forearm blood flow(ml min⁻¹) and blood pressure (mmHg). To further examine the effects of ageing on the compensatory vasodilator response to hypoxic exercise we compared the difference in ΔFVC (% change compared to respective normoxic exercise trial) between the older subjects (present study) and previously published data from an identical protocol in young subjects. During the control condition, the compensatory vasodilator response to hypoxia was similar between the old and young groups at 10% exercise (28 ± 6% vs. 40 ± 8%, P =0.11) but attenuated at 20% exercise (14 ± 4% vs. 31 ± 6%, P <0.05). L-NMMA during hypoxic exercise only blunted the compensatory vasodilator response in the young group (P <0.05). Our data suggest that ageing reduces the compensatory vasodilator response to hypoxic exercise via blunted NO signalling.
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Sex-specific effect of aging on submaximal leg exercise hemodynamics in middle-aged and older adults. Eur J Appl Physiol 2010; 111:1369-79. [PMID: 21153657 DOI: 10.1007/s00421-010-1766-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2010] [Indexed: 10/18/2022]
Abstract
The purpose of the study was to examine predictors of the leg hemodynamic response to exercise in middle- and older-aged men and women. Femoral artery blood flow (FBF), mean arterial pressure (MAP), and femoral vascular conductance (FVC, calculated as the quotient of FBF and MAP) were measured at rest and during 5 min of single knee-extensor exercise at ~10 W workload in healthy men (n = 31) and women (n = 32) (age 40-72 years). Age, menopausal status, maximal quadriceps strength, blood lipids, vitamin D levels, maximal oxygen uptake (VO(2max)), physical activity, blood pressure, estimated quadriceps muscle mass, and body mass index (BMI) were also assessed. The effect of age on FBF and FVC was negative and significant in men (r = -0.44 and -0.42 and p = 0.01 and 0.02, respectively) but was abolished by normalization to estimated quadriceps muscle (p = 0.18 and 0.73, respectively). There was no effect of age on leg hemodynamic responses to exercise in women (alone or normalized to quadriceps muscle), but menopausal status was a significant predictor of FVC and normalized FVC (p = 0.04 and 0.02, respectively). The multivariate model for exercising FVC in men (in order of strongest to weakest predictors) included quadriceps strength, BMI, resting FVC, age, and high-density lipoprotein cholesterol. The multivariate model for exercising FVC in women included quadriceps mass, systolic blood pressure, vitamin D, age, VO(2max), waist circumference, and physical activity score. These findings suggest that factors besides chronological age mediate exercising leg hemodynamics in middle-aged to older adults and that these factors are sex-specific.
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The lung cancer exercise training study: a randomized trial of aerobic training, resistance training, or both in postsurgical lung cancer patients: rationale and design. BMC Cancer 2010; 10:155. [PMID: 20409311 PMCID: PMC2888787 DOI: 10.1186/1471-2407-10-155] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 04/21/2010] [Indexed: 11/24/2022] Open
Abstract
Background The Lung Cancer Exercise Training Study (LUNGEVITY) is a randomized trial to investigate the efficacy of different types of exercise training on cardiorespiratory fitness (VO2peak), patient-reported outcomes, and the organ components that govern VO2peak in post-operative non-small cell lung cancer (NSCLC) patients. Methods/Design Using a single-center, randomized design, 160 subjects (40 patients/study arm) with histologically confirmed stage I-IIIA NSCLC following curative-intent complete surgical resection at Duke University Medical Center (DUMC) will be potentially eligible for this trial. Following baseline assessments, eligible participants will be randomly assigned to one of four conditions: (1) aerobic training alone, (2) resistance training alone, (3) the combination of aerobic and resistance training, or (4) attention-control (progressive stretching). The ultimate goal for all exercise training groups will be 3 supervised exercise sessions per week an intensity above 70% of the individually determined VO2peak for aerobic training and an intensity between 60 and 80% of one-repetition maximum for resistance training, for 30-45 minutes/session. Progressive stretching will be matched to the exercise groups in terms of program length (i.e., 16 weeks), social interaction (participants will receive one-on-one instruction), and duration (30-45 mins/session). The primary study endpoint is VO2peak. Secondary endpoints include: patient-reported outcomes (PROs) (e.g., quality of life, fatigue, depression, etc.) and organ components of the oxygen cascade (i.e., pulmonary function, cardiac function, skeletal muscle function). All endpoints will be assessed at baseline and postintervention (16 weeks). Substudies will include genetic studies regarding individual responses to an exercise stimulus, theoretical determinants of exercise adherence, examination of the psychological mediators of the exercise - PRO relationship, and exercise-induced changes in gene expression. Discussion VO2peak is becoming increasingly recognized as an outcome of major importance in NSCLC. LUNGEVITY will identify the optimal form of exercise training for NSCLC survivors as well as provide insight into the physiological mechanisms underlying this effect. Overall, this study will contribute to the establishment of clinical exercise therapy rehabilitation guidelines for patients across the entire NSCLC continuum. Trial Registration NCT00018255
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Exercise-induced brachial artery vasodilation: effects of antioxidants and exercise training in elderly men. Am J Physiol Heart Circ Physiol 2009; 298:H671-8. [PMID: 19966056 DOI: 10.1152/ajpheart.00761.2009] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aging, vascular function, and exercise are thought to have a common link in oxidative stress. Of the 28 subjects studied (young, 26 +/- 2 yr; old, 71 +/- 6 yr), 12 took part in a study to validate an antioxidant cocktail (AOC: vitamins C, E, and alpha-lipoic acid), while the remaining 8 young and 8 old subjects performed submaximal forearm handgrip exercise with placebo or AOC. Old subjects repeated forearm exercise with placebo or AOC following knee-extensor (KE) exercise training. Brachial arterial diameter and blood velocity (Doppler ultrasound) were measured at rest and during exercise. During handgrip exercise, brachial artery vasodilation in the old subjects was attenuated compared with that in young subjects following placebo (maximum = approximately 3.0 and approximately 6.0%, respectively). In contrast to the previously documented attenuation in exercise-induced brachial artery vasodilation in the young group with AOC, in the old subjects the AOC restored vasodilation (maximum = approximately 7.0%) to match the young. KE training also improved exercise-induced brachial artery vasodilation. However, in the trained state, AOC administration no longer augmented brachial artery vasodilation in the elderly, but rather attenuated it. These data reveal an age-related pro-/antioxidant imbalance that impacts vascular function and show that exercise training is capable of restoring equilibrium such that vascular function is improved and the AOC-mediated reduction in free radicals now negatively impacts brachial artery vasodilation, as seen in the young.
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Abstract
BACKGROUND Ageing is known to be associated with a decrease in peak oxygen consumption (VO2peak) and maximal tolerated power (MTP). Regular physical exercise is the most appropriate to improve aerobic capacity, but its effect still remained discussed in old people. DESIGN The aim of this study was to determine whether a short interval training session would be associated with improvements in exercise efficiency in aged subjects in both genders. METHODS In all, 19 women and 16 men (65.4 +/- 4.9 years) performed a cycle incremental exercise test before and after a 9-week period of aerobic interval training (twice a week, 30 min session where 6 x 4-min at the first ventilatory threshold alternated with 1-min at the second ventilatory threshold) with cycle ergometer. Minute ventilation (MV), O(2) uptake (VO(2)) and CO(2) output (VCO(2)) were measured breath-by-breath and by an open-circuit metabolic cart. RESULTS Before training, maximal values of MV (MMV), VO2peak, heart rate, systolic blood pressure, MTP, blood lactate at MTP recovery and the power at the first (pVT(1)) and second ventilatory thresholds (pVT(2)) were higher in men compared with women. Nine weeks of interval training induced a significant increase in MMV, VO2peak, MTP, pVT(1) and pVT(2) and decrease in systolic blood pressure in the same way in men than in women, without any significant effect on their maximal heart rate values. CONCLUSIONS These findings suggest that the age-related declines in aerobic index are attenuated by a short exercise interval training sessions in women and men.
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Transcriptional and post-transcriptional regulation of mitochondrial biogenesis in skeletal muscle: effects of exercise and aging. Biochim Biophys Acta Gen Subj 2009; 1800:223-34. [PMID: 19682549 DOI: 10.1016/j.bbagen.2009.07.031] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 07/27/2009] [Accepted: 07/30/2009] [Indexed: 12/18/2022]
Abstract
Acute contractile activity of skeletal muscle initiates the activation of signaling kinases. This promotes the phosphorylation of transcription factors, leading to enhanced DNA binding and transcriptional activation and/or repression. The mRNA products of nuclear genes encoding mitochondrial proteins are translated in the cytosol and imported into pre-existing mitochondria. When contractile activity is repeated, the recapitulation of these cellular events progressively leads to an expansion of the mitochondrial reticulum within muscle. This has physiologically relevant health benefit, including enhanced lipid metabolism and reduced muscle fatigability. In aging skeletal muscle, the response to contractile activity appears to be attenuated, suggesting that a greater contractile stimulus is required to attain a similar phenotype adaptation. This review summarizes our current understanding of the effects of exercise on the gene expression pathway leading to organelle biogenesis in muscle.
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[Aging and physical activity data on which to base recommendations for exercise in older adults]. Appl Physiol Nutr Metab 2009; 32 Suppl 2F:S75-S171. [PMID: 19377547 DOI: 10.1139/h07-165] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An abundance of epidemiological research confirms the benefits of physical activity in reducing risk of various age-related morbidities and all-cause mortality. Analysis of the literature focusing on key exercise variables (e.g., intensity, type, and volume) suggests that the requisite beneficial amount of activity is that which engenders improved cardiorespiratory fitness, strength, power, and, indirectly, balance. Age-related declines in these components are such that physical limitations impinge on functional activities of daily living. However, an exercise programme can minimize declines, thus preventing older adults (age 65+ years) from crossing functional thresholds of inability. Cross-sectional and longitudinal data demonstrate that cardiorespiratory fitness is associated with functional capacity and independence; strength and, importantly, power are related to performance and activities of daily living; and balance-mobility in combination with power are important factors in preventing falls. Exercise interventions have documented that older adults can adapt physiologically to exercise training, with gains in functional capacities. The few studies that have explored minimal or optimal activity requirements suggest that a threshold (intensity) within the moderately vigorous domain is needed to achieve and preserve related health benefits. Thus, physical activity and (or) exercise prescriptions should emphasize activities of the specificity and type to improve components related to the maintenance of functional capacity and independence; these will also delay morbidity and mortality. An appropriate recommendation for older adults includes moderately vigorous cardiorespiratory activities (e.g., brisk walking), strength and (or) power training for maintenance of muscle mass and specific muscle-group performance, as well as "balance-mobility practice" and flexibility (stretching) exercise as needed.
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Oral antioxidants and cardiovascular health in the exercise-trained and untrained elderly: a radically different outcome. Clin Sci (Lond) 2009; 116:433-41. [PMID: 18795893 DOI: 10.1042/cs20080337] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Both antioxidant supplementation and exercise training have been identified as interventions which may reduce oxidative stress and thus improve cardiovascular health, but the interaction of these interventions on arterial BP (blood pressure) and vascular function has not been studied in older humans. Thus in six older (71+/-2 years) mildly hypertensive men, arterial BP was evaluated non-invasively at rest and during small muscle mass (knee-extensor) exercise with and without a pharmacological dose of oral antioxidants (vitamins C and E, and alpha-lipoic acid). The efficacy of the antioxidant intervention to decrease the plasma free radical concentration was verified via EPR (electron paramagnetic resonance) spectroscopy, while changes in endothelial function in response to exercise training and antioxidant administration were evaluated via FMD (flow-mediated vasodilation). Subjects were re-evaluated after a 6-week aerobic exercise training programme. Prior to training, acute antioxidant administration did not change resting arterial BP or FMD. Six weeks of knee-extensor exercise training reduced systolic BP (from 150+/-8 mmHg at pre-training to 138+/-3 mmHg at post-training) and diastolic BP (from 91+/-5 mmHg at pre-training to 79+/-3 mmHg at post-training), and improved FMD (1.5+/-1 to 4.9+/-1% for pre- and post-training respectively). However, antioxidant administration after exercise training negated these improvements, returning subjects to a hypertensive state and blunting training-induced improvements in FMD. In conclusion, the paradoxical effects of these interventions suggest a need for caution when exercise and acute antioxidant supplementation are combined in elderly mildly hypertensive individuals.
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Abstract
PURPOSE OF REVIEW To provide a brief overview of the main techniques to measure muscle blood flow in humans and highlight some of the strengths and weaknesses associated with each technique. RECENT FINDINGS Peak muscle blood flow values of 300 ml/min per 100 g are possible in humans during heavy exercise performed with small muscle mass. This value is far higher than that which appears in most textbooks. Accurate and reliable techniques are therefore essential in measuring muscle blood flow. Current invasive techniques commonly used include indicator dilution (thermodilution and dye dilution) and radiolabel tracer washout (e.g. 133Xe washout) methods. Although invasive techniques have provided valuable insight into tissue blood flow, noninvasive techniques such as venous occlusion plethysmography and Doppler ultrasound are frequently used and provide accurate measurements of blood flow. Newer imaging techniques (MRI, positron emission tomography, and contrast-enhanced ultrasonography) promise increased resolution of measurements of local blood flow, including in discrete tissues in which more classical techniques are not able to be used. SUMMARY Muscle blood flow is a key link in the interplay and regulation of systemic and local muscle metabolism. Recognizing the advantages and limitations of each technique is essential to translational researchers studying the effects of nutrition and metabolism on muscle blood flow.
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Abstract
Our previous work suggests that healthy human aging is associated with sex-specific differences in leg vascular responses during large muscle mass exercise (2-legged cycling) (Proctor DN, Parker BA. Microcirculation 13: 315-327, 2006). The present study determined whether age x sex interactions in exercising leg hemodynamics persist during small muscle mass exercise that is not limited by cardiac output. Thirty-one young (20-30 yr; 15 men/16 women) and 31 older (60-79 yr; 13 men/18 women) healthy, normally active adults performed graded single-leg knee extensions to maximal exertion. Femoral artery blood velocity and diameter (Doppler ultrasound), heart rate (ECG), and beat-to-beat arterial blood pressure (mean arterial pressure, radial artery tonometry) were measured during each 3-min work rate (4.8 and 8 W/stage for women and men, respectively). The results (means +/- SE) were as follows. Despite reduced resting leg blood flow and vascular conductance, older men exhibited relatively preserved exercising leg hemodynamic responses. Older women, by contrast, exhibited attenuated hyperemic (young: 52 +/- 3 ml.min(-1).W(-1); vs. older: 40 +/- 4 ml.min(-1).W(-1); P = 0.02) and vasodilatory responses (young: 0.56 +/- 0.06 ml.min(-1).mmHg(-1).W(-1) vs. older: 0.37 +/- 0.04 ml.min(-1).mmHg(-1) W(-1); P < 0.01) to exercise compared with young women. Relative (percentage of maximal) work rate comparisons of all groups combined also revealed attenuated vasodilator responses in older women (P < 0.01 for age x sex x work rate interaction). These sex-specific age differences were not abolished by consideration of hemoglobin, quadriceps muscle, muscle recruitment, and mechanical influences on muscle perfusion. Collectively, these findings suggest that local factors contribute to the sex-specific effects of aging on exercising leg hemodynamics in healthy adults.
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Ageing and physical activity: evidence to develop exercise recommendations for older adultsThis article is part of a supplement entitled Advancing physical activity measurement and guidelines in Canada: a scientific review and evidence-based foundation for the future of Canadian physical activity guidelines co-published by Applied Physiology, Nutrition, and Metabolism and the Canadian Journal of Public Health. It may be cited as Appl. Physiol. Nutr. Metab. 32(Suppl. 2E) or as Can. J. Public Health 98(Suppl. 2). Appl Physiol Nutr Metab 2007. [DOI: 10.1139/h07-111] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An abundance of epidemiological research confirms the benefits of physical activity in reducing risk of various age-related morbidities and all-cause mortality. Analysis of the literature focusing on key exercise variables (e.g., intensity, type, and volume) suggests that the requisite beneficial amount of activity is that which engenders improved cardiorespiratory fitness, strength, power, and, indirectly, balance. Age-related declines in these components are such that physical limitations impinge on functional activities of daily living. However, an exercise programme can minimize declines, thus preventing older adults (age 65+ years) from crossing functional thresholds of inability. Cross-sectional and longitudinal data demonstrate that cardiorespiratory fitness is associated with functional capacity and independence; strength and, importantly, power are related to performance and activities of daily living; and balance-mobility in combination with power are important factors in preventing falls. Exercise interventions have documented that older adults can adapt physiologically to exercise training, with gains in functional capacities. The few studies that have explored minimal or optimal activity requirements suggest that a threshold (intensity) within the moderately vigorous domain is needed to achieve and preserve related health benefits. Thus, physical activity and (or) exercise prescriptions should emphasize activities of the specificity and type to improve components related to the maintenance of functional capacity and independence; these will also delay morbidity and mortality. An appropriate recommendation for older adults includes moderately vigorous cardiorespiratory activities (e.g., brisk walking), strength and (or) power training for maintenance of muscle mass and specific muscle-group performance, as well as “balance-mobility practice” and flexibility (stretching) exercise as needed.
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Abstract
The role of the referee is far from minimal in the economy of soccer, as very often, particularly in professional soccer, a wrong judgment may have profound implications on the outcome of the game. In this regard, a better knowledge of soccer refereeing can obviously benefit the game. Recent studies have shown that during a competitive match, an elite soccer referee may cover 9-13 km attaining approximately 85-90% and approximately 70-80% of maximal heart rate and maximal oxygen uptake (VO2max), respectively. Of the total distance covered about 4-18% is covered at high intensity. Blood lactate concentration has been reported to be in the range of 4-5 mmol/L; however, during competitive matches, blood lactate concentrations as high as 14 mmol/L have been observed. This figure is similar to that extensively reported for soccer players, specifically paralleling that observed in midfield players. However, compared with players, referees are 15-20 years older, often have a non-professional status and cannot be substituted during the game. Furthermore, this important physical stress superimposes onto a high perceptual-cognitive workload throughout the entire game. In relation to fitness status, referees possess VO2max values somewhat lower than the players they officiate, with mean values in the range of 44-50 mL/kg/min. However, the methods used by the Federation Internationale de Football Association and the Union of European Football Associations to test referee fitness need to be changed as the current fitness tests do not relate to match performance. More task-specific tests such as the Yo-Yo Intermittent Recovery Test (YYIRT) have been devised and validated for use with referees. Given that aerobic performance is positively correlated with match performance, it is important that referees are trained to improve their ability to cover large distances during a match and also to repeat high-intensity efforts. A number of studies have shown large improvements in YYIRT performance following both short-term (12 weeks) and long-term (16 months) high-intensity interval training. Future research needs to focus on a number of important areas including the decision-making ability of referees when officiating under different conditions, such as high thermal strain, and the impact of age on both physical and mental performance.
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Abstract
Unlike quadrupeds, human limbs are exposed to differing homeostatic challenges and uses, which results in significant functional heterogeneity between the arms and legs. In these ACSM symposium proceedings, we report findings from three studies with the overall aim of investigating between-limb vascular differences through evaluation of arm (brachial artery) and leg (common, superficial, and deep femoral arteries) limb blood flow (ultrasound Doppler) during isolated-limb-specific exercise and after postcuff occlusion hyperemia. In a study of young, trained cyclists, a substantial conduit vessel vasodilation (deep femoral artery, approximately 9%) was observed during exercise, but responsiveness normalized to shear stimuli was still less than a conduit vessel in the arm. A subsequent aging study did not demonstrate any significant difference in resting leg or arm blood flow between young and old subjects when flow was normalized for muscle mass. However, we observed an approximately 10-15% reduction in exercising leg blood flow and vascular conductance in these older subjects, whereas exercising arm blood flow was similar between age groups. A separate aging study evaluated age-related changes in flow-mediated vasodilation (FMD), with the older group enrolled in a 6-wk knee-extensor exercise training program. Before training, a significant FMD was observed in the arm of young (3 +/- 1%) but not old (1 +/- 1%) subjects, and a significant leg FMD was observed in both groups. However, pretraining arm vasodilation was similar between young and old when normalized for shear rate. Exercise training significantly improved arm FMD (5 +/- 1%), whereas leg FMD was unchanged. Collectively, these studies demonstrate a significant between-limb vascular heterogeneity in humans that is influenced by age and by exercise training.
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Abstract
In older humans, infusions of endothelial agonists suggest endothelial dysfunction, due in part to less nitric oxide (NO)- and prostaglandin (PG)-mediated vasodilatation, and a shift toward PG-mediated vasoconstriction. Ageing can also be associated with lower exercise blood flow (exercise hyperaemia), but the vascular mechanisms mediating this remain unknown. Notably, in young adults, inhibition of NO and PGs during exercise decreases exercise hyperaemia by approximately 20 and approximately 12%, respectively. We tested our first hypothesis that in older humans inhibition of NO would decrease hyperaemia, but that inhibition of PGs would increase hyperaemia by blocking vasoconstrictor PGs. Fifteen older subjects (65 +/- 3 years) performed dynamic forearm exercise for 20 min (20 contractions min(-1)). Forearm blood flow (FBF) was measured beat-to-beat with Doppler ultrasound, while saline or drugs were infused sequentially via brachial artery catheter in the exercising forearm. After achieving steady-state exercise, L-NAME (25 mg) was infused over 5 min to inhibit NO synthase. After a further 2 min of exercise (saline), ketorolac (6 mg) was infused over 5 min to inhibit PGs, followed by a further 3 min of exercise with saline. Drug order was reversed in seven subjects. L-NAME reduced steady-state exercise hyperaemia by 12 +/- 3% in older subjects (P<0.01), whereas ketorolac had no net effect on blood flow (3 +/- 6%, P>0.4). The effects of l-NAME and ketorolac were independent of drug order. By comparing these results with our previous results in young adults, we tested our second hypothesis that in older humans inhibition of NO or PGs would have less impact on exercise hyperaemia due to less vasodilatation from these signals. Our results suggest that, compared with young adults, in older humans the relative contribution of NO to exercise hyperaemia is reduced approximately 45% (22 +/- 4 versus 12 +/- 3%), but the role of PG in mediating vasodilatation is lost in ageing human skeletal muscle. Lower exercise hyperaemia in older humans may be mediated in part by less NO- and PG-mediated vasodilatation during exercise.
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Aerobic fitness and field test performance in elite Spanish soccer referees of different ages. J Sci Med Sport 2006; 10:382-9. [PMID: 17116419 DOI: 10.1016/j.jsams.2006.08.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 08/28/2006] [Accepted: 08/31/2006] [Indexed: 11/28/2022]
Abstract
The major aim of this study was to examine the physical fitness of elite Spanish soccer referees in relation to their age. A secondary aim was to assess the population criterion validity of the 12 min running test (12 MRT) against aerobic-fitness laboratory tests. Participants were 45 soccer referees (age 35.5+/-4.4 years, height 178.3+/-5.0 cm, body mass 75.1+/-6.6 kg, body fat 11.3+/-2.15%, VO2(max), 54.9+/-3.9 ml kg(-1) min(-1)) who were enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. They were divided into three age groups: young (Y, 27-32 years, n=15), average (A, 33-38 years, n=17) and old (O, 39-45 years, n=13). No age-related effects were observed for VO2(max), 12 MRT or 200 m sprint performance in either the pooled or grouped data. However, age-related performance decrements were observed for 50 m sprint performance and the ventilatory threshold (VT) running speed. Twelve MRT performance was moderately related to VO2(max), (r=0.46, P=0.002), VT (km h(-1)) (r=0.49, P<0.001), and peak treadmill velocity (PTV) (r=0.60, P<0.001). The results showed that older elite-level referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, these results show that older referees are able to reach physical fitness levels that have been suggested to be appropriate for coping with match demands.
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Abstract
The arterial vessels within the arms and legs are exposed to different hydrostatic pressures and blood-flow demands during the course of daily life. There is compelling indirect evidence that arterial reactivity differs in the arms and legs of humans; greater blood-flow responses to physiological vasodilator stimuli are generally reported in the arms of healthy younger subjects, whereas greater sympathetically mediated vasoconstrictor responsiveness is generally observed in the legs. Limb blood-flow responses to local arterial infusions of vasoactive agents reveal a similar pattern of heterogeneity in human arms versus legs. The advantages and assumptions of these pharmacological approaches for evaluating limb arterial reactivity are discussed, and methodological issues pertaining to the normalization and interpretation of vascular responses in the human arm and leg are critically examined. The article concludes with recent data from our laboratory indicating that limb-specific variation in arterial function may be age-, sex-, and physical activity dependent.
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Abstract
Recent developments in noninvasive imaging techniques have enabled the study of local changes in perfusion and metabolism in skeletal muscle as well as patterns of heterogeneity in these variables in humans. In this review, the principles of these techniques along with some recent findings on functional heterogeneity in human skeletal muscle will be presented.
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Abstract
Aging appears to attenuate leg blood flow during exercise; in contrast, such data are scant and do not support this contention in the arm. Therefore, to determine whether aging has differing effects on blood flow in the arm and leg, eight young (22 ± 6 yr) and six old (71 ± 15 yr) subjects separately performed dynamic knee extensor [0, 3, 6, 9 W; 20, 40, 60% maximal work rate (WRmax)] and handgrip exercise (3, 6, 9 kg at 0.5 Hz; 20, 40, 60% WRmax). Arterial diameter, blood velocity (Doppler ultrasound), and arterial blood pressure (radial tonometry) were measured simultaneously at each of the submaximal workloads. Quadriceps muscle mass was smaller in the old (1.6 ± 0.1 kg) than the young (2.1 ± 0.2 kg). When normalized for this difference in muscle mass, resting seated blood flow was similar in young and old subjects (young, 115 ± 28; old, 114 ± 39 ml·kg−1·min−1). During exercise, blood flow and vascular conductance were attenuated in the old whether expressed in absolute terms for a given absolute workload or more appropriately expressed as blood flow per unit muscle mass at a given relative exercise intensity (young, 1,523 ± 329; old, 1,340 ± 157 ml·kg−1·min−1 at 40% WRmax). In contrast, aging did not affect forearm muscle mass or attenuate rest or exercise blood flow or vascular conductance in the arm. In conclusion, aging induces limb-specific alterations in exercise blood flow regulation. These alterations result in reductions in leg blood flow during exercise but do not impact forearm blood flow.
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Abstract
We sought to identify the relationship between shear stimuli and flow-mediated vasodilation and to determine whether small muscle mass exercise training could provoke limb-specific improvements in endothelial function in older subjects. In five young (22 +/- 1 yr old) and six old (71 +/- 2 yr old) subjects, ultrasound Doppler measurements were taken in the arm (brachial artery) and leg (deep and superficial femoral arteries) after suprasystolic cuff occlusion with and without ischemic exercise to evaluate flow-mediated dilation (FMD) in both limbs. Older subjects were reevaluated after 6 wk of single-leg knee extensor exercise training. Before the training, a significant FMD was observed in the arm of young (3 +/- 1%) but not old (1 +/- 1%) subjects, whereas a significant leg FMD was observed in both groups (5 +/- 1% old vs. 3 +/- 1% young). However, arm vasodilation was similar between young and old when normalized for shear rate, and cuff occlusion with superimposed handgrip exercise provoked additional shear, which proportionately improved the FMD response in both groups. Exercise training significantly improved arm FMD (5 +/- 1%), whereas leg FMD was unchanged. However, ischemic handgrip exercise did not provoke additional arm vasodilation after training, which may indicate an age-related limit to shear-induced vasodilation. Together, these data demonstrate that vascular reactivity is dependent on limb and degree of shear stimuli, challenging the convention of diminished endothelial function typically associated with age. Likewise, exercise training improved arm vasodilation, indicating some preservation of vascular plasticity with age.
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Effect of physical activity on MRI-measured blood oxygen level-dependent transients in skeletal muscle after brief contractions. J Appl Physiol (1985) 2005; 99:715-22. [PMID: 15802369 PMCID: PMC8495996 DOI: 10.1152/japplphysiol.00272.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The signal intensity (SI) in gradient-echo, echo-planar magnetic resonance images (repetition time/echo time = 1,000/40) of anterior tibialis muscle in active [estimated energy expenditure 42.4 +/- 3.7 (SD), n = 8] vs. sedentary (32.3 +/- 0.6 kcal.kg(-1).day(-1), n = 8) young adult (18-34 yr old) human subjects was measured after single, 1-s-duration maximum voluntary ankle dorsiflexion contractions. There was no difference between groups in anterior tibial muscle cross-sectional area or peak force. In both groups there was a transient increase in anterior tibialis muscle SI, which peaked 5-7 s after the end of each contraction. The magnitude of the SI transient was over threefold greater [5.5 +/- 1.0 (SE) vs. 1.5 +/- 0.4%] and persisted twice as long (half-recovery time 5.4 +/- 0.4 vs. 2.7 +/- 0.3 s) in the active subjects. In the same subjects, blood flow in popliteal, anterior tibial, and posterior tibial arteries was measured by cardiac-gated CINE magnetic resonance angiography before and after 2 min of dynamic, repetitive ankle dorsiflexion exercise. There was no difference between groups in resting or postexercise flow in anterior tibial artery, although popliteal and posterior tibial artery flow after exercise tended to be greater in the active group. The results indicate that transient hyperemia and oxygenation in muscle after single contractions are enhanced by chronic physical activity to a greater extent than peak muscle blood flow.
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Abstract
Chronic heart failure (CHF) is manifested principally in the elderly population. Therefore, to understand the causes of exercise intolerance in CHF patients, it is imperative to resolve the effects of aging on muscle blood flow (BF) in CHF. To address this issue, we determined the muscle BF response to submaximal treadmill exercise (20 m/min, 5% grade) in young (Y(CHF): 6-8 mo, 412 +/- 11 g, n = 11) and old (O(CHF): 27-29 mo, 494 +/- 10 g, n = 8) Fischer 344 x Brown Norway rats with similar degrees of myocardial infarction-induced left ventricular (LV) dysfunction [resting LV end-diastolic pressure: Y(CHF) = 24 +/- 2, O(CHF) = 22 +/- 2 mmHg; derivative of LV pressure over time: Y(CHF) = 5,168 +/- 285; O(CHF) = 5,050 +/- 165 mmHg/s; lung weight normalized to body weight: Y(CHF) = 9.14 +/- 0.72; O(CHF) = 8.21 +/- 0.29 mg/g (all P > 0.05)]. The exercising heart rate response was blunted in O(CHF) compared with Y(CHF) rats (Y(CHF) = 454 +/- 8, O(CHF) = 395 +/- 9 beats/min; P < 0.05). BF (radiolabeled microspheres) to the total hindlimb musculature and to each of the 28 individual muscles examined was similar between Y(CHF) and O(CHF) rats under resting conditions. During exercise, BF to five of the hindlimb muscles that normally possess a majority of slow-twitch oxidative and fast-twitch oxidative glycolytic muscle fibers increased significantly less (-25 to -42%) for O(CHF) compared with Y(CHF) rats. In contrast, BF to 14 of the hindlimb muscles that normally possess a majority of fast-twitch glycolytic muscle fibers was increased (+22 to +337%) for O(CHF) vs. Y(CHF) rats, which contributed to a greater mass-specific total hindlimb BF response in O(CHF) rats (Y(CHF) = 78 +/- 5, O(CHF) = 100 +/- 11 ml.min(-1).100 g(-1); P < 0.05) and coincided with greater reductions in BF to the kidneys and splanchnic organs during exercise in O(CHF) vs. Y(CHF). In conclusion, there appears to be a profound age-related redistribution of BF from the highly oxidative to the highly glycolytic muscles of the hindlimb during exercise in O(CHF) compared with Y(CHF) rats. This phenomenon is qualitatively similar to that reported previously for healthy young and old rats.
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