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Norbury R, Grant I, Woodhead A, Hughes L, Tallent J, Patterson SD. Acute hypoalgesic, neurophysiological and perceptual responses to low-load blood flow restriction exercise and high-load resistance exercise. Exp Physiol 2024; 109:672-688. [PMID: 38578259 PMCID: PMC11061633 DOI: 10.1113/ep091705] [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: 12/04/2023] [Accepted: 03/13/2024] [Indexed: 04/06/2024]
Abstract
This study compared the acute hypoalgesic and neurophysiological responses to low-load resistance exercise with and without blood flow restriction (BFR), and free-flow, high-load exercise. Participants performed four experimental conditions where they completed baseline measures of pain pressure threshold (PPT), maximum voluntary force (MVF) with peripheral nerve stimulation to determine central and peripheral fatigue. Corticospinal excitability (CSE), corticospinal inhibition and short interval intracortical inhibition (SICI) were estimated with transcranial magnetic stimulation. Participants then performed low-load leg press exercise at 30% of one-repetition maximum (LL); low-load leg press with BFR at 40% (BFR40) or 80% (BFR80) of limb occlusion pressure; or high-load leg press of four sets of 10 repetitions at 70% one-repetition maximum (HL). Measurements were repeated at 5, 45 min and 24 h post-exercise. There were no differences in CSE or SICI between conditions (all P > 0.05); however, corticospinal inhibition was reduced to a greater extent (11%-14%) in all low-load conditions compared to HL (P < 0.005). PPTs were 12%-16% greater at 5 min post-exercise in BFR40, BFR80 and HL compared to LL (P ≤ 0.016). Neuromuscular fatigue displayed no clear difference in the magnitude or time course between conditions (all P > 0.05). In summary, low-load BFR resistance exercise does not induce different acute neurophysiological responses to low-load, free-flow exercise but it does promote a greater degree of hypoalgesia and reduces corticospinal inhibition more than high-load exercise, making it a useful rehabilitation tool. The changes in neurophysiology following exercise were not related to changes in PPT.
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Affiliation(s)
- Ryan Norbury
- Faculty of Sport, Technology and Health SciencesSt Mary's UniversityTwickenhamUK
| | - Ian Grant
- Faculty of Sport, Technology and Health SciencesSt Mary's UniversityTwickenhamUK
| | - Alex Woodhead
- Faculty of Sport, Technology and Health SciencesSt Mary's UniversityTwickenhamUK
| | - Luke Hughes
- Department of Sport, Exercise and RehabilitationNorthumbria UniversityNewcastle‐Upon TyneUK
| | - Jamie Tallent
- School of Sport, Rehabilitation and Exercise SciencesUniversity of EssexColchesterUK
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health ScienceMonash UniversityMelbourneVAAustralia
| | - Stephen D. Patterson
- Faculty of Sport, Technology and Health SciencesSt Mary's UniversityTwickenhamUK
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Callovini A, Fornasiero A, Savoldelli A, Decet M, Skafidas S, Pellegrini B, Bortolan L, Schena F. Independent, additive and interactive effects of acute normobaric hypoxia and cold on submaximal and maximal endurance exercise. Eur J Appl Physiol 2024; 124:1185-1200. [PMID: 37962573 PMCID: PMC10955012 DOI: 10.1007/s00421-023-05343-9] [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: 03/29/2023] [Accepted: 10/16/2023] [Indexed: 11/15/2023]
Abstract
PURPOSE To evaluate the independent and combined effects of hypoxia (FiO2 = 13.5%) and cold (- 20 °C) on physiological and perceptual responses to endurance exercise. METHODS 14 trained male subjects ( V . O2max: 64 ± 5 mL/kg/min) randomly performed a discontinuous maximal incremental test to exhaustion on a motorized treadmill under four environmental conditions: Normothermic-Normoxia (N), Normothermic-Hypoxia (H), Cold-Normoxia (C) and Cold-Hypoxia (CH). Performance and physiological and perceptual responses throughout exercise were evaluated. RESULTS Maximal WorkLoad (WL) and WL at lactate threshold (LT) were reduced in C (- 2.3% and - 3.5%) and H (- 18.0% and - 21.7%) compared to N, with no interactive (p = 0.25 and 0.81) but additive effect in CH (- 21.5% and - 24.6%). Similarly, HRmax and Vemax were reduced in C (- 3.2% and - 14.6%) and H (- 5.0% and - 7%), showing additive effects in CH (- 7.7% and - 16.6%). At LT, additive effect of C (- 2.8%) and H (- 3.8%) on HR reduction in CH (- 5.7%) was maintained, whereas an interactive effect (p = 0.007) of the two stressors combined was noted on Ve (C: - 3.1%, H: + 5.5%, CH: - 10.9%). [La] curve shifted on the left in CH, displaying an interaction effect between the 2 stressors on this parameter. Finally, RPE at LT was exclusively reduced by hypoxia (p < 0.001), whereas TSmax is synergistically reduced by cold and hypoxia (interaction p = 0.047). CONCLUSION If compared to single stress exposure, exercise performance and physiological and perceptual variables undergo additive or synergistic effects when cold and hypoxia are combined. These results provide new insight into human physiological responses to extreme environments.
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Affiliation(s)
- A Callovini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - A Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - A Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
| | - M Decet
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - S Skafidas
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - B Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - L Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - F Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Rodríguez-Zamora L, Benavente C, Petrer I, Padial P, Timón R, Arguelles J, Feriche B. Hypoxia matters: comparison of external and internal training load markers during an 8-week resistance training program in normoxia, normobaric hypoxia and hypobaric hypoxia. Eur J Appl Physiol 2024:10.1007/s00421-024-05442-1. [PMID: 38446192 DOI: 10.1007/s00421-024-05442-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 02/14/2024] [Indexed: 03/07/2024]
Abstract
PURPOSE To compare external and internal training load markers during resistance training (RT) in normoxia (N), intermittent hypobaric hypoxia (HH), and intermittent normobaric hypoxia (NH). METHODS Thirty-three volunteers were assigned an 8-week RT program in either N (690 m, n = 10), HH (2320 m, n = 10), or NH (inspired fraction of oxygen = 15.9%; ~ 2320 m, n = 13). The RT program (3x/week) consisted of six exercises, with three sets of six to 12 repetitions at ~ 70% of one repetition maximum (1RM) with the first session of each week used for analysis. 1RM in back squat and bench press was used to evaluate muscle strength before and after the program. External load was assessed by the volume load relative to body mass (RVL, kg·kg-1). Internal load was assessed by the ratings of perceived exertion (RPE) and heart rate (HR). RESULTS Smaller relative improvements were found for the back squat in the N group (11.5 ± 8.8%) when compared to the NH group (22.2 ± 8.2%, P = 0.01) and the HH group (22 ± 8.1%, P = 0.02). All groups showed similar RVL, HR responses and RPE across the program (P˃0.05). However, reduced HR recovery values, calculated as the difference between the highest HR value (HRpeak) and the resting heart rate after a two min rest, were seen in the N and NH groups across the program (P < 0.05). CONCLUSION It seems that 8 weeks of intermittent RT in hypoxic environments could maximize time-efficiency when aiming to improve strength levels in back squat without evoking higher levels of physiological stress. Performing RT at hypobaric hypoxia may improve the cardiorespiratory response, which in turn could speed recovery.
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Affiliation(s)
- Lara Rodríguez-Zamora
- School of Health and Medical Sciences, Division of Sport Sciences, Örebro University, Örebro, Sweden.
| | - Cristina Benavente
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - Irene Petrer
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - Paulino Padial
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - Rafa Timón
- Faculty of Sport Sciences, University of Extremadura, Cáceres, Spain
| | - Javier Arguelles
- High Performance Center of Sierra Nevada, Spanish Sport Council, Granada, Spain
| | - Belén Feriche
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
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Li SN, Peeling P, Scott BR, Peiffer JJ, Shaykevich A, Girard O. Maintenance of internal load despite a stepwise reduction in external load during moderate intensity heart rate clamped cycling with acute graded normobaric hypoxia in males. J Sci Med Sport 2023; 26:628-635. [PMID: 37852804 DOI: 10.1016/j.jsams.2023.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023]
Abstract
OBJECTIVES To investigate the acute effects of graded hypoxia on external and internal loads during 60 min of endurance cycling at a clamped heart rate. DESIGN Repeated measures. METHODS On separate visits, 16 trained males cycled for 60 min at a clamped heart rate corresponding to 80 % of their first ventilatory threshold at sea-level and 2500 m, 3000 m, 3500 m and 4000 m simulated altitudes (inspired oxygen fractions of 20.9 %, 15.4 %, 14.5 %, 13.6 % and 12.7 %, respectively). Markers of external (power output) and internal (blood lactate concentration, tissue saturation index, cardio-respiratory and perceptual responses) loads were measured every 15 min during cycling. Neuromuscular function of knee extensors was characterised pre- and post-exercise. RESULTS Compared to sea-level (101 ± 22 W), there was a stepwise reduction in power output with increasing hypoxia severity (-17.9 ± 8.9 %, -27.1 ± 10.7 %, -34.2 ± 12.0 % and - 44.6 ± 15.1 % at 2500 m, 3000 m, 3500 m, and 4000 m, respectively, all p < 0.05). Blood lactate and tissue saturation index were not different across hypoxia severities, and perceptual responses were exacerbated at 4000 m only, with increased breathing difficulty. Knee extensor torque decreased post-exercise (-14.5 ± 9.0 %, p < 0.05), independent of condition. CONCLUSIONS Increasing hypoxia severity reduces cycling power output and arterial oxygen saturation in a stepwise fashion without affecting exercise responses between sea-level and simulated altitudes up to 3500 m despite breathing difficulty being elevated at 4000 m.
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Affiliation(s)
- Siu Nam Li
- School of Human Sciences (Exercise and Sports Science), The University of Western Australia, Australia.
| | - Peter Peeling
- School of Human Sciences (Exercise and Sports Science), The University of Western Australia, Australia; Department of Sport Science, Western Australian Institute of Sport, Australia
| | - Brendan R Scott
- Murdoch Applied Sport Science Laboratory, Discipline of Exercise Science, Murdoch University, Australia; Centre for Healthy Ageing, Murdoch University, Australia
| | - Jeremiah J Peiffer
- Murdoch Applied Sport Science Laboratory, Discipline of Exercise Science, Murdoch University, Australia; Centre for Healthy Ageing, Murdoch University, Australia
| | - Alex Shaykevich
- School of Human Sciences (Exercise and Sports Science), The University of Western Australia, Australia; Perron Institute for Neurological and Translational Science, Australia
| | - Olivier Girard
- School of Human Sciences (Exercise and Sports Science), The University of Western Australia, Australia.
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Berger MM, Luks AM. High Altitude. Semin Respir Crit Care Med 2023; 44:681-695. [PMID: 37816346 DOI: 10.1055/s-0043-1770063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
With ascent to high altitude, barometric pressure declines, leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. This leads, in turn, to a series of changes over varying time frames across multiple organ systems that serve to maintain tissue oxygen delivery at levels sufficient to prevent acute altitude illness and preserve cognitive and locomotor function. This review focuses primarily on the physiological adjustments and acclimatization processes that occur in the lungs of healthy individuals, including alterations in control of breathing, ventilation, gas exchange, lung mechanics and dynamics, and pulmonary vascular physiology. Because other organ systems, including the cardiovascular, hematologic and renal systems, contribute to acclimatization, the responses seen in these systems, as well as changes in common activities such as sleep and exercise, are also addressed. While the pattern of the responses highlighted in this review are similar across individuals, the magnitude of such responses often demonstrates significant interindividual variability which accounts for subsequent differences in tolerance of the low oxygen conditions in this environment.
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Affiliation(s)
- Marc Moritz Berger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Andrew M Luks
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, Washington
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Cherouveim ED, Miliotis PG, Koskolou MD, Dipla K, Vrabas IS, Geladas ND. The Effect of Skeletal Muscle Oxygenation on Hemodynamics, Cerebral Oxygenation and Activation, and Exercise Performance during Incremental Exercise to Exhaustion in Male Cyclists. BIOLOGY 2023; 12:981. [PMID: 37508410 PMCID: PMC10376807 DOI: 10.3390/biology12070981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023]
Abstract
This study aimed to elucidate whether muscle blood flow restriction during maximal exercise is associated with alterations in hemodynamics, cerebral oxygenation, cerebral activation, and deterioration of exercise performance in male participants. Thirteen healthy males, cyclists (age 33 ± 2 yrs., body mass: 78.6 ± 2.5 kg, and body mass index: 25.57 ± 0.91 kg·m-1), performed a maximal incremental exercise test on a bicycle ergometer in two experimental conditions: (a) with muscle blood flow restriction through the application of thigh cuffs inflated at 120 mmHg (with cuffs, WC) and (b) without restriction (no cuffs, NC). Exercise performance significantly deteriorated with muscle blood flow restriction, as evidenced by the reductions in V˙O2max (-17 ± 2%, p < 0.001), peak power output (-28 ± 2%, p < 0.001), and time to exhaustion (-28 ± 2%, p < 0.001). Muscle oxygenated hemoglobin (Δ[O2Hb]) during exercise declined more in the NC condition (p < 0.01); however, at exhaustion, the magnitude of muscle oxygenation and muscle deoxygenation were similar between conditions (p > 0.05). At maximal effort, lower cerebral deoxygenated hemoglobin (Δ[HHb]) and cerebral total hemoglobin (Δ[THb]) were observed in WC (p < 0.001), accompanied by a lower cardiac output, heart rate, and stroke volume vs. the NC condition (p < 0.01), whereas systolic blood pressure, rating of perceived exertion, and cerebral activation (as assessed by electroencephalography (EEG) activity) were similar (p > 0.05) between conditions at task failure, despite marked differences in exercise duration, maximal aerobic power output, and V˙O2max. In conclusion, in trained cyclists, muscle blood flow restriction during an incremental cycling exercise test significantly limited exercise performance. Exercise intolerance with muscle blood flow restriction was mainly associated with attenuated cardiac responses, despite cerebral activation reaching similar maximal levels as without muscle blood flow restriction.
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Affiliation(s)
- Evgenia D Cherouveim
- Division of Sports Medicine and Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, 17237 Athens, Greece
| | - Panagiotis G Miliotis
- Division of Sports Medicine and Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, 17237 Athens, Greece
| | - Maria D Koskolou
- Division of Sports Medicine and Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, 17237 Athens, Greece
| | - Konstantina Dipla
- Laboratory of Exercise Physiology and Biochemistry, School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62122 Serres, Greece
| | - Ioannis S Vrabas
- Laboratory of Exercise Physiology and Biochemistry, School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62122 Serres, Greece
| | - Nickos D Geladas
- Division of Sports Medicine and Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, 17237 Athens, Greece
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Shiffman VJ, Rose P, Hughes B, Koehle MS, McKinney J, McKenzie DC, Leahy MG, Kipp S, Peters CM, Sheel AW. EXERCISE-INDUCED ARTERIAL HYPOXEMIA IN FEMALE MASTERS ATHTLETES. Respir Physiol Neurobiol 2023:104099. [PMID: 37385421 DOI: 10.1016/j.resp.2023.104099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/21/2023] [Accepted: 06/25/2023] [Indexed: 07/01/2023]
Abstract
The purpose of the study was to characterize exercise induced arterial hypoxemia (EIAH) in female masters athletes (FMA). We hypothesized that FMA would experience EIAH during treadmill running. Eight FMA (48-57 years) completed pulmonary function testing and an incremental exercise test until exhaustion (V̇O2max=45.7±6.5, range:35-54ml/kg/min). On a separate day, the participants were instrumented with a radial arterial catheter and an esophageal temperature probe. Participants performed three to four constant load exercise tests at 60-70, 75, 90, 95, and 100% of maximal oxygen uptake while sampling arterial blood and recording esophageal temperature. We found that FMA decrease their partial pressure of oxygen (86.0±7.6, range:73-108mmHg), arterial saturation (96.2±1.2, range:93-98%), and widen their alveolar to arterial oxygen difference (23.2±8.8, range:5-42mmHg) during all exercise intensities however, with variability in terms of severity and pattern. Our findings suggest that FMA experience EIAH however aerobic fitness appears unrelated to occurrence or severity (r=0.13, p=0.756).
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Affiliation(s)
- Viviana J Shiffman
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.
| | - Peter Rose
- Department of Anesthesia, Vancouver Coastal Health, Vancouver BC, Canada.
| | - Bevan Hughes
- Department of Anesthesia, Vancouver Coastal Health, Vancouver BC, Canada.
| | - Michael S Koehle
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada; Division of Sport and Exercise Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - James McKinney
- Division of Cardiology, University of British Columbia, Vancouver, BC, Canada.
| | - Donald C McKenzie
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada; Division of Sport and Exercise Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - Michael G Leahy
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.
| | - Shalaya Kipp
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.
| | - Carli M Peters
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.
| | - A William Sheel
- School of Kinesiology, The University of British Columbia, Vancouver, BC, Canada.
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King DG, Stride E, Mendis J, Gurton WH, Macrae H, Jones L, Hunt J. A Double-Blind, Randomized, Placebo-Controlled Pilot Study examining an Oxygen Nanobubble Beverage for 16.1-km Time Trial and Repeated Sprint Cycling Performance. J Diet Suppl 2023; 21:167-181. [PMID: 37127913 DOI: 10.1080/19390211.2023.2203738] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
There is growing interest of ergogenic aids that deliver supplemental oxygen during exercise and recovery, however, breathing supplemental oxygen via specialist facemasks is often not feasible. Therefore, this study investigated the effect of an oxygen-nanobubble beverage during submaximal and repeated sprint cycling. In a double-blind, randomized, placebo-controlled study, 10 male cyclists (peak aerobic capacity, 56.9 ± 6.1 mL·kg-1·min-1; maximal aerobic power, 385 ± 25 W) completed submaximal or maximal exercise after consuming an oxygen-nanobubble (O2) or placebo (PLA) beverage. Submaximal trials comprised 30-min of steady-state cycling at 60% peak aerobic capacity and 16.1-km time-trial (TT). Maximal trials involved 4 × 30 s Wingate tests interspersed by 4-min recovery. Time-to-completion during the 16.1-km TT was 2.4% faster after O2 compared with PLA (95% CI = 0.7-4.0%, p = 0.010, d = 0.41). Average power for the 16.1-km TT was 4.1% higher for O2 vs. PLA (95% CI = 2.1-7.3%, p = 0.006, d = 0.28). Average peak power during the repeated Wingate tests increased by 7.1% for O2 compared with PLA (p = 0.002, d = 0.58). An oxygen-nanobubble beverage improves performance during submaximal and repeated sprint cycling, therefore may provide a practical and effective ergogenic aid for competitive cyclists.
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Affiliation(s)
- David G King
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Eleanor Stride
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - Jeewaka Mendis
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - William H Gurton
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Heather Macrae
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Louise Jones
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Julie Hunt
- Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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Doherty CJ, Chang JC, Thompson BP, Swenson ER, Foster GE, Dominelli PB. The Impact of Acetazolamide and Methazolamide on Exercise Performance in Normoxia and Hypoxia. High Alt Med Biol 2023; 24:7-18. [PMID: 36802203 DOI: 10.1089/ham.2022.0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Doherty, Connor J., Jou-Chung Chang, Benjamin P. Thompson, Erik R. Swenson, Glen E. Foster, and Paolo B. Dominelli. The impact of acetazolamide and methazolamide on exercise performance in normoxia and hypoxia. High Alt Med Biol. 24:7-18, 2023.-Carbonic anhydrase (CA) inhibitors are commonly prescribed for acute mountain sickness (AMS). In this review, we sought to examine how two CA inhibitors, acetazolamide (AZ) and methazolamide (MZ), affect exercise performance in normoxia and hypoxia. First, we briefly describe the role of CA inhibition in facilitating the increase in ventilation and arterial oxygenation in preventing and treating AMS. Next, we detail how AZ affects exercise performance in normoxia and hypoxia and this is followed by a discussion on MZ. We emphasize that the overarching focus of the review is how the two drugs potentially affect exercise performance, rather than their ability to prevent/treat AMS per se, their interrelationship will be discussed. Overall, we suggest that AZ hinders exercise performance in normoxia, but may be beneficial in hypoxia. Based upon head-to-head studies of AZ and MZ in humans on diaphragmatic and locomotor strength in normoxia, MZ may be a better CA inhibitor when exercise performance is crucial at high altitude.
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Affiliation(s)
- Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jou-Chung Chang
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik R Swenson
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Washington, USA
- Medical Service, VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Glen E Foster
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Marzouk M, McKeown DJ, Borg DN, Headrick J, Kavanagh JJ. Perceptions of fatigue and neuromuscular measures of performance fatigability during prolonged low-intensity elbow flexions. Exp Physiol 2023; 108:465-479. [PMID: 36763088 PMCID: PMC10103868 DOI: 10.1113/ep090981] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the predictive relationship between self-reported scales to quantify perceptions of fatigue during exercise and gold standard measures used to quantify the development of neuromuscular fatigue? What is the main finding and its importance? No scale was determined to be substantively more effective than another. However, the number of ongoing contractions performed was shown to be a better predictor of fatigue in the motor system than any of the subjective scales. ABSTRACT The purpose of this study was to determine the relationship between transcranial magnetic stimulation (TMS) measures of performance fatigability and commonly used scales that quantify perceptions of fatigue during exercise. Twenty healthy participants (age 23 ± 3 years, 10 female) performed 10 submaximal isometric elbow flexions at 20% maximal voluntary contraction (MVC) for 2 min, separated by 45 s of rest. Biceps brachii muscle electromyography and elbow flexion torque responses to single-pulse TMS were obtained at the end of each contraction to assess central factors of performance fatigability. A rating of perceived exertion (RPE) scale, Omnibus Resistance scale, Likert scale, Rating of Fatigue scale and a visual analogue scale (VAS) were used to assess perceptions of fatigue at the end of each contraction. The RPE (root mean square error (RMSE) = 0.144) and Rating of Fatigue (RMSE = 0.145) scales were the best predictors of decline in MVC torque, whereas the Likert (RMSE= 0.266) and RPE (RMSE= 0.268) scales were the best predictors of electromyographic amplitude. Although the Likert (RMSE = 7.6) and Rating of Fatigue (RMSE = 7.6) scales were the best predictors of voluntary muscle activation of any scale, the number of contractions performed during the protocol was a better predictor (RMSE = 7.3). The ability of the scales to predict TMS measures of performance fatigability were in general similar. Interestingly, the number of contractions performed was a better predictor of TMS measures than the scales themselves.
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Affiliation(s)
- Monica Marzouk
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Daniel J. McKeown
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - David N. Borg
- The Australian Centre for Health Services Innovation and Centre for Healthcare Transformation, School of Public Health and Social WorkQueensland University of TechnologyBrisbaneQueenslandAustralia
| | - Jonathon Headrick
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
| | - Justin J. Kavanagh
- Neural Control of Movement LaboratoryMenzies Health Institute QueenslandGriffith UniversityGold CoastQueenslandAustralia
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Reinhard PA, Archiza B, Welch JF, Benbaruj J, Guenette JA, Koehle MS, Sheel AW. Effects of hypoxia on exercise-induced diaphragm fatigue in healthy males and females. Physiol Rep 2023; 11:e15589. [PMID: 36695726 PMCID: PMC9875747 DOI: 10.14814/phy2.15589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 01/04/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023] Open
Abstract
Following high-intensity, normoxic exercise there is evidence to show that healthy females, on average, exhibit less fatigue of the diaphragm relative to males. In the present study, we combined hypoxia with exercise to test the hypothesis that males and females would develop a similar degree of diaphragm fatigue following cycle exercise at the same relative exercise intensity. Healthy young participants (n = 10 male; n = 10 female) with a high aerobic capacity (120% predicted) performed two time-to-exhaustion (TTE; ~85% maximum) cycle tests on separate days breathing either a normoxic or hypoxic (FiO2 = 0.15) gas mixture. Fatigue of the diaphragm was assessed in response to cervical magnetic stimulation prior to, immediately post-exercise, 10-, 30-, and 60-min post-exercise. Males and females had similar TTE durations in normoxia (males: 690 ± 181 s; females: 852 ± 401 s) and hypoxia (males: 381 ± 160 s; females: 400 ± 176 s) (p > 0.05). Cycling time was significantly shorter in hypoxia versus normoxia in both males and females (p < 0.05) and did not differ on the basis of sex (p > 0.05). Following the hypoxic TTE tests, males and females experienced a similar degree of diaphragm fatigue compared to normoxia as shown by 20%-25% reductions in transdiaphragmatic twitch pressure. This occurred despite the fact that exercise time in hypoxia was substantially shorter relative to normoxia and the cumulative diaphragm work was lower. We also observed that females did not fully recover from diaphragm fatigue in hypoxia, whereas males did (p < 0.05). Sex differences in the rate of diaphragm contractility recovery following exercise in hypoxia might relate to sex-based differences in substrate utilization or diaphragm blood flow.
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Affiliation(s)
- Paige A. Reinhard
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Bruno Archiza
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Physical TherapyFederal University of São CarlosSão CarlosSPBrazil
| | - Joseph F. Welch
- Breathing Research and Therapeutics Center, Department of Physical TherapyUniversity of FloridaGainesvilleFloridaUSA
- School of Sport, Exercise and Rehabilitation SciencesUniversity of BirminghamBirminghamUK
| | - Jenna Benbaruj
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Jordan A. Guenette
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Physical TherapyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Centre for Heart Lung Innovation, Providence ResearchThe University of British Columbia and St. Paul's HospitalVancouverBritish ColumbiaCanada
| | - Michael S. Koehle
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - A. William Sheel
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
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12
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Cristina-Souza G, Santos PS, Santos-Mariano AC, Coelho DB, Rodacki A, DE-Oliveira FR, Bishop DJ, Bertuzzi R, Lima-Silva AE. Caffeine Increases Endurance Performance via Changes in Neural and Muscular Determinants of Performance Fatigability. Med Sci Sports Exerc 2022; 54:1591-1603. [PMID: 35969166 DOI: 10.1249/mss.0000000000002944] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE In the present study, we tested the hypothesis that caffeine would increase endurance performance via attenuation of neural and muscular determinants of performance fatigability during high-intensity, whole-body exercise. METHODS Ten healthy males cycled until exhaustion (89% ± 2% of V̇O2max) after the ingestion of caffeine or placebo. During another four visits, the same exercise was performed after either caffeine or placebo ingestion but with exercise discontinued after completing either 50% or 75% of the duration of placebo trial. An additional trial with caffeine ingestion was also performed with interruption at the placebo time to exhaustion (isotime). Performance fatigability was measured via changes in maximal voluntary contraction, whereas neural and muscular determinants of performance fatigability were quantified via preexercise to postexercise decrease in quadriceps voluntary activation (VA) and potentiated twitch force, respectively. RESULTS Compared with the placebo, caffeine increased time to exhaustion (+14.4 ± 1.6%, P = 0.017, 314.4 ± 47.9 vs 354.9 ± 40.8 s). Caffeine did not change the rate of decline in maximal voluntary contraction (P = 0.209), but caffeine reduced the twitch force decline at isotime when stimulating at single twitch (-58.6 ± 22.4 vs -45.7 ± 21.9%, P = 0.014) and paired 10 Hz electrical stimuli (-37.3 ± 13.2 vs -28.2 ± 12.9%, P = 0.025), and reduced the amplitude of electromyography signal during cycling at isotime (P = 0.034). The decline in VA throughout the trial was lower (P = 0.004) with caffeine (-0.5 ± 4.2%) than with placebo (-5.8 ± 8.5%). Caffeine also maintained peripheral oxygen saturation at higher levels (95.0 ± 1.9%) than placebo (92.0 ± 6.2%, P = 0.016). CONCLUSIONS Caffeine ingestion improves performance during high-intensity, whole-body exercise via attenuation of exercise-induced reduction in VA and contractile function.
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Affiliation(s)
| | | | | | | | - Andre Rodacki
- Department of Physical Education, Federal University of Paraná, Paraná, BRAZIL
| | | | - David J Bishop
- Institute for Health and Sport, Victoria University, Melbourne, AUSTRALIA
| | - Romulo Bertuzzi
- Endurance Performance Research Group (GEDAE-USP), University of São Paulo, São Paulo, BRAZIL
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Rupp T, Saugy JJ, Bourdillon N, Millet GP. Brain-muscle interplay during endurance self-paced exercise in normobaric and hypobaric hypoxia. Front Physiol 2022; 13:893872. [PMID: 36091393 PMCID: PMC9453479 DOI: 10.3389/fphys.2022.893872] [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] [Received: 03/10/2022] [Accepted: 07/27/2022] [Indexed: 11/30/2022] Open
Abstract
Purpose: Hypoxia is one major environmental factor, supposed to mediate central motor command as well as afferent feedbacks at rest and during exercise. By using a comparison of normobaric (NH) and hypobaric (HH) hypoxia with the same ambient pressure in oxygen, we examined the potential differences on the cerebrovascular and muscular regulation interplay during a self-paced aerobic exercise. Methods: Sixteen healthy subjects performed three cycling time-trials (250 kJ) in three conditions: HH, NH and normobaric normoxia (NN) after 24 h of exposure. Cerebral and muscular oxygenation were assessed by near-infrared spectroscopy, cerebral blood flow by Doppler ultrasound system. Gas exchanges, peripheral oxygen saturation, power output and associated pacing strategies were also continuously assessed. Results: The cerebral oxygen delivery was lower in hypoxia than in NN but decreased similarly in both hypoxic conditions. Overall performance and pacing were significantly more down-regulated in HH versus NH, in conjunction with more impaired systemic (e.g. saturation and cerebral blood flow) and prefrontal cortex oxygenation during exercise. Conclusions: The difference in pacing was likely the consequence of a complex interplay between systemic alterations and cerebral oxygenation observed in HH compared to NH, aiming to maintain an equivalent cerebral oxygen delivery despite higher adaptive cost (lower absolute power output for the same relative exercise intensity) in HH compared to NH.
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Affiliation(s)
- Thomas Rupp
- LIBM, Inter-university Laboratory of Human Movement Science, University Savoie Mont Blanc, Chambéry, France
| | - Jonas J. Saugy
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Bourdillon
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Grégoire P. Millet
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
- *Correspondence: Grégoire P. Millet,
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14
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Paneroni M, Vitacca M, Comini L, Salvi B, Saleri M, Schena F, Venturelli M. Relationship between perceived and neuromuscular fatigue in COPD patients with chronic respiratory failure with long-term oxygen therapy: a cross-sectional study. Eur J Appl Physiol 2022; 122:2403-2416. [PMID: 35951129 DOI: 10.1007/s00421-022-05021-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 08/01/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate perceived fatigue (PF) and neuromuscular fatigue (NMF) in patients with COPD and chronic respiratory failure (CRF) on long-term oxygen therapy (CRF-COPD group), and the relationships between PF, NMF, patient's characteristics, comparing severe patients with COPD to patients without CRF (COPD group). METHODS This cross-sectional study compared 19 CRF-COPD patients with 10 COPD patients attending a rehabilitation program. PF was determined by Fatigue Severity Scale (FSS), while dyspnea by the Barthel Dyspnea Index (BDI). We assessed quadriceps NMF via electrical nerve stimulation during and following a Maximal Voluntary Contraction (MVC) detecting changes after a Constant Workload Cycling Test (CWCT) at 80% of the peak power output at exhaustion. RESULTS CRF-COPD patients showed higher PF (+ 1.79 of FSS score, p = 0.0052) and dyspnea (+ 21.03 of BDI score, p = 0.0023) than COPD patients. After the fatiguing task and normalization for the total work, there was a similar decrease in the MVC (CRF-COPD -1.5 ± 2.4 vs COPD -1.1 ± 1.2% baseline kJ-1, p = 0.5819), in the potentiated resting twitch force (CRF-COPD -2.8 ± 4.7 vs COPD -2.0 ± 3.3% baseline kJ-1, p = 0.7481) and in the maximal voluntary activation (CRF-COPD -0.1 ± 3.9 vs COPD -0.9 ± 1.2 -2.0 ± 3.3% baseline kJ-1, p = 0.4354). FSS and BDI were closely related (R = 0.5735, p = 0.0011), while no correlation between PF and NMF was found. CONCLUSION Patients with CRF-COPD develop higher levels of perceived fatigue and dyspnea than patients with COPD; while neuromuscular fatigue is similar, suggesting a mismatch between symptoms and neuromuscular dysfunction.
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Affiliation(s)
- Mara Paneroni
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Via G Mazzini 129, Lumezzane, 25065, Brescia, Italy.
| | - Michele Vitacca
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Via G Mazzini 129, Lumezzane, 25065, Brescia, Italy
| | - Laura Comini
- Istituti Clinici Scientifici Maugeri IRCCS, Scientific Direction of the Institute of Lumezzane, Lumezzane, 25065, Brescia, Italy
| | - Beatrice Salvi
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Via G Mazzini 129, Lumezzane, 25065, Brescia, Italy
| | - Manuela Saleri
- Istituti Clinici Scientifici Maugeri IRCCS, Respiratory Rehabilitation of the Institute of Lumezzane, Via G Mazzini 129, Lumezzane, 25065, Brescia, Italy
| | - Federico Schena
- Department of Neuroscience, Biomedicine, and Movement Science, Section of Movement Science, University of Verona, 37134, Verona, Italy
| | - Massimo Venturelli
- Department of Neuroscience, Biomedicine, and Movement Science, Section of Movement Science, University of Verona, 37134, Verona, Italy.,Department of Internal Medicine Section of Geriatrics, University of Utah, Salt Lake City, UT, 84132, USA
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15
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McKeown DJ, McNeil CJ, Simmonds MJ, Kavanagh JJ. Post-fatigue ability to activate muscle is compromised across a wide range of torques during acute hypoxic exposure. Eur J Neurosci 2022; 56:4653-4668. [PMID: 35841186 PMCID: PMC9546238 DOI: 10.1111/ejn.15773] [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: 02/17/2022] [Revised: 06/11/2022] [Accepted: 07/13/2022] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to assess how severe acute hypoxia alters the neural mechanisms of muscle activation across a wide range of torque output in a fatigued muscle. Torque and electromyography responses to transcranial and motor nerve stimulation were collected from 10 participants (27 years ± 5 years, 1 female) following repeated performance of a sustained maximal voluntary contraction that reduced torque to 60% of the pre‐fatigue peak torque. Contractions were performed after 2 h of hypoxic exposure and during a sham intervention. For hypoxia, peripheral blood oxygen saturation was titrated to 80% over a 15‐min period and remained at 80% for 2 h. Maximal voluntary torque, electromyography root mean square, voluntary activation and corticospinal excitability (motor evoked potential area) and inhibition (silent period duration) were then assessed at 100%, 90%, 80%, 70%, 50% and 25% of the target force corresponding to the fatigued maximal voluntary contraction. No hypoxia‐related effects were identified for voluntary activation elicited during motor nerve stimulation. However, during measurements elicited at the level of the motor cortex, voluntary activation was reduced at each torque output considered (P = .002, ηp2 = .829). Hypoxia did not impact the correlative linear relationship between cortical voluntary activation and contraction intensity or the correlative curvilinear relationship between motor nerve voluntary activation and contraction intensity. No other hypoxia‐related effects were identified for other neuromuscular variables. Acute severe hypoxia significantly impairs the ability of the motor cortex to voluntarily activate fatigued muscle across a wide range of torque output.
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Affiliation(s)
- Daniel J McKeown
- Neural Control of Movement Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Chris J McNeil
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Michael J Simmonds
- Biorheology Research Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Justin J Kavanagh
- Neural Control of Movement Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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16
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ARIMITSU T, YAMANAKA R, YUNOKI T, YANO T. Effects of exercise-induced muscle fatigue on V̇O2 slow component during heavy constant load exercise. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2022. [DOI: 10.23736/s0393-3660.20.04469-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Acute Exercise with Moderate Hypoxia Reduces Arterial Oxygen Saturation and Cerebral Oxygenation without Affecting Hemodynamics in Physically Active Males. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19084558. [PMID: 35457425 PMCID: PMC9027900 DOI: 10.3390/ijerph19084558] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/05/2022] [Accepted: 04/08/2022] [Indexed: 01/02/2023]
Abstract
Hemodynamic changes during exercise in acute hypoxia (AH) have not been completely elucidated. The present study aimed to investigate hemodynamics during an acute bout of mild, dynamic exercise during moderate normobaric AH. Twenty-two physically active, healthy males (average age; range 23–40 years) completed a cardiopulmonary test on a cycle ergometer to determine their maximum workload (Wmax). On separate days, participants performed two randomly assigned exercise tests (three minutes pedaling at 30% of Wmax): (1) during normoxia (NORMO), and (2) during normobaric AH at 13.5% inspired oxygen (HYPO). Hemodynamics were assessed with impedance cardiography, and peripheral arterial oxygen saturation (SatO2) and cerebral oxygenation (Cox) were measured by near-infrared spectroscopy. Hemodynamic responses (heart rate, stroke volume, cardiac output, mean arterial blood pressure, ventricular emptying rate, and ventricular filling rate) were not any different between NORMO and HYPO. However, the HYPO test significantly reduced both SatO2 (96.6 ± 3.3 vs. 83.0 ± 4.5%) and Cox (71.0 ± 6.6 vs. 62.8 ± 7.4 A.U.) when compared to the NORMO test. We conclude that an acute bout of mild exercise during acute moderate normobaric hypoxia does not induce significant changes in hemodynamics, although it can cause significant reductions in SatO2 and Cox.
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18
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Ruggiero L, Harrison SWD, Rice CL, McNeil CJ. Neuromuscular fatigability at high altitude: Lowlanders with acute and chronic exposure, and native highlanders. Acta Physiol (Oxf) 2022; 234:e13788. [PMID: 35007386 PMCID: PMC9286620 DOI: 10.1111/apha.13788] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 01/18/2023]
Abstract
Ascent to high altitude is accompanied by a reduction in partial pressure of inspired oxygen, which leads to interconnected adjustments within the neuromuscular system. This review describes the unique challenge that such an environment poses to neuromuscular fatigability (peripheral, central and supraspinal) for individuals who normally reside near to sea level (SL) (<1000 m; ie, lowlanders) and for native highlanders, who represent the manifestation of high altitude-related heritable adaptations across millennia. Firstly, the effect of acute exposure to high altitude-related hypoxia on neuromuscular fatigability will be examined. Under these conditions, both supraspinal and peripheral fatigability are increased compared with SL. The specific mechanisms contributing to impaired performance are dependent on the exercise paradigm and amount of muscle mass involved. Next, the effect of chronic exposure to high altitude (ie, acclimatization of ~7-28 days) will be considered. With acclimatization, supraspinal fatigability is restored to SL values, regardless of the amount of muscle mass involved, whereas peripheral fatigability remains greater than SL except when exercise involves a small amount of muscle mass (eg, knee extensors). Indeed, when whole-body exercise is involved, peripheral fatigability is not different to acute high-altitude exposure, due to competing positive (haematological and muscle metabolic) and negative (respiratory-mediated) effects of acclimatization on neuromuscular performance. In the final section, we consider evolutionary adaptations of native highlanders (primarily Himalayans of Tibet and Nepal) that may account for their superior performance at altitude and lesser degree of neuromuscular fatigability compared with acclimatized lowlanders, for both single-joint and whole-body exercise.
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Affiliation(s)
- Luca Ruggiero
- Laboratory of Physiomechanics of Locomotion Department of Pathophysiology and Transplantation University of Milan Milan Italy
| | - Scott W. D. Harrison
- School of Kinesiology Faculty of Health Sciences The University of Western Ontario London Ontario Canada
| | - Charles L. Rice
- School of Kinesiology Faculty of Health Sciences The University of Western Ontario London Ontario Canada
- Department of Anatomy and Cell Biology Schulich School of Medicine and Dentistry The University of Western Ontario London Ontario Canada
| | - Chris J. McNeil
- Centre for Heart, Lung & Vascular Health School of Health and Exercise Sciences University of British Columbia Kelowna British Columbia Canada
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19
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Volianitis S, Rasmussen P, Petersen NC, Secher NH. The Effect of Hyperoxia on Central and Peripheral Factors of Arm Flexor Muscles Fatigue Following Maximal Ergometer Rowing in Men. Front Physiol 2022; 13:829097. [PMID: 35185623 PMCID: PMC8850913 DOI: 10.3389/fphys.2022.829097] [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] [Received: 12/04/2021] [Accepted: 01/11/2022] [Indexed: 11/16/2022] Open
Abstract
Purpose This study evaluates the effect of hyperoxia on cerebral oxygenation and neuromuscular fatigue mechanisms of the elbow flexor muscles following ergometer rowing. Methods In 11 competitive male rowers (age, 30 ± 4 years), we measured near-infrared spectroscopy determined frontal lobe oxygenation (ScO2) and transcranial Doppler ultrasound determined middle cerebral artery mean flow velocity (MCA Vmean) combined with maximal voluntary force (MVC), peak resting twitch force (Ptw) and cortical voluntary activation (VATMS) of the elbow flexor muscles using electrical motor point and magnetic motor cortex stimulation, respectively, before, during, and immediately after 2,000 m all-out effort on rowing ergometer with normoxia and hyperoxia (30% O2). Results Arterial hemoglobin O2 saturation was reduced to 92.5 ± 0.2% during exercise with normoxia but maintained at 98.9 ± 0.2% with hyperoxia. The MCA Vmean increased by 38% (p < 0.05) with hyperoxia, while only marginally increased with normoxia. Similarly, ScO2 was not affected with hyperoxia but decreased by 7.0 ± 4.8% from rest (p = 0.04) with normoxia. The MVC and Ptw were reduced (7 ± 3% and 31 ± 9%, respectively, p = 0.014), while VATMS was not affected by the rowing effort in normoxia. With hyperoxia, the deficit in MVC and Ptw was attenuated, while VATMS was unchanged. Conclusion These data indicate that even though hyperoxia restores frontal lobe oxygenation the resultant attenuation of arm muscle fatigue following maximal rowing is peripherally rather than centrally mediated.
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Affiliation(s)
- Stefanos Volianitis
- Department of Physical Education, College of Education, Qatar University, Doha, Qatar
| | - Peter Rasmussen
- Department of Anesthesiology, Rigshospitalet, Institute for Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Nicolas C Petersen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels H Secher
- Department of Anesthesiology, Rigshospitalet, Institute for Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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20
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Price JW. Osteopathic model of the development and prevention of occupational musculoskeletal disorders. J Osteopath Med 2021; 121:287-305. [PMID: 33635956 DOI: 10.1515/jom-2020-0060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Context The direct and indirect costs of work-related musculoskeletal disorders are significant. Prevention is the most effective way to control these costs. To do that, we must understand how these disorders develop. Objectives To use the five models of osteopathic care to illustrate how cellular processes and neural reflexes interact to create work-related musculoskeletal pathology and to provide evidence-informed musculoskeletal injury and disability prevention recommendations. Methods A literature review of electronic databases (Google Scholar, PubMed, OVID, Cochrane Central Register of Controlled Trials, PEDro, and OSTMED.DR) from inception to October 16, 2019 and hand-search of publication references was performed for systematic reviews, cohort studies, case-control studies, and randomized controlled trials. The search terms reflected topics related to occupational injury and injury prevention, and included supplementary laboratory studies and narrative reviews related to the biological aspects of musculoskeletal injury. The eligible studies contained the following criteria: (1) the population of working age; (2) exposures to known risk factors, musculoskeletal disorders, and psychosocial factors; (3) written in English; (4) full text papers published in peer-reviewed journals; and (5) systematic review, cohort study, case-control study, and randomized controlled trial methodology. Studies were excluded if they included outcomes of productivity and costs only or outcomes that were assessed through qualitative methods only. Results The literature search resulted in 1,074 citations; 26 clinical studies and 14 systematic reviews were used in this review. A comprehensive workplace musculoskeletal disorder prevention program should match demands to capacity, correct dysfunctional movement patterns, and limit tissue vulnerability (biomechanical-structural model); restore alpha-gamma balance, tonic-phasic synergistic function, and autonomic balance (neurological model); maximize physiologic reserve (metabolic-energy model) component of a prevention program; optimize respiration and circulation (respiratory-circulatory model); and address cognitive distortions (behavioral-biopsychosocial model). Conclusions The presented osteopathic model of the development and prevention of work-related musculoskeletal disorders suggests that a combination of preventive interventions will be more effective than any single preventive intervention.
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Affiliation(s)
- James William Price
- Ascension St. Vincent Occupational Medicine Clinic, Evansville, IN, USA.,College of Osteopathic Medicine, Marion University, Indianapolis, IN, USA
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21
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Azevedo RA, Milioni F, Murias JM, Bertuzzi R, Millet GY. Dynamic Changes of Performance Fatigability and Muscular O2 Saturation in a 4-km Cycling Time Trial. Med Sci Sports Exerc 2021; 53:613-623. [PMID: 33300756 DOI: 10.1249/mss.0000000000002499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The current study characterized the performance fatigability etiology, immediately after exercise cessation, and its relation to the dynamic changes in muscle O2 saturation (SmO2) at different TT phases. METHODS Twelve males performed three separated TT of different distances, in a crossover counterbalanced design, until the end of the fast-start (FS, 827 ± 135 m), even-pace (EP, 3590 ± 66 m), or end-spurt (ES, 4000 m) TT phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVC), whereas the maximal voluntary activation (VA) and contractile function of knee extensors (e.g., peak torque of potentiated twitches [TwPt]) were evaluated using electrically evoked contractions performed before and immediately after each exercise bouts. SmO2, power output (PO), and EMG were also recorded. RESULTS Immediately after the FS phase, there were lower values for IMVC (-23%), VA (-8%), and TwPt (-43%) (all P < 0.001), but no further changes were measured after EP (IMVC, -28%; VA, -8%; TwPt, -38%). After the ES phase, IMVC (-34%) and TwPt (-59%) further decreased compared with the previous phases (P < 0.05). There were lower SmO2 and higher EMG/PO values during FS and ES compared with EP phase. CONCLUSION FS and EP phases had similar performance fatigability etiology, but ES showed further impairments in contractile function. This later finding might be due to the abrupt changes in SmO2 and EMG/PO because of the high exercise intensity during the ES, which elicited maximal decline in contractile function at the finish line.
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Affiliation(s)
| | | | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, CANADA
| | - Romulo Bertuzzi
- Endurance Performance Research Group (GEDAE-USP), School of Physical Education and Sport (GEDAE-USP), University of São Paulo, São Paulo, BRAZIL
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22
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Oxygen availability affects exercise capacity, but not neuromuscular fatigue characteristics of knee extensors, during exhaustive intermittent cycling. Eur J Appl Physiol 2020; 121:95-107. [PMID: 32995960 DOI: 10.1007/s00421-020-04495-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/05/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE To compare the effects of different hypoxia severities on exercise capacity, cardio-respiratory, tissue oxygenation and neuromuscular fatigue characteristics in response to exhaustive intermittent cycling. METHODS Eleven well-trained cyclists, repeated supra-maximal cycling efforts of 15 s (30% of anaerobic power reserve, 609 ± 23 W), interspersed with 45 s of passive rest until task failure. The exercise was performed on separate days in normoxia (SL; simulated altitude/end-exercise arterial oxygen saturation = 0 m/~ 96%), moderate (MH; 2200 m/~ 90%) and severe (SH; 4200 m/~ 79%) hypoxia in a cross-over design. Neuromuscular tests, including brief (5 s) and sustained (30 s) maximal isometric voluntary contractions of the knee extensors, were performed at baseline and exhaustion. RESULTS Exercise capacity decreased with hypoxia severity (23 ± 9, 16 ± 6 and 9 ± 3 cycle efforts in SL, MH and SH, respectively; P < 0.001; η2 = 0.72). Both cerebral (P < 0.001; η2 = 0.86) and muscle (P < 0.01; η2 = 0.54) oxygenation decreased throughout the exercise, independent of condition (P ≥ 0.45; η2 ≥ 0.14). Compared to SL, muscle oxygenation was globally lower in MH and SH (P = 0.011; η2 = 0.36). Cardiovascular solicitation neared maximal values at exhaustion in all conditions. Peak twitch amplitude with single and paired electrical stimuli (P < 0.001; η2 ≥ 0.87), maximal torque (P < 0.001; η2 ≥ 0.48) and voluntary activation measured using transcranial magnetic stimulation (P ≤ 0.034; η2 ≥ 0.31) during brief and sustained MVCs were all reduced at exhaustion, independent of condition (P ≥ 0.196; η2 ≥ 0.15). CONCLUSION Despite reduced exercise capacity with increasing severity of hypoxia during exhaustive intermittent cycling, neuromuscular fatigue characteristics were not different at task failure and cardiovascular solicitation neared maximum values.
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Ferreira GA, Felippe LC, Silva-Cavalcante MD, De-Mello APA, Coelho DB, Maranhão R, Bertuzzi R, Dolinsky M, De-Oliveira FR, Lima-Silva AE, Da-Silva KJ. Maytenus ilicifolia Extract Increases Oxygen Uptake without Changes in Neuromuscular Fatigue Development during a High-Intensity Interval Exercise. J Am Coll Nutr 2020; 40:419-428. [PMID: 32790496 DOI: 10.1080/07315724.2020.1787906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE We investigated the effects of acute ingestion of Maytenus ilicifolia extract on metabolic and cardiopulmonary responses during a high-intensity interval exercise (HIIE), and its consequence on neuromuscular fatigue. METHODS Ten healthy men underwent a HIIE (4 x 4 min, 3 min recovery) one hour after ingesting 400 mg of Maytenus ilicifolia extract (MIE) or placebo. Oxygen uptake (V̇O2), dioxide carbon production (V̇CO2), ventilation (V̇E) and heart rate (HR) were measured throughout the HIIE. Maximal voluntary contraction (MVC), voluntary activation (VA), and evoked 1, 10 and 100 Hz force twitch were measured before supplementation (baseline), and before (pre-HIIE) and after the HIIE (post-HIIE). RESULTS The V̇O2, V̇E, V̇E/V̇O2 ratio and HR increased progressively throughout the HIIE under both conditions (p < 0.05). MIE increased HR, however, at bouts 1 and 2 and mean V̇O2 during HIIE. The mean respiratory exchange ratio during recovery was also reduced with MIE (p < 0.05). MVC and evoked force at 1, 10 and 100 Hz declined similarly after HIIE, regardless of the condition (MIE: -18 ± 17%, -50 ± 15%, -61 ± 13% and -34 ± 10% vs. placebo: -19 ± 15%, -48 ± 16%, -58 ± 12 and -29 ± 11%, respectively, p < 0.05). There was no effect of exercise or MIE on VA (p > 0.05). CONCLUSION MIE increases heart rate in the first bouts and mean oxygen uptake during HIIE without changes in neuromuscular fatigue development.
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Affiliation(s)
- Guilherme A Ferreira
- Associated Program of Post-Graduation in Physical Education UPE/UFPB, University of Pernambuco, Recife, Brazil.,Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil.,Human Performance Research Group, Federal University of Technology - Parana (UTFPR), Curitiba, Brazil
| | - Leandro C Felippe
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil.,Human Performance Research Group, Federal University of Technology - Parana (UTFPR), Curitiba, Brazil
| | - Marcos D Silva-Cavalcante
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil.,Human Performance Research Group, Federal University of Technology - Parana (UTFPR), Curitiba, Brazil
| | - Ana Paula A De-Mello
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil
| | - Daniel B Coelho
- Center of Engineering, Modeling, and Applied Social Science, Federal University of ABC, São Paulo, São Paulo, Brazil
| | - Renato Maranhão
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil
| | - Rômulo Bertuzzi
- Endurance Performance Research Group (GEDAE-USP), University of São Paulo, São Paulo, Brazil
| | - Manuela Dolinsky
- Departament of Nutrition and Dietetic, Federal Fluminense University, Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Adriano E Lima-Silva
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil.,Human Performance Research Group, Federal University of Technology - Parana (UTFPR), Curitiba, Brazil
| | - Kleber J Da-Silva
- Sports Science Research Group, Academic Center of Vitoria, Federal University of Pernambuco, Pernambuco, Brazil.,Human Performance Research Group, Federal University of Technology - Parana (UTFPR), Curitiba, Brazil
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Tabuchi A, Craig JC, Hirai DM, Colburn TD, Kano Y, Poole DC, Musch TI. Systemic NOS inhibition reduces contracting muscle oxygenation more in intact female than male rats. Nitric Oxide 2020; 100-101:38-44. [PMID: 32371102 DOI: 10.1016/j.niox.2020.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/14/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022]
Abstract
Females respond to baroreceptor stimulation with enhanced modulation of heart rate (HR) to regulate blood pressure and also express greater reliance on nitric oxide (NO) for vascular control compared to males. Sex differences in muscle oxygenation consequent to central hemodynamic challenge induced by systemic NO synthase (NOS) inhibition are unknown. We tested the hypotheses that systemic NOS inhibition would induce lower contracting skeletal muscle oxygenation in females compared to males. The spinotrapezius of Sprague-Dawley rats (females (♀) = 9, males (♂) = 9) was surgically exposed and contracted by electrical stimulation (180s, 1 Hz, ~6 V) under pentobarbital sodium anesthesia. Oxyphor G4 was injected into the muscle and phosphorescence quenching was used to measure the interstitial PO2 (PO2is, determined by O2 delivery-to-utilization matching) under control (Krebs-Henseleit solution) and after intra-arterial infusion of nitro-l-arginine methyl ester (l-NAME; NOS blockade; 10 mg kg-1). At rest, females showed a greater PO2is increase (ΔPO2is/ΔMAP) and HR (ΔHR/ΔMAP) reduction than males in response to the elevated MAP induced by systemic NOS inhibition (both p < 0.05). Following l-NAME, during the contracting steady-state, females exhibited lower PO2is than males (♂: 17.1 ± 1.4 vs ♀: 10.8 ± 1.4 mmHg, p < 0.05). The rate pressure product was lower in females than males (♂: 482 ± 14 vs ♀: 392 ± 29, p < 0.05) and correlated with the steady-state PO2is (r = 0.66, p < 0.05). These results support that females express greater reductions in HR than males in response to l-NAME-induced elevation of MAP via the baroreceptor reflex and provide new insights on how central hemodynamics affect skeletal muscle oxygenation in a sex-specific manner.
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Affiliation(s)
- Ayaka Tabuchi
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA; Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - Jesse C Craig
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Daniel M Hirai
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - David C Poole
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA
| | - Timothy I Musch
- Departments of Kinesiology and Anatomy & Physiology, Kansas State University, Manhattan, KS, USA.
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Radhakrishnan J, Baetiong A, Gazmuri RJ. Constitutive cyclophilin-D ablation in mice increases exercise and cognitive-behavioral performance under normoxic and hypoxic conditions. Physiol Behav 2020; 219:112828. [PMID: 32061681 DOI: 10.1016/j.physbeh.2020.112828] [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: 01/19/2020] [Revised: 02/04/2020] [Accepted: 02/05/2020] [Indexed: 11/17/2022]
Abstract
We recently reported that constitutive ablation of cyclophilin-D (Cyp-D) in mice reduces oxygen consumption (VO2) while paradoxically increasing exercise endurance, thereby demonstrating increased O2 utilization efficiency. This response was associated with augmented glucose uptake and glucose utilization, in part mediated through adenosine monophosphate-activated kinase signaling. We now hypothesized that Cyp-D knock-out (KO) mice might also exhibit improved cognitive-behavioral performance and that these favorable adaptive responses may persist under hypoxic conditions. We therefore assessed under normoxic (20.9% O2, simulating ground O2 levels) and hypoxic (8% O2, simulating 7600 m altitude O2 levels) conditions exercise capacity and cognitive-behavioral performance. We used a treadmill test to assess exercise capacity, a pole-test to assess agility, an elevated-plus-maze test to assess anti-anxiety, and a passive avoidance test to assess learning and memory retention. Compared to wild type, Cyp-D KO mice showed comparable treadmill work under normoxia (48 ± 12 vs 47 ± 9 Joules) but increased treadmill work (12 ± 1 vs 8 ± 1 Joules; p = 0.02) under hypoxia. Cyp-D KO mice displayed increased pole-descending time (17 ± 3 vs 8 ± 2 s; p ≤ 0.05) under normoxia but shorter pole-descending time (21 ± 3 vs 37 ± 4 s; p ≤ 0.01) under hypoxia. In addition, the Cyp-D KO mice demonstrated increased elevated plus-maze open arm time (91 ± 31 vs 23 ± 12 s; p ≤ 0.05) under hypoxia and increased latency to enter dark chamber (261 ± 23 vs 185 ± 42 s; p ≤ 0.05) under normoxia. Thus, our experiments showed that under normoxia Cyp-D KO mice displayed anti-anxiety behavior and improved learning and memory retention. Under hypoxia, Cyp-D KO mice displayed increased exercise capacity, increased agility, and increased anti-anxiety consistent with our previously reported findings of increased O2 utilization efficiency. Identifying interventions to elicit these effects could be beneficial in a myriad of physiological and clinical conditions in which increasing O2 utilization efficiency would be advantageous.
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Affiliation(s)
- Jeejabai Radhakrishnan
- Resuscitation Institute, Rosalind Franklin University of Medicine and Science, 3333, Green Bay Rd, North Chicago, Illinois 60064, USA; Department of Clinical Sciences, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA.
| | - Alvin Baetiong
- Resuscitation Institute, Rosalind Franklin University of Medicine and Science, 3333, Green Bay Rd, North Chicago, Illinois 60064, USA; Department of Clinical Sciences, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA
| | - Raúl J Gazmuri
- Resuscitation Institute, Rosalind Franklin University of Medicine and Science, 3333, Green Bay Rd, North Chicago, Illinois 60064, USA; Department of Clinical Sciences, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, USA; Captain James A. Lovell Federal Health Care Center, North Chicago, Illinois, USA.
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26
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Kojima Y, Fukusaki C, Ishii N. Effects of hyperoxia on dynamic muscular endurance are associated with individual whole-body endurance capacity. PLoS One 2020; 15:e0231643. [PMID: 32315330 PMCID: PMC7173853 DOI: 10.1371/journal.pone.0231643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/27/2020] [Indexed: 11/18/2022] Open
Abstract
Low-intensity training involving high repetitions is recommended to enhance muscular endurance. Hyperoxic conditions could increase the number of repetitions until exhaustion and thereby improve the results of muscular endurance training. This study aimed to investigate the acute effects of hyperoxia on dynamic muscular endurance, and determine individual factors that may be related to these effects. A single-blinded, counterbalanced crossover design was used. Twenty-five young men performed repetitions of the one-arm preacher curl at 30% of their 1-repetition maximum until exhaustion under hyperoxic and normoxic conditions. The maximum number of repetitions was recorded as an index of muscular endurance. Electromyogram (EMG) and near-infrared spectroscopy parameters were measured in the biceps brachii. The maximum number of repetitions was greater (P < 0.001) under hyperoxic conditions (132 ± 59 repetitions) than under normoxic conditions (114 ± 40 repetitions). The root mean square amplitude of EMG and oxygenated hemoglobin concentration for the last five repetitions under normoxic conditions were greater than those under hyperoxic conditions (P = 0.015 and P = 0.003, respectively). The percent change in the maximum number of repetitions between hyperoxic and normoxic conditions had significant positive correlations with individual maximal oxygen uptake measured using an incremental cycle ergometer test (r = 0.562, 95% confidence intervals [CI] = 0.213-0.783, P = 0.003), but not with muscle strength (τ = -0.124, 95% CI = -0.424-0.170, P = 0.387). The 95% CI for the correlation coefficient between the percent change in the maximum number of repetitions and muscular endurance included 0 (τ = 0.284, 95% CI = -0.003-0.565, P = 0.047); this indicated no significant correlation between the two parameters. The results suggest that hyperoxia can acutely enhance dynamic muscular endurance, with delayed elevation of EMG amplitude due to fatigue, and the effects are associated with individual whole-body endurance capacity.
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Affiliation(s)
- Yuta Kojima
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Chiho Fukusaki
- Research Center for Total Life Health and Sports Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
- * E-mail:
| | - Naokata Ishii
- Research Center for Total Life Health and Sports Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo, Japan
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27
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MIRA JOSÉ, FLOREANI MIRCO, SAVOLDELLI ALDO, AMERY KHALED, KORAL JEROME, ORANCHUK DUSTINJ, MESSONNIER LAURENTA, RUPP THOMAS, MILLET GUILLAUMEY. Neuromuscular Fatigue of Cycling Exercise in Hypoxia. Med Sci Sports Exerc 2020; 52:1888-1899. [DOI: 10.1249/mss.0000000000002331] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Jeker D, Falbriard M, Vernillo G, Meyer F, Savoldelli A, Degache F, Schena F, Aminian K, Millet GP. Changes in spatio-temporal gait parameters and vertical speed during an extreme mountain ultra-marathon. Eur J Sport Sci 2020; 20:1339-1345. [PMID: 31914356 DOI: 10.1080/17461391.2020.1712480] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The aim of the present study was to investigate the effects of altitude and distance on uphill vertical speed (VS) and the main spatio-temporal gait parameters during an extreme mountain ultra-marathon. The VS, stride height (SH) and stride frequency (SF) of 27 runners were measured with an inertial sensor at the shank for two different altitude ranges (low 1300-2000 m vs high 2400-3200 m) of 10 mountains passes distributed over a 220 km course. There was a significant interaction (F(4,52) = 4.04, p < 0.01) for the effect of altitude and distance on VS. During the first passes, the mean VS was faster at lower altitudes, but this difference disappeared at a quarter of the race length, suggesting that neuromuscular fatigue influenced the uphill velocity to a larger extent than the oxygen delivery. The average VS, SH and SF were 547 ± 135 m/h, 0.23 ± 0.05 m and 0.66 ± 0.09 Hz. The individual VS change for each uphill portions was more strongly correlated with the changes in SH (r = 0.80, P < 0.001, n = 321) than SF (r = 0.43, P < 0.001, n = 321). This suggests a large effect of the knee extensors strength loss on the diminution of VS.
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Affiliation(s)
- David Jeker
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Mathieu Falbriard
- Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Gianluca Vernillo
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada.,CeRiSM, Research Centre 'Sport, Mountain and Health', University of Verona, Rovereto, Italy
| | - Frederic Meyer
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Aldo Savoldelli
- CeRiSM, Research Centre 'Sport, Mountain and Health', University of Verona, Rovereto, Italy
| | - Francis Degache
- School of Health Sciences, University of Applied Science and Arts Western Switzerland, Lausanne, Switzerland
| | - Federico Schena
- CeRiSM, Research Centre 'Sport, Mountain and Health', University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Kamiar Aminian
- Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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29
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Azevedo RDA, Béjar Saona JE, Inglis EC, Iannetta D, Murias JM. The effect of the fraction of inspired oxygen on the NIRS-derived deoxygenated hemoglobin "breakpoint" during ramp-incremental test. Am J Physiol Regul Integr Comp Physiol 2019; 318:R399-R409. [PMID: 31850819 DOI: 10.1152/ajpregu.00291.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During ramp-incremental (RI) exercise to exhaustion, the near-infrared spectroscopy-derived deoxygenated hemoglobin ([HHb]) signal in the vastus lateralis muscle shows a linear increase up to a point at which a plateau-like response is manifested ([HHb]bp). This study investigated if 1) the [HHb]bp is affected by different fractions of inspired O2 (FIO2) [hypoxia (16%; HYPO); normoxia (21%; NORM); hyperoxia (30%; HYPER)]; and 2) an abrupt change to hyperoxic-inspired gas just before the occurrence of the [HHb]bp (HYPERSWITCH) would affect the [HHb] plateau-like response. Ten physically active male participants reported to the laboratory on four separate occasions to perform an RI test to exhaustion in NORM, HYPO, and HYPER and an RI test to exhaustion with an abrupt increase in FIO2 (30%; HYPERSWITCH) 15 W before the power output (PO) associated with [HHb]bp in normoxia. PO, [HHb], tissue O2 (StO2), and pulse O2 saturation (SpO2) were recorded continuously. Peak PO was significantly lower in HYPO (290 ± 21 W) and higher in HYPER (321 ± 22 W) and HYPERSWITCH (320 ± 19 W) compared with NORM (311 ± 18 W). The PO associated with [HHb]bp was not different between NORM and HYPER (246 ± 23 vs. 247 ± 24 W), but it was lower in HYPO (198 ± 31 W) than NORM and HYPER. The PO associated with the [HHb]bp in HYPERSWITCH (240 ± 23) was not different compared with NORM. HYPER and HYPERSWITCH resulted in greater StO2 and SpO2 compared with NORM. These results suggest that the [HHb]bp response is not dependent of O2 driving pressure and that other physiological mechanisms might determine its occurrence.
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Affiliation(s)
| | | | | | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
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30
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Slower Skeletal Muscle Oxygenation Kinetics in Adults With Complex Congenital Heart Disease. Can J Cardiol 2019; 35:1815-1823. [DOI: 10.1016/j.cjca.2019.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/30/2019] [Accepted: 05/01/2019] [Indexed: 12/19/2022] Open
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Rodríguez-Zamora L, Padial P, Schoenfeld BJ, Feriche B. Mean Propulsive Velocity Is a Viable Method for Adjusting the Resistance-Training Load at Moderate Altitude. Front Sports Act Living 2019; 1:52. [PMID: 33344975 PMCID: PMC7739744 DOI: 10.3389/fspor.2019.00052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 10/10/2019] [Indexed: 01/26/2023] Open
Abstract
We examined the viability of using mean propulsive velocity (MPV) to adjust the load in the countermovement jump (CMJ) at moderate altitude. Twenty-four volunteers were assigned to a 4-week power-oriented resistance training (RT) program in either normoxia (N, 690 m) or intermittent hypobaric hypoxia (IH, 2,320 m). The load was adjusted to maintain execution velocity of CMJ at 1m·s-1 of MPV. Relative peak power output (Prel), and percentage of velocity loss throughout the sets (VL) were determined for each session. The internal load was measured by the rating of perceived exertion (RPE). The absolute load lifted was higher in IH compared to N (75.6 ± 8.4 vs. 58.5 ± 12.3 kg P < 0.001). However, similar relative increases for both groups were found when comparing the final values (IH: 8.2%, P = 0.007; N: 9.8%, P = 0.03) with no changes in VL between groups (P = 0.36). Post-study Prel improved significantly only in IH (+7% W·kg-1, P = 0.002). Mean RPE was greater in IH vs. N (6.8 ± 1.5 vs. 5.6 ± 2, P < 0.001). The MPV seems to be a viable method for adjusting external load during RT at moderate altitude. However, given that RT at moderate altitude increases RPE, it is prudent to monitor internal load when using the MPV to best determine the actual physiological stress of the session.
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Affiliation(s)
- Lara Rodríguez-Zamora
- Division of Sport Sciences, School of Health and Medical Sciences, Örebro University, Örebro, Sweden.,Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Paulino Padial
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | | | - Belén Feriche
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
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32
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Geary CM, Welch JF, McDonald MR, Peters CM, Leahy MG, Reinhard PA, Sheel AW. Diaphragm fatigue and inspiratory muscle metaboreflex in men and women matched for absolute diaphragmatic work during pressure-threshold loading. J Physiol 2019; 597:4797-4808. [PMID: 31348520 DOI: 10.1113/jp278380] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/23/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The female diaphragm fatigues at a slower rate compared to that of males, with blunted cardiovascular consequences (i.e. inspiratory muscle metaboreflex). It is unclear if these findings are a function of relative or absolute diaphragmatic work. We asked if sex differences in diaphragm fatigue and the inspiratory muscle metaboreflex persisted during inspiratory loading performed at equal absolute intensities. We found that matching men and women for absolute diaphragmatic work resulted in an equal degree of diaphragm fatigue, despite women performing significantly greater work relative to body mass. Metabolite-induced reflex influences in sympathetic outflow originating from the diaphragm are attenuated in women, with potential implications for blood flow distribution during exercise. ABSTRACT In response to inspiratory pressure-threshold loading (PTL), women have greater inspiratory muscle endurance time, slower rate of diaphragm fatigue development, and a blunted pressor response compared to men. It is unclear if these differences are due to discrepancies in absolute diaphragm force output. We tested the hypothesis that following inspirations performed at equal absolute intensities, females would develop a similar level of diaphragm fatigue and an attenuated cardiovascular response relative to men. Healthy young men (n = 8, age = 24 ± 3 years) and women (n = 8, age = 23 ± 3 years) performed PTL whilst targeting a transdiaphragmatic pressure (Pdi ) of 92 cmH2 O for 5 min. Diaphragm fatigue was assessed via twitch Pdi (Pdi,tw ) using cervical magnetic stimulation. Heart rate (HR) and mean arterial blood pressure were monitored continuously. During PTL, the absolute amount of diaphragm work was not different between men (13,399 ± 2019 cmH2 O s) and women (12,986 ± 1846 cmH2 O s; P > 0.05); however, women performed the PTL task at a higher relative P ¯ di /Pdi,max . Following inspiratory PTL, the magnitude of reduction in Pdi,tw was similar between men (-27.1 ± 7.2%) and women (-23.8 ± 13.8%; P > 0.05). There were significant increases in HR over time (P < 0.05), but this did not differ on the basis of sex (P > 0.05). Mean arterial blood pressure increased significantly over time in both men and women (P < 0.05); however, the rate of change was higher in men (6.24 ± 2.54 mmHg min-1 ) than in women (4.15 ± 2.52 mmHg min-1 ) (P < 0.05). We conclude that the female diaphragm is protected against severe fatigue when inspiratory work is excessive and as a result does not evoke overt sympathoexcitation.
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Affiliation(s)
- Caitlin M Geary
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joseph F Welch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Malcolm R McDonald
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Carli M Peters
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Michael G Leahy
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paige A Reinhard
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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33
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Myers CM, Kim JS, Florian JP. Consecutive, Resting, Long-Duration Hyperoxic Exposures Alter Neuromuscular Responses During Maximal Strength Exercises in Trained Men. Front Physiol 2019; 10:960. [PMID: 31417421 PMCID: PMC6684734 DOI: 10.3389/fphys.2019.00960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 07/11/2019] [Indexed: 11/13/2022] Open
Abstract
Purpose: The main objective of this study was to investigate the physiological effects of repetitive diving-induced hyperoxic conditions at 1.35 atmospheres absolute (ATA) on neuromuscular strength performance. We hypothesized that following five days of consecutive, resting, long-duration (6 h or more) hyperoxic water immersions (WIs) neuromuscular strength performance would be reduced with a longer recovery time in comparison to previously reported normoxic WIs. Methods: Thirteen (n = 13) active male divers [31.3 ± 1.7 (24-43) years, mean ± years] completed five consecutive days of 6-h resting WIs with 18-h surface intervals while breathing 100% O2 (n = 13) at 1.35 ATA. Skeletal muscle performance assessments occurred immediately before and after each WI and 24 and 72 h after the final WI. Performance assessments included maximum voluntary isometric contraction (MVIC) and maximal isokinetic (IK) knee extensions and elbow flexions, and isometric maximum handgrip (MHG) strength. Neuromuscular activation was also measured on the quadriceps, biceps brachii, and brachioradialis via surface electromyography (sEMG). Results: MHG declined by 7.8% (p < 0.001) by WI 5 with performance returning to baseline by 24-h post-WI. Brachioradialis neuromuscular activation increased by 42% on WI 5. MVIC knee extension performance dropped by 4% (p = 0.001) on WI 3 with a 11% overall decrease in quadriceps neuromuscular activation. Maximal IK knee extension dropped by 3.3% on WI 5 with 9% drop in overall quadriceps activation during the same period. MVIC elbow flexion declined by 5.1% on WI 5 but returned to baseline by 72-h post-WI. Maximal IK elbow flexion performance dropped by 8.6% on WI 5 with a continual decline in biceps brachii neuromuscular activation of 24% on WI 5. Conclusion: Consecutive, resting, long-duration hyperoxic WIs reduce muscular performance in multiple muscle groups and alter neuromuscular activation after 3 days of WI with performance adaptations recovering toward baseline by the end of the WI 5. However, neuromuscular activation remains decreased and appears to last beyond the 72-h post-WI recovery period.
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Affiliation(s)
- Christopher M Myers
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, United States.,Navy Experimental Diving Unit, Panama City Beach, FL, United States
| | - Jeong-Su Kim
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, United States
| | - John P Florian
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, United States.,Navy Experimental Diving Unit, Panama City Beach, FL, United States
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The effect of severe and moderate hypoxia on exercise at a fixed level of perceived exertion. Eur J Appl Physiol 2019; 119:1213-1224. [PMID: 30820661 PMCID: PMC6469630 DOI: 10.1007/s00421-019-04111-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 02/21/2019] [Indexed: 02/08/2023]
Abstract
Purpose The purpose of this study was to determine the primary cues regulating perceived effort and exercise performance using a fixed-RPE protocol in severe and moderate hypoxia. Methods Eight male participants (26 ± 6 years, 76.3 ± 8.6 kg, 178.5 ± 3.6 cm, 51.4 ± 8.0 mL kg− 1 min− 1\documentclass[12pt]{minimal}
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\begin{document}$$\dot {V}$$\end{document}V˙O2max) completed three exercise trials in environmental conditions of severe hypoxia (FIO2 0.114), moderate hypoxia (FIO2 0.152), and normoxia (FIO2 0.202). They were instructed to continually adjust their power output to maintain a perceived effort (RPE) of 16, exercising until power output declined to 80% of the peak 30-s power output achieved. Results Exercise time was reduced (severe hypoxia 428 ± 210 s; moderate hypoxia 1044 ± 384 s; normoxia 1550 ± 590 s) according to a reduction in FIO2 (P < 0.05). The rate of oxygen desaturation during the first 3 min of exercise was accelerated in severe hypoxia (− 5.3 ± 2.8% min− 1) relative to moderate hypoxia (− 2.5 ± 1.0% min− 1) and normoxia (− 0.7 ± 0.3% min− 1). Muscle tissue oxygenation did not differ between conditions (P > 0.05). Minute ventilation increased at a faster rate according to a decrease in FIO2 (severe hypoxia 27.6 ± 6.6; moderate hypoxia 21.8 ± 3.9; normoxia 17.3 ± 3.9 L min− 1). Moderate-to-strong correlations were identified between breathing frequency (r = − 0.718, P < 0.001), blood oxygen saturation (r = 0.611, P = 0.002), and exercise performance. Conclusions The primary cues for determining perceived effort relate to progressive arterial hypoxemia and increases in ventilation.
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Abel A, Baron B, Grappe F, Francaux M. Effect of environmental feedbacks on pacing strategy and affective load during a self-paced 30 min cycling time trial. J Sports Sci 2018; 37:291-297. [PMID: 30020858 DOI: 10.1080/02640414.2018.1497934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The purpose of this study was to analyze the pacing strategy and its affective consequences during self-paced cycling time trials (TT) performed at different severity of hypoxia. Eight competitive cyclists performed five 30 min self-paced TTs at their best performance in the following conditions: 1) normobaric normoxia (NNSL); 2) normobaric hypoxia under two simulated altitudes: 2000 m (NH2000) and 3500 m (NH3500) and 3) normobaric hypoxia but the cyclists were deceived and thought to be at sea level for 2000 m (DecNH2000) and 3500 m (DecNH3500). Power Output (PO), oxygen uptake (VO2), and blood lactate concentration ([La]) were recorded to assess exercise intensity and physiological adaptations. The rate of perceived exertion (RPE) and pleasure were measured with a CR10 Borg scale to evaluate the affective load (AL). PO and VO2 decreased with the severity of hypoxia but no significantly difference on performance was measured between deceived and real conditions, except for pacing strategy. The started intensity depends on the exercise expectations, but PO was rapidly adjusted with the physiological constraints and the rate of increase of RPE. Finally, AL did not reach maximal values so that the athletes sustained a physiological and emotional reserve to perform a final spurt.
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Affiliation(s)
- Alexandre Abel
- a Health and Sports Department , University of Franche Comte , Besançon , France.,b Institute of Neuroscience, UCLouvain , Louvain-la-Neuve , Belgium
| | - Bertrand Baron
- c Université de La Réunion , UFR des Sciences et Techniques des Activités Physiques et Sportives (STAPS) , Le Tampon , France
| | - Frédéric Grappe
- d Université de Franche Comté , UFR des Sciences et Techniques des Activités Physiques et Sportives (STAPS) , Besançon , France
| | - Marc Francaux
- b Institute of Neuroscience, UCLouvain , Louvain-la-Neuve , Belgium
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Energy cost and lower leg muscle activities during erect bipedal locomotion under hyperoxia. J Physiol Anthropol 2018; 37:18. [PMID: 29914562 PMCID: PMC6006575 DOI: 10.1186/s40101-018-0177-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/28/2018] [Indexed: 11/13/2022] Open
Abstract
Background Energy cost of transport per unit distance (CoT) against speed shows U-shaped fashion in walking and linear fashion in running, indicating that there exists a specific walking speed minimizing the CoT, being defined as economical speed (ES). Another specific gait speed is the intersection speed between both fashions, being called energetically optimal transition speed (EOTS). We measured the ES, EOTS, and muscle activities during walking and running at the EOTS under hyperoxia (40% fraction of inspired oxygen) on the level and uphill gradients (+ 5%). Methods Oxygen consumption \documentclass[12pt]{minimal}
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\begin{document}$$ \left(\dot{V}{\mathrm{O}}_2\right) $$\end{document}V˙O2 and carbon dioxide output \documentclass[12pt]{minimal}
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\begin{document}$$ \left(\dot{V}{\mathrm{CO}}_2\right) $$\end{document}V˙CO2 were measured to calculate the CoT values at eight walking speeds (2.4–7.3 km h−1) and four running speeds (7.3–9.4 km h− 1) in 17 young males. Electromyography was recorded from gastrocnemius medialis, gastrocnemius lateralis (GL), and tibialis anterior (TA) to evaluate muscle activities. Mean power frequency (MPF) was obtained to compare motor unit recruitment patterns between walking and running. Results \documentclass[12pt]{minimal}
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\begin{document}$$ \dot{V}{\mathrm{O}}_2 $$\end{document}V˙O2, \documentclass[12pt]{minimal}
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\begin{document}$$ \dot{V}{\mathrm{CO}}_2 $$\end{document}V˙CO2, and CoT values were lower under hyperoxia than normoxia at faster walking speeds and any running speeds. A faster ES on the uphill gradient and slower EOTS on both gradients were observed under hyperoxia than normoxia. GL and TA activities became lower when switching from walking to running at the EOTS under both FiO2 conditions on both gradients, so did the MPF in the TA. Conclusions ES and EOTS were influenced by reduced metabolic demands induced by hyperoxia. GL and TA activities in association with a lower shift of motor unit recruitment patterns in the TA would be related to the gait selection when walking or running at the EOTS. Trial registration UMIN000017690 (R000020501). Registered May 26, 2015, before the first trial. Electronic supplementary material The online version of this article (10.1186/s40101-018-0177-7) contains supplementary material, which is available to authorized users.
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Poitras VJ, Hudson RW, Tschakovsky ME. Exercise intolerance in Type 2 diabetes: is there a cardiovascular contribution? J Appl Physiol (1985) 2018; 124:1117-1139. [PMID: 29420147 DOI: 10.1152/japplphysiol.00070.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Physical activity is critically important for Type 2 diabetes management, yet adherence levels are poor. This might be partly due to disproportionate exercise intolerance. Submaximal exercise tolerance is highly sensitive to muscle oxygenation; impairments in exercising muscle oxygen delivery may contribute to exercise intolerance in Type 2 diabetes since there is considerable evidence for the existence of both cardiac and peripheral vascular dysfunction. While uncompromised cardiac output during submaximal exercise is consistently observed in Type 2 diabetes, it remains to be determined whether an elevated cardiac sympathetic afferent reflex could sympathetically restrain exercising muscle blood flow. Furthermore, while deficits in endothelial function are common in Type 2 diabetes and are often cited as impairing exercising muscle oxygen delivery, no direct evidence in exercise exists, and there are several other vasoregulatory mechanisms whose dysfunction could contribute. Finally, while there are findings of impaired oxygen delivery, conflicting evidence also exists. A definitive conclusion that Type 2 diabetes compromises exercising muscle oxygen delivery remains premature. We review these potentially dysfunctional mechanisms in terms of how they could impair oxygen delivery in exercise, evaluate the current literature on whether an oxygen delivery deficit is actually manifest, and correspondingly identify key directions for future research.
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Affiliation(s)
- Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada.,Department of Physiology, Queen's University , Kingston, Ontario , Canada.,Children's Hospital of Eastern Ontario, Research Institute , Ottawa, Ontario , Canada
| | - Robert W Hudson
- Department of Medicine, Division of Endocrinology, Queen's University , Kingston, Ontario , Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada
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Villar R, Hughson RL. Vascular conductance and muscle blood flow during exercise are altered by inspired oxygen fraction and arterial perfusion pressure. Physiol Rep 2017; 5:5/5/e13144. [PMID: 28292884 PMCID: PMC5350166 DOI: 10.14814/phy2.13144] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/08/2017] [Indexed: 01/02/2023] Open
Abstract
We tested the hypothesis during the combined challenges of altered inspired O2 fraction (FIO2) and posture changes at lower power output regardless of body position that the vascular conductance (VC) recruitment to the exercising muscle would not limit muscle perfusion and estimated O2 delivery (DO2est). However, in head‐down tilt at the higher power output exercise in hypoxia, the recruitment of VC would have a functional limitation which would restrict muscle blood flow (MBF) leading to a limitation in DO2est with consequent increases in metabolic stress. Ten healthy volunteers repeated plantar flexion contractions at 20% (low power output = LPO) and 30% (higher power output = HPO) of their maximal voluntary contraction in horizontal (HOR), 35° head‐down‐tilt (HDT) and 45° head‐up‐tilt (HUT). Popliteal diameter and muscle blood flow velocity were measured by ultrasound determining MBF. VC was estimated by dividing MBF flow by MPP, and DO2est was estimated by MBF times saturation. LPOHUT in hypoxia was associated with no changes in VC and MBF leading to reduced DO2est. In LPOHDT under hypoxia, despite no apparent functional limitation in the VC recruitment, rise in MBF to maintain DO2est was associated with marked increase in muscle electromyographic activity, indicating greater metabolic stress. In HPOHDT under hypoxia, a functional limitation for the recruitment of VC constrained MBF and DO2est. Elevated muscle electromyographic signal in HPOHDT under hypoxia was consistent with challenged aerobic metabolisms which contributed to a greater increase in the relative stress of the exercise challenge and advance the onset of muscle fatigue.
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Affiliation(s)
- Rodrigo Villar
- Division of Natural Sciences, Faculty of Health Sciences, Franklin Pierce University, Rindge, New Hampshire .,Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada.,Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Brasilia DF, Brazil
| | - Richard L Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada.,Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
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Thomas K, Elmeua M, Howatson G, Goodall S. Intensity-Dependent Contribution of Neuromuscular Fatigue after Constant-Load Cycling. Med Sci Sports Exerc 2017; 48:1751-60. [PMID: 27187101 DOI: 10.1249/mss.0000000000000950] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE We tested the hypothesis that central and peripheral fatigue after constant-load cycling exercise would vary with exercise intensity and duration. METHODS Twelve well-trained male cyclists (V˙O2max, 4.49 ± 0.35 L·min) completed three constant-load cycling trials to the limit of tolerance in a randomized crossover design. Exercise intensities were set according to the respiratory responses to a preliminary ramp test to elicit cardiorespiratory and metabolic responses consistent with exercise in the severe and heavy exercise domains: 1) at power at V˙O2max (S+, 379 ± 31 W), 2) at 60% of the difference between gas exchange threshold and V˙O2max (S-, 305 ± 23 W), and 3) at the respiratory compensation point (RCP, 254 ± 26 W). Pre- and postexercise twitch responses from the quadriceps to the electrical stimulation of the femoral nerve and magnetic stimulation of the motor cortex were recorded to assess neuromuscular and corticospinal function, respectively. RESULTS Exercise time was 3.14 ± 0.59, 11.11 ± 1.86, and 42.14 ± 9.09 min for S+, S-, and RCP, respectively. All trials resulted in similar reductions in maximum voluntary force (P = 0.61). However, the degree of peripheral fatigue varied in an intensity-dependent manner, with greater reductions in potentiated twitch force after S+ (-33% ± 9%) compared with both S- (-16% ± 9%, P < 0.001) and RCP trials (-11% ± 9%, P < 0.001) and greater after S- compared with RCP (P < 0.05). For central fatigue, this trend was reversed, with smaller reductions in voluntary activation after S+ compared with RCP (-2.7% ± 2.2% vs -9.0% ± 4.7%, P < 0.01). CONCLUSION These data suggest the magnitude of peripheral and central fatigue after locomotor cycling exercise is exacerbated with exercise intensity and duration, respectively.
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Affiliation(s)
- Kevin Thomas
- 1Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UNITED KINGDOM; and 2Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, SOUTH AFRICA
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Lloyd A, Picton L, Raccuglia M, Hodder S, Havenith G. Localized and systemic variations in central motor drive at different local skin and muscle temperatures. Am J Physiol Regul Integr Comp Physiol 2017; 313:R219-R228. [PMID: 28592458 DOI: 10.1152/ajpregu.00055.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/12/2017] [Accepted: 06/05/2017] [Indexed: 11/22/2022]
Abstract
This study investigated the ability to sustain quadriceps central motor drive while subjected to localized heat and metaboreceptive feedback from the contralateral leg. Eight active males each completed two counter-balanced trials, in which muscle temperature (Tm) of a single-leg (TEMP-LEG) was altered to 29.4°C (COOL) or 37.6°C (WARM), while the contralateral leg (CL-LEG) remained thermoneutral: 35.3°C and 35.2°C Tm in COOL and WARM, respectively. To activate metaboreceptive feedback, participants first performed one 120-s isometric maximal voluntary contraction (MVC) of the knee extensors in the TEMP-LEG, immediately followed by postexercise muscle ischemia (PEMI) via femoral blood flow occlusion. To assess central motor drive of a remote muscle group immediately following PEMI, another 120-s MVC was subsequently performed in the CL-LEG. Voluntary muscle activation (VA) was assessed using the twitch interpolation method. Perceived mental effort and limb discomfort were also recorded. In a cooled muscle, a significant increase in mean force output and mean VA (force, P < 0.001; VA, P < 0.05), as well as a significant decrease in limb discomfort (P < 0.05) occurred during the sustained MVC in the TEMP-LEG. However, no differences between Tm were observed in mean force output, mean VA, or limb discomfort during the sustained MVC in the CL-LEG (force, P = 0.33; VA, P > 0.68; and limb discomfort, P = 0.73). The present findings suggest that elevated local skin temperature and Tm can increase limb discomfort and decrease central motor drive, but this does not limit systemic motor activation of a thermoneutral muscle group.
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Affiliation(s)
- Alex Lloyd
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
| | - Lewis Picton
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
| | - Margherita Raccuglia
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
| | - Simon Hodder
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
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Bentley RF, Poitras VJ, Hong T, Tschakovsky ME. Characteristics and effectiveness of vasodilatory and pressor compensation for reduced relaxation time during rhythmic forearm contractions. Exp Physiol 2017; 102:621-634. [PMID: 28397384 DOI: 10.1113/ep086069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/30/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Reduced relaxation time between contractions in exercise requires increased vasodilatation and/or pressor response to prevent hypoperfusion and potential compromise to exercise tolerance. However, it remains unknown whether and to what extent local vasodilatation and/or systemic pressor compensation occurs and whether the efficacy of compensation is exercise intensity dependent. What is the main finding and its importance? We demonstrate that in a forearm exercise model vasodilatory but not pressor compensation occurs and is adequate to prevent hypoperfusion below but not above ∼40% peak work rate. Inadequate compensation occurs with exercise still well inside the submaximal domain, despite a vasodilatory reserve, and compromises exercise performance. During muscle contraction in rhythmic exercise, muscle blood flow is significantly impeded by microvascular compression. The purpose of this study was to establish the nature and magnitude of vasodilatory and/or pressor compensatory responses during forearm exercise in the face of an increased duration of mechanical microvascular compression, and whether the effectiveness of such compensation was exercise intensity dependent. Seven healthy males (21.0 ± 1.8 years old) completed progressive forearm exercise (24.5 N every 3 min; 2 s contraction-4 s relaxation duty cycle) in two conditions: control (CON), 2 s 100 mmHg forearm cuff inflation during contraction; and impedance (IMP), extension of cuff inflation 2 s beyond contraction. Forearm blood flow (in millilitres per minute); brachial artery Doppler and echo ultrasound), mean arterial blood pressure (in millimetres of mercury; finger photoplethysmography) and exercising forearm venous effluent (antecubital vein catheter) measurements revealed an exercise intensity-dependent compensatory vasodilatation effectiveness whereby increased vasodilatation fully protected forearm blood flow up to the 30% exercise intensity in IMP. Above this exercise intensity, forearm blood flow was defended only in part, although submaximal oxygen uptake was not compromised for any completed work rate. As a result, peak exercise intensity (175 ± 22 versus 196 ± 28 N, P = 0.04) and oxygen delivery (76 ± 14 versus 112 ± 22 ml O2 min-1 , P = 0.01) were significantly reduced in IMP compared with CON. In conclusion, reducing relaxation time compromised exercise capacity without compromise to oxygen uptake. Vasodilatory compensation was complete at lower but not higher exercise intensities, whereas pressor compensation was absent. The reasons for the exercise intensity dependence of the efficacy of vasodilatory compensation remain to be determined.
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Affiliation(s)
- Robert F Bentley
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada, K7L 3N6
| | - Veronica J Poitras
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada, K7L 3N6
| | - Terrence Hong
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada, K7L 3N6
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada, K7L 3N6
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Carroll TJ, Taylor JL, Gandevia SC. Recovery of central and peripheral neuromuscular fatigue after exercise. J Appl Physiol (1985) 2017; 122:1068-1076. [DOI: 10.1152/japplphysiol.00775.2016] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 12/29/2022] Open
Abstract
Sustained physical exercise leads to a reduced capacity to produce voluntary force that typically outlasts the exercise bout. This “fatigue” can be due both to impaired muscle function, termed “peripheral fatigue,” and a reduction in the capacity of the central nervous system to activate muscles, termed “central fatigue.” In this review we consider the factors that determine the recovery of voluntary force generating capacity after various types of exercise. After brief, high-intensity exercise there is typically a rapid restitution of force that is due to recovery of central fatigue (typically within 2 min) and aspects of peripheral fatigue associated with excitation-contraction coupling and reperfusion of muscles (typically within 3–5 min). Complete recovery of muscle function may be incomplete for some hours, however, due to prolonged impairment in intracellular Ca2+ release or sensitivity. After low-intensity exercise of long duration, voluntary force typically shows rapid, partial, recovery within the first few minutes, due largely to recovery of the central, neural component. However, the ability to voluntarily activate muscles may not recover completely within 30 min after exercise. Recovery of peripheral fatigue contributes comparatively little to the fast initial force restitution and is typically incomplete for at least 20–30 min. Work remains to identify what factors underlie the prolonged central fatigue that usually accompanies long-duration single joint and locomotor exercise and to document how the time course of neuromuscular recovery is affected by exercise intensity and duration in locomotor exercise. Such information could be useful to enhance rehabilitation and sports performance.
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Affiliation(s)
- T. J. Carroll
- Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, University of Queensland; and
| | - J. L. Taylor
- Neuroscience Research Australia and University of New South Wales
| | - S. C. Gandevia
- Neuroscience Research Australia and University of New South Wales
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Townsend NE, Nichols DS, Skiba PF, Racinais S, Périard JD. Prediction of Critical Power and W' in Hypoxia: Application to Work-Balance Modelling. Front Physiol 2017; 8:180. [PMID: 28386237 PMCID: PMC5362642 DOI: 10.3389/fphys.2017.00180] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/08/2017] [Indexed: 11/23/2022] Open
Abstract
Purpose: Develop a prediction equation for critical power (CP) and work above CP (W′) in hypoxia for use in the work-balance (WBAL′) model. Methods: Nine trained male cyclists completed cycling time trials (TT; 12, 7, and 3 min) to determine CP and W′ at five altitudes (250, 1,250, 2,250, 3,250, and 4,250 m). Least squares regression was used to predict CP and W′ at altitude. A high-intensity intermittent test (HIIT) was performed at 250 and 2,250 m. Actual and predicted CP and W′ were used to compute W′ during HIIT using differential (WBALdiff′) and integral (WBALint′) forms of the WBAL′ model. Results: CP decreased at altitude (P < 0.001) as described by 3rd order polynomial function (R2 = 0.99). W′ decreased at 4,250 m only (P < 0.001). A double-linear function characterized the effect of altitude on W′ (R2 = 0.99). There was no significant effect of parameter input (actual vs. predicted CP and W′) on modelled WBAL′ at 2,250 m (P = 0.24). WBALdiff′ returned higher values than WBALint′ throughout HIIT (P < 0.001). During HIIT, WBALdiff′ was not different to 0 kJ at completion, at 250 m (0.7 ± 2.0 kJ; P = 0.33) and 2,250 m (−1.3 ± 3.5 kJ; P = 0.30). However, WBALint′ was lower than 0 kJ at 250 m (−0.9 ± 1.3 kJ; P = 0.058) and 2,250 m (−2.8 ± 2.8 kJ; P = 0.02). Conclusion: The altitude prediction equations for CP and W′ developed in this study are suitable for use with the WBAL′ model in acute hypoxia. This enables the application of WBAL′ modelling to training prescription and competition analysis at altitude.
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Affiliation(s)
- Nathan E Townsend
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - David S Nichols
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - Philip F Skiba
- Department of Sports Medicine, Advocate Lutheran General Hospital Park Ridge, IL, USA
| | - Sebastien Racinais
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
| | - Julien D Périard
- Athlete Health and Performance Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
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Saugy JJ, Rupp T, Faiss R, Lamon A, Bourdillon N, Millet GP. Cycling Time Trial Is More Altered in Hypobaric than Normobaric Hypoxia. Med Sci Sports Exerc 2016; 48:680-8. [PMID: 26559447 DOI: 10.1249/mss.0000000000000810] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Slight physiological differences between acute exposure in normobaric hypoxia (NH) and hypobaric hypoxia (HH) have been reported. Taken together, these differences suggest different physiological responses to hypoxic exposure to a simulated altitude (NH) versus a terrestrial altitude (HH). For this purpose, in the present study, we aimed to directly compare the time-trial performance after acute hypoxia exposure (26 h, 3450 min) by the same subjects under three different conditions: NH, HH, and normobaric normoxia (NN). Based on all of the preceding studies examining the differences among these hypoxic conditions, we hypothesized greater performance impairment in HH than in NH. METHODS The experimental design consisted of three sessions: NN (Sion: FiO2, 20.93), NH (Sion, hypoxic room: FiO2, 13.6%; barometric pressure, 716 mm Hg), and HH (Jungfraujoch: FiO2, 20.93; barometric pressure, 481 mm Hg). The performance was evaluated at the end of each session with a cycle time trial of 250 kJ. RESULTS The mean time trial duration in NN was significantly shorter than under the two hypoxic conditions (P < 0.001). In addition, the mean duration in NH was significantly shorter than that in HH (P < 0.01). The mean pulse oxygen saturation during the time trial was significantly lower for HH than for NH (P < 0.05), and it was significantly higher in NN than for the two other sessions (P < 0.001). CONCLUSION As previously suggested, HH seems to be a more stressful stimulus, and NH and HH should not be used interchangeability when endurance performance is the main objective. The principal factor in this performance difference between hypoxic conditions seemed to be the lower peripheral oxygen saturation in HH at rest, as well as during exercise.
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Affiliation(s)
- Jonas J Saugy
- 1ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, SWITZERLAND; 2Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, SWITZERLAND; 3Exercise Physiology Laboratory, Savoie Mont Blanc University, Chambery, FRANCE
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Smirmaul BPC, de Moraes AC, Angius L, Marcora SM. Effects of caffeine on neuromuscular fatigue and performance during high-intensity cycling exercise in moderate hypoxia. Eur J Appl Physiol 2016; 117:27-38. [PMID: 27864638 PMCID: PMC5306327 DOI: 10.1007/s00421-016-3496-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 10/24/2016] [Indexed: 11/24/2022]
Abstract
Purpose To investigate the effects of caffeine on performance, neuromuscular fatigue and perception of effort during high-intensity cycling exercise in moderate hypoxia. Methods Seven adult male participants firstly underwent an incremental exercise test on a cycle ergometer in conditions of acute normobaric hypoxia (fraction inspired oxygen = 0.15) to establish peak power output (PPO). In the following two visits, they performed a time to exhaustion test (78 ± 3% PPO) in the same hypoxic conditions after caffeine ingestion (4 mg kg−1) and one after placebo ingestion in a double-blind, randomized, counterbalanced cross-over design. Results Caffeine significantly improved time to exhaustion by 12%. A significant decrease in subjective fatigue was found after caffeine consumption. Perception of effort and surface electromyographic signal amplitude of the vastus lateralis were lower and heart rate was higher in the caffeine condition when compared to placebo. However, caffeine did not reduce the peripheral and central fatigue induced by high-intensity cycling exercise in moderate hypoxia. Conclusion The caffeine-induced improvement in time to exhaustion during high-intensity cycling exercise in moderate hypoxia seems to be mediated by a reduction in perception of effort, which occurs despite no reduction in neuromuscular fatigue.
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Affiliation(s)
- Bruno P C Smirmaul
- Department of Physical Education, São Paulo State University (UNESP), Rio Claro, SP, Brazil
| | | | - Luca Angius
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent at Medway, Chatham Maritime, Kent, ME4 4AG, UK
| | - Samuele M Marcora
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent at Medway, Chatham Maritime, Kent, ME4 4AG, UK.
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Sundberg CW, Hunter SK, Bundle MW. Rates of performance loss and neuromuscular activity in men and women during cycling: evidence for a common metabolic basis of muscle fatigue. J Appl Physiol (1985) 2016; 122:130-141. [PMID: 27856712 DOI: 10.1152/japplphysiol.00468.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 11/13/2016] [Accepted: 11/14/2016] [Indexed: 11/22/2022] Open
Abstract
The durations that muscular force and power outputs can be sustained until failure fall predictably on an exponential decline between an individual's 3-s burst maximum to the maximum performance they can sustain aerobically. The exponential time constants describing these rates of performance loss are similar across individuals, suggesting that a common metabolically based mechanism governs muscle fatigue; however, these conclusions come from studies mainly on men. To test whether the same physiological understanding can be applied to women, we compared the performance-duration relationships and neuromuscular activity between seven men [23.3 ± 1.9 (SD) yr] and seven women (21.7 ± 1.8 yr) from multiple exhaustive bouts of cycle ergometry. Each subject performed trials to obtain the peak 3-s power output (Pmax), the mechanical power at the aerobic maximum (Paer), and 11-14 constant-load bouts eliciting failure between 3 and 300 s. Collectively, men and women performed 180 exhaustive bouts spanning an ~6-fold range of power outputs (118-1116 W) and an ~35-fold range of trial durations (8-283 s). Men generated 66% greater Pmax (956 ± 109 W vs. 632 ± 74 W) and 68% greater Paer (310 ± 47 W vs. 212 ± 15 W) than women. However, the metabolically based time constants describing the time course of performance loss were similar between men (0.020 ± 0.003/s) and women (0.021 ± 0.003/s). Additionally, the fatigue-induced increases in neuromuscular activity did not differ between the sexes when compared relative to the pedal forces at Paer These data suggest that muscle fatigue during short-duration dynamic exercise has a common metabolically based mechanism determined by the extent that ATP is resynthesized by anaerobic metabolism. NEW & NOTEWORTHY Although men and women differed considerably in their absolute cycling performances, there was no sex difference in the metabolically based exponential time constant that described the performance-duration relationship. Similarly, the fatigue-induced increases in neuromuscular activity were not different between the sexes when compared from a metabolic perspective. These data suggest that men and women have similar rate-limiting mechanisms for short-duration dynamic exercise that are determined by the extent the exercise is supported by anaerobic metabolism.
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Affiliation(s)
- Christopher W Sundberg
- Biomechanics Laboratory, Departments of Health and Human Performance and Organismal Biology and Ecology, University of Montana, Missoula, Montana; and .,Neuromuscular Physiology Laboratory, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Sandra K Hunter
- Neuromuscular Physiology Laboratory, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Matthew W Bundle
- Biomechanics Laboratory, Departments of Health and Human Performance and Organismal Biology and Ecology, University of Montana, Missoula, Montana; and
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Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc 2016; 48:2320-2334. [PMID: 27031742 PMCID: PMC5070974 DOI: 10.1249/mss.0000000000000939] [Citation(s) in RCA: 299] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
: The hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise, and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power [CP]) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles-respiratory, metabolic, and contractile-within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2max is attained, and intolerance is manifested. CP may be regarded as a "fatigue threshold" in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
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Affiliation(s)
- David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas, U.S.A
| | - Mark Burnley
- School of Sport and Exercise Sciences, University of Kent, Chatham, U.K
| | - Anni Vanhatalo
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
| | - Harry B. Rossiter
- Faculty of Biological Sciences University of Leeds, Leeds, U.K
- Rehabilitaion Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, U.S.A
| | - Andrew M. Jones
- Sport and Health Sciences, St. Luke’s Campus, University of Exeter, Exeter, U.K
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Girard O, Bula S, Faiss R, Brocherie F, Millet GY, Millet GP. Does altitude level of a prior time-trial modify subsequent exercise performance in hypoxia and associated neuromuscular responses? Physiol Rep 2016. [PMCID: PMC4962066 DOI: 10.14814/phy2.12804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We examined the influence of prior time‐trials performed at different altitudes on subsequent exercise in moderate hypoxia and associated cardiometabolic and neuromuscular responses. In normobaric hypoxia (simulated altitude 2000 m; FiO2: 0.163), 10 healthy males performed (1) an incremental test to exhaustion (VO2max_2000) and (2) a test to exhaustion at 80% of the power output associated to VO2max_2000 for a reference time (947 ± 336 sec). Thereafter, two sessions were conducted in a randomized order: a cycle time‐trial corresponding to the reference time (TT1) followed 22 min later (passive rest at 2000 m) by a 6‐min cycle time‐trial (TT2). TT1 was either performed at 2000 or 3500 m (FiO2: 0.135), while TT2 was always performed at 2000 m. As expected, during TT1, the mean power output (247 ± 42 vs. 227 ± 37 W; P < 0.001) was higher at 2000 than 3500 m. During TT2, the mean power output (256 ± 42 vs. 252 ± 36 W) did not differ between conditions. Before and after TT1, maximal isometric voluntary contraction torque in knee extensors (pooled conditions: −7.9 ± 8.4%; P < 0.01), voluntary activation (−4.1 ± 3.1%; P < 0.05), and indices of muscle contractility (peak twitch torque: −39.1 ± 11.9%; doublet torques at 100 Hz: −15.4 ± 8.9%; 10/100 Hz ratio: −25.8 ± 7.7%; all P < 0.001) were equally reduced at 2000 m or 3500 m. Irrespective of the altitude of TT1, neuromuscular function remained similarly depressed after TT1 both before and after TT2 at 2000 m. A prior time‐trial performed at different altitude influenced to the same extent performance and associated cardiometabolic and neuromuscular responses during a subsequent exercise in moderate hypoxia.
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Affiliation(s)
- Olivier Girard
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Simone Bula
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Raphaël Faiss
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Franck Brocherie
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Guillaume Y. Millet
- Human Performance Laboratory; Faculty of Kinesiology; University of Calgary; Calgary AB Canada
| | - Grégoire P. Millet
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
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49
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Fan JL, Kayser B. Fatigue and Exhaustion in Hypoxia: The Role of Cerebral Oxygenation. High Alt Med Biol 2016; 17:72-84. [DOI: 10.1089/ham.2016.0034] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jui-Lin Fan
- Centre for Translational Physiology, University of Otago, Wellington, New Zealand
- Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand
| | - Bengt Kayser
- Institute of Sports Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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50
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Tofari PJ, Opar DA, Kemp JG, Billaut F, Cormack S. Reliability of measures of quadriceps muscle function using magnetic stimulation. Muscle Nerve 2016; 53:770-8. [PMID: 26427047 DOI: 10.1002/mus.24926] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 09/23/2015] [Accepted: 09/29/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Paul J Tofari
- School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia
| | - David A Opar
- School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia
| | - Justin G Kemp
- School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia
| | - Francois Billaut
- Département de Kinésiologie, Université Laval, Quebec City, Quebec, Canada
| | - Stuart Cormack
- School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia
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