1
|
Mornas A, Brocherie F, Hollville E, Derouck T, Racinais S, Guilhem G. Running 40 Minutes under Temperate or Hot Environment Does Not Affect Operating Fascicle Length. Med Sci Sports Exerc 2024; 56:1140-1150. [PMID: 38233977 DOI: 10.1249/mss.0000000000003387] [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: 01/19/2024]
Abstract
PURPOSE Muscle mechanics is paramount in our understanding of motor performance. However, little is known regarding the sensitivity of fascicle dynamics and connective tissues stiffness to exercise duration and ambient temperature during running, both increasing muscle temperature. This study aimed to determine gastrocnemius medialis (GM) fascicle dynamics in vivo during running in temperate and hot conditions, as well as muscle-tendon unit responses. METHODS Using ultrafast ultrasound, 15 participants (8 men, 7 women; 26 ± 3 yr) were tested before, during (2 and 40 min), and after a running task (40 min at 10 km·h -1 ) in temperate (TEMP; ~23°C) and hot (HOT: ~38°C) conditions. RESULTS Although core, skin temperatures, and heart rate increased from the beginning to the end of the exercise and in a larger extent in HOT than TEMP ( P < 0.001), the physiological stress elicited did not alter running temporal parameters and GM fascicle operating lengths, with similar behavior of the fascicles on their force-length relationship, over time (2 vs 40 min) or across condition (TEMP vs HOT; P ≥ 0.248). Maximal voluntary force production did not reported statistical changes after exercise ( P = 0.060), and the connective tissues stiffness measured (i.e., passive muscle and stiffness of the series-elastic elements) did not show neither time ( P ≥ 0.281), condition ( P ≥ 0.256) nor time-condition interaction ( P ≥ 0.465) effect. CONCLUSIONS This study revealed that prolonged running exercise does not alter muscle-tendon unit properties and interplay, which are not influenced by ambient temperature. These findings may rule out potential detrimental effects of heat on muscle properties and encourage further investigations on longer and more intense running exercise.
Collapse
Affiliation(s)
| | - Franck Brocherie
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, FRANCE
| | - Enzo Hollville
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, FRANCE
| | | | | | - GaËL Guilhem
- French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, FRANCE
| |
Collapse
|
2
|
Oberholzer L, Aamaas NS, Hallén J. Changes in cycling economy and fractional utilization of V̇O 2peak during a 40-min maximal effort exercise test with acute hypobaric hypoxia corresponding to 2800 m of altitude. Scand J Med Sci Sports 2024; 34:e14511. [PMID: 37828810 DOI: 10.1111/sms.14511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/16/2023] [Accepted: 09/25/2023] [Indexed: 10/14/2023]
Abstract
INTRODUCTION Peak oxygen uptake (V̇O2peak ) declines by ~7% per 1000 m of increasing altitude, whereas exercise performance seems reduced to a lesser extent. For example, 800-10 000 m track and field performances are decreased by 0.4%-2.4% above 1000 m as compared to below and some studies show similar drops in cycling performance. A greater decline in V̇O2peak than in endurance performance with altitude suggests a higher fractional utilization of V̇O2peak (%V̇O2peak ). Therefore, we hypothesized that the %V̇O2peak is higher with acute hypoxic exposure than near sea level. METHODS Sixteen lowlanders (8 women, age: 31 ± 7 years [mean ± SD], body mass: 68 ± 8 kg, V̇O2peak : 60 ± 8 mL min-1 kg-1 ) underwent cycling testing in a hypobaric hypoxic chamber on 6 test days, three conducted at 300 m and three at 2800 m of acute altitude. At both altitudes, V̇O2peak was determined, and during a 40-min all out maximal effort time trial (TT), mean power output (MPO) and mean V̇O2 (%V̇O2peak ) were assessed. RESULTS V̇O2peak decreased by 11.2 ± 3.0% (p < 0.001), while MPO during the TT declined by 10.7 ± 3.1% (p < 0.001) at 2800 m as compared to 300 m. During the TT, %V̇O2peak was higher at altitude, corresponding to 75.9 ± 4.5% at 300 m and 78.8 ± 4.2% at 2800 m (p = 0.011), and cycling economy (mL O2 kJ-1 ) was poorer (+3.4 ± 2.7%, p < 0.001). CONCLUSION The %V̇O2peak was higher during a cycling TT at 2800 m of altitude than near sea level, while cycling economy was poorer. This resulted in a similar reduction in performance and V̇O2peak . Future studies should address the physiological mechanisms underlying the elevated %V̇O2peak .
Collapse
Affiliation(s)
- Laura Oberholzer
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | | | - Jostein Hallén
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| |
Collapse
|
3
|
Renaghan E, Wittels HL, Feigenbaum LA, Wishon MJ, Chong S, Wittels ED, Hendricks S, Hecocks D, Bellamy K, Girardi J, Lee S, Vo T, McDonald SM, Wittels SH. Exposures to Elevated Core Temperatures during Football Training: The Impact on Autonomic Nervous System Recovery and Function. Sports (Basel) 2023; 12:8. [PMID: 38251282 PMCID: PMC10819443 DOI: 10.3390/sports12010008] [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: 10/17/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
Exercising with elevated core temperatures may negatively affect autonomic nervous system (ANS) function. Additionally, longer training duration under higher core temperatures may augment these negative effects. This study evaluated the relationship between exercise training duration and 24 h ANS recovery and function at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds in a sample of male Division I (D1) collegiate American football athletes. Fifty athletes were followed over their 25-week season. Using armband monitors (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA), core temperature (°C) and 24 h post-exercise baseline heart rate (HR), HR recovery and heart rate variability (HRV) were measured. For HRV, two time-domain indices were measured: the root mean square of the standard deviation of the NN interval (rMSSD) and the standard deviation of the NN interval (SDNN). Linear regression models were performed to evaluate the associations between exercise training duration and ANS recovery (baseline HR and HRV) and function (HR recovery) at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds. On average, the athletes were 21.3 (± 1.4) years old, weighed 103.0 (±20.2) kg and had a body fat percentage of 15.4% (±7.8%, 3.0% to 36.0%). The duration of training sessions was, on average, 161.1 (±40.6) min and they ranged from 90.1 to 339.6 min. Statistically significant associations between training duration and 24 h ANS recovery and function were observed at both the ≥38.0 °C (baseline HR: β = 0.10 ± 0.02, R2 = 0.26, p < 0.0000; HR recovery: β = -0.06 ± 0.02, R2 = 0.21, p = 0.0002; rMSSD: β = -0.11 ± 0.02, R2 = 0.24, p < 0.0000; and SDNN: β = -0.16 ± 0.04, R2 = 0.22, p < 0.0000) and ≥39.0 °C thresholds (β = 0.39 ± 0.05, R2 = 0.62, p < 0.0000; HR recovery: β = -0.26 ± 0.04, R2 = 0.52, p < 0.0000; rMSSD: β = -0.37 ± 0.05, R2 = 0.58, p < 0.0000; and SDNN: β = -0.67 ± 0.09, R2 = 0.59, p < 0.0000). With increasing core temperatures, increases in slope steepness and strengths of the associations were observed, indicating accelerated ANS deterioration. These findings demonstrate that exercise training under elevated core temperatures (≥38 °C) may negatively influence ANS recovery and function 24 h post exercise and progressively worsen.
Collapse
Affiliation(s)
- Eric Renaghan
- Department of Athletics, Sports Science, University of Miami, Miami, FL 33146, USA; (E.R.); (L.A.F.)
| | - Harrison L. Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Luis A. Feigenbaum
- Department of Athletics, Sports Science, University of Miami, Miami, FL 33146, USA; (E.R.); (L.A.F.)
- Department of Physical Therapy, Miller School of Medicine, University of Miami, Miami, FL 33146, USA;
| | - Michael J. Wishon
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Stephanie Chong
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Eva D. Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Stephanie Hendricks
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Dustin Hecocks
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Kyle Bellamy
- Department of Athletics, Nutrition, University of Miami, Miami, FL 33146, USA;
| | - Joe Girardi
- Department of Physical Therapy, Miller School of Medicine, University of Miami, Miami, FL 33146, USA;
| | - Stephen Lee
- United States Army Research Laboratory, Adelphi, MD 20783, USA;
| | - Tri Vo
- Navy Medical Center—San Diego, San Diego, CA 92134, USA;
| | - Samantha M. McDonald
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
- School of Kinesiology and Recreation, Illinois State University, Normal, IL 61761, USA
| | - S. Howard Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
- Department of Anesthesiology, Mount Sinai Medical Center, Miami, FL 33140, USA
- Department of Anesthesiology, Wertheim School of Medicine, Florida International University, Miami, FL 33199, USA
- Miami Beach Anesthesiology Associates, Miami, FL 33140, USA
| |
Collapse
|
4
|
Bright FM, Clark B, Jay O, Périard JD. Influence of Air Velocity on Self-Paced Exercise Performance in Hot Conditions. Med Sci Sports Exerc 2023; 55:1382-1391. [PMID: 36989528 DOI: 10.1249/mss.0000000000003168] [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: 03/31/2023]
Abstract
PURPOSE This study aimed to determine the effect of different air velocities on heat exchange and performance during prolonged self-paced exercise in the heat. METHODS Twelve male cyclists performed a 700-kJ time trial in four different air velocity conditions (still air, 16, 30, and 44 km·h -1 ) in 32°C and 40% relative humidity. Performance, thermal, cardiovascular, and perceptual responses were measured, and heat balance parameters were estimated using partitional calorimetry, including the maximum potential for sweat evaporation ( Emax ). RESULTS Mean power output was lower in still air (232 ± 42 W) than 16 (247 ± 30 W), 30 (250 ± 32 W), and 44 km·h -1 (248 ± 32 W; all P < 0.001), but similar between the 16-, 30-, and 44-km·h -1 air velocity conditions ( P ≥ 0.275). Emax was lower in still air (160 ± 13 W·m -2 ) than 16 (298 ± 25 W·m -2 ), 30 (313 ± 23 W·m -2 ), and 44 km·h -1 (324 ± 31 W·m -2 ) and lower in 16 than 44 km·h -1 (all P < 0.001). Peak core temperature was higher in still air (39.4°C ± 0.7°C) than 16 (39.0°C ± 0.45°C), 30 (38.8°C ± 0.3°C), and 44 km·h -1 (38.8°C ± 0.5°C; all P ≤ 0.002). Mean skin temperature was lower with greater airflow ( P < 0.001) but similar in 30 and 40 km·h -1 ( P = 1.00). Mean heart rate was ~2 bpm higher in still air than 44 km·h -1 ( P = 0.035). RPE was greater in still air than 44 km·h -1 ( P = 0.017). CONCLUSIONS Self-paced cycling in still air was associated with a lower Emax and subsequently higher thermal strain, along with a similar or greater cardiovascular strain, despite work rate being lower than in conditions with airflow. The similarity in performance between the 16-, 30-, and 44-km·h -1 air velocity conditions suggests that airflow ≥16 km·h -1 does not further benefit self-paced exercise performance in the heat because of modest improvements in evaporative efficiency.
Collapse
Affiliation(s)
- Felicity M Bright
- Research Institute for Sport and Exercise, University of Canberra, Canberra, AUSTRALIA
| | - Brad Clark
- Research Institute for Sport and Exercise, University of Canberra, Canberra, AUSTRALIA
| | - Ollie Jay
- Thermal Ergonomics Laboratory, Faculty of Medicine and Health, The University of Sydney, Sydney, AUSTRALIA
| | - Julien D Périard
- Research Institute for Sport and Exercise, University of Canberra, Canberra, AUSTRALIA
| |
Collapse
|
5
|
Bennett S, Brocherie F, Phelan MM, Tiollier E, Guibert E, Morales‐Artacho AJ, Lalire P, Morton JP, Louis JB, Owens DJ. Acute heat stress amplifies exercise-induced metabolomic perturbations and reveals variation in circulating amino acids in endurance-trained males. Exp Physiol 2023; 108:838-851. [PMID: 36691850 PMCID: PMC10988456 DOI: 10.1113/ep090911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 01/03/2023] [Indexed: 01/25/2023]
Abstract
NEW FINDINGS What is the central question of this study? Whole-body substrate utilisation is altered during exercise in hot environments, characterised by increased glycolytic metabolism: does heat stress alter the serum metabolome in response to high intensity exercise? What are the main finding and its importance? Alongside increases in glycolytic metabolite abundance, circulating amino acid concentrations are reduced following exercise under heat stress. Prior research has overlooked the impact of heat stress on protein metabolism during exercise, raising important practical implications for protein intake recommendations in the heat. ABSTRACT Using untargeted metabolomics, we aimed to characterise the systemic impact of environmental heat stress during exercise. Twenty-three trained male triathletes (V ̇ O 2 peak ${\dot V_{{{\rm{O}}_2}{\rm{peak}}}}$ = 64.8 ± 9.2 ml kg min-1 ) completed a 30-min exercise test in hot (35°C) and temperate (21°C) conditions. Venous blood samples were collected immediately pre- and post-exercise, and the serum fraction was assessed via untargeted 1 H-NMR metabolomics. Data were analysed via uni- and multivariate analyses to identify differences between conditions. Mean power output was higher in temperate (231 ± 36 W) versus hot (223 ± 31 W) conditions (P < 0.001). Mean heart rate (temperate, 162 ± 10 beats min-1 , hot, 167 ± 9 beats min-1 , P < 0.001), peak core temperature (Trec ), core temperature change (ΔTrec ) (P < 0.001) and peak rating of perceived exertion (P = 0.005) were higher in hot versus temperate conditions. Change in metabolite abundance following exercise revealed distinct clustering following multivariate analysis. Six metabolites increased (2-hydroxyvaleric acid, acetate, alanine, glucarate, glucose, lactate) in hot relative to temperate (P < 0.05) conditions. Leucine and lysine decreased in both conditions but to a greater extent in temperate conditions (P < 0.05). Citrate (P = 0.04) was greater in temperate conditions whilst creatinine decreased in hot conditions only (P > 0.05). Environmental heat stress increased glycolytic metabolite abundance and led to distinct alterations in the circulating amino acid availability, including increased alanine, glutamine, leucine and isoleucine. The data highlight the need for additional exercise nutrition and metabolism research, specifically focusing on protein requirements for exercise under heat stress.
Collapse
Affiliation(s)
- Samuel Bennett
- Research Institute of Sport and Exercise Science (RISES)Liverpool John Moores UniversityLiverpoolUK
- Laboratory SportExpertise and Performance (EA 7370)French Institute of SportParisFrance
| | - Franck Brocherie
- Laboratory SportExpertise and Performance (EA 7370)French Institute of SportParisFrance
| | - Marie M. Phelan
- NMR Metabolomics Shared Research FacilityTechnology DirectorateUniversity of LiverpoolLiverpoolUK
| | - Eve Tiollier
- Laboratory SportExpertise and Performance (EA 7370)French Institute of SportParisFrance
| | - Elodie Guibert
- Laboratory SportExpertise and Performance (EA 7370)French Institute of SportParisFrance
| | | | - Paul Lalire
- French Triathlon Federation (FFTri)Saint Denis La PlaineFrance
| | - James P. Morton
- Research Institute of Sport and Exercise Science (RISES)Liverpool John Moores UniversityLiverpoolUK
| | - Julien B. Louis
- Research Institute of Sport and Exercise Science (RISES)Liverpool John Moores UniversityLiverpoolUK
| | - Daniel J. Owens
- Research Institute of Sport and Exercise Science (RISES)Liverpool John Moores UniversityLiverpoolUK
| |
Collapse
|
6
|
Toro-Román V, Prieto-González I, Siquier-Coll J, Bartolomé I, Grijota FJ, Maynar-Mariño M. Effects of High Temperature Exposure on the Wingate Test Performance in Male University Students. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4782. [PMID: 36981697 PMCID: PMC10049338 DOI: 10.3390/ijerph20064782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/05/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
It has been suggested that heat exposure prior to exercise could induce changes in anaerobic exercise. Therefore, the purpose of this study was to observe the effects of high temperature heat exposure prior to an anaerobic test. Twenty-one men (age: 19.76 ± 1.22 years; height: 1.69 ± 0.12 m; weight: 67.89 ± 11.78 kg) voluntarily participated in this investigation. All of them performed two Wingate tests, vertical jump and macronutrient intake control. On the first day, the test was performed under normal environmental conditions. On the second day, it was performed in a similar way, but with previous exposure to heat at high sauna temperatures (15 min; 100 ± 2 °C). There were no differences in the vertical jump and macronutrient intake. However, the results showed an improvement in power (W) (p < 0.05), relative power (W/kg) (p < 0.01) and revolutions per minute (p < 0.05) 10 s after the start of the test. There was also an increase in thigh (p < 0.01) and skin temperature (p < 0.01) with pre-heat exposure. The results obtained suggest that this pre-exercise protocol could improve power in short and intensive actions.
Collapse
Affiliation(s)
- Víctor Toro-Román
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
| | - Isaac Prieto-González
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
| | - Jesús Siquier-Coll
- SER Research Group, Center of Higher Education Alberta Giménez, Comillas Pontifical University, Costa de Saragossa 16, 07013 Palma Mallorca, Spain
| | - Ignacio Bartolomé
- Department of Sport Science, Faculty of Education, Pontifical University of Salamanca, C/Henry Collet, 52-70, 37007 Salamanca, Spain
| | - Francisco J. Grijota
- Faculty of Life and Nature Sciences, University of Nebrija, Campus La Berzosa, Calle del Hostal, Hoyo de Manzanares, 28248 Madrid, Spain
| | - Marcos Maynar-Mariño
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
| |
Collapse
|
7
|
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.
Collapse
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,
| |
Collapse
|
8
|
Lloyd A, Fiala D, Heyde C, Havenith G. A mathematical model for predicting cardiovascular responses at rest and during exercise in demanding environmental conditions. J Appl Physiol (1985) 2022; 133:247-261. [PMID: 35652831 PMCID: PMC9342140 DOI: 10.1152/japplphysiol.00619.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present research describes the development and validation of a cardiovascular model (CVR Model) for use in conjunction with advanced thermophysiological models, where usually only a total cardiac output is estimated. The CVR Model detailed herein estimates cardio-dynamic parameters (changes in cardiac output, stroke volume, and heart rate), regional blood flow, and muscle oxygen extraction, in response to rest and physical workloads, across a range of ages and aerobic fitness levels, as well as during exposure to heat, dehydration, and altitude. The model development strategy was to first establish basic resting and exercise predictions for cardio-dynamic parameters in an "ideal" environment (cool, sea level, and hydrated person). This basic model was then advanced for increasing levels of altitude, heat strain, and dehydration, using meta-analysis and reaggregation of published data. Using the estimated altitude- and heat-induced changes in maximum oxygen extraction and maximum cardiac output, the decline in maximum oxygen consumption at high altitude and in the heat was also modeled. A validation of predicted cardiovascular strain using heart rate was conducted using a dataset of 101 heterogeneous individuals (1,371 data points) during rest and exercise in the heat and at altitude, demonstrating that the CVR Model performs well (R2 = 0.82-0.84) in predicting cardiovascular strain, particularly at a group mean level (R2 = 0.97). The development of the CVR Model is aimed at providing the Fiala thermal Physiology & Comfort (FPC) Model and other complex thermophysiological models with improved estimations of cardiac strain and exercise tolerance, across a range of individuals during acute exposure to environmental stressors.NEW & NOTEWORTHY The present research promotes the adaption of thermophysiological modeling to the estimation of cardiovascular strain in individuals exercising under acute environmental stress. Integration with advanced models of human thermoregulation opens doors for detailed numerical analysis of athletes' performance and physiology during exercise, occupational safety, and individual work tolerability. The research provides a simple-to-validate metric of cardiovascular function (heart rate), as well as a method to evaluate key principles influencing exercise- and thermoregulation in humans.
Collapse
Affiliation(s)
- Alex Lloyd
- 1Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Dusan Fiala
- 2ERGONSIM—Human Thermal Modelling, Messstetten, Germany
| | | | - George Havenith
- 1Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| |
Collapse
|
9
|
Tan GCW, Zheng K, Cheong WK, Byrne C, Iversen JN, Lee JKW. Small changes in thermal conditions hinder marathon running performance in the tropics. Temperature (Austin) 2022; 9:373-388. [PMID: 36339089 PMCID: PMC9629073 DOI: 10.1080/23328940.2022.2086777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We examined marathon performance of the same group of runners in relation to small changes in dry bulb temperature (Tdb) and wet bulb temperature (Twb) across 3 consecutive y, and investigated whether performance was poorer during an evening marathon compared with morning marathons. Marathon results were obtained from the 2017, 2018, and 2019 Standard Chartered Singapore Marathons. Tdb, Twb, Td, relative humidity, and absolute humidity were gathered for each marathon. K-means clustering and linear regressions were performed on 610 runners who participated in all three marathons. Analysis of the 610 runners’ marathon performance was contrasted with Tdb and Twb. Linear regressions were also performed on 190 runners filtered by percentile, yielding similar results. For clusters with similar Tdb from all runners K-means clustering, an increase in mean Twb by 1.5°C coincided with an increase in finishing time by 559 s (9.3 min) (p < 0.033). Twb hinders marathon performance more than Tdb, with each percentage rise in Tdb and Twb resulting in an increase in net time by 7.6% and 39.1%, respectively (p < 0.025). Male and female runners’ response to Tdb and Twb changes were similar (overlap in 95% confidence intervals for the respective regression coefficients). In conclusion, small variations in environmental parameters affected marathon performance, with Twb impairing marathon performance more than Tdb. Marathon performance was likely better in the morning than evening, possibly due to time of day differences, along with unfavorable Tdb that superseded training effects and the effects of lower Twb.
Collapse
Affiliation(s)
- Glenn C. W. Tan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Kaiyuan Zheng
- Meteorological Service Singapore, Singapore, Singapore
| | - Wee K. Cheong
- Meteorological Service Singapore, Singapore, Singapore
| | - Christopher Byrne
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Jan N. Iversen
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jason K. W. Lee
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Global Asia Institute, National University of Singapore, Singapore, Singapore
- N.1 Institute for Health, National University of Singapore, Singapore, Singapore
- Institute for Digital Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| |
Collapse
|
10
|
De Wachter J, Proost M, Habay J, Verstraelen M, Díaz-García J, Hurst P, Meeusen R, Van Cutsem J, Roelands B. Prefrontal Cortex Oxygenation During Endurance Performance: A Systematic Review of Functional Near-Infrared Spectroscopy Studies. Front Physiol 2021; 12:761232. [PMID: 34764885 PMCID: PMC8576380 DOI: 10.3389/fphys.2021.761232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/27/2021] [Indexed: 01/17/2023] Open
Abstract
Introduction: A myriad of factors underlie pacing-/exhaustion-decisions that are made during whole-body endurance performance. The prefrontal cortex (PFC) is a brain region that is crucial for decision-making, planning, and attention. PFC oxygenation seems to be a mediating factor of performance decisions during endurance performance. Nowadays, there is no general overview summarizing the current knowledge on how PFC oxygenation evolves during whole-body endurance performance and whether this is a determining factor. Methods: Three electronic databases were searched for studies related to the assessment of PFC oxygenation, through near-IR spectroscopy (NIRS), during endurance exercise. To express PFC oxygenation, oxygenated (HbO2) and deoxygenated hemoglobin (HHb) concentrations were the primary outcome measures. Results: Twenty-eight articles were included. Ten articles focused on assessing prefrontal oxygenation through a maximal incremental test (MIT) and 18 focused on using endurance tasks at workloads ranging from low intensity to supramaximal intensity. In four MIT studies measuring HbO2, an increase of HbO2 was noticed at the respiratory compensation point (RCP), after which it decreased. HbO2 reached a steady state in the four studies and increased in one study until exhaustion. All studies found a decrease or steady state in HHb from the start until RCP and an increase to exhaustion. In regard to (non-incremental) endurance tasks, a general increase in PFC oxygenation was found while achieving a steady state at vigorous intensities. PCF deoxygenation was evident for near-to-maximal intensities at which an increase in oxygenation and the maintenance of a steady state could not be retained. Discussion/Conclusion: MIT studies show the presence of a cerebral oxygenation threshold (ThCox) at RCP. PFC oxygenation increases until the RCP threshold, thereafter, a steady state is reached and HbO2 declines. This study shows that the results obtained from MIT are transferable to non-incremental endurance exercise. HbO2 increases during low-intensity and moderate-intensity until vigorous-intensity exercise, and it reaches a steady state in vigorous-intensity exercise. Furthermore, ThCox can be found between vigorous and near-maximal intensities. During endurance exercise at near-maximal intensities, PFC oxygenation increases until the value exceeding this threshold, resulting in a decrease in PFC oxygenation. Future research should aim at maintaining and improving PFC oxygenation to help in improving endurance performance and to examine whether PFC oxygenation has a role in other performance-limiting factors.
Collapse
Affiliation(s)
- Jonas De Wachter
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Matthias Proost
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jelle Habay
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Matthias Verstraelen
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jesús Díaz-García
- Faculty of Sport Sciences, University of Extremadura, Caceres, Spain
| | - Philip Hurst
- The School of Psychology & Life Sciences, Canterbury Christ Church University, Canterbury, United Kingdom
| | - Romain Meeusen
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jeroen Van Cutsem
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium.,VIPER Research Unit, Royal Military Academy, Brussels, Belgium
| | - Bart Roelands
- Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| |
Collapse
|
11
|
de Korte JQ, Bongers CCWG, Hopman MTE, Teunissen LPJ, Jansen KMB, Kingma BRM, Ballak SB, Maase K, Moen MH, van Dijk JW, Daanen HAM, Eijsvogels TMH. Performance and thermoregulation of Dutch Olympic and Paralympic athletes exercising in the heat: Rationale and design of the Thermo Tokyo study: The journal Temperature toolbox. Temperature (Austin) 2021; 8:209-222. [PMID: 34485618 PMCID: PMC8409773 DOI: 10.1080/23328940.2021.1925618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The environmental conditions during the Tokyo Olympic and Paralympic Games are expected to be challenging, which increases the risk for participating athletes to develop heat-related illnesses and experience performance loss. To allow safe and optimal exercise performance of Dutch elite athletes, the Thermo Tokyo study aimed to determine thermoregulatory responses and performance loss among elite athletes during exercise in the heat, and to identify personal, sports-related, and environmental factors that contribute to the magnitude of these outcomes. For this purpose, Dutch Olympic and Paralympic athletes performed two personalized incremental exercise tests in simulated control (15°C, relative humidity (RH) 50%) and Tokyo (32°C, RH 75%) conditions, during which exercise performance and (thermo)physiological parameters were obtained. Thereafter, athletes were invited for an additional visit to conduct anthropometric, dual-energy X-ray absorptiometry (DXA), and 3D scan measurements. Collected data also served as input for a thermophysiological computer simulation model to estimate the impact of a wider range of environmental conditions on thermoregulatory responses. Findings of this study can be used to inform elite athletes and their coaches on how heat impacts their individual (thermo)physiological responses and, based on these data, advise which personalized countermeasures (i.e. heat acclimation, cooling interventions, rehydration plan) can be taken to allow safe and maximal performance in the challenging environmental conditions of the Tokyo 2020 Olympic and Paralympic Games.
Collapse
Affiliation(s)
- Johannus Q de Korte
- Department of Physiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Coen C W G Bongers
- Department of Physiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands.,Faculty of Health Sciences, Thermal Ergonomics Laboratory, The University of Sydney, Sydney, Australia
| | - Maria T E Hopman
- Department of Physiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Lennart P J Teunissen
- Department of Design Engineering, Delft University of Technology, Delft, The Netherlands
| | - Kaspar M B Jansen
- Department of Design Engineering, Delft University of Technology, Delft, The Netherlands
| | - Boris R M Kingma
- Department of Training and Performance Innovations, Unit Defence, Safety and Security, TNO, the Netherlands Organization for Applied Sciences, Soesterberg, The Netherlands.,Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Sam B Ballak
- Sport Science & Innovation Papendal, Sportcentrum Papendal, Arnhem, The Netherlands
| | - Kamiel Maase
- Netherlands Olympic Committee Netherlands Sports Federation, Arnhem, The Netherlands
| | - Maarten H Moen
- Netherlands Olympic Committee Netherlands Sports Federation, Arnhem, The Netherlands
| | - Jan-Willem van Dijk
- Institute of Sport and Exercise Studies, HAN University of Applied Sciences, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Faculty of Behavioural and Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.,Sizing Science, Soesterberg, The Netherlands
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| |
Collapse
|
12
|
de Korte JQ, Bongers CCWG, Hopman MTE, Eijsvogels TMH. Exercise Performance and Thermoregulatory Responses of Elite Athletes Exercising in the Heat: Outcomes of the Thermo Tokyo Study. Sports Med 2021; 51:2423-2436. [PMID: 34396493 PMCID: PMC8514392 DOI: 10.1007/s40279-021-01530-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2021] [Indexed: 11/30/2022]
Abstract
Objective We examined the impact of simulated Tokyo 2020 environmental condition on exercise performance, thermoregulatory responses and thermal perception among Dutch elite athletes. Methods 105 elite athletes from different sport disciplines performed two exercise tests in simulated control (15.9 ± 1.2 °C, relative humidity (RH) 55 ± 6%) and Tokyo (31.6 ± 1.0 °C, RH 74 ± 5%) environmental conditions. Exercise tests consisted of a 20-min warm-up (70% HRmax), followed by an incremental phase until volitional exhaustion (5% workload increase every 3 min). Gastrointestinal temperature (Tgi), heart rate, exercise performance and thermal perception were measured. Results Time to exhaustion was 16 ± 8 min shorter in the Tokyo versus the control condition (− 26 ± 11%, whereas peak power output decreased with 0.5 ± 0.3 W/kg (16 ± 7%). Greater exercise-induced increases in Tgi (1.8 ± 0.6 °C vs. 1.5 ± 0.5 °C, p < 0.001) and higher peak Tgi (38.9 ± 0.6 °C vs. 38.7 ± 0.4 °C, p < 0.001) were found in the Tokyo versus control condition. Large interindividual variations in exercise-induced increase in Tgi (range 0.7–3.5 °C) and peak Tgi (range 37.6–40.4 °C) were found in the Tokyo condition, with greater Tgi responses in endurance versus mixed- and skill-trained athletes. Peak thermal sensation and thermal comfort scores deteriorated in the Tokyo condition, with aggravated responses for power versus endurance- and mixed-trained athletes. Conclusion Large performance losses and Tgi increases were found among elite athletes exercising in simulated Tokyo conditions, with a substantial interindividual variation and significantly different responses across sport disciplines. These findings highlight the importance of an individual approach to optimally prepare athletes for safe and maximal exercise performance during the Tokyo Olympics. Supplementary Information The online version contains supplementary material available at 10.1007/s40279-021-01530-w.
Collapse
Affiliation(s)
- Johannus Q de Korte
- Department of Physiology (392), Radboud University Medical Centre, Radboud Institute for Health Sciences, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Coen C W G Bongers
- Department of Physiology (392), Radboud University Medical Centre, Radboud Institute for Health Sciences, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Maria T E Hopman
- Department of Physiology (392), Radboud University Medical Centre, Radboud Institute for Health Sciences, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Thijs M H Eijsvogels
- Department of Physiology (392), Radboud University Medical Centre, Radboud Institute for Health Sciences, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
| |
Collapse
|
13
|
Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 135] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
Collapse
Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
14
|
Konings MJ, Hettinga FJ. Preexercise Cycling Protocol Alters Pacing Behavior in Competitive Time Trials. Int J Sports Physiol Perform 2020; 15:1303-1308. [PMID: 32932234 DOI: 10.1123/ijspp.2019-0763] [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: 09/26/2019] [Revised: 12/14/2019] [Accepted: 01/03/2020] [Indexed: 11/18/2022]
Abstract
PURPOSE The behavior of an opponent has been shown to alter pacing and performance. To advance our understanding of the impact of perceptual stimuli such as an opponent on pacing and performance, this study examined the effect of a preexercise cycling protocol on exercise regulation with and without an opponent. METHODS Twelve trained cyclists performed 4 experimental, self-paced 4-km time-trial conditions on an advanced cycle ergometer in a randomized, counterbalanced order. Participants started the time trial in rested state (RS) or performed a 10-min cycling protocol at 67% peak power output (CP) before the time trial. During the time trials, participants had to ride alone (NO) or against a virtual opponent (OP). The experimental conditions were (1) RS-NO, (2) RS-OP, (3) CP-NO, and (4) CP-OP. Repeated-measures analyses of variance (P < .05) were used to examine differences in pacing and performance in terms of power output. RESULTS A faster pace was adopted in the first kilometer during RS-OP (318 [72] W) compared with RS-NO (291 [81] W; P = .03), leading to an improved finishing time during RS-OP compared with RS-NO (P = .046). No differences in either pacing or performance were found between CP-NO and CP-OP. CONCLUSIONS The evoked response by the opponent to adopt a faster initial pace in the 4-km time trial disappeared when cyclists had to perform a preceding cycling protocol. The outcomes of this study highlight that perceived exertion alters the responsiveness to perceptual stimuli of cyclists during competition.
Collapse
|
15
|
Pryor JL, Johnson EC, Yoder HA, Looney DP. Keeping Pace: A Practitioner-Focused Review of Pacing Strategies in Running. Strength Cond J 2020. [DOI: 10.1519/ssc.0000000000000505] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
16
|
Resting β-Adrenergic Blockade Does Not Alter Exercise Thermoregulation in Children With Burn Injury: A Randomized Control Trial. J Burn Care Res 2019; 39:402-412. [PMID: 28661984 DOI: 10.1097/bcr.0000000000000610] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The objective of this study was to test the hypothesis that propranolol, a commonly prescribed β-blocker to burned children, in combination with exercise-heat stress, increases the risk of heat illness and exercise intolerance. In a randomized double-blind study, propranolol was given to 10 burned children, and placebo was given to 10 additional burned children (matched for TBSA burned; mean ± SD, 62 ± 13%), while nonburned children served as healthy controls. All groups were matched for age and body morphology (11.2 ± 3.0 years; 146 ± 19 cm; 45 ± 18 kg; 1.3 ± 0.4 m2). All children exercised in hot conditions (34.3 ± 1.0°C; 26 ± 2% relative humidity) at 75% of their peak aerobic capacity. At the end of exercise, none of the groups differed for final or change from baseline intestinal temperature (38.0 ± 0.5°C; 0.02 ± 0.01Δ°C·min-1), unburned (37.0 ± 0.6°C) and burned skin temperatures (36.9 ± 0.7°C; nonburn group excluded), heat loss (21 ± 18 W m-2), whole-body thermal conductance (118 ± 113 W m-2), or physiological strain index (5.6 ± 1). However, burn children exercised less than nonburn group (21.2 ± 8.6 vs 30 ± 0.0 min; P < .001) and had a lower calculated exercise tolerance index (1.0 ± 0.0 vs 6.7 ± 4.3; P < .01). Burned children had lower peak heart rates than nonburned children (173 ± 13 vs 189 ± 7 bpm; P < .01), with greater relative cardiac work rates at the end of exercise (97 ± 10 vs 85 ± 11% peak heart rate; P < .01). Resting β-adrenergic blockade does not affect internal body temperature of burned children exercising at similar relative intensities as nonburn children in the heat. Independent of propranolol, a suppressed cardiac function may be associated to exercise intolerance in children with severe burn injury.
Collapse
|
17
|
Périard JD, Houtkamp D, Bright F, Daanen HAM, Abbiss CR, Thompson KG, Clark B. Hyperoxia enhances self‐paced exercise performance to a greater extent in cool than hot conditions. Exp Physiol 2019; 104:1398-1407. [DOI: 10.1113/ep087864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/02/2019] [Indexed: 11/08/2022]
Affiliation(s)
- J. D. Périard
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
| | - D. Houtkamp
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
- Department of Human Movement SciencesFaculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam Amsterdam The Netherlands
| | - F. Bright
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
| | - H. A. M. Daanen
- Department of Human Movement SciencesFaculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam Amsterdam The Netherlands
| | - C. R. Abbiss
- Centre for Exercise and Sports Science ResearchSchool of Medical and Health Sciences, Edith Cowan University Joondalup WA Australia
| | - K. G. Thompson
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
- New South Wales Institute of Sport Sydney NSW Australia
| | - B. Clark
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
| |
Collapse
|
18
|
Bradbury KE, Coffman KE, Mitchell KM, Luippold AJ, Fulco CS, Kenefick RW. Separate and combined influences of heat and hypobaric hypoxia on self-paced aerobic exercise performance. J Appl Physiol (1985) 2019; 127:513-519. [PMID: 31219777 DOI: 10.1152/japplphysiol.00023.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heat and hypobaric hypoxia independently compromise exercise performance; however, their combined impact on exercise performance has yet to be quantified. This study examined the effects of heat, hypobaric hypoxia, and the combination of these environments on self-paced cycling time trial (TT) performance. Twelve subjects [2 female, 10 male; sea level (SL) peak oxygen consumption (V̇o2peak), 41.5 ± 4.4 mL·kg-1·min-1, mean ± SD] completed 30 min of steady-state cycling exercise (50% SL V̇o2peak), followed by a 15-min self-paced TT in four environmental conditions: SL thermoneutral [SLTN; 250 m, 20°C, 30-50% relative humidity (rh)], SL hot (SLH; 250 m, 35°C, 30% rh), hypobaric hypoxia thermoneutral (HTN; 3,000 m, 20°C, 30-50% rh), and hypobaric hypoxia hot (HH; 3,000 m, 35°C, 30% rh). Performance was assessed by the total work (kJ) completed. TT performance was lower (P < 0.05) in SLH, HTN, and HH relative to SLTN (-15.4 ± 9.7, -24.1 ± 16.2, and -33.1 ± 13.4 kJ, respectively). Additionally, the total work completed in HTN and HH was lower (P < 0.05) than that in SLH. In SLH, HTN, and HH, work rate was reduced versus SLTN (P < 0.05) within the first 3 min of exercise and was consistent for the remainder of the bout. No differences (P > 0.05) existed for heart rate or Ratings of Perceived Exertion at the end of exercise among conditions. The decrease in self-paced TT performance in the heat and/or hypobaric hypoxia conditions compared with SLTN conditions resulted from a nearly immediate reduction in work rate that may have been regulated by environmentally induced changes in physiological strain and perception of effort in response to TT exercise.NEW & NOTEWORTHY This is the first known study to examine the combined effects of heat and hypobaric hypoxia on short-duration self-paced cycling time trial performance. Regardless of environmental condition, subjects utilized an even work rate for the entire duration of the time trial. The presence of both environmental stressors led to a greater performance impairment than heat or hypobaric hypoxia alone, and the performance decrement stemmed from an early reduction of work rate.
Collapse
Affiliation(s)
- Karleigh E Bradbury
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Kirsten E Coffman
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Katherine M Mitchell
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Adam J Luippold
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| |
Collapse
|
19
|
Abstract
High-level athletes are always looking at ways to maximize training adaptations for competition performance, and using altered environmental conditions to achieve this outcome has become increasingly popular by elite athletes. Furthermore, a series of potential nutrition and hydration interventions may also optimize the adaptation to altered environments. Altitude training was first used to prepare for competition at altitude, and it still is today; however, more often now, elite athletes embark on a series of altitude training camps to try to improve sea-level performance. Similarly, the use of heat acclimation/acclimatization to optimize performance in hot/humid environmental conditions is a common practice by high-level athletes and is well supported in the scientific literature. More recently, the use of heat training to improve exercise capacity in temperate environments has been investigated and appears to have positive outcomes. This consensus statement will detail the use of both heat and altitude training interventions to optimize performance capacities in elite athletes in both normal environmental conditions and extreme conditions (hot and/or high), with a focus on the importance of nutritional strategies required in these extreme environmental conditions to maximize adaptations conducive to competitive performance enhancement.
Collapse
|
20
|
Abstract
Background Although the acquisition of heat acclimation (HA) is well-documented, less is known about HA decay (HAD) and heat re-acclimation (HRA). The available literature suggests 1 day of HA is lost following 2 days of HAD. Understanding this relationship has the potential to impact upon the manner in which athletes prepare for major competitions, as a HA regimen may be disruptive during final preparations (i.e., taper). Objective The aim of this systematic review and meta-analysis was to determine the rate of HAD and HRA in three of the main physiological adaptations occurring during HA: heart rate (HR), core temperature (Tc), and sweat rate (SR). Data Sources Data for this systematic review were retrieved from Scopus and critical review of the cited references. Study Selection Studies were included when they met the following criteria: HA, HAD, and HRA (when available) were quantified in terms of exposure and duration. HA had to be for at least 5 days and HAD for at least 7 days for longitudinal studies. HR, Tc, or SR had to be monitored in human participants. Study Appraisal The level of bias in each study was assessed using the McMaster critical review form. Multiple linear regression techniques were used to determine the dependency of HAD in HR, Tc, and SR from the number of HA and HAD days, daily HA exposure duration, and intensity. Results Twelve studies met the criteria and were systematically reviewed. HAD was quantified as a percentage change relative to HA (0% = HA, 100% = unacclimated state). Adaptations in end-exercise HR decreased by 2.3% (P < 0.001) for every day of HAD. For end-exercise Tc, the daily decrease was 2.6% (P < 0.01). The adaptations in Tc during the HA period were more sustainable when the daily heat exposure duration was increased and heat exposure intensity decreased. The decay in SR was not related to the number of decay days. However, protracted HA-regimens seem to induce longer-lasting adaptations in SR. High heat exposure intensities during HA seem to evoke more sustained adaptations in SR than lower heat stress. Only eight studies investigated HRA. HRA was 8–12 times faster than HAD at inducing adaptations in HR and Tc, but no differences could be established for SR. Limitations The available studies lacked standardization in the protocols for HA and HAD. Conclusions HAD and HRA differ considerably between physiological systems. Five or more HA days are sufficient to cause adaptations in HR and Tc; however, extending the daily heat exposure duration enhances Tc adaptations. For every decay day, ~ 2.5% of the adaptations in HR and Tc are lost. For SR, longer HA periods are related to better adaptations. High heat exposure intensities seem beneficial for adaptations in SR, but not in Tc. HRA induces adaptations in HR and Tc at a faster rate than HA. HRA may thus provide a practical and less disruptive means of maintaining and optimizing HA prior to competition.
Collapse
Affiliation(s)
- Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Van der Boechorststraat 7, 1081BT, Amsterdam, The Netherlands.
| | - Sebastien Racinais
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Julien D Périard
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| |
Collapse
|
21
|
James CA, Richardson AJ, Watt PW, Willmott AGB, Gibson OR, Maxwell NS. Short-Term Heat Acclimation and Precooling, Independently and Combined, Improve 5-km Time Trial Performance in the Heat. J Strength Cond Res 2018; 32:1366-1375. [PMID: 28486332 DOI: 10.1519/jsc.0000000000001979] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
James, CA, Richardson, AJ, Watt, PW, Willmott, AGB, Gibson, OR, and Maxwell, NS. Short-term heat acclimation and precooling, independently and combined, improve 5-km time trial performance in the heat. J Strength Cond Res 32(5): 1366-1375, 2018-Following heat acclimation (HA), endurance running performance remains impaired in hot vs. temperate conditions. Combining HA with precooling (PC) demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. This study investigated the effect of short-term HA (STHA) combined with mixed methods PC, on endurance running performance and directly compared PC and HA. Nine amateur trained runners completed 5-km treadmill time trials (TTs) in the heat (32° C, 60% relative humidity) under 4 conditions; no intervention (CON), PC, short-term HA (5 days-HA) and STHA with PC (HA + PC). Mean (±SD) performance times were; CON 1,476 (173) seconds, PC 1,421 (146) seconds, HA 1,378 (116) seconds and HA + PC 1,373 (121) seconds. This equated to the following improvements versus CON; PC -3.7%, HA -6.6% and HA + PC -7.0%. Statistical differences were only observed between HA and CON (p = 0.004, d = 0.68, 95% CI [-0.27 to 1.63]) however, similar effect sizes were observed for HA + PC vs. CON (d = 0.70, 95% CI [-0.25 to 1.65]), with smaller effects between PC vs. CON (d = 0.34, 95% CI [-0.59 to 1.27]), HA vs. PC (d = 0.33, 95% CI [-0.60 to 1.26]) and HA + PC vs. PC (d = 0.36, 95% CI [-0.57 to 1.29]). Pilot testing revealed a TT typical error of 16 seconds (1.2%). Precooling offered no further benefit to performance in the acclimated individual, despite modest alleviation of physiological strain. Maintenance of running speed in HA + PC, despite reduced physiological strain, may indicate an inappropriate pacing strategy therefore, further familiarization is recommended to optimize a combined strategy. Finally, these data indicate HA, achieved through cycle training, yields a larger ergogenic effect than PC on 5-km running performance in the heat, although PC remains beneficial when HA is not possible.
Collapse
Affiliation(s)
- Carl A James
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom.,National Sports Institute, Kompleks Sukan Negara, Kuala Lumpur, Malaysia
| | - Alan J Richardson
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Peter W Watt
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Ashley G B Willmott
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| | - Oliver R Gibson
- Center for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, London, United Kingdom
| | - Neil S Maxwell
- Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom
| |
Collapse
|
22
|
Mourot L. Limitation of Maximal Heart Rate in Hypoxia: Mechanisms and Clinical Importance. Front Physiol 2018; 9:972. [PMID: 30083108 PMCID: PMC6064954 DOI: 10.3389/fphys.2018.00972] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/02/2018] [Indexed: 12/17/2022] Open
Abstract
The use of exercise intervention in hypoxia has grown in popularity amongst patients, with encouraging results compared to similar intervention in normoxia. The prescription of exercise for patients largely rely on heart rate recordings (percentage of maximal heart rate (HRmax) or heart rate reserve). It is known that HRmax decreases with high altitude and the duration of the stay (acclimatization). At an altitude typically chosen for training (2,000-3,500 m) conflicting results have been found. Whether or not this decrease exists or not is of importance since the results of previous studies assessing hypoxic training based on HR may be biased due to improper intensity. By pooling the results of 86 studies, this literature review emphasizes that HRmax decreases progressively with increasing hypoxia. The dose–response is roughly linear and starts at a low altitude, but with large inter-study variabilities. Sex or age does not seem to be a major contributor in the HRmax decline with altitude. Rather, it seems that the greater the reduction in arterial oxygen saturation, the greater the reduction in HRmax, due to an over activity of the parasympathetic nervous system. Only a few studies reported HRmax at sea/low level and altitude with patients. Altogether, due to very different experimental design, it is difficult to draw firm conclusions in these different clinical categories of people. Hence, forthcoming studies in specific groups of patients are required to properly evaluate (1) the HRmax change during acute hypoxia and the contributing factors, and (2) the physiological and clinical effects of exercise training in hypoxia with adequate prescription of exercise training intensity if based on heart rate.
Collapse
Affiliation(s)
- Laurent Mourot
- EA 3920 Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform, University of Franche-Comté, Besançon, France.,Tomsk Polytechnic University, Tomsk, Russia
| |
Collapse
|
23
|
Horiuchi M, Handa Y, Fukuoka Y. Impact of ambient temperature on energy cost and economical speed during level walking in healthy young males. Biol Open 2018; 7:bio.035121. [PMID: 29970478 PMCID: PMC6078347 DOI: 10.1242/bio.035121] [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] [Indexed: 02/03/2023] Open
Abstract
We measured oxygen consumption and carbon dioxide output during walking [per unit distance (Cw) values] for 14 healthy young human males at seven speeds from 0.67 to 1.67 m s−1 (4 min per stage) in thermoneutral (23°C), cool (13°C), and hot (33°C) environments. The Cw at faster gait speeds in the 33°C trial was slightly higher compared to those in the 23°C and 13°C trials. We found the speed at which the young males walked had a significant effect on the Cw values (P<0.05), but the different environmental temperatures showed no significant effect (P>0.05). Economical speed (ES) which can minimize the Cw in each individual was calculated from a U-shaped relationship. We found a significantly slower ES at 33°C [1.265 (0.060) m s−1 mean (s.d.)] compared to 23°C [1.349 (0.077) m s−1] and 13°C [1.356 (0.078) m s−1, P<0.05, respectively] with no differences between 23°C and 13°C (P>0.05). Heart rate and mean skin temperature responses in the 33°C condition increased throughout the walking trial compared to 23°C and 13°C (all P<0.05). These results suggest that an acutely hot environment slowed the ES by ∼7%, but an acutely cool environment did not affect the Cw and ES. Summary: Energy cost of walking in a hot environment was greater than in a comfortable environment. Thus, to prevent heat related injury, walking speed should be reduced in a hot environment.
Collapse
Affiliation(s)
- Masahiro Horiuchi
- Division of Human Environmental Science, Mt. Fuji Research Institute, Kamiyoshida, 5597-1 Fuji yoshida City, Yamanashi 4030005, Japan
| | - Yoko Handa
- Division of Human Environmental Science, Mt. Fuji Research Institute, Kamiyoshida, 5597-1 Fuji yoshida City, Yamanashi 4030005, Japan
| | - Yoshiyuki Fukuoka
- Faculty of Health and Sports Science, Doshisha University, Tatara 1-3, Kyotanabe, Kyoto 6100394, Japan
| |
Collapse
|
24
|
Abstract
The rating-of-perceived-exertion (RPE) template is thought to regulate pacing and has been shown to be very robust in different circumstances. PURPOSE The primary purpose was to investigate whether the RPE template can be manipulated by changing the race distance during the course of a time trial. The secondary purpose was to study how athletes cope with this manipulation, especially in terms of the RPE template. METHOD Trained male subjects (N = 10) performed 3 cycling time trials: a 10-km (TT10), a 15-km (TT15), and a manipulated 15-km (TTman). During the TTman, subjects started the time trial believing that they were going to perform a 10-km time trial. However, at 7.5 km they were told that it was a 15-km time trial. RESULTS A significant main effect of time-trial condition on RPE scores until kilometer 7.5 was found (P = .016). Post hoc comparisons showed that the RPE values of the TT15 were lower than the RPE values of the TT10 (difference 0.60; CI95% 0.11, 1.0) and TTman (difference 0.73; CI95% 0.004, 1.5). After the 7.5 km, a transition phase occurs, in which an interaction effect is present (P = .011). After this transition phase, the RPE values of TTman and TT15 did not statistically differ (P = 1.00). CONCLUSIONS This novel distance-endpoint manipulation demonstrates that it is possible to switch between RPE templates. A clear shift in RPE during the TTman is present between the RPE templates of the TT10 and TT15. The shift strongly supports suggestions that pacing is regulated using an RPE template.
Collapse
|
25
|
FRIESEN BRIANJ, PÉRIARD JULIEND, POIRIER MARTINP, LAUZON MARTIN, BLONDIN DENISP, HAMAN FRANCOIS, KENNY GLENP. Work Rate during Self-paced Exercise is not Mediated by the Rate of Heat Storage. Med Sci Sports Exerc 2018; 50:159-168. [DOI: 10.1249/mss.0000000000001421] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
26
|
Périard JD, De Pauw K, Zanow F, Racinais S. Cerebrocortical activity during self-paced exercise in temperate, hot and hypoxic conditions. Acta Physiol (Oxf) 2018; 222. [PMID: 28686002 DOI: 10.1111/apha.12916] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/02/2017] [Accepted: 07/03/2017] [Indexed: 12/14/2022]
Abstract
AIM Heat stress and hypoxia independently influence cerebrocortical activity and impair prolonged exercise performance. This study examined the relationship between electroencephalography (EEG) activity and self-paced exercise performance in control (CON, 18 °C, 40% RH), hot (HOT, 35 °C, 60% RH) and hypoxic (HYP, 18 °C, 40% RH FiO2 : 0.145) conditions. METHODS Eleven well-trained cyclists completed a 750 kJ cycling time trial in each condition on separate days in a counterbalanced order. EEG activity was recorded with α- and β-activity evaluated in the frontal (F3 and F4) and central (C3 and C4) areas. Standardized low-resolution brain electromagnetic tomography (sLORETA) was also utilized to localize changes in cerebrocortical activity. RESULTS Both α- and β-activity decreased in the frontal and central areas during exercise in HOT relative to CON (P < 0.05). α-activity was also lower in HYP compared with CON (P < 0.05), whereas β-activity remained similar. β-activity was higher in HYP than in HOT (P < 0.05). sLORETA revealed that α- and β-activity increased at the onset of exercise in the primary somatosensory and motor cortices in CON and HYP, while only β-activity increased in HOT. A decrease in α- and β-activity occurred thereafter in all conditions, with α-activity being lower in the somatosensory and somatosensory association cortices in HOT relative to CON. CONCLUSION High-intensity prolonged self-paced exercise induces cerebrocortical activity alterations in areas of the brain associated with the ability to inhibit conflicting attentional processing under hot and hypoxic conditions, along with the capacity to sustain mental readiness and arousal under heat stress.
Collapse
Affiliation(s)
- J. D. Périard
- Research Institute for Sport and Exercise; University of Canberra; Canberra ACT Australia
- Athlete Health and Performance Research Centre; Aspetar Orthopaedic and Sports Medicine Hospital; Doha Qatar
| | - K. De Pauw
- Research Group Human Physiology; Faculty of Physical Education and Physiotherapy; Vrije Universiteit Brussel; Brussels Belgium
| | - F. Zanow
- ANT Neuro bv; Enschede the Netherlands
| | - S. Racinais
- Athlete Health and Performance Research Centre; Aspetar Orthopaedic and Sports Medicine Hospital; Doha Qatar
| |
Collapse
|
27
|
Deb SK, Brown DR, Gough LA, Mclellan CP, Swinton PA, Andy Sparks S, Mcnaughton LR. Quantifying the effects of acute hypoxic exposure on exercise performance and capacity: A systematic review and meta-regression. Eur J Sport Sci 2017; 18:243-256. [PMID: 29220311 DOI: 10.1080/17461391.2017.1410233] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE To quantify the effects of acute hypoxic exposure on exercise capacity and performance, which includes continuous and intermittent forms of exercise. DESIGN A systematic review was conducted with a three-level mixed effects meta-regression. The ratio of means method was used to evaluate main effects and moderators providing practical interpretations with percentage change. DATA SOURCES A systemic search was performed using three databases (Google scholar, PubMed and SPORTDiscus). Eligibility criteria for selecting studies: Inclusion was restricted to investigations that assessed exercise performance (time trials (TTs), sprint and intermittent exercise tests) and capacity (time to exhaustion test, TTE) with acute hypoxic (<24 h) exposure and a normoxic comparator. RESULTS Eighty-two outcomes from 53 studies (N = 798) were included in this review. The results show an overall reduction in exercise performance/capacity -17.8 ± 3.9% (95% CI -22.8% to -11.0%), which was significantly moderated by -6.5 ± 0.9% per 1000 m altitude elevation (95% CI -8.2% to -4.8%) and oxygen saturation (-2.0 ± 0.4%; 95% CI -2.9% to -1.2%). TT (-16.2 ± 4.3%; 95% CI -22.9% to -9%) and TTE (-44.5 ± 6.9%; 95% CI -51.3% to -36.7%) elicited a negative effect, whilst indicating a quadratic relationship between hypoxic magnitude and both TTE and TT performance. Furthermore, exercise less than 2 min exhibited no ergolytic effect from acute hypoxia. Summary/Conclusion: This review highlights the ergolytic effect of acute hypoxic exposure, which is curvilinear for TTE and TT performance with increasing hypoxic levels, but short duration intermittent and sprint exercise seem to be unaffected.
Collapse
Affiliation(s)
- Sanjoy K Deb
- a Sports Nutriton and Performance Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - Daniel R Brown
- a Sports Nutriton and Performance Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - Lewis A Gough
- a Sports Nutriton and Performance Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | | | - Paul A Swinton
- c School of Health Sciences , Robert Gordon University , Aberdeen , UK
| | - S Andy Sparks
- a Sports Nutriton and Performance Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK
| | - Lars R Mcnaughton
- a Sports Nutriton and Performance Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK.,d Department of Sport and Movement Studies, Faculty of Health Science , University of Johannesburg , Johannesburg , South Africa
| |
Collapse
|
28
|
Piil JF, Lundbye-Jensen J, Trangmar SJ, Nybo L. Performance in complex motor tasks deteriorates in hyperthermic humans. Temperature (Austin) 2017; 4:420-428. [PMID: 29435481 PMCID: PMC5800368 DOI: 10.1080/23328940.2017.1368877] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 10/25/2022] Open
Abstract
Heat stress, leading to elevations in whole-body temperature, has a marked impact on both physical performance and cognition in ecological settings. Lab experiments confirm this for physically demanding activities, whereas observations are inconsistent for tasks involving cognitive processing of information or decision-making prior to responding. We hypothesized that divergences could relate to task complexity and developed a protocol consisting of 1) simple motor task [TARGET_pinch], 2) complex motor task [Visuo-motor tracking], 3) simple math task [MATH_type], 4) combined motor-math task [MATH_pinch]. Furthermore, visuo-motor tracking performance was assessed both in a separate- and a multipart protocol (complex motor tasks alternating with the three other tasks). Following familiarization, each of the 10 male subjects completed separate and multipart protocols in randomized order in the heat (40°C) or control condition (20°C) with testing at baseline (seated rest) and similar seated position, following exercise-induced hyperthermia (core temperature ∼ 39.5°C in the heat and 38.2°C in control condition). All task scores were unaffected by control exercise or passive heat exposure, but visuo-motor tracking performance was reduced by 10.7 ± 6.5% following exercise-induced hyperthermia when integrated in the multipart protocol and 4.4 ± 5.7% when tested separately (both P < 0.05). TARGET_pinch precision declined by 2.6 ± 1.3% (P < 0.05), while no significant changes were observed for the math tasks. These results indicate that heat per se has little impact on simple motor or cognitive test performance, but complex motor performance is impaired by hyperthermia and especially so when multiple tasks are combined.
Collapse
Affiliation(s)
- Jacob F Piil
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Lundbye-Jensen
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Steven J Trangmar
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
29
|
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.
Collapse
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
| |
Collapse
|
30
|
Racinais S, Cocking S, Périard JD. Sports and environmental temperature: From warming-up to heating-up. Temperature (Austin) 2017; 4:227-257. [PMID: 28944269 DOI: 10.1080/23328940.2017.1356427] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 01/22/2023] Open
Abstract
Most professional and recreational athletes perform pre-conditioning exercises, often collectively termed a 'warm-up' to prepare for a competitive task. The main objective of warming-up is to induce both temperature and non-temperature related responses to optimize performance. These responses include increasing muscle temperature, initiating metabolic and circulatory adjustments, and preparing psychologically for the upcoming task. However, warming-up in hot and/or humid ambient conditions increases thermal and circulatory strain. As a result, this may precipitate neuromuscular and cardiovascular impairments limiting endurance capacity. Preparations for competing in the heat should include an acclimatization regimen. Athletes should also consider cooling interventions to curtail heat gain during the warm-up and minimize dehydration. Indeed, although it forms an important part of the pre-competition preparation in all environmental conditions, the rise in whole-body temperature should be limited in hot environments. This review provides recommendations on how to build an effective warm-up following a 3 stage RAMP model (Raise, Activate and Mobilize, Potentiate), including general and context specific exercises, along with dynamic flexibility work. In addition, this review provides suggestion to manipulate the warm-up to suit the demands of competition in hot environments, along with other strategies to avoid heating-up.
Collapse
Affiliation(s)
- Sébastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, France
| | - Scott Cocking
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,Research Institute for Sport and Exercise Science, Liverpool John Moores University, United Kingdom
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia
| |
Collapse
|
31
|
James CA, Hayes M, Willmott AGB, Gibson OR, Flouris AD, Schlader ZJ, Maxwell NS. Defining the determinants of endurance running performance in the heat. Temperature (Austin) 2017; 4:314-329. [PMID: 28944273 PMCID: PMC5605161 DOI: 10.1080/23328940.2017.1333189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/16/2017] [Accepted: 05/16/2017] [Indexed: 10/25/2022] Open
Abstract
In cool conditions, physiologic markers accurately predict endurance performance, but it is unclear whether thermal strain and perceived thermal strain modify the strength of these relationships. This study examined the relationships between traditional determinants of endurance performance and time to complete a 5-km time trial in the heat. Seventeen club runners completed graded exercise tests (GXT) in hot (GXTHOT; 32°C, 60% RH, 27.2°C WBGT) and cool conditions (GXTCOOL; 13°C, 50% RH, 9.3°C WBGT) to determine maximal oxygen uptake (V̇O2max), running economy (RE), velocity at V̇O2max (vV̇O2max), and running speeds corresponding to the lactate threshold (LT, 2 mmol.l-1) and lactate turnpoint (LTP, 4 mmol.l-1). Simultaneous multiple linear regression was used to predict 5 km time, using these determinants, indicating neither GXTHOT (R2 = 0.72) nor GXTCOOL (R2 = 0.86) predicted performance in the heat as strongly has previously been reported in cool conditions. vV̇O2max was the strongest individual predictor of performance, both when assessed in GXTHOT (r = -0.83) and GXTCOOL (r = -0.90). The GXTs revealed the following correlations for individual predictors in GXTHOT; V̇O2maxr = -0.7, RE r = 0.36, LT r = -0.77, LTP r = -0.78 and in GXTCOOL; V̇O2maxr = -0.67, RE r = 0.62, LT r = -0.79, LTP r = -0.8. These data indicate (i) GXTHOT does not predict 5 km running performance in the heat as strongly as a GXTCOOL, (ii) as in cool conditions, vV̇O2max may best predict running performance in the heat.
Collapse
Affiliation(s)
- Carl A. James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
- National Sports Institute of Malaysia (Institut Sukan Negara), Bukit Jalil Stadium, Kuala Lumpur, Malaysia
| | - Mark Hayes
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
| | - Ashley G. B. Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
| | - Oliver R. Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, London, UK
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Zachary J. Schlader
- Centre for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Neil S. Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK
| |
Collapse
|
32
|
Skorski S, Abbiss CR. The Manipulation of Pace within Endurance Sport. Front Physiol 2017; 8:102. [PMID: 28289392 PMCID: PMC5326767 DOI: 10.3389/fphys.2017.00102] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 02/07/2017] [Indexed: 01/14/2023] Open
Abstract
In any athletic event, the ability to appropriately distribute energy is essential to prevent premature fatigue prior to the completion of the event. In sport science literature this is termed "pacing." Within the past decade, research aiming to better understand the underlying mechanisms influencing the selection of an athlete's pacing during exercise has dramatically increased. It is suggested that pacing is a combination of anticipation, knowledge of the end-point, prior experience and sensory feedback. In order to better understand the role each of these factors have in the regulation of pace, studies have often manipulated various conditions known to influence performance such as the feedback provided to participants, the starting strategy or environmental conditions. As with all research there are several factors that should be considered in the interpretation of results from these studies. Thus, this review aims at discussing the pacing literature examining the manipulation of: (i) energy expenditure and pacing strategies, (ii) kinematics or biomechanics, (iii) exercise environment, and (iv) fatigue development.
Collapse
Affiliation(s)
- Sabrina Skorski
- Institute of Sports and Preventive Medicine, Saarland University Saarbrücken, Germany
| | - Chris R Abbiss
- Centre for Exercise and Sports Science Research, School of Exercise and Health Sciences, Edith Cowan University Joondalup, WA, Australia
| |
Collapse
|
33
|
Davies MJ, Clark B, Welvaert M, Skorski S, Garvican-Lewis LA, Saunders P, Thompson KG. Effect of Environmental and Feedback Interventions on Pacing Profiles in Cycling: A Meta-Analysis. Front Physiol 2016; 7:591. [PMID: 27994554 PMCID: PMC5136559 DOI: 10.3389/fphys.2016.00591] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 11/14/2016] [Indexed: 11/15/2022] Open
Abstract
In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling, and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p < 0.05), but not the start section of hypoxia and heat-stress trials compared to the control trials. In contrast, there was no significant change in trial or section MPO for hyperoxic or pre-cooling conditions compared to the control condition (p > 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p < 0.05), while informed feedback improved overall trial MPO (p < 0.05). However, positive, neutral and no feedback had no significant effect on overall trial or section MPO (p > 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception.
Collapse
Affiliation(s)
- Michael J Davies
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Bradley Clark
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
| | - Marijke Welvaert
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Sabrina Skorski
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Institute of Sports and Preventive Medicine, Saarland UniversitySaarbrücken, Germany
| | - Laura A Garvican-Lewis
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia; Mary Mackillop Institute for Health Research, Australian Catholic UniversityMelbourne, VIC, Australia
| | - Philo Saunders
- Department of Physiology, Australian Institute of Sport Bruce, ACT, Australia
| | - Kevin G Thompson
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
| |
Collapse
|
34
|
Junge N, Jørgensen R, Flouris AD, Nybo L. Prolonged self-paced exercise in the heat - environmental factors affecting performance. Temperature (Austin) 2016; 3:539-548. [PMID: 28090557 PMCID: PMC5198812 DOI: 10.1080/23328940.2016.1216257] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 07/10/2016] [Accepted: 07/19/2016] [Indexed: 11/03/2022] Open
Abstract
In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (≥30°C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatized subjects, where performance may be maintained in outdoor time trials at ambient temperatures as high as 36°C (36°C UTCI; 28°C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27°C when humidity is modest and wind speed matches the movement speed generated during outdoor cycling, whereas marked reductions are observed when air movement is minimal. For running, representing an exercise mode with lower movement speed and higher heat production for a given metabolic rate, it appears that endurance is affected even at much lower ambient temperatures. On this basis we conclude that environmental heat stress impacts self-paced endurance performance. However, the effect is markedly modified by acclimatization status and exercise mode, as the wind generated by the exercise (movement speed) or the environment (natural or fan air movement) exerts a strong influence.
Collapse
Affiliation(s)
- Nicklas Junge
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
| | - Rasmus Jørgensen
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly , Trikala, Greece
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
| |
Collapse
|
35
|
James CA, Willmott AGB, Richardson AJ, Watt PW, Maxwell NS. Ischaemic preconditioning does not alter the determinants of endurance running performance in the heat. Eur J Appl Physiol 2016; 116:1735-45. [PMID: 27406142 DOI: 10.1007/s00421-016-3430-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/05/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE Ischaemic preconditioning (IP) has been shown to be ergogenic for endurance performance in normothermic conditions and alleviate physiological strain under hypoxia, potentially through haemodynamic and/or metabolic mechanisms. Exertional hyperthermia is characterised by competition for blood flow between the muscles and skin, an enhanced metabolic strain and impaired endurance performance. This study investigated the effect of IP on the determinants of endurance performance, through an incremental exercise test in the heat. METHOD Eleven males completed two graded exercise tests in the heat (32 °C, 62 % RH) until volitional exhaustion, preceded by IP (4 × 5 min 220 mmHg bilateral upper leg occlusion) or a control (CON) condition (4 × 5-min 50 mmHg bilateral). RESULT IP did not improve running speeds at fixed blood lactate concentrations of 2 and 4 mMol L(-1) (p = 0.828), or affect blood glucose concentration throughout the trial [mean (±SD); CON 5.03 (0.94) mMol L(-1), IP 5.47 (1.38) mMol L(-1), p = 0.260). There was no difference in [Formula: see text]O2max [CON 55.5 (3.7) mL kg(-1) min(-1), IP 56.0 (2.6) mL kg(-1) min(-1), p = 0.436], average running economy [CON 222.3 (18.0) mL kg(-1) km(-1), IP 218.9 (16.5) mL kg(-1) km(-1), p = 0.125], or total running time during graded exercise [CON 347 (42) s, IP 379 (68) s, p = 0.166]. The IP procedure did not change muscle temperature [CON ∆ = 0.55 (0.57) °C, IP ∆ = 0.78 (0.85) °C, p = 0.568], but did reduce T CORE during exercise (~-0.1 °C, p = 0.001). CONCLUSION The novel application of IP prior to exercise in the heat does not enhance the determinants of endurance performance. For events where IP appears ergogenic, muscle warming strategies are unnecessary as IP does not influence deep muscle temperature.
Collapse
Affiliation(s)
- Carl A James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK.
| | - Ashley G B Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Alan J Richardson
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Peter W Watt
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| | - Neil S Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK
| |
Collapse
|
36
|
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.
Collapse
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
| |
Collapse
|