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Willmott AGB, James CA, Hayes M, Maxwell NS, Roberts J, Gibson OR. The reliability of a portable steam sauna pod for the whole-body passive heating of humans. J Therm Biol 2023; 118:103743. [PMID: 37979477 DOI: 10.1016/j.jtherbio.2023.103743] [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: 06/23/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 11/20/2023]
Abstract
INTRODUCTION Passive heating is receiving increasing attention within human performance and health contexts. A low-cost, portable steam sauna pod may offer an additional tool for those seeking to manipulate physiological (cardiovascular, thermoregulatory and sudomotor) and perceptual responses for improving sporting or health profiles. This study aimed to 1) report the different levels of heat stress and determine the pods' inter-unit reliability, and 2) quantify the reliability of physiological and perceptual responses to passive heating. METHOD In part 1, five pods were assessed for temperature and relative humidity (RH) every 5 min across 70 min of heating for each of the 9 settings. In part 2, twelve males (age: 24 ± 4 years) completed two 60 min trials of passive heating (3 × 20 min at 44 °C/99% RH, separated by 1 week). Heart rate (HR), rectal (Trectal) and tympanic temperature (Ttympanic) were recorded every 5 min, thermal comfort (Tcomfort) and sensation (Tsensation) every 10 min, mean arterial pressure (MAP) at each break period and sweat rate (SR) after exiting the pod. RESULTS In part 1, setting 9 provided the highest temperature (44.3 ± 0.2 °C) and longest time RH remained stable at 99% (51±7 min). Inter-unit reliability data demonstrated agreement between pods for settings 5-9 (intra-class correlation [ICC] >0.9), but not for settings 1-4 (ICC <0.9). In part 2, between-visits, high correlations, and low typical error of measurement (TEM) and coefficient of variation (CV) were found for Trectal, HR, MAP, SR, and Tcomfort, but not for Ttympanic or Tsensation. A peak Trectal of 38.09 ± 0.30 °C, HR of 124 ± 15 b min-1 and a sweat loss of 0.73 ± 0.33 L were reported. No between-visit differences (p > 0.05) were observed for Trectal, Ttympanic, Tsensation or Tcomfort, however HR (+3 b.min-1) and MAP (+4 mmHg) were greater in visit 1 vs. 2 (p < 0.05). CONCLUSION Portable steam sauna pods generate reliable heat stress between-units. The highest setting (44 °C/99% RH) also provides reliable but modest adjustments in physiological and perceptual responses.
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Affiliation(s)
- A G B Willmott
- Cambridge Centre for Sport and Exercise Sciences (CCSES), Anglia Ruskin University, Cambridge, UK; Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK.
| | - C A James
- Hong Kong Sports Institute (HKSI), Hong Kong; Department of Sport, Physical Education and Health, Hong Kong Baptist University. Kowloon Tong, Hong Kong
| | - M Hayes
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
| | - N S Maxwell
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
| | - J Roberts
- Cambridge Centre for Sport and Exercise Sciences (CCSES), Anglia Ruskin University, Cambridge, UK
| | - O R Gibson
- Centre for Physical Activity in Health and Disease (CHPAD), Division of Sport, Health and Exercise Sciences, Brunel University London, Uxbridge, UK
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Wheelock CE, Looney DP, Potter AW, Pryor RR, Pryor JL, Florian J, Hostler D. Diver Underwater Cycling Endurance After Short-Term Warm and Hot Water Acclimation. Mil Med 2023; 188:3071-3078. [PMID: 35822881 DOI: 10.1093/milmed/usac204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/11/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION It is unclear whether immersion heat acclimation benefits exercise in warm water conditions. This study examined the effects of heat acclimation strategies on heart rate (HR), core temperature, and time to exhaustion (TTE) during cycling exercise in varying warm water conditions. METHODS Twenty male divers completed this study at the Navy Experimental Diving Unit. Subjects were randomly assigned to one of two 9-day heat acclimation groups. The first group (WARM; n = 10) cycled for 2 hours at 50 W in 34.4 °C water, while the second group (HOT; n = 10) cycled for 1 hour against minimal resistance in 36.7 °C water. Following acclimation, TTE was tested by underwater cycling (30 W) in 35.8 °C, 37.2 °C, and 38.6 °C water. RESULTS Throughout acclimation, the rate of core temperature rise in the first 30 minutes of exercise increased (P = .02), but the maximum core temperature reached was not different for either group. Time to exhaustion (TTE) was reduced, and the rate of core temperature rise during performance testing increased (both P < .001) with increasing water temperature but was not different between groups. Core temperature and HR increased throughout performance testing in each water condition and were lower in the HOT compared to the WARM acclimation group (all P < .05) with the exception of core temperature in the 37.2 °C condition. CONCLUSIONS Underwater exercise performance did not differ between the two acclimation strategies. This study suggests that passive acclimation to a higher water temperature may improve thermoregulatory and cardiovascular responses to exercise in warm water. Hot water immersion adaptations are dependent on exercise intensity and water temperature.
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Affiliation(s)
- Courtney E Wheelock
- Center for Research and Education in Special Environments (CRESE), Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - David P Looney
- Military Performance Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, MA 01760, USA
| | - Adam W Potter
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, MA 01760, USA
| | - Riana R Pryor
- Center for Research and Education in Special Environments (CRESE), Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - J Luke Pryor
- Center for Research and Education in Special Environments (CRESE), Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - John Florian
- Navy Experimental Diving Unit (NEDU), Panama City, FL 32407, USA
| | - David Hostler
- Center for Research and Education in Special Environments (CRESE), Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA
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Kelly MK, Bowe SJ, Jardine WT, Condo D, Guy JH, Snow RJ, Carr AJ. Heat Adaptation for Females: A Systematic Review and Meta-Analysis of Physiological Adaptations and Exercise Performance in the Heat. Sports Med 2023; 53:1395-1421. [PMID: 37222863 PMCID: PMC10289939 DOI: 10.1007/s40279-023-01831-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2023] [Indexed: 05/25/2023]
Abstract
BACKGROUND Heat adaptation regimes are used to prepare athletes for exercise in hot conditions to limit a decrement in exercise performance. However, the heat adaptation literature mostly focuses on males, and consequently, current heat adaptation guidelines may not be optimal for females when accounting for the biological and phenotypical differences between sexes. OBJECTIVES We aimed to examine: (1) the effects of heat adaptation on physiological adaptations in females; (2) the impact of heat adaptation on performance test outcomes in the heat; and (3) the impact of various moderators, including duration (minutes and/or days), total heat dose (°C.min), exercise intensity (kcal.min-1), total energy expended (kcal), frequency of heat exposures and training status on the physiological adaptations in the heat. METHODS SPORTDiscus, MEDLINE Complete and Embase databases were searched to December 2022. Random-effects meta-analyses for resting and exercise core temperature, skin temperature, heart rate, sweat rate, plasma volume and performance tests in the heat were completed using Stata Statistical Software: Release 17. Sub-group meta-analyses were performed to explore the effect of duration, total heat dose, exercise intensity, total energy expended, frequency of heat exposure and training status on resting and exercise core temperature, skin temperature, heart rate and sweat rate. An explorative meta-regression was conducted to determine the effects of physiological adaptations on performance test outcomes in the heat following heat adaptation. RESULTS Thirty studies were included in the systematic review; 22 studies were meta-analysed. After heat adaptation, a reduction in resting core temperature (effect size [ES] = - 0.45; 95% confidence interval [CI] - 0.69, - 0.22; p < 0.001), exercise core temperature (ES = - 0.81; 95% CI - 1.01, - 0.60; p < 0.001), skin temperature (ES = - 0.64; 95% CI - 0.79, - 0.48; p < 0.001), heart rate (ES = - 0.60; 95% CI - 0.74, - 0.45; p < 0.001) and an increase in sweat rate (ES = 0.53; 95% CI 0.21, 0.85; p = 0.001) were identified in females. There was no change in plasma volume (ES = - 0.03; 95% CI - 0.31, 0.25; p = 0.835), whilst performance test outcomes were improved following heat adaptation (ES = 1.00; 95% CI 0.56, 1.45; p < 0.001). Across all moderators, physiological adaptations were more consistently observed following durations of 451-900 min and/or 8-14 days, exercise intensity ≥ 3.5 kcal.min-1, total energy expended ≥ 3038 kcal, consecutive (daily) frequency and total heat dose ≥ 23,000 °C.min. The magnitude of change in performance test outcomes in the heat was associated with a reduction in heart rate following heat adaptation (standardised mean difference = - 10 beats.min-1; 95% CI - 19, - 1; p = 0.031). CONCLUSIONS Heat adaptation regimes induce physiological adaptations beneficial to thermoregulation and performance test outcomes in the heat in females. Sport coaches and applied sport practitioners can utilise the framework developed in this review to design and implement heat adaptation strategies for females.
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Affiliation(s)
- Monica K Kelly
- Centre for Sport Research, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
| | - Steven J Bowe
- Deakin Biostatistics Unit, Faculty of Health, Deakin University, Burwood, VIC, Australia
- Faculty and School of Health, Victoria University of Wellington, Kelburn, Wellington, New Zealand
| | - William T Jardine
- Centre for Sport Research, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Dominique Condo
- Centre for Sport Research, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Joshua H Guy
- School of Health, Medical and Applied Sciences, Central Queensland University, Cairns, QLD, Australia
| | - Rodney J Snow
- Institute for Physical Activity and Nutrition, Deakin University, Burwood, VIC, Australia
| | - Amelia J Carr
- Centre for Sport Research, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
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Short-term heat acclimation protocols for an aging population: Systematic review. PLoS One 2023; 18:e0282038. [PMID: 36862716 PMCID: PMC9980817 DOI: 10.1371/journal.pone.0282038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/06/2023] [Indexed: 03/03/2023] Open
Abstract
INTRODUCTION Elderly and sedentary individuals are particularly vulnerable to heat related illness. Short-term heat acclimation (STHA) can decrease both the physical and mental stress imposed on individuals performing tasks in the heat. However, the feasibility and efficacy of STHA protocols in an older population remains unclear despite this population being particularly vulnerable to heat illness. The aim of this systematic review was to investigate the feasibility and efficacy of STHA protocols (≤twelve days, ≥four days) undertaken by participants over fifty years of age. METHODS Academic Search Premier, CINAHL Complete, MEDLINE, APA PsycInfo, and SPORTDiscus were searched for peer reviewed articles. The search terms were; (heat* or therm*) N3 (adapt* or acclimati*) AND old* or elder* or senior* or geriatric* or aging or ageing. Only studies using primary empirical data and which included participants ≥50 years of age were eligible. Extracted data includes participant demographics (sample size, gender, age, height, weight, BMI and [Formula: see text]), acclimation protocol details (acclimation activity, frequency, duration and outcome measures taken) and feasibility and efficacy outcomes. RESULTS Twelve eligible studies were included in the systematic review. A total of 179 participants took part in experimentation, 96 of which were over 50 years old. Age ranged from 50 to 76. All twelve of the studies involved exercise on a cycle ergometer. Ten out of twelve protocols used a percentage of [Formula: see text] or [Formula: see text] to determine the target workload, which ranged from 30% to 70%. One study-controlled workload at 6METs and one implemented an incremental cycling protocol until Tre was reached +0.9°C. Ten studies used an environmental chamber. One study compared hot water immersion (HWI) to an environmental chamber while the remaining study used a hot water perfused suit. Eight studies reported a decrease in core temperature following STHA. Five studies demonstrated post-exercise changes in sweat rates and four studies showed decreases in mean skin temperature. The differences reported in physiological markers suggest that STHA is viable in an older population. CONCLUSION There remains limited data on STHA in the elderly. However, the twelve studies examined suggest that STHA is feasible and efficacious in elderly individuals and may provide preventative protection to heat exposures. Current STHA protocols require specialised equipment and do not cater for individuals unable to exercise. Passive HWI may provide a pragmatic and affordable solution, however further information in this area is required.
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Heating Up to Keep Cool: Benefits and Persistence of a Practical Heat Acclimation Protocol in Elite Female Olympic Team-Sport Athletes. Int J Sports Physiol Perform 2023; 18:276-283. [PMID: 36720237 DOI: 10.1123/ijspp.2022-0071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 10/14/2022] [Accepted: 11/07/2022] [Indexed: 02/02/2023]
Abstract
PURPOSE Although recommendations for effective heat acclimation (HA) strategies for many circumstances exist, best-practice HA protocols specific to elite female team-sport athletes are yet to be established. Therefore, the authors aimed to investigate the effectiveness and retention of a passive HA protocol integrated in a female Olympic rugby sevens team training program. METHODS Twelve elite female rugby sevens athletes undertook 10 days of passive HA across 2 training weeks. Tympanic temperature (TTymp), sweat loss, heart rate, and repeated 6-second cycling sprint performance were assessed using a sport-specific heat stress test Pre-HA, after 3 days (Mid-HA), after 10 days (Post-HA), and 15 days post-HA (Decay). RESULTS Compared with Pre-HA, submaximal TTymp was lower Mid-HA and Post-HA (both by -0.2 [0.7] °C; d ≥ 0.71), while resting TTymp was lower Post-HA (by -0.3 [0.2] °C; d = 0.81). There were no differences in TTymp at Decay compared with Pre-HA, nor were there any differences in heart rate or sweat loss at any time points. Mean peak 6-second power output improved Mid-HA and Post-HA (76 [36] W; 75 [34] W, respectively; d ≥ 0.45) compared with Pre-HA. The observed performance improvement persisted at Decay by 65 (45) W (d = 0.41). CONCLUSIONS Ten days of passive HA can elicit some thermoregulatory and performance benefits when integrated into a training program in elite female team-sport athletes. However, such a protocol does not provide a sufficient thermal impulse for thermoregulatory adaptations to be retained after 15 days with no further heat stimulus.
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Dennis MC, Goods PSR, Binnie MJ, Girard O, Wallman KE, Dawson B, Billaut F, Peeling P. Increased air temperature during repeated-sprint training in hypoxia amplifies changes in muscle oxygenation without decreasing cycling performance. Eur J Sport Sci 2023; 23:62-72. [PMID: 34743674 DOI: 10.1080/17461391.2021.2003868] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The present study aims to investigate the acute performance and physiological responses, with specific reference to muscle oxygenation, to ambient air temperature manipulation during repeated-sprint training in hypoxia (RSH). Thirteen male team-sport players completed one familiarisation and three experimental sessions at a simulated altitude of ∼3000 m (FIO2 0.144). Air temperatures utilised across the three experimental sessions were: 20°C, 35°C and 40°C (all 50% relative humidity). Participants performed 3 × 5 × 10-s maximal cycle sprints, with 20-s passive recovery between sprints, and 5 min active recovery between sets. There were no differences between conditions for cycling peak power, mean power, and total work (p>0.05). Peak core temperature (Tc) was not different between conditions (38.11 ± 0.36°C). Vastus lateralis muscle deoxygenation during exercise and reoxygenation during recovery was of greater magnitude in 35°C and 40°C than 20°C (p<0.001 for all). There was no condition × time interaction for Tc, skin temperature, pulse oxygen saturation, heart rate, rating of perceived exertion and thermal sensation (P>0.05). Exercise-induced increases in blood lactate concentration were higher in 35°C and 40°C than 20°C (p=0.010 and p=0.001, respectively). Integrating ambient temperatures up to 40°C into a typical RSH session had no detrimental effect on performance. Additionally, the augmented muscle oxygenation changes experienced during exercise and recovery in temperatures ≥35°C may indicate that the potency of RSH training is increased with additional heat. However, alterations to the training session may be required to generate a sufficient rise in Tc for heat training purposes.Highlights Heat exposure (35-40°C) did not affect mechanical performance during a typical RSH session. This indicates hot ambient temperature can be implemented during RSH, without negative consequence to training output.Hotter ambient conditions (35-40°C) likely result in greater muscle oxygenation changes during both exercise and recovery compared to temperate conditions.Although hotter sessions were perceived as more difficult and more thermally challenging, they did not further elevate Tc beyond that of temperate conditions. Accordingly, if intended to be used for heat acclimation purposes, alterations to the session may be required to increase heat load.
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Affiliation(s)
- Myles C Dennis
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia.,Department of Sport Science, Western Australian Institute of Sport, Mt Claremont, Australia
| | - Paul S R Goods
- Department of Sport Science, Western Australian Institute of Sport, Mt Claremont, Australia.,Murdoch Applied Sports Science Laboratory, Murdoch University, Murdoch, Australia.,Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Murdoch, Australia
| | - Martyn J Binnie
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia.,Department of Sport Science, Western Australian Institute of Sport, Mt Claremont, Australia
| | - Olivier Girard
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia
| | - Karen E Wallman
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia
| | - Brian Dawson
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia
| | | | - Peter Peeling
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Crawley, Australia.,Department of Sport Science, Western Australian Institute of Sport, Mt Claremont, Australia
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Ashworth E, Cotter J, Kilding A. Post-exercise, passive heat acclimation with sauna or hot-water immersion provide comparable adaptations to performance in the heat in a military context. ERGONOMICS 2023; 66:49-60. [PMID: 35332846 DOI: 10.1080/00140139.2022.2058096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
To mitigate the effects of heat during operations in hot environments, military personnel will likely benefit from heat acclimation (HA) conducted prior to deployment. Using post-exercise, passive heating, 25 participants completed a 5 d HA regime in sauna (70 °C, 18% RH) or hot-water immersion (HWI) (40 °C) for ≤40 min, preceded and followed by a heat stress test (1-h walking at 5 km.h-1 in 33 °C, 77% RH in military uniform (20 kg) before an incremental ramp to exhaustion). Fifteen completed both regimes in a randomised, cross-over manner. While performance did not significantly improve (+14%, [-1, 29], p = .079), beneficial adaptations were observed for mean exercising core temperature (-0.2 °C, [-0.2, -0.2], p <.001), skin temperature (-0.2 °C, [-0.2, -0.2], p = 035) and heart rate (-8 bpm, [-6, -10], p<.001) in both conditions. Post-exercise, passive HA of either modality may benefit military units operating in the heat.Practitioner summary: Strategies are required to prevent health and performance impairments during military operations upon arrival in hot environments. Using a randomised, cross-over design, participants completed five-day passive, post-exercise heat acclimation using sauna or hot-water immersion. Both regimes elicited beneficial albeit modest heat adaptations.Abbreviations: HA: heat acclimation; HST: heat stress test; HWI: hot-water immersion; RH: relative humidity.
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Affiliation(s)
- Edward Ashworth
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - James Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Andrew Kilding
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
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Dennis MC, Goods PSR, Binnie MJ, Girard O, Wallman KE, Dawson BT, Peeling P. Taking the plunge: When is best for hot water immersion to complement exercise in heat and hypoxia. J Sports Sci 2022; 40:2055-2061. [PMID: 36263975 DOI: 10.1080/02640414.2022.2133390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This investigation assessed the psycho-physiological and performance effects of hot water immersion (HWI) implemented either before or after a repeated-sprint training in hypoxia (RSH) session conducted in the heat. Ten participants completed three RSH trials (3 × 10 × 5-s sprints), conducted at 40°C and simulated altitude of 3000 m. A 30-min monitoring period preceded and followed all exercise sessions. In PRE, the pre-exercise period was HWI, and the post-exercise period was seated rest in temperate conditions. This combination was reversed in POST. In CON, participants were seated in temperate conditions for both periods. Compared to CON, PRE elicited a reduction in power output during each repeated-sprint set (14.8-16.2%, all p < 0.001), and a significantly higher core temperature (Tc) during the pre-exercise period and throughout the exercise session (p < 0.001 and p = 0.025, respectively). In POST, power output and Tc until the end of exercise were similar to CON, with Tc higher at the conclusion of the post-exercise period (p < 0.001). Time across the entire protocol spent ≥38.5°C Tc was significantly longer in PRE (48.1 ± 22.5 min) than POST (31.0 ± 11.3 min, p = 0.05) and CON (15.8 ± 16.3 min, p < 0.001). Employing HWI following RSH conducted in the heat provides effective outcomes regarding physiological strain and cycling performance when compared to pre-exercise or no HWI.
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Affiliation(s)
- Myles C Dennis
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009.,Department of Physiology, Western Australian Institute of Sport, WA, Australia, 6010
| | - Paul S R Goods
- Department of Physiology, Western Australian Institute of Sport, WA, Australia, 6010.,Murdoch Applied Sports Science Laboratory, Murdoch University, WA, Australia, 6150.,Centre for Healthy Ageing, Health Futures Institute, Murdoch University, WA, Australia, 6150
| | - Martyn J Binnie
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009.,Department of Physiology, Western Australian Institute of Sport, WA, Australia, 6010
| | - Olivier Girard
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009
| | - Karen E Wallman
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009
| | - Brian T Dawson
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009
| | - Peter Peeling
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, WA, Australia, 6009.,Department of Physiology, Western Australian Institute of Sport, WA, Australia, 6010
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Fenemor S, Driller MW, Gill N, Mills B, Casadio J, Beaven CM. Practical application of a mixed active and passive heat acclimation protocol in elite male Olympic team sport athletes. Appl Physiol Nutr Metab 2022; 47:981-991. [PMID: 35793560 DOI: 10.1139/apnm-2022-0112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate effectiveness and retention of heat acclimation (HA) integrated within an elite rugby sevens team training program, 12 elite male rugby sevens athletes undertook 10-days of mixed active/passive HA across two-weeks of normal training. Physiological and performance variables were assessed using a sport specific, repeated high-intensity heat-response test Pre-HA; after five days (Mid-HA); after 10 days (Post-HA); and 16-days post-HA (Decay). Resting, submaximal, and end-exercise core temperature were lower at Mid-HA (≤ -0.26 °C; d ≥-0.47), Post-HA (≤ -0.30 °C; d ≥-0.72), and Decay (≤ -0.29 °C; d ≥-0.56), compared to Pre-HA. Sweat rate was greater Post-HA compared to Pre-HA (0.3 ± 0.3 L·hr-1; d =0.63). Submaximal HR was lower at Mid (-9 ±4 bpm; d =-0.68) and Post-HA (-11 ± 4 bpm; d =-0.90) compared to Pre-HA. Mean and peak 6-s power output improved Mid-HA (83 ± 52 W; 112 ± 67 W; d ≥0.47) and Post-HA (125 ± 62 W; 172 ± 85 W; d ≥0.72) compared to Pre-HA. Improvements in HR and performance persisted at Decay (d ≥0.66). The initial five days of mixed-methods HA elicited many typical HA adaptations, with an additional five days eliciting further thermoregulatory, sudomotor, and performance improvements. Adaptations were well-retained after 16-days of normal training, without any further heat stimulus. The trial was retrospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622000732785).
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Affiliation(s)
- Stephen Fenemor
- University of Waikato, 3717, Te Huataki Waiora School of Health, Adams Centre for High Performance, Tauranga, Waikato, New Zealand.,High Performance Sport New Zealand, 540744, Auckland, New Zealand;
| | - Matthew W Driller
- La Trobe University School of Allied Health Human Services and Sport, 110570, Sport and Exercise Science, Bundoora, Victoria, Australia;
| | - Nicholas Gill
- University of Waikato, 3717, Te Huataki Waiora School of Health, Adams Centre for High Performance, Tauranga, Waikato, New Zealand.,New Zealand Rugby Union, Wellington, New Zealand;
| | - Blair Mills
- New Zealand Rugby Union, Wellington, New Zealand;
| | - Julia Casadio
- High Performance Sport New Zealand, 540744, Auckland, New Zealand;
| | - Christopher Martyn Beaven
- University of Waikato, 3717, Te Huataki Waiora School of Health, Adams Centre for High Performance, Tauranga, Waikato, New Zealand;
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McIntyre RD, Zurawlew MJ, Oliver SJ, Cox AT, Mee JA, Walsh NP. A comparison of heat acclimation by post-exercise hot water immersion and exercise in the heat. J Sci Med Sport 2021; 24:729-734. [DOI: 10.1016/j.jsams.2021.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/01/2021] [Accepted: 05/12/2021] [Indexed: 11/26/2022]
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Lundby C, Svendsen IS, Urianstad T, Hansen J, Rønnestad BR. Training wearing thermal clothing and training in hot ambient conditions are equally effective methods of heat acclimation. J Sci Med Sport 2021; 24:763-767. [DOI: 10.1016/j.jsams.2021.06.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 05/27/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
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Adams WM, Hosokawa Y, Casa DJ, Périard JD, Racinais S, Wingo JE, Yeargin SW, Scarneo-Miller SE, Kerr ZY, Belval LN, Alosa D, Csillan D, LaBella C, Walker L. Roundtable on Preseason Heat Safety in Secondary School Athletics: Heat Acclimatization. J Athl Train 2021; 56:352-361. [PMID: 33878177 DOI: 10.4085/1062-6050-596-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To provide best-practice recommendations for developing and implementing heat-acclimatization strategies in secondary school athletics. DATA SOURCES An extensive literature review on topics related to heat acclimatization and heat acclimation was conducted by a group of content experts. Using the Delphi method, action-oriented recommendations were developed. CONCLUSIONS A period of heat acclimatization consisting of ≥14 consecutive days should be implemented at the start of fall preseason training or practices for all secondary school athletes to mitigate the risk of exertional heat illness. The heat-acclimatization guidelines should outline specific actions for secondary school athletics personnel to use, including the duration of training, the number of training sessions permitted per day, and adequate rest periods in a cool environment. Further, these guidelines should include sport-specific and athlete-specific recommendations, such as phasing in protective equipment and reintroducing heat acclimatization after periods of inactivity. Heat-acclimatization guidelines should be clearly detailed in the secondary school's policy and procedures manual and disseminated to all stakeholders. Heat-acclimatization guidelines, when used in conjunction with current best practices surrounding the prevention, management, and care of secondary school student-athletes with exertional heat stroke, will optimize their health and safety.
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Affiliation(s)
- William M Adams
- Hydration, Environment, and Thermal Stress Lab, Department of Kinesiology, University of North Carolina at Greensboro
| | - Yuri Hosokawa
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Julien D Périard
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Sebastien Racinais
- Research and Scientific Support Department, ASPETAR Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | | | - Susan W Yeargin
- Department of Exercise Science, University of South Carolina, Columbia
| | | | - Zachary Y Kerr
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill
| | - Luke N Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas
| | - Denise Alosa
- Athletic Medicine, South Burlington School District, Burlington, VT.,College of Nursing and Health Science, University of Vermont, Burlington
| | - David Csillan
- Department of Physical Therapy, Princeton Orthopedic Associates, NJ
| | - Cynthia LaBella
- Department of Pediatrics, Northwestern University Feinberg School of Medicine Institute for Sports Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, IL
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13
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Greenfield AM, Pereira FG, Boyer WR, Apkarian MR, Kuennen MR, Gillum TL. Short-term hot water immersion results in substantial thermal strain and partial heat acclimation; comparisons with heat-exercise exposures. J Therm Biol 2021; 97:102898. [PMID: 33863451 DOI: 10.1016/j.jtherbio.2021.102898] [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: 07/22/2020] [Revised: 01/30/2021] [Accepted: 02/19/2021] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To examine the effectiveness of hot water immersion (HWI) as a heat acclimation strategy in comparison to time and temperature matched, exercise-heat acclimation (EHA). METHODS 8 males performed heat stress tests (HST) (45 min of cycling at 50% of VO2max in 40 °C, 40% RH) before and after heat acclimation sessions. Acclimation sessions were either three consecutive bouts of HWI (40 min of submersion at 40 °C) or EHA (40 min of cycling at 50% VO2max in 40 °C, 40% RH). RESULTS Average change in tympanic temperature (TTympanic) was significantly higher following HWI (2.1 °C ± 0.4) compared to EHA (1.5 °C ± 0.4) (P < 0.05). Decreases in peak heart rate (HR) (HWI: -10 bpm ± 8; EHA: -6 ± 7), average HR (-7 bpm ± 6; -3 ± 4), and average core temperature (-0.4 °C ± 0.3; -0.2 ± 0.4) were evident following acclimation (P < 0.05), but not different between interventions (P > 0.05). Peak rate of perceived exertion (RPEPeak) decreased for HWI and EHA (P < 0.05). Peak thermal sensation (TSPeak) decreased following HWI (P < 0.05) but was not different between interventions (P > 0.05). Plasma volume increased in both intervention groups (HWI: 5.9% ± 5.1; EHA: 5.4% ± 3.7) but was not statistically different (P > 0.05). CONCLUSION HWI induced significantly greater thermal strain compared to EHA at equivalent temperatures during time-matched exposures. However, the greater degree of thermal strain did not result in between intervention differences for cardiovascular, thermoregulatory, or perceptual variables. Findings suggest three HWI sessions may be a potential means to lower HR, TCore, and perceptual strain during exercise in the heat.
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Affiliation(s)
- Andrew M Greenfield
- Department of Kinesiology, California Baptist University, 8432 Magnolia Ave, Riverside, CA, 92504, USA.
| | - Felipe Gorini Pereira
- Department of Kinesiology, California Baptist University, 8432 Magnolia Ave, Riverside, CA, 92504, USA.
| | - William R Boyer
- Department of Kinesiology, California Baptist University, 8432 Magnolia Ave, Riverside, CA, 92504, USA.
| | - Marc R Apkarian
- Department of Kinesiology and Health Science, Biola University, 13800 Biola Ave, La Mirada, CA, 90639, USA.
| | - Matthew R Kuennen
- Department of Exercise Science, High Point University, 1 N. University Parkway, High Point, NC, 27268, USA.
| | - Trevor L Gillum
- Department of Kinesiology, California Baptist University, 8432 Magnolia Ave, Riverside, CA, 92504, USA.
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14
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Cao Y, Liu Y, Dong Q, Wang T, Niu C. Alterations in the gut microbiome and metabolic profile in rats acclimated to high environmental temperature. Microb Biotechnol 2021; 15:276-288. [PMID: 33620148 PMCID: PMC8719808 DOI: 10.1111/1751-7915.13772] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 01/26/2021] [Accepted: 01/30/2021] [Indexed: 12/29/2022] Open
Abstract
Heat acclimation (HA) is the best strategy to improve heat stress tolerance by inducing positive physiological adaptations. Evidence indicates that the gut microbiome plays a fundamental role in the development of HA, and modulation of gut microbiota can improve tolerance to heat exposure and decrease the risks of heat illness. In this study, for the first time, we applied 16S rRNA gene sequencing and untargeted liquid chromatography–mass spectrometry (LC‐MS) metabolomics to explore variations in the gut microbiome and faecal metabolic profiles in rats after HA. The gut microbiota of HA subjects exhibited higher diversity and richer microbes. HA altered the gut microbiota composition with significant increases in the genera Lactobacillus (a major probiotic) and Oscillospira alongside significant decreases in the genera Blautia and Allobaculum. The faecal metabolome was also significantly changed after HA, and among the 13 perturbed metabolites, (S)‐AL 8810 and celastrol were increased. Moreover, the two increased genera were positively correlated with the two upregulated metabolites and negatively correlated with the other 11 downregulated metabolites, while the correlations between the two decreased genera and the upregulated/downregulated metabolites were completely contrary. In summary, both the structure of the gut microbiome community and the faecal metabolome were improved after 28 days of HA. These findings provide novel insights regarding the improvement of the gut microbiome and its functions as a potential mechanism by which HA confers protection against heat stress.
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Affiliation(s)
- Yang Cao
- Department of Environmental Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Ying Liu
- Department of Environmental Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Qingyang Dong
- Department of Environmental Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Tao Wang
- Department of Environmental Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Chao Niu
- Department of Environmental Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
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15
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Maloy W, Hulsopple C. Novel Use of Water Immersion in the Management of Exertional Heat Stress. TRANSLATIONAL JOURNAL OF THE AMERICAN COLLEGE OF SPORTS MEDICINE 2021. [DOI: 10.1249/tjx.0000000000000146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Ashworth ET, Cotter JD, Kilding AE. Methods for improving thermal tolerance in military personnel prior to deployment. Mil Med Res 2020; 7:58. [PMID: 33248459 PMCID: PMC7700709 DOI: 10.1186/s40779-020-00287-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022] Open
Abstract
Acute exposure to heat, such as that experienced by people arriving into a hotter or more humid environment, can compromise physical and cognitive performance as well as health. In military contexts heat stress is exacerbated by the combination of protective clothing, carried loads, and unique activity profiles, making them susceptible to heat illnesses. As the operational environment is dynamic and unpredictable, strategies to minimize the effects of heat should be planned and conducted prior to deployment. This review explores how heat acclimation (HA) prior to deployment may attenuate the effects of heat by initiating physiological and behavioural adaptations to more efficiently and effectively protect thermal homeostasis, thereby improving performance and reducing heat illness risk. HA usually requires access to heat chamber facilities and takes weeks to conduct, which can often make it impractical and infeasible, especially if there are other training requirements and expectations. Recent research in athletic populations has produced protocols that are more feasible and accessible by reducing the time taken to induce adaptations, as well as exploring new methods such as passive HA. These protocols use shorter HA periods or minimise additional training requirements respectively, while still invoking key physiological adaptations, such as lowered core temperature, reduced heart rate and increased sweat rate at a given intensity. For deployments of special units at short notice (< 1 day) it might be optimal to use heat re-acclimation to maintain an elevated baseline of heat tolerance for long periods in anticipation of such an event. Methods practical for military groups are yet to be fully understood, therefore further investigation into the effectiveness of HA methods is required to establish the most effective and feasible approach to implement them within military groups.
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Affiliation(s)
- Edward Tom Ashworth
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, 17 Antares Place, Rosedale, Auckland, 0632 New Zealand
| | - James David Cotter
- School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, Otago 9016 New Zealand
| | - Andrew Edward Kilding
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, 17 Antares Place, Rosedale, Auckland, 0632 New Zealand
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17
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Malgoyre A, Siracusa J, Tardo-Dino PE, Garcia-Vicencio S, Koulmann N, Charlot K. A basal heat stress test to detect military operational readiness after a 14-day operational heat acclimatization period. Temperature (Austin) 2020; 7:277-289. [PMID: 33123621 DOI: 10.1080/23328940.2020.1742572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A basal heat stress test (HST) to predict the magnitude of adaptive responses during heat acclimatization (HA) would be highly useful for the armed forces. The aim was to identify physiological markers assessed during a HST (three 8-min running sets at 50% of the speed at VO2max) performed just before a 14-day HA period that would identify participants still at "risk" at the end of HA. Individuals that responded poorly (large increases in rectal temperature [Trec] and heart rate [HR]) during the initial HST were more likely to respond favorably to HA (large reductions in Trec and HR). However, they were also more likely to exhibit lower tolerance to HST at D15. Basal Trec was found to efficiently discriminate participants showing a Trec > 38.5°C after HA, who are considered to be "at risk". Finally, participants were classified by quartiles based on basal Trec and HR at the end of the HST and physiological strain index (PSI). Most of the participants "at risk" were among the upper quartile (i.e. the least tolerant) of Trec and PSI (p = 0.011 for both). Overall, these results show that the individuals who are less tolerant to a basal HST are very likely to benefit the most from HA but they also remain less tolerant to heat at the end of HA than those who better tolerated the basal HST. A basal HST could therefore theoretically help the command to select the most-ready personnel in hot conditions while retaining those who are less tolerant 6.
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Affiliation(s)
- Alexandra Malgoyre
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France
| | - Julien Siracusa
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France
| | - Pierre-Emmanuel Tardo-Dino
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France
| | - Sebastian Garcia-Vicencio
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France
| | - Nathalie Koulmann
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France.,Ecole du Val-de-Grâce, Paris, France
| | - Keyne Charlot
- Département Environnements Opérationnels, Unité de Physiologie de l'Exercice et des Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, France Bretigny-Sur-Orge, France.,LBEPS, Univ Evry, IRBA, Université Paris Saclay, Evry, France
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18
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Fundamental Concepts of Human Thermoregulation and Adaptation to Heat: A Review in the Context of Global Warming. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17217795. [PMID: 33114437 PMCID: PMC7662600 DOI: 10.3390/ijerph17217795] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022]
Abstract
The international community has recognized global warming as an impending catastrophe that poses significant threat to life on earth. In response, the signatories of the Paris Agreement (2015) have committed to limit the increase in global mean temperature to <1.5 °C from pre-industry period, which is defined as 1850–1890. Considering that the protection of human life is a central focus in the Paris Agreement, the naturally endowed properties of the human body to protect itself from environmental extremes should form the core of an integrated and multifaceted solution against global warming. Scholars believe that heat and thermoregulation played important roles in the evolution of life and continue to be a central mechanism that allows humans to explore, labor and live in extreme conditions. However, the international effort against global warming has focused primarily on protecting the environment and on the reduction of greenhouse gases by changing human behavior, industrial practices and government policies, with limited consideration given to the nature and design of the human thermoregulatory system. Global warming is projected to challenge the limits of human thermoregulation, which can be enhanced by complementing innate human thermo-plasticity with the appropriate behavioral changes and technological innovations. Therefore, the primary aim of this review is to discuss the fundamental concepts and physiology of human thermoregulation as the underlying bases for human adaptation to global warming. Potential strategies to extend human tolerance against environmental heat through behavioral adaptations and technological innovations will also be discussed. An important behavioral adaptation postulated by this review is that sleep/wake cycles would gravitate towards a sub-nocturnal pattern, especially for outdoor activities, to avoid the heat in the day. Technologically, the current concept of air conditioning the space in the room would likely steer towards the concept of targeted body surface cooling. The current review was conducted using materials that were derived from PubMed search engine and the personal library of the author. The PubMed search was conducted using combinations of keywords that are related to the theme and topics in the respective sections of the review. The final set of articles selected were considered “state of the art,” based on their contributions to the strength of scientific evidence and novelty in the domain knowledge on human thermoregulation and global warming.
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19
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Hyldahl RD, Peake JM. Combining cooling or heating applications with exercise training to enhance performance and muscle adaptations. J Appl Physiol (1985) 2020; 129:353-365. [PMID: 32644914 DOI: 10.1152/japplphysiol.00322.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Athletes use cold water immersion, cryotherapy chambers, or icing in the belief that these strategies improve postexercise recovery and promote greater adaptations to training. A number of studies have systematically investigated how regular cold water immersion influences long-term performance and muscle adaptations. The effects of regular cold water immersion after endurance or high-intensity interval training on aerobic capacity, lactate threshold, power output, and time trial performance are equivocal. Evidence for changes in angiogenesis and mitochondrial biogenesis in muscle in response to regular cold water immersion is also mixed. More consistent evidence is available that regular cold water immersion after strength training attenuates gains in muscle mass and strength. These effects are attributable to reduced activation of satellite cells, ribosomal biogenesis, anabolic signaling, and muscle protein synthesis. Athletes use passive heating to warm up before competition or improve postexercise recovery. Emerging evidence indicates that regular exposure to ambient heat, wearing garments perfused with hot water, or microwave diathermy can mimic the effects of endurance training by stimulating angiogenesis and mitochondrial biogenesis in muscle. Some passive heating applications may also mitigate muscle atrophy through their effects on mitochondrial biogenesis and muscle fiber hypertrophy. More research is needed to consolidate these findings, however. Future research in this field should focus on 1) the optimal modality, temperature, duration, and frequency of cooling and heating to enhance long-term performance and muscle adaptations and 2) whether molecular and morphological changes in muscle in response to cooling and heating applications translate to improvements in exercise performance.
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Affiliation(s)
- Robert D Hyldahl
- Department of Exercise Sciences, Brigham Young University, Provo, Utah
| | - Jonathan M Peake
- Queensland University of Technology, School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Brisbane, Queensland, Australia.,Sport Performance Innovation and Knowledge Excellence, Queensland Academy of Sport, Brisbane, Queensland, Australia
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20
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Ely BR, Ely MR. Running in the Heat: Performance Consequences and Strategies to Prepare for Hot-Weather Racing. Strength Cond J 2020. [DOI: 10.1519/ssc.0000000000000484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Heathcote SL, Hassmén P, Zhou S, Taylor L, Stevens CJ. How Does a Delay Between Temperate Running Exercise and Hot-Water Immersion Alter the Acute Thermoregulatory Response and Heat-Load? Front Physiol 2019; 10:1381. [PMID: 31824325 PMCID: PMC6886377 DOI: 10.3389/fphys.2019.01381] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 10/21/2019] [Indexed: 11/13/2022] Open
Abstract
Hot-water immersion following exercise in a temperate environment can elicit heat acclimation in endurance-trained individuals. However, a delay between exercise cessation and immersion is likely a common occurrence in practice. Precisely how such a delay potentially alters hot-water immersion mediated acute physiological responses (e.g., total heat-load) remains unexplored. Such data would aid in optimizing prescription of post-exercise hot-water immersion in cool environments, relative to heat acclimation goals. Twelve male recreational runners (mean ± SD; age: 38 ± 13 years, height: 180 ± 7 cm, body mass: 81 ± 13.7 kg, body fat: 13.9 ± 3.5%) completed three separate 40-min treadmill runs (18°C), followed by either a 10 min (10M), 1 h (1H), or 8 h (8H) delay, prior to a 30-min hot-water immersion (39°C), with a randomized crossover design. Core and skin temperatures, heart rate, sweat, and perceptual responses were measured across the trials. Mean core temperature during immersion was significantly lower in 1H (37.39 ± 0.30°C) compared to 10M (37.83 ± 0.24°C; p = 0.0032) and 8H (37.74 ± 0.19°C; p = 0.0140). Mean skin temperature was significantly higher in 8H (32.70 ± 0.41°C) compared to 10M (31.93 ± 0.60°C; p = 0.0042) at the end of the hot-water immersion. Mean and maximal heart rates were also higher during immersion in 10M compared to 1H and 8H (p < 0.05), despite no significant differences in the sweat or perceptual responses. The shortest delay between exercise and immersion (10M) provoked the greatest heat-load during immersion. However, performing the hot-water immersion in the afternoon (8H), which coincided with peak circadian body temperature, provided a larger heat-load stimulus than the 1 h delay (1H).
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Affiliation(s)
- Storme L Heathcote
- School of Health and Human Sciences, Southern Cross University, Coffs Harbour, NSW, Australia.,Laboratory for Athlete Development, Experience and Performance, Southern Cross University, Coffs Harbour, NSW, Australia
| | - Peter Hassmén
- School of Health and Human Sciences, Southern Cross University, Coffs Harbour, NSW, Australia
| | - Shi Zhou
- School of Health and Human Sciences, Southern Cross University, Coffs Harbour, NSW, Australia
| | - Lee Taylor
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom.,Faculty of Health, Sport and Exercise Discipline Group, University of Technology Sydney, Sydney, NSW, Australia.,Human Performance Research Centre, University of Technology Sydney, Sydney, NSW, Australia.,ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
| | - Christopher J Stevens
- School of Health and Human Sciences, Southern Cross University, Coffs Harbour, NSW, Australia.,Laboratory for Athlete Development, Experience and Performance, Southern Cross University, Coffs Harbour, NSW, Australia
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22
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Gibson OR, James CA, Mee JA, Willmott AG, Turner G, Hayes M, Maxwell NS. Heat alleviation strategies for athletic performance: A review and practitioner guidelines. Temperature (Austin) 2019; 7:3-36. [PMID: 32166103 PMCID: PMC7053966 DOI: 10.1080/23328940.2019.1666624] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/06/2019] [Accepted: 09/08/2019] [Indexed: 12/19/2022] Open
Abstract
International competition inevitably presents logistical challenges for athletes. Events such as the Tokyo 2020 Olympic Games require further consideration given historical climate data suggest athletes will experience significant heat stress. Given the expected climate, athletes face major challenges to health and performance. With this in mind, heat alleviation strategies should be a fundamental consideration. This review provides a focused perspective of the relevant literature describing how practitioners can structure male and female athlete preparations for performance in hot, humid conditions. Whilst scientific literature commonly describes experimental work, with a primary focus on maximizing magnitudes of adaptive responses, this may sacrifice ecological validity, particularly for athletes whom must balance logistical considerations aligned with integrating environmental preparation around training, tapering and travel plans. Additionally, opportunities for sophisticated interventions may not be possible in the constrained environment of the athlete village or event arenas. This review therefore takes knowledge gained from robust experimental work, interprets it and provides direction on how practitioners/coaches can optimize their athletes' heat alleviation strategies. This review identifies two distinct heat alleviation themes that should be considered to form an individualized strategy for the athlete to enhance thermoregulatory/performance physiology. First, chronic heat alleviation techniques are outlined, these describe interventions such as heat acclimation, which are implemented pre, during and post-training to prepare for the increased heat stress. Second, acute heat alleviation techniques that are implemented immediately prior to, and sometimes during the event are discussed. Abbreviations: CWI: Cold water immersion; HA: Heat acclimation; HR: Heart rate; HSP: Heat shock protein; HWI: Hot water immersion; LTHA: Long-term heat acclimation; MTHA: Medium-term heat acclimation; ODHA: Once-daily heat acclimation; RH: Relative humidity; RPE: Rating of perceived exertion; STHA: Short-term heat acclimation; TCORE: Core temperature; TDHA: Twice-daily heat acclimation; TS: Thermal sensation; TSKIN: Skin temperature; V̇O2max: Maximal oxygen uptake; WGBT: Wet bulb globe temperature.
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Affiliation(s)
- Oliver R. Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Division of Sport, Health and Exercise Sciences, Brunel University London, Uxbridge, UK
| | - Carl A. James
- Institut Sukan Negara (National Sports Institute), Kuala Lumpur, Malaysia
| | - Jessica A. Mee
- School of Sport and Exercise Sciences, University of Worcester, Worcester, UK
| | - Ashley G.B. Willmott
- Cambridge Centre for Sport and Exercise Sciences, Anglia Ruskin University, Cambridge, UK
| | - Gareth Turner
- Bisham Abbey National High-Performance Centre, English Institute of Sport, EIS Performance Centre, Marlow, UK
| | - Mark Hayes
- Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
| | - Neil S. Maxwell
- Environmental Extremes Laboratory, School of Sport and Service Management, University of Brighton, Eastbourne, UK
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23
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Kissling LS, Akerman AP, Cotter JD. Heat-induced hypervolemia: Does the mode of acclimation matter and what are the implications for performance at Tokyo 2020? Temperature (Austin) 2019; 7:129-148. [PMID: 33015241 DOI: 10.1080/23328940.2019.1653736] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Tokyo 2020 will likely be the most heat stressful Olympics to date, so preparation to mitigate the effects of humid heat will be essential for performance in several of the 33 sports. One key consideration is heat acclimation (HA); the repeated exposure to heat to elicit physiological and psychophysical adaptations that improve tolerance and exercise performance in the heat. Heat can be imposed in various ways, including exercise in the heat, hot water immersion, or passive exposure to hot air (e.g., sauna). The physical requirements of each sport will determine the impact that the heat has on performance, and the adaptations required from HA to mitigate these effects. This review focuses on one key adaptation, plasma volume expansion (PVE), and how the mode of HA may affect the kinetics of adaptation. PVE constitutes a primary HA-mediated adaptation and contributes to functional adaptations (e.g., lower heart rate and increased heat loss capacity), which may be particularly important in athletes of "sub-elite" cardiorespiratory fitness (e.g., team sports), alongside athletes of prolonged endurance events. This review: i) highlights the ability of exercise in the heat, hot-water immersion, and passive hot air to expand PV, providing the first quantitative assessment of the efficacy of different heating modes; ii) discusses how this may apply to athletes at Tokyo 2020; and iii) provides recommendations regarding the protocol of HA and the prospect for achieving PVE (and the related outcomes).
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Affiliation(s)
- Lorenz S Kissling
- The School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
| | - Ashley P Akerman
- The School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - James D Cotter
- The School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand
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24
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Zurawlew MJ, Mee JA, Walsh NP. Post-exercise Hot Water Immersion Elicits Heat Acclimation Adaptations That Are Retained for at Least Two Weeks. Front Physiol 2019. [PMID: 31555140 DOI: 10.3389/fphys.2019.01080, 10.3389/fpls.2019.01080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Heat acclimation by post-exercise hot water immersion (HWI) on six consecutive days reduces thermal strain and improves exercise performance during heat stress. However, the retention of adaptations by this method remains unknown. Typically, adaptations to short-term, exercise-heat-acclimation (<7 heat exposures) decay rapidly and are lost within 2 weeks. Short-term protocols should therefore be completed within 2 weeks of relocating to the heat; potentially compromising pre-competition/deployment training. To establish whether adaptations from post-exercise HWI are retained for up to 2 weeks, participants completed a 40-min treadmill run at 65% max in the heat (33°C, 40% RH) before (PRE) and 24 h after (POST) the HWI intervention (n = 13) and then at 1 week (WK 1) and 2 weeks (WK 2) after the HWI intervention (n = 9). Heat acclimation involved a 40-min treadmill run (65% max) on six consecutive days in temperate conditions (20°C), followed by ≤40 min HWI (40°C). Post-exercise HWI induced heat acclimation adaptations that were retained for at least 2 weeks, evidenced by reductions from PRE to WK 2 in: resting rectal core temperature (T re, -0.36 ± 0.25°C), T re at sweating onset (-0.26 ± 0.24°C), and end-exercise T re (-0.36 ± 0.37°C). Furthermore, mean skin temperature (T sk) (-0.77 ± 0.70°C), heart rate (-14 ± 10 beats⋅min-1), rating of perceived exertion (-1 ± 2), and thermal sensation (-1 ± 1) were reduced from PRE to WK 2 (P < 0.05). However, PRE to POST changes in total hemoglobin mass, blood volume, plasma volume, the drive for sweating onset, sweating sensitivity and whole body sweating rate did not reach significance (P > 0.05). As such, the reduction in thermal strain during exercise-heat stress appears likely due to the reduction in resting T re evident at POST, WK 1, and WK 2. In summary, 6 days of post-exercise HWI is an effective, practical and accessible heat acclimation strategy that induces adaptations, which are retained for at least 2 weeks. Therefore, post-exercise HWI can be completed during an athlete's pre-taper phase and does not suffer from the same practical limitations as short-term, exercise-heat-acclimation.
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Affiliation(s)
| | - Jessica A Mee
- School of Sport and Exercise Science, University of Worcester, Worcester, United Kingdom
| | - Neil P Walsh
- College of Human Sciences, Bangor University, Bangor, United Kingdom
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Zurawlew MJ, Mee JA, Walsh NP. Post-exercise Hot Water Immersion Elicits Heat Acclimation Adaptations That Are Retained for at Least Two Weeks. Front Physiol 2019; 10:1080. [PMID: 31555140 PMCID: PMC6722194 DOI: 10.3389/fphys.2019.01080] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/06/2019] [Indexed: 11/13/2022] Open
Abstract
Heat acclimation by post-exercise hot water immersion (HWI) on six consecutive days reduces thermal strain and improves exercise performance during heat stress. However, the retention of adaptations by this method remains unknown. Typically, adaptations to short-term, exercise-heat-acclimation (<7 heat exposures) decay rapidly and are lost within 2 weeks. Short-term protocols should therefore be completed within 2 weeks of relocating to the heat; potentially compromising pre-competition/deployment training. To establish whether adaptations from post-exercise HWI are retained for up to 2 weeks, participants completed a 40-min treadmill run at 65% max in the heat (33°C, 40% RH) before (PRE) and 24 h after (POST) the HWI intervention (n = 13) and then at 1 week (WK 1) and 2 weeks (WK 2) after the HWI intervention (n = 9). Heat acclimation involved a 40-min treadmill run (65% max) on six consecutive days in temperate conditions (20°C), followed by ≤40 min HWI (40°C). Post-exercise HWI induced heat acclimation adaptations that were retained for at least 2 weeks, evidenced by reductions from PRE to WK 2 in: resting rectal core temperature (T re, -0.36 ± 0.25°C), T re at sweating onset (-0.26 ± 0.24°C), and end-exercise T re (-0.36 ± 0.37°C). Furthermore, mean skin temperature (T sk) (-0.77 ± 0.70°C), heart rate (-14 ± 10 beats⋅min-1), rating of perceived exertion (-1 ± 2), and thermal sensation (-1 ± 1) were reduced from PRE to WK 2 (P < 0.05). However, PRE to POST changes in total hemoglobin mass, blood volume, plasma volume, the drive for sweating onset, sweating sensitivity and whole body sweating rate did not reach significance (P > 0.05). As such, the reduction in thermal strain during exercise-heat stress appears likely due to the reduction in resting T re evident at POST, WK 1, and WK 2. In summary, 6 days of post-exercise HWI is an effective, practical and accessible heat acclimation strategy that induces adaptations, which are retained for at least 2 weeks. Therefore, post-exercise HWI can be completed during an athlete's pre-taper phase and does not suffer from the same practical limitations as short-term, exercise-heat-acclimation.
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Affiliation(s)
| | - Jessica A Mee
- School of Sport and Exercise Science, University of Worcester, Worcester, United Kingdom
| | - Neil P Walsh
- College of Human Sciences, Bangor University, Bangor, United Kingdom
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Zurawlew MJ, Mee JA, Walsh NP. Post-exercise Hot Water Immersion Elicits Heat Acclimation Adaptations That Are Retained for at Least Two Weeks. Front Physiol 2019. [PMID: 31555140 PMCID: PMC6722194 DOI: 10.3389/fphys.2019.01080,+10.3389/fpls.2019.01080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Heat acclimation by post-exercise hot water immersion (HWI) on six consecutive days reduces thermal strain and improves exercise performance during heat stress. However, the retention of adaptations by this method remains unknown. Typically, adaptations to short-term, exercise-heat-acclimation (<7 heat exposures) decay rapidly and are lost within 2 weeks. Short-term protocols should therefore be completed within 2 weeks of relocating to the heat; potentially compromising pre-competition/deployment training. To establish whether adaptations from post-exercise HWI are retained for up to 2 weeks, participants completed a 40-min treadmill run at 65% max in the heat (33°C, 40% RH) before (PRE) and 24 h after (POST) the HWI intervention (n = 13) and then at 1 week (WK 1) and 2 weeks (WK 2) after the HWI intervention (n = 9). Heat acclimation involved a 40-min treadmill run (65% max) on six consecutive days in temperate conditions (20°C), followed by ≤40 min HWI (40°C). Post-exercise HWI induced heat acclimation adaptations that were retained for at least 2 weeks, evidenced by reductions from PRE to WK 2 in: resting rectal core temperature (T re, -0.36 ± 0.25°C), T re at sweating onset (-0.26 ± 0.24°C), and end-exercise T re (-0.36 ± 0.37°C). Furthermore, mean skin temperature (T sk) (-0.77 ± 0.70°C), heart rate (-14 ± 10 beats⋅min-1), rating of perceived exertion (-1 ± 2), and thermal sensation (-1 ± 1) were reduced from PRE to WK 2 (P < 0.05). However, PRE to POST changes in total hemoglobin mass, blood volume, plasma volume, the drive for sweating onset, sweating sensitivity and whole body sweating rate did not reach significance (P > 0.05). As such, the reduction in thermal strain during exercise-heat stress appears likely due to the reduction in resting T re evident at POST, WK 1, and WK 2. In summary, 6 days of post-exercise HWI is an effective, practical and accessible heat acclimation strategy that induces adaptations, which are retained for at least 2 weeks. Therefore, post-exercise HWI can be completed during an athlete's pre-taper phase and does not suffer from the same practical limitations as short-term, exercise-heat-acclimation.
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Affiliation(s)
- Michael J. Zurawlew
- College of Human Sciences, Bangor University, Bangor, United Kingdom,*Correspondence: Michael J. Zurawlew,
| | - Jessica A. Mee
- School of Sport and Exercise Science, University of Worcester, Worcester, United Kingdom
| | - Neil P. Walsh
- College of Human Sciences, Bangor University, Bangor, United Kingdom
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