Maximum Skin Wettedness after Aerobic Training with and without Heat Acclimation

Ravanelli, Nicholas; Coombs, Geoff B.; Imbeault, Pascal; Jay, Ollie

doi:10.1249/mss.0000000000001439

Cited by 58 publications

(58 citation statements)

References 33 publications

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“…Few studies have attempted to separate the effects of heat acclimation from aerobic fitness. A study by Ravanelli et al (2018) showed that a greater maximum skin wittedness occurred at the end of aerobic training in temperate conditions (22°C, 30% relative humidity), and this was further augmented by heat acclimation in a hot and humid condition (38°C, 65% relative humidity). This suggests that studies that include aerobic training in the heat acclimation/acclimatization protocols may have had their thermoregulatory effects augmented.…”

Section: Discussionmentioning

confidence: 98%

Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis

2019

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Background: A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat, the rapid rise of body core temperature ( T c ) often results in an impairment of exercise capacity and performance. As such, heat mitigation strategies such as aerobic fitness (AF), heat acclimation/acclimatization (HA), pre-exercise cooling (PC) and fluid ingestion (FI) can be introduced to counteract the debilitating effects of heat strain. We performed a meta-analysis to evaluate the effectiveness of these mitigation strategies using magnitude-based inferences. Methods: A computer-based literature search was performed up to 24 July 2018 using the electronic databases: PubMed, SPORTDiscus and Google Scholar. After applying a set of inclusion and exclusion criteria, a total of 118 studies were selected for evaluation. Each study was assessed according to the intervention's ability to lower T c before exercise, attenuate the rise of T c during exercise, extend T c at the end of exercise and improve endurance. Weighted averages of Hedges' g were calculated for each strategy. Results: PC ( g = 1.01) was most effective in lowering T c before exercise, followed by HA ( g = 0.72), AF ( g = 0.65), and FI ( g = 0.11). FI ( g = 0.70) was most effective in attenuating the rate of rise of T c , followed by HA ( g = 0.35), AF ( g = −0.03) and PC ( g = −0.46). In extending T c at the end of exercise, AF ( g = 1.11) was most influential, followed by HA ( g = −0.28), PC ( g = −0.29) and FI ( g = −0.50). In combination, AF ( g = 0.45) was most effective at favorably altering T c , followed by HA ( g = 0.42), PC ( g = 0.11) and FI ( g = 0.09). AF (1.01) was also found to be most effective in improving endurance, followed by HA (0.19), FI (−0.16) and PC (−0.20). Conclusion: AF was found to be the most effective in terms of a strategy's ability to favorably alter T c , followed by HA, PC and lastly, FI. Interestingly, a similar ranking was observed in improving endurance, with AF being the most effective, followed by HA, FI, and PC. Knowledge gained from this meta-analysis will be useful in allowing athletes, coaches and sport scientists to mak...

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Section: Discussionmentioning

confidence: 98%

Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis

2019

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“…For all subject, the total sweat rate or sweat Na + measured during the TT in cool conditions did not increase (from pre to post). This apparent lack of adaptation may be explained by testing in compensable conditions where sweating is dictated by the evaporative requirements (Ravanelli et al, 2018) and due to rapid alterations in the onset and decay of sweat sodium Na + (Williams et al, 1967; Armstrong and Maresh, 1991). Taken together with the lowered resting rectal temperature, these measures provide strong evidence that the participants were successfully acclimated following the prolonged heat training period.…”

Section: Discussionmentioning

confidence: 99%

Prolonged Heat Acclimation and Aerobic Performance in Endurance Trained Athletes

et al. 2019

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Heat acclimation (HA) involves physiological adaptations that directly promote exercise performance in hot environments. However, for endurance-athletes it is unclear if adaptations also improve aerobic capacity and performance in cool conditions, partly because previous randomized controlled trial (RCT) studies have been restricted to short intervention periods. Prolonged HA was therefore deployed in the present RCT study including 21 cyclists [38 ± 2 years, 184 ± 1 cm, 80.4 ± 1.7 kg, and maximal oxygen uptake (VO2max) of 58.1 ± 1.2 mL/min/kg; mean ± SE] allocated to either 5½ weeks of training in the heat [HEAT (n = 12)] or cool control [CON (n = 9)]. Training registration, familiarization to test procedures, determination of VO2max, blood volume and 15 km time trial (TT) performance were assessed in cool conditions (14°C) during a 2-week lead-in period, as well as immediately pre and post the intervention. Participants were instructed to maintain total training volume and complete habitual high intensity intervals in normal settings; but HEAT substituted part of cool training with 28 ± 2 sessions in the heat (1 h at 60% VO2max in 40°C; eliciting core temperatures above 39°C in all sessions), while CON completed all training in cool conditions. Acclimation for HEAT was verified by lower sweat sodium [Na+], reduced steady-state heart rate and improved submaximal exercise endurance in the heat. However, when tested in cool conditions both peak power output and VO2max remained unchanged for HEAT (pre 60.0 ± 1.5 vs. 59.8 ± 1.3 mL O2/min/kg). TT performance tested in 14°C was improved for HEAT and average power output increased from 298 ± 6 to 315 ± 6 W (P < 0.05), but a similar improvement was observed for CON (from 294 ± 11 to 311 ± 10 W). Based on the present findings, we conclude that training in the heat was not superior compared to normal (control) training for improving aerobic power or TT performance in cool conditions.

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“…With exercise training, there are increases in sweat output for the same T c increase, in addition to elevations in maximal sweat output ( Nadel et al, 1974 ; Henane et al, 1977 ; Roberts et al, 1977 ). Most recently, 8 weeks exercise training ( V̇ O 2 max increase from 46 to 52 ml/kg/min) increased local sweat rate, and thus skin wettedness from 72 to 85% surface area ( Ravanelli et al, 2018 ). The increased sweating function in the above studies may not be related to aerobic fitness per se , but more due to frequent and persistent rises in T c due to the training itself, evoking a mild heat adaptation ( Ravanelli et al, 2020 ).…”

Section: Aerobic Fitness and Trainingmentioning

confidence: 99%

Individual Responses to Heat Stress: Implications for Hyperthermia and Physical Work Capacity

2020

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Background: Extreme heat events are increasing in frequency, severity, and duration. It is well known that heat stress can have a negative impact on occupational health and productivity, particularly during physical work. However, there are no up-to-date reviews on how vulnerability to heat changes as a function of individual characteristics in relation to the risk of hyperthermia and work capacity loss. The objective of this narrative review is to examine the role of individual characteristics on the human heat stress response, specifically in relation to hyperthermia risk and productivity loss in hot workplaces. Finally, we aim to generate practical guidance for industrial hygienists considering our findings. Factors included in the analysis were body mass, body surface area to mass ratio, body fat, aerobic fitness and training, heat adaptation, aging, sex, and chronic health conditions. Findings: We found the relevance of any factor to be dynamic, based on the work-type (fixed pace or relative to fitness level), work intensity (low, moderate, or heavy work), climate type (humidity, clothing vapor resistance), and variable of interest (risk of hyperthermia or likelihood of productivity loss). Heat adaptation, high aerobic fitness, and having a large body mass are the most protective factors during heat exposure. Primary detrimental factors include low fitness, low body mass, and lack of heat adaptation. Aging beyond 50 years, being female, and diabetes are less impactful negative factors, since their independent effect is quite small in well matched participants. Skin surface area to mass ratio, body composition, hypertension, and cardiovascular disease are not strong independent predictors of the heat stress response. Conclusion: Understanding how individual factors impact responses to heat stress is necessary for the prediction of heat wave impacts on occupational health and work capacity. The recommendations provided in this report could be utilized to help curtail hyperthermia risk and productivity losses induced by heat.

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Maximum Skin Wettedness after Aerobic Training with and without Heat Acclimation

Cited by 58 publications

References 33 publications

Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis

Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis

Prolonged Heat Acclimation and Aerobic Performance in Endurance Trained Athletes

Individual Responses to Heat Stress: Implications for Hyperthermia and Physical Work Capacity

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