Cottle, R M

Larry Kenney, W

Lichter, Z S

Tony Wolf, S

Vecellio, D J

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           Core Temperature Responses to Compensable vs. Uncompensable Heat Stress in Young Adults (PSU Heat Project)    Rachel M. Cottle, Zachary S. Lichter, Daniel J. Vecellio, S. Tony Wolf, and W. Larry Kenney, The Pennsylvania State University, University Park, PA  Purpose: With global warming, much attention has been paid to the upper limits of human adaptability. However, the time to reach a generally-accepted core temperature criterion (40.2°C) associated with heat-related illness above (uncompensable heat stress) and just below (compensable heat stress) the upper limits for heat balance remains unclear. Methods: Forty-eight (22 men/26 women; 23±4 y) subjects were exposed to progressive heat stress in an environmental chamber during minimal activity (MinAct, 159±34W) and light ambulation (LightAmb, 260±55W) in warm-humid (WH; ~35°C, >60% RH) and hot-dry (HD; 43-48°C, <25% RH) environments until heat stress became uncompensable. For each condition, we compared heat storage (S) and the change in gastrointestinal temperature (∆Tgi) over time during compensable and uncompensable heat stress. Using the slopes of the Tgi response, we estimated the time to reach Tgi=40.2°C. Finally, we examined whether individual characteristics or seasonality were associated with the rate of increase in Tgi. Results: During compensable heat stress, S was higher in HD than in WH environments (p<0.05) resulting in a greater but more variable ∆Tgi (p≥0.06) for both metabolic rates. There were no differences among conditions during uncompensable heat stress (all p>0.05). There was no influence of sex, aerobic fitness, or seasonality, but a larger body size was associated with a greater ∆Tgi during LightAmb in WH (p=0.003). Conclusion: Sustained light activity without intervention in uncompensable thermal environments may result in a Tc of 40.2°C (from a 37°C baseline) in 3-7 hours even in young adults vs. several days under compensable heat stress.     Supported by NIA Grant T32 AG049676 and NIH Grant R01 AG067471   Mid Atlantic Regional Chapter of the American College of Sports Medicine  45th Annual Scientific Meeting, November 4th- 5th, 2022 Conference Proceedings International Journal of Exercise Science, Issue 9, Volume 11 

Core Temperature Responses to Compensable vs. Uncompensable Heat Stress in Young Adults (PSU Heat Project)

https://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=6615&context=ijesab

Core Temperature Responses to Compensable vs. Uncompensable Heat Stress in Young Adults (PSU Heat Project)

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