Endocrine Responses to Heated Resistance Exercise in Men and Women

Pryor, JL, Sweet, DK, Rosbrook, P, Qiao, J, Looney, DP, Mahmood, S, and Rideout, T. Endocrine responses to heated resistance exercise in men and women. J Strength Cond Res 38(7): 1248-1255, 2024-We examined the endocrine responses of 16 (female = 8) resistance trained volunteers to a single bout of whole-body high-volume load resistance exercise in hot (HOT; 40° C) and temperate (TEMP; 20° C) environmental conditions. Thermoregulatory and heart rate (HR) data were recorded, and venous blood was acquired before and after resistance exercise to assess serum anabolic and catabolic hormones. In men, testosterone increased after resistance exercise in HOT and TEMP ( p < 0.01), but postexercise testosterone was not different between condition ( p = 0.51). In women, human growth hormone was different between condition at pre-exercise ( p = 0.02) and postexercise ( p = 0.03). After controlling for pre-exercise values, the between-condition postexercise difference was abolished ( p = 0.16). There were no differences in insulin-like growth factor-1 for either sex ( p ≥ 0.06). In women, cortisol increased from pre-exercise to postexercise in HOT ( p = 0.04) but not TEMP ( p = 0.19), generating a between-condition difference at postexercise ( p < 0.01). In men, cortisol increased from pre-exercise to postexercise in HOT only ( p < 0.01). Rectal temperature increased to a greater extent in HOT compared with TEMP in both men ( p = 0.01) and women ( p = 0.02). Heart rate increased after exercise under both conditions in men and women ( p = 0.01), but only women experience greater postexercise HR in HOT vs. TEMP ( p = 0.04). The addition of heat stress to resistance exercise session did not overtly shift the endocrine response toward an anabolic or catabolic response. When acute program variables are prescribed to increase postresistance exercise anabolic hormones, adding heat stress is not synergistic but does increase physiologic strain (i.e., elevated HR and rectal temperature).