Elimination of Eccentric Exercise-Induced Interleukin-6 Response by Heat Preconditioning

Abstract

Exercise training lowers the mortality rate of animals under heat stress. It is currently unknown whether heat preconditioning can attenuate exercise-induced increases in circulating interleukin-6 (IL-6) for athletes. Sixteen male basketball players were randomly assigned to the control (n = 8) and heat preconditioning (n = 8) groups. The heat preconditioning program consisted of a 30-min hot water immersion at 41°C performed every 72 h up to 4 sessions, which slightly elevated circulating creatine kinase (CK) and thiobarbituric acid-reactive substances (TBARS) by 27% and 21%, respectively (P ＜ 0.05). Seventy two hours after the last hot water immersion, both groups were challenged with an acute bout of eccentric exercise (6 squats at 85% maximal voluntary effort for 6 sets), which elicited significant increases in IL-6 (+120%) and CK (+34%) above pre-exercise level of the control group (P ＜ 0.05). This increase was absent in the heat preconditioning group. Heart rate variability (HRV) and high frequency power (HF) were increased following heat preconditioning, and remained elevated after exercise challenge. Our study provides evidence that eccentric exercise-induced stress response can be attenuated by a heat preconditioning protocol at 41°C.