Effects of short-term high-intensity interval training on growth hormone, cortisol, and leptin levels

Abstract

Exercise is known to be very effective for increasing hormone levels; however, the effects of high-intensity interval training (HIIT) protocols are uncertain. The study aimed to examine the effect of HIIT on growth hormone (GH), cortisol, leptin levels and anaerobic capacity (AC) with the intention of contributing to the development of exercise protocols better adapted to athletes’ training programs and optimized for hormone regulation. In the study, participants underwent a 2-week HIIT protocol. They were randomly divided into two groups (n = 10 for HIIT and n = 10 for the control) in a double-blind manner. Twenty healthy male athletes aged 18–30 years were subjected to a short-term HIIT exercise on a bicycle ergometer. The blood and Wingate AC data collected in the first and last sessions of the protocol were analyzed, and the GH, cortisol, leptin and AC levels were examined. Based on the results of the analysis, statistically significant differences were observed in GH (p < 0.05), cortisol (p < 0.05), leptin (p < 0.001) and AC (p < 0.01) levels between the initial and final tests among the participants. However, while there were no statistically significant differences between the groups in GH (p = 0.088), cortisol (p = 0.905), leptin (p = 0.262) and AC (p = 0.06) levels. The study’s findings indicate that the short-term HIIT protocol caused significant differences in GH, leptin, cortisol and WAnT AC levels within the group depending on the time main effect. These results suggest that HIIT is efficient for biochemical changes and performance. However, no significant differences were found between the groups. Results suggest that HIIT protocols may elicit different responses between individuals and that time modulates these effects. It is recommended that future studies should be conducted with more participants and longer HIIT protocols.