Acute effect of HIIT on testosterone and cortisol levels in healthy individuals: A systematic review and meta-analysis

Abstract

To determine the acute effect of a single high- intensity interval training (HIIT) ses-sion on testosterone and cortisol levels in healthy individuals, a systematic search of studies was conducted in MEDLINE and Web of Science databases from inception to February 2020. Meta- analyses were performed to establish the acute effect of HIIT on testosterone and cortisol levels immediately after a single HIIT session; after 30 min and 60 min (primary outcomes); and after 120 min, 180 min, and 24 h (secondary outcomes, only for pre- post intervention groups). Potential effect- size modifiers were assessed by meta- regression analyses and analyses of variance. Study quality was assessed using the Cochrane's risk of bias tool and the Physiotherapy Evidence Database scale. The meta- analyses of 10 controlled studies (213 participants) and 50 pre- post intervention groups (677 participants) revealed a significant increase in testosterone immediately after a single HIIT session (d = 0.92 and 0.52, respectively), which disappeared after 30 min (d = 0.18 and −0.04), and returned to baseline val-ues after 60 min (d = −0.37 and −0.16). Significant increases of cortisol were found immediately after (d = 2.17 and 0.64), after 30 min (d = 1.62 and 0.67) and 60 min (d = 1.32 and 0.27). Testosterone and cortisol levels decreased significantly after 120 min (d = −0.48 and −0.95, respectively) and 180 min (d = −0.29 and −1.08), and returned to baseline values after 24 h (d = 0.14 and −0.02). HIIT components and participant's characteristics seem to moderate the effect sizes. In conclusion, testos-terone and cortisol increase immediately after a single HIIT session, then drop below baseline levels, and finally return to baseline values after 24 h. This meta- analysis provides a better understanding of the acute endocrine response to a single HIIT ses-sion, which would certainly be valuable for both clinicians and coaches in the pre-scription of exercise programs to improve health and performance. Testosterone and cortisol may be used as sensitive biomarkers to monitor the anabolic and catabolic response to HIIT.