Comparison of Hormonal, Inflammatory, Muscle Damage and Oxidative Stress Biomarkers Changes in Response to High-Intensity Interval, Circuit and Concurrent Exercise Bouts.

PURPOSE: Although chronic resting hormonal changes were traditionally considered to modulate muscle tissue remodeling and growth, our knowledge of exercise on the acute post-exercise hormonal response is limited. Moreover, the type of exercise protocol may trigger different hormonal profiles. The aim of this study was to evaluate changes in muscle damage, as well as hormonal and inflammatory markers following the response to three different resistance training protocols. METHODS: A crossover study was conducted in which 33 recreationally active men were randomly assigned to three different training groups: high-intensity interval training (HIIT), concurrent training (CT), and high-intensity resistance circuit (HRC) training. Blood biomarkers were measured by standard procedures at rest, after exercise (P0), 30 min (P1), 24 h (P24), and 48 h (P48) after exercise. RESULTS: Regarding testosterone, the Friedman test detected a significant time × group interaction (p = 0.004), and Durbin-Conover showed higher levels in HRC compared to HIIT at P1 (p = 0.006) and P48 (p = 0.021). However, CT showed higher levels than HIIT (p = 0.008) at P1. Concerning myostatin, there was a trend in the time × group interaction (p = 0.056) with lower values in HRC compared to CT in P1 (p = 0.003), and a trend between HRC and HIIT in P1 (p = 0.056). CONCLUSIONS: HRC generates higher levels of testosterone than HIIT in the acute (P1) and late (P48) phases of recovery and produces lower levels of myostatin than CT and HIIT (P1) in the acute phase of recovery.