Effects of 4-Week Tangeretin Supplementation on Cortisol Stress Response Induced by High-Intensity Resistance Exercise: A Randomized Controlled Trial

Objective: This study aimed to investigate the effects of 4-week tangeretin supplementation on the cortisol stress response induced by high-intensity resistance exercise.Methods: A randomized controlled trial of twenty-four soccer players was conducted during the winter training season. The experimental group (EG) took the oral supplement with tangeretin (200 mg/day) and the control group (CG) took placebo for 4 weeks. Before and after the 4-week intervention, all players performed a high intensity bout of resistance exercise to stimulate their cortisol stress responses. Serum cortisol, adreno-corticotropic hormone (ACTH) and superoxide dismutase (SOD) were obtained by collecting blood samples before (PRE), immediately after (P0), and 10 (P10), 20 (P20) and 30 minutes (P30) after the exercise.Results: The serum cortisol level (PRE, p = 0.017; P10, p = 0.010; P20, p = 0.014; P30, p = 0.007) and ACTH (P10, p = 0.037; P30, p = 0.049) of experimental group significantly decreased after the 4-week intervention. Compared with control group, EG displayed a significantly lower level of the serum cortisol (PRE, p = 0.036; P10, p = 0.031) and ACTH (P30, p = 0.044). Additionally, EG presented significantly higher superoxide dismutase activity level compared with CG at P30 (p = 0.044). The white blood cell of EG decreased significantly (PRE, p = 0.037; P30, p = 0.046) and was significantly lower than CG at P20 (p = 0.01) and P30 (p = 0.003).Conclusion: Four-week tangeretin supplementation can reduce serum cortisol and ACTH, which may ameliorate the cortisol stress response in soccer players during high-intensity resistance exercise training. It can also enhance antioxidant capacity, accelerate the elimination of inflammation throughout the body, and shorten recovery time after high-intensity exercise.