The effects of 4-weeks oral tangeretin supplementation on serum testosterone and cortisol levels in sprinters during the winter training season

Objective
Tangeretin ingestion has shown broad benefits to humans. However, the potential impact of tangeretin supplementation on athletes remains unknown. The purpose of this study was to examine the influence of oral tangeretin supplementation on serum testosterone and cortisol in sprinters during winter training.
Methods
In this double-blinded, placebo-controlled, paired group trial, twenty-four sprinters were randomly assigned to an oral supplement with tangeretin (200 mg/d) (experimental group [EXP], n = 12) or a placebo (control group [CTROL], n = 12) for four weeks during a winter training season. Levels of serum testosterone, cortisol, superoxide dismutase (SOD) activity, and adrenocorticotrophic hormone (ACTH) were measured at the first day of each week and the day after the 4-week intervention. Body composition was measured before and after the intervention.
Results
For EXP, the levels of serum cortisol (P = 0.019) and ACTH (P = 0.001) significantly decreased, serum testosterone concentration remained unchanged, and SOD activity slightly increased after the 4-week intervention; for CTROL, the level of serum cortisol increased, and serum testosterone concentration (P = 0.02) and SOD activity (P = 0.014) decreased significantly. Sprinters in both EXP and CTROL increased muscle mass, but the increment in EXP was greater.
Conclusion
Four-week oral tangeretin supplementation reduced the oxidative stress response induced by high-intensity exercise training, maintained the serum testosterone concentration, reduced serum cortisol concentration, and promoted muscle protein synthesis in sprinters during a winter training season.