Evidence check: Testosteron in the context of Sport

Testosterone is a key hormone in sports, influencing muscle mass, recovery, and performance. Strong human evidence supports its anabolic effects, but consumer tests (blood, saliva, or DNA) have limited utility for optimizing athletic performance. A single testosterone measurement is highly variable due to circadian rhythms, exercise, and lifestyle factors. Genetic variants (e.g., in SHBG, AR, or CYP19A1) have small effect sizes and cannot predict individual training responses. Moreover, testosterone supplementation without medical supervision is dangerous and often constitutes doping. For athletes, a clinical evaluation is recommended over self-testing. Evidence for consumer tests in this context is mixed: robust physiological evidence exists, but direct application to personalized sport advice is weak. Safety note: Do not self-medicate with testosterone.