Effects of endurance training on the androgenic response to exercise in man.

Six healthy subjects, aged 35.8 +/- 4.4 years, volunteered to participate in a 40-week training program on a bicycle ergometer [three 60-min sessions per week at 80%-85% of maximal oxygen uptake (VO2 max)]. Before training and at the 10th, 20th, 30th, and 40th weeks of the training program, plasma testosterone, cortisol, and androstenedione concentrations were measured at rest (t0) and at the end (t60) of a 1-h endurance exercise requiring 85%-90% of VO2 max. Training resulted in significant increases of anaerobic threshold (12.6%) and VO2 max (7.3%). The training program did not significantly alter the resting values of plasma testosterone, androstenedione, and cortisol; in contrast, the exercise responses (delta = t60-t0) of testosterone, androstenedione, and cortisol were increased. The highest amplitude of these responses was reached at the 30th week for cortisol and androstenedione and at the 40th for testosterone. These results suggest that long-term training enhances both testicular adrenal and responses to endurance exercise. The possible role of hormonal changes in the mobilization of energy substrates during exercise is discussed.