Effect of endurance exercise on resting testosterone levels in sedentary subjects.

Objective: To investigate the effects of moderate-intensity and low frequency exercise on resting serum testosterone and cortisol levels, resting heart rate, and isokinetic strength among healthy sedentary young men.

Design: A randomized controlled study. Forty sedentary young men aged 18 to 25 years old, pedaled 50 minutes on a bicycle ergometry at 60% of maximal effort once a week for 12 weeks in an exercise group.

Outcome Measures: Resting total and free serum testosterone, serum cortisol, anthropometric data, resting heart rate, and isokinetic strength during shoulder and knee extensions.

Results: Resting serum total and free testosterone, as well as cortisol did not differ significantly between groups. Neither group showed any significant changes in anthropometric data and isokinetic strength at the end of study. However, the resting heart rate of the exercise group reduced significantly after the training (p < 0.05). Also, the isokinetic strength of shoulder and knee significantly increased (p < 0.05).

Conclusions: Twelve weeks of moderate-intensity and low frequency training had no effect on resting serum testosterone, but were sufficient to increase aerobic fitness among sedentary young men. The type of exercise training may encourage sedentary individuals to participate regularly in the program on physical activity.