[10iscoach]

plasma testosterone concentration is increased 10-37 percent during prolonged submaximal work, exercise taken to maximal levels, and during endurance or strength training workouts. Some feel that these small changes are due to a reduction in plasma volume, or to a decrease in the rate of inactivation and removal of testosterone.however, others conclude on the basis of parrallel increase in LH concentration that the increase in plasma testosterone is due to an increased rate of production. While the testosterone response to exercise is small and returns to resting values two hours after exercise there is evidence that the resting plasma concentration is lower in both endurance trained ahtlete's. In a recent study, high mileage runners had lower levels of testosterone, sperm count, and sperm mobility compared to moderate mileage runners.