[Relation between the duration of exertion and levels of serum testosterone]

The serum testosterone levels have been shown to be increased following middle- and long distance competitions (up to 42,195 km). The hormone serum levels have been now studied in 63 runners before and after a 107 km race and in an ultramarathon runner before, during and after a 6 hours race. After the 107 km race the mean hormone levels have been found to be reduced from 9,72 to 7,45 ng/ml for the age class 20-29 years; from 6,57 to 4,69 ng/ml for the group 30-39; from 6,22 to 5,13 ng/ml for the group 40-49 years; from 7,56 to 5,46 ng/ml for the age class 50-59. In the ultramarathon runner the testosterone levels sharply rose at the beginning of the training session (from the 7,20 ng/ml to 11,50 ng/ml after 20' training), and subsequently decrease after 3 hours (9,20 ng/ml) and at the end of the 6 hours training (4,60 ng/ml). Based on these and on previous findings the Authors hypothesize that a prolonged exertion produces an initial stimulation of the hormone producing system, followed by its functional exhaustion.