Variations of Serum Testosterone Concentrations after Physical Exercises of Different Duration

Abstract

Serum testosterone concentration was determined before and after physical activities of different duration. The subjects under study were:
(1) 7 competitive walkers before and after a 20-km race (average race time 1 h 30 min);
(2) 9 middle-distance runners before and after 1-h training;
(3) 16 marathon runners before and after a marathon run (average running time 2 h 33 min);
(4) 30 Ultramarathon runners before and after a 107-km race (average running time 14 h).

Serum testosterone increased by 51.8% (NS) in competitive walkers, by 38.2% (P < 0.05) in middle-distance runners, and by 44.9% (P < 0.01) in marathon runners; it decreased by 31.9% (P < 0.001) in the Ultramarathon runners. These findings, and similar variations of serum testosterone observed in an Ultramarathon runner during a 6-h training session, suggest that serum testosterone increases during physical activities lasting up to 3 h and decreases to or even below the pre-exercise values for longer physical efforts. The possible mechanisms responsible for these differences are discussed.

Key words

testosterone - duration of the exercise