Abstract

To examine endogenous hormonal responses to heavy-resistance exercise, ten male strength athletes performed two fatiquing but different types of sessions on separate days. In session A the loads for the leg extensor muscles in the squat-lift exercise were maximal so that the subjects performed 20 sets at 1 repetition maximum (RM) (20x1RMx100%), whereas during session B the loads were submaximal (70%) but the subjects performed each of the 10 sets until the RM (i.e., 10 repetitions/set or 10x10x70%). Recovery time between all sets was 3 min. A decrease of 10.3+-4.7% occurred in the squat-lift in 1 RM during session A, whereas session B led to a decrease of 24.6+-18.9% in 10 RM. Increases in the concentrations of serum total and free testosterone, cortisol, and growth hormone (GH) were observed during session B, whereas the corresponding changes during session A were statistically insignificant except for the relatively slight increase in serum GH level. The significant increase in blood lactate concentration during the two sessions correlated significantly with the increase in serum GH concentration. The morning values of serum testosterone and free testosterone were significantly lowered on the 1st and 2nd rest days after the sessions. The present findings demonstrate that heavy-resistance exercises cause acute endogenous hormone responses that can differ depending on the type and/or magnitude of the stress of the exercise protocol utilized. Verf.-Referat