SERUM HORMONES AND STRENGTH DEVELOPMENT DURING STRENGTH TRAINING IN MIDDLE-AGED AND ELDERLY MALES AND FEMALES

Effects of a 12-week progressive strength training period on serum concentrations of testosterone, cortisol and sex-hormone-binding globulin (SHBG) as well as on strength development of the leg extensor muscles were investigated in nine middle-aged males (M50; range 44-57 years) and in nine middle-aged females (F50; range 43-54 years) as well as in 10 elderly males (M70; range 64-73 years) and in 11 elderly females (F70; range 66-73 years). Substantial increases took place in maximal isometric strength during the 12-week training period both in M50 (from 2834+/-452 to 3941+/-772 Ni; P < 0.001) and in F50 (from 2627+/-725 to 3488+/-1017 N; P < 0.001) as well as in M70 (from 2591+/-736 to 3075+/-845 N; P < 0.01) and in F70 (from 1816+/-427 to 2483+/-408 N; P < 0.001). The relative increases in strength during the 12-week training period did not differ significantly between the groups. However, during the last 4 weeks of the training none of the groups demonstrated further increases in strength but it actually decreased in F50 (P < 0.05), M70 (P < 0.01) and in F70 (P < 0.05). No systematic changes were observed during the training in the mean concentrations of serum total testosterone, free testosterone, cortisol, and SHBG, nor in testosterone/cortisol and testosterone/SHBG ratios. However, the individual levels of serum testosterone and testosterone/cortisol ratio and the individual changes in strength during the last four most intensive training weeks of the 12-week period were in significant positive linear correlation in F70 (r = 0.57; P < 0.05) and in M70 (r = 0.61; P < 0.05). The present findings demonstrate that considerable gains may take place in strength during progressive strength training both in middle-aged and elderly people. The findings also point out the importance of the anabolic hormonal level for the trainability of muscle strength of an individual during prolonged strength training especially in elderly males and females. This indicates a need to plan strength training programmes carefully with regard for to the overall volume and the length of each training period to optimize the training process in elderly people both in preventive purposes and in rehabilitation.