Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women

Effects of 6 months of heavy resistance training combined with explosive ex ercises on both basal concentrations and acute responses of total and free testosterone, growth hormone (CH), dehydroepiandrosterone (DHEA), dehydroep iandrosterone sulfate (DHEAS), cortisol and sex hormone-binding globulin (S HBG), as well as voluntary neural activation and maximal strength of knee e xtensors were examined in 10 middle-aged men (M40; 42 +/- 2 years), 11 midd le-aged women (W40; 39 +/- 3 years), 11 elderly men (M70; 72 +/- 3 years), and in 10 elderly women (W70; 67 +/- 3 gears), The maximal integrated elect romyographic (iEMG) and 1 repetition maximum (RM) knee-extension values rem ained unaltered in all groups during a 1-month control period with no stren gth training. During the 6-month training the 1RM values increased in M40 b y 27 +/- 9 % (p < .001), in M70 by 16 +/- 6% (p < .001), in W40 by 28 +/- 1 1 % (p < .001), and in W70 by 24 +/- 10% (p < .001). The iEMGs of the vastu s lateralis and medialis muscles increased (p < .05-.001) in M40, M70, W40, and W70, No systematic changes occurred during the experimental period in the mean concentrations of serum total and free testosterone, DHEA, DHEAS, GH, cortisol, or SHBG, However, the mean le,els of individual serum free te stosterone in W70 and serum testosterone in the total group of women correl ated with the individual changes recorded in strength during the training ( r = .55, p < .05; and r = .43, p < .05). The single exercise session both b efore and after the training resulted in significant responses in serum tot al and free testosterone concentrations in both male groups (p < .05-.01), but not in the female groups, as well as in serum GH levels in all groups ( p < .05-.01) except W70 (ns). In summary, the present strength training led to great increases in maximal strength not only in middle-aged but also in elderly men and women. The strength gains were accompanied by large increa ses in the maximal voluntary activation of the trained muscles. None of the groups showed systematic changes in the mean serum concentrations of hormo nes examined. However, a low level of testosterone, especially in older wom en, may be a limiting factor in strength development and testosterone could mediate interactions with the nervous system contributing to strength deve lopment. The physiological significance of the lack of acute responsiveness of serum GH to heavy resistance exercise in older women fur their trainabi lity during prolonged strength training requires further examination.