Effect of recombinant XXXX growth hormone on the muscle strength response to resistance exercise in elderly @entity1 .

@entity1 @entity442 @entity174 @entity2301
Normal aging is characterized by detrimental changes in body composition, muscle strength, and somatotropic function. Reduction in muscle strength contributes to frailty and risk for @entity174 in the elderly. Although older adults increase muscle strength as a result of resistance exercise training, the strength gains quickly level off, with only modest increases thereafter despite continued training. To investigate whether age-related deficits in the somatotropic axis limit the degree to which muscle strength can improve with resistance training in older individuals, we conducted a double blind, placebo-controlled exercise trial. Eighteen healthy elderly @entity1 (65-82 yr) initially underwent progressive weight training for 14 weeks to invoke a trained state. Subjects were then randomized to receive either 0.02 mg/kg BW.day recombinant @entity1 GH (rhGH) or placebo, given sc, while undertaking a further 10 weeks of strength training. Sequential measurements were made of muscle strength (one repetition maximum), body composition (dual energy x-ray absorptiometry), and circulating levels of @entity442 ( @entity442 ) and @entity2301 . For each exercise, strength increased for both groups (P = 0.0001) through 14 weeks of training, with little improvement thereafter. Increases in muscle strength ranged from 24-62% depending on the muscle group. Baseline plasma @entity442 concentrations were similar in both groups (mean +/- SEM, 106 +/- 9 micrograms/L), approximately half that observed in healthy young adults. In the rhGH group, @entity442 levels increased to 255 +/- 32 micrograms/L at week 15 and 218 +/- 21 micrograms/L at week 24 (P < 0.001). In the placebo group, @entity442 increased slightly to 119 +/- 6 micrograms/L at 24 weeks. @entity2301 also increased in the rhGH group (P < 0.05). rhGH had no effect on muscle strength at any time, and no systematic difference in muscle strength was observed between groups throughout the study. Body weight did not change in either group, but lean body mass increased, and fat mass decreased (P < 0.05) in the rhGH group. Supplementation with rhGH does not augment the response to strength training in elderly @entity1 . These results suggest that deficits in GH secretion do not underlie the time-dependent leveling off of muscle strength seen with training in the elderly and provide no support for the popular view of GH as an ergogenic aid.
