Resistance Training and Testosterone Replacement Induced Changes in Body Composition, Free Testosterone, IGF‐1, and IGFBP‐3 in the Frail Elderly

The purpose of this study was to examine the effects of two resistance exercise intensities and testosterone replacement on changes in hormone/growth factors and their relationship to body composition changes in the frail elderly. The study design was 2 X 2 X 2 with Drug (100 mg/wk of testosterone; T or no‐testosterone), Resistance Exercise (Low Intensity and High‐Intensity) and Time (Pre and Post intervention). Sixty‐one men with a mean age of 77.8 (6.1) and a total testosterone of < 480 ng/dL participated. Serum was analyzed for insulin like growth factor‐1 (IGF‐1), IGF binding protein 3 (IGFBP‐3), sex hormone binding globulin (SHBG), and total testosterone. Leg strength and mid‐thigh cross‐sectional muscle area were measured pre‐ and post‐intervention. A significant association was observed between the % change in IGF‐1/IGFBP‐3 and the % change in thigh cross‐sectional muscle area (%MCSA; r=0.28, p<0.05). A significant drug effect was observed for the % change in IGFBP‐3 with those on T having a significant decrease compared to no T. Total T at post was related to the % MSCA (r=0.32, p<0.05) and to the % change in leg strength (r=0.35, p<0.05). The associations between the % change in serum IGF‐I/IGFBP‐3 and % MCSA and between total T at post and both % MCSA and % change in leg strength are important as there are few markers in blood which indicate a change in muscle anabolism.