Resistance Training RESISTANCE TRAINING AND TESTOSTERONE REPLACEMENT INDUCED CHANGES IN BODY COMPOSITION, FREE TESTOSTERONE, IGF-1, and IGFBP-3 IN THE FRAIL ELDERLY

Lambert CP, Bopp MM, Johnson LE, Sullivan DH. Resistance Training and Testosterone Replacement Induced Changes in Body Composition, Free Testosterone, IGF-I, and IGFBP-3 in the Frail Elderly. JEPonline 2007;10(1):48-56. The purpose of this investigation was to examine the effects of two resistance exercise intensities and testosterone replacement on changes in circulating hormone/growth factor concentrations and their relationship to body composition changes in frail elderly individuals. This study design was a 2 x 2 x 2 factorial with Drug (100 mg/wk of testosterone; T or no-testosterone), Resistance Exercise (Low Intensity and High-Intensity) and Time (Pre and Post Intervention). The duration of the interventions was 12 weeks. Subjects for this investigation were sixty-one men with a mean age of 77.8+6.1, a total testosterone concentration of <480 ng/dL, and who were in the recuperative phase of a recent illness. 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 also measured preand post-intervention. As expected, total testosterone and free testosterone were significantly elevated by testosterone administration (each p<0.001). There were trends for a reduction in IGFBP-3 (p=0.175) and an increase in IGF-I/IGFBP-3 ratio (p=0.094) by testosterone administration. There was a significant time effect with regard to IGF-I with the mean of the four groups increasing over time (p=0.013). Significant correlations were observed between the post-intervention Resistance Training in the Frail Elderly 49 total (r=0.385; p=0.002) and free (r=0.315;p=0.013) testosterone concentrations and the % change in mid-thigh cross-sectional muscle area. The Post-intervention IGF-I/IGFBP-3 ratio correlated significantly with % change in mid-thigh cross-sectional muscle area (r=0.269 p=0.036) and the % change in fat free mass (r=0.261; p=0.05). These data would suggest that elevations in the total and free testosterone as well as in the IGF-I/IGFBP-3 ratio after testosterone administration may be indicators of changes in muscle mass with testosterone administration in older hypogonadal men recovering from a recent illness.