Testosterone and growth hormone improve body composition and muscle performance in older men

Abstract

Context: Impairments in the pituitary-gonadal axis with aging are associated with loss of muscle mass and function and accumulation of upper body fat.

Objectives: We tested the hypothesis that physiological supplementation with testosterone and GH together improves body composition and muscle performance in older men.

Design, setting, and participants: One hundred twenty-two community-dwelling men 70.8 +/- 4.2 yr of age with body mass index of 27.4 +/- 3.4 kg/m2, testosterone of 550 ng/dl or less, and IGF-I in lower adult tertile (< or =167 ng/dl) were randomized to receive transdermal testosterone (5 or 10 g/d) during a Leydig cell clamp plus GH (0, 3, or 5 microg/kg . d) for 16 wk.

Main outcome measures: Body composition by dual-energy x-ray absorptiometry, muscle performance, and safety tests were conducted.

Results: Total lean body mass increased (1.0 +/- 1.7 to 3.0 +/- 2.2 kg) as did appendicular lean tissue (0.4 +/- 1.4 to 1.5 +/- 1.3 kg), whereas total fat mass decreased by 0.4 +/- 0.9 to 2.3 +/- 1.7 kg as did trunk fat (0.5 +/- 0.9 to 1.5 +/- 1.0 kg) across the six treatment groups and by dose levels for each parameter (P < or = 0.0004 for linear trend). Composite maximum voluntary strength of upper and lower body muscles increased by 14 +/- 34 to 35 +/- 31% (P < 0.003 in the three highest dose groups) that correlated with changes in appendicular lean mass. Aerobic endurance increased in all six groups (average 96 +/- 137 sec longer). Systolic and diastolic blood pressure increased similarly in each group with mean increases of 12 +/- 14 and 8 +/- 8 mm Hg, respectively. Other predictable adverse events were modest and reversible.

Conclusions: Supplemental testosterone produced significant gains in total and appendicular lean mass, muscle strength, and aerobic endurance with significant reductions in whole-body and trunk fat. Outcomes appeared to be further enhanced with GH supplementation.

Figures

Figure 1

Schema depicts the subjects screened for study, most common reasons for exclusion, numbers of eligible subjects enrolled and how they were randomized to study therapies, reasons for study discontinuation during the 16 wk of treatment interventions, and final numbers of evaluable subjects in the six allocation groups. NSAID, nonsteroidal antiinflammatory drug.

Figure 2

Changes (mean ± 1 se) in serum testosterone (A) and IGF-I (B) from baseline to wk 16 according to dose. *, Within group significant changes (P < 0.05); †, significant difference in change (P < 0.001) between 5 and 10 g/d testosterone dose groups and significant differences in change (P < 0.05) for IFG-1 between the 3 or 5 μg/kg · d and the 0 μg/kg · d rhGH dose groups.

Figure 3

DEXA-derived changes (mean ± 1 se) in LBM and fat mass for each treatment group from baseline to wk 17. A, Increases in total LBM (solid bars) and appendicular lean mass (hatched bars). Changes across groups are significant for linear trend for total lean mass (P = 0.0002) and appendicular lean (P = 0.0002). B, Decreases in total body fat mass (solid bars) and trunk fat (hatched bars). Changes across groups are significant for linear trend for total fat mass (P = 0.0004) and trunk fat (P = 0.0003). *, Bonferoni adjusted within group changes (P < 0.008). Pairs of treatment groups with different letters (e.g. a vs. b) are significantly different by one-way ANCOVA with pairwise comparison (Tukey adjusted; P < 0.05).