Higher muscle protein synthesis in women than men across the lifespan, and failure of androgen administration to amend age-related decrements.Henderson GC, Dhatariya K, Ford GC, Klaus KA, Basu R, Rizza RA, Jensen MD, Khosla S, O’Brien P, Nair KS.
Division of Endocrinology, Mayo Clinic, Rochester, MN 55905, USA.
We investigated age and sex effects and determined whether androgen replacement in elderly individuals (> or = 60 yr) could augment protein synthesis. Thirty young men and 32 young women (18-31 yr) were studied once, whereas 87 elderly men were studied before and after 1 yr of treatment with 5 mg/day testosterone (T), 75 mg/day dehydroepiandrosterone (DHEA), or placebo (P); and 57 elderly women were studied before and after 1 yr of treatment with 50 mg/day DHEA or P. [(15)N]Phenylalanine and [(2)H(4)]tyrosine tracers were infused, with measurements in plasma and vastus lateralis muscle. Whole-body protein synthesis per fat-free mass and muscle protein fractional synthesis rate (FSR) were lower in elderly than in young individuals (P<0.001), not significantly affected by hormone treatments, and higher in women than in men (P<0.0001), with no sex x age interaction. In regression analyses, peak O2 consumption (VO2peak), resting energy expenditure (REE), and sex were independently associated with muscle FSR, as were VO2peak, REE, and interactions of sex with insulin-like growth factor-II and insulin for whole-body protein synthesis. Women maintain higher protein synthesis than men across the lifespan as rates decline in both sexes, and neither full replacement of DHEA (in elderly men and women) nor partial replacement of bioavailable T (in elderly men) is able to amend the age-related declines.
Weight training population or non-weight training?
This study shows otherwise. I guess one study is just one study, biased or not. Just strange how such different conclusions.
J Clin Endocrinol Metab. 2009 Mar 17.
Testosterone and Growth Hormone Improve Body Composition and Muscle Performance in Older Men.Sattler FR, Castaneda-Sceppa C, Binder EF, Schroeder ET, Wang Y, Bhasin S, Kawakubo M, Stewart Y, Yarasheski KE, Ulloor J, Colletti P, Roubenoff R, Azen SP.
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 physiologic supplementation with testosterone and growth hormone together improves body composition and muscle performance in older men. Design, Setting and Participants: 122 community dwelling men 70.8+/-4.2 years-of-age with BMI 27.4+/-3.4kg/m(2), testosterone </=550ng/dL, and IGF-1 in lower adult tertile (</=167ng/dL) were randomized to receive transdermal testosterone (5g or 10g/day) during a Leydig cell clamp plus growth hormone (0, 3, or 5ug/kg/day) for 16 weeks. Main Outcome Measures: Body composition by DEXA, muscle performance, and safety tests. Results: Total lean body mass increased (1.0+/-1.7kg-to-3.0+/-2.2kg) as did appendicular lean tissue (0.4+/-1.4kg-to-1.5+/-1.3kg), whereas total fat mass decreased by (0.4+/-0.9kg-to-2.3+/-1.7kg) as did trunk fat (0.5+/-0.9kg-to-1.5+/-1.0kg) across the six treatment groups and by dose levels for each parameter (p</=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+/-137sec longer). Systolic and diastolic blood pressure increased similarly in each group with mean increases of 12+/-14 and 8+/-8mmHg, 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 growth hormone supplementation.