Serum Concentrations of Myostatin and Myostatin-Interacting Proteins Do Not Differ Between Young and Sarcopenic Elderly Men

Sarcopenia is the loss of muscle size and function during ageing. The aim of this study was to test whether serum concentrations of myostatin and interacting proteins (GASP-I, FLRG, and follistatin) differed between young and elderly sarcopenic men. Isometric knee extensor maximal voluntary contraction and quadriceps cross-sectional area (magnetic resonance imagine measurement) were significantly higher in young (22 +/- 2 years; 266 +/- 54 N/m; 8,686 +/- 1,154 mm(2)) than in mildly sarcopenic (69 +/- 3 years; 183 +/- 17 N/m; 6,621 +/- 718 mm(2)) and severely sarcopenic men (76 +/- 6 years: 127 +/- 23 N/m; 5,846 +/- 591 mm(2)), respectively (p <=.01 for all comparisons). There was a trend (p =.06) toward higher FLRG in young (20 +/- 8 ng/mL) than in mildly (15 +/- 6 ng/mL) and severely sarcopenic men (17 +/- 8 ng/mL). Myostatin, follistatin, GASP-1, tumor necrosis factor alpha, and interleukin-6 did not differ significantly. Insulin-like growth factor-1 and free testosterone were both significantly lower in sarcopenic men (p <.001). This suggests that altered serum concentrations of myostatin and myostatin-interacting proteins are not contributing to sarcopenia with the possible exception of FLRG.