Leg extensor power and dehydroepiandrosterone sulfate, insulin-like growth factor-I and testosterone in healthy active elderly people

Abstract

We examined the association between quadriceps muscle function and serum levels of dehydroepiandrosterone sulphate (DHEAS), insulin-like growth factor I (IGF-I) and testosterone in a group of healthy elderly people. Fifty-three independent, community-dwelling elderly subjects (26 men and 27 women) aged from 66 to 84 years volunteered to participate in the study. Physical activity (PA) was evaluated by a questionnaire. Quadriceps maximal muscle power (W˙ _max) and optimal shortening velocity (v _opt) were measured on a friction-loaded non-isokinetic cycle ergometer. The W˙ _max is expressed in relation to body mass (W˙ _max/kg, W · kg⁻¹), and in relation to the mass of the two quadriceps muscles (W˙ _max/Quadr, W · kg_Quadr ⁻¹). In women, when adjusted for age, anthropometric measurements and PA indices, IGF-I correlated significantly with W˙ _max/kg (partial correlation: r=0.59; P=0.001), W˙ _max/Quadr (r=0.58; P=0.002) and v _opt (r=0.53; P=0.004), whereas DHEAS was correlated significantly with W˙ _max/kg (r=0.54; P=0.003) and W˙ _max/Quadr (r=0.58; P=0.002). No such correlation was found in men. These findings indicate that in healthy elderly women lower values for quadriceps muscle W˙ _max and v _opt are related, independently of age, anthropometric measurements and PA indices, to lower circulating levels of DHEAS and IGF-I.