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

We examined the association between quadriceps muscle function and serum levels of dehydroepiandrosterone sulphate (DHEAS), insulin-like growth factor I (IGF-T) 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)over dot(max)) and optimal shortening velocity (nu(opt)) were measured on a friction-loaded non-isokinetic cycle ergometer. The (W)over dot(max) is expressed in relation to body mass (Wmax:kg, W. kg-l), and in relation to the mass of the two quadriceps muscles ((W)over dot(max/Quadr), W . kg(Quadr)(-1)). In women, when adjusted for age, anthropometric measurements and PA indices, IGF-I correlated significantly with (W)over dot(max/kg) (partial correlation: r = 0.59; P = 0.001), (W)over dot(max/Quadr) (r = 0.58; P = 0.002) and nu(opt) (r = 0.53; P = 0.004), whereas DHEAS was correlated significantly with (W)over dot(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)over dot(max) and nu(opt) are related, independently of age, anthropometric measurements and PA indices, to lower circulating levels of DHEAS and IGF-I.