Quadriceps muscle function in relation to habitual physical activity and VO2max in men and women aged more than 65 years.

The relationship of quadriceps maximal muscle power (Pmax), corresponding optimal shortening velocity (v(opt)), and relative fatigability (Pmax%D) to maximal oxygen uptake (VO2max) and habitual physical activity (PA) was examined in healthy community-dwelling subjects (29 women and 25 men) aged more than 65 years old. PA was evaluated by a questionnaire and expressed using two activity indices: mean habitual daily energy expenditure (MHDEE) and the daily energy expenditure corresponding to leisure time sports activities (Sports Activity). In women, Pmax correlated positively with VO2max (r = .56) and with Sports Activity (rho = .41). Both Sports Activity and Pmax were significant independent predictors of VO2max and accounted for 62% of variance in VO2max. In men, v(opt) was significantly negatively related to MHDEE (r = -.59) and to Sports Activity (rho = -.40). Neither in women nor in men was Pmax%D correlated with VO2max or PA indices. The different relationship of Pmax and v(opt) with VO2max and PA indices suggests that habitual PA may be sufficient in active older women, but not in men, to positively influence quadriceps muscle function. These gender differences may suggest different approaches in exercise programming for elderly women and men.