The mechanisms underlying age-related differences in maximum power production during multi-joint exercises are not fully understood. Strength and power differences between children and adults can not be solely explained by differences in muscle size (De Ste Croix et al., 2002). One factor that could potentially contribute to the age-related differences in maximum power production during multi-joint exercises is a differential development of the ability to generate maximum strength and power across the involved joints (De Ste Croix et al., 2004; Korff & Jensen, 2006). Therefore, the purpose of this study was to investigate the age-related changes in strength and maximum power at the ankle and knee joints. Twelve male volunteers participated in the study. They were divided into two age groups: children (n = 5, 10.3 ± 2.4 yrs) and adults (n = 7, 27.0 ± 4.7 yrs). Maximal isometric torque and maximal instantaneous power at 120 deg.s- 1 were determined during concentric ankle plantarflexion and knee extension using a Biodex system 3 (Shirley, New York, USA). Using multivariate analyses of variance, we found significant age by joint interactions for both isometric peak torque and maximal instantaneous power (P<0.05). During isometric actions adults produced 101% more torque at the ankle joint than children while this difference was 156% at the knee joint. During the isokinetic exercises, adults produced 167% more power than children at the ankle joint, while this difference was 144% at the knee joint. Our results suggest that age-related increases in muscle strength and power are joint specific. The joint specific development of maximum strength and power is a possible contributor to age-related changes in maximum power production during maximum lower limb tasks such as cycling (Martin et al., 2000). A possible explanation for the joint specific development of strength and power is a muscle specific development of muscle structure or of motor unit recruitment capabilities, which should be the subject of future work.
© Copyright 2007 12th Annual Congress of the European College of Sport Science, Jyväskylä, Finland - July 11-14th 2007. Alle Rechte vorbehalten.