Changes in Isokinetic Torque and Muscular Activity of Elbow Flexors Muscles with Age

This study examined the influence of aging on torque-angular velocity relationships for elbow flexion and the corresponding muscular activity levels in order to target the mechanisms involved in the eccentric muscle action in older adults. Maximal constant angular torque (CAT) at 90 degrees was measured at different angular velocities for concentric (CON; 60, 120, 180, 240 degrees s(-1)), isometric (ISO) and eccentric (ECC; -60, -120 degrees s(-1)) elbow flexor muscle actions in older (OG; 6 females and 4 males, 64-82 years) and young adult subjects (YG; 6 females, 6 males, 19-24 years) on an isokinetic dynamometer. Myoelectrical activity was quantified on biceps and triceps muscles, using the root mean square (RMS) procedure over a range of 30 degrees motion (75-105 degrees ). Absolute CAT was significantly greater (p<0.04) for YG in comparison with OG for all types of actions (CON, ECC, ISO). The only effect of gender concerned absolute strength values (p=0.00007). However, the OG showed higher (p<0.001) relative CAT values (expressed as percentage of CON 60 degrees s(-1) value) during ECC muscle action than the YG. Nevertheless, RMS values for elbow flexors were significantly (p<0.03) lower in the OG than in the YG. The antagonist (triceps) co-activation was similar for both groups. The relative ECC force preservation with aging seems to be independent of a muscular activation phenomenon.