AN EVALUATION OF THE LENGTH-TENSION RELATIONSHIP IN ELDERLY HUMAN PLANTARFLEXOR MUSCLES

The purpose of this study was to determine the effect of aging on the muscle length-tension relationship ill the plantarflexor muscles of 10 subjects aged 20-30 yr (Mean = 23; 5 males, 5 females), 10 subjects a ged 60-80 yr (Mean = 72.3; 5 males, 5 females), and 10 subjects over 8 0 yr (Mean = 84.1, 5 males, 5 females). Isometric twitch properties, m aximum voluntary strength, passive tension, and range of motion were m easured at five different joint angles [20 degrees dorsiflexion (DF), 10 degrees DF, 0 degrees, 10 degrees plantarflexion (TF), and 20 degre es PF]. Active (evoked and voluntary) and passive torque production we re maximal when the ankle was rotated into the DF positions for all th ree age groups, whereas the lowest values were recorded when the ankle was rotated into 20 degrees PF. Males were stronger than females at a ll joint angles (p <.01). Also, young adults were stronger than both e lderly adult groups (p <.01). These results illustrate that despite th e consider able age-associated loss in both voluntary and evoked stren gth in the plantarflexors, the optimal angle for torque production rem ains the same for younger and older adults.