Force, Velocity and Power relationship of elbow flexors in the elderly

Abstract

The present study aimed to investigate the characteristics of force, velocity and power relations of elbow flexion in elderly people. The subjects were 22 elderly men (aged 61-77 y) and 19 college male students (ages 20-24 y). Using a modified Wilkie's apparatus, the force, velocity and resultant power output by the elbow flexor muscles were measured, and the force-velocity relations were calculated according to Hill's equation : (F + a) (V + b)=(Fmax + a) b. Cross-sectional area (CSA-ante) of the upper arm was estimated from the square of the muscle thickness measured by an ultrasonic apparatus. The force-velocity curve for the elderly group (G-aged) was found to be less concave (larger a/Fmax) than that of the college students (G-young). The maximal power values, which appeared at an Fmax under about 34% in both age groups, were 107.8 W in G-aged and 155.0 W in G-young. There were significant differences (G-aged < G-young) in Pmax as well as in Fmax and Vmax. The ratios of Fmax/CSA-ante, Pmax/CSA-ante and Vmax/upper arm length were also significantly lower in G-aged than in G-young. The half time to reach Fmax (1/2RFD) was significantly longer in G-aged (117.4 ms) than in G-young (93.1 ms). Compared with G-young, G-aged showed a greater reduction in Pmax (69.3%) than in Fmax (76.0%) and Vmax (83.5%). In CSA-ante, however, no significant difference was observed between the two age groups, suggesting a considerable effect of neuromuscular function. From these results, it was suggested that the ability to develop muscular power may be reduced more functionally than morphologically with increasing age.