Force, velocity and power relationship of ankle plantar flexors and ankle dorsiflexors in the elderly

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The present study aimed to investigate the characteristics of force, velocity and power relations of ankle plantar flexors and ankle dorsiflexors in elderly. The subjects were 15 elderly men (G-aged) and 15 college male students (G-young) Using specially designed apparatus, the force, velocity and resultant power output by the plantar-and dorsi-flexors muscles were measured, and the force-velocity relations were calculated according to Hill's equation: (F+a)(V+b)=(Fmax+a)b. Ante and post cross-sectional area (CSA-ante, CSA-poste) of the lower limb was estimated from the square of the muscle thickness measured by an ultrasonic apparatus. In CSA-poste, no significant difference was observed between the two age groups, however, the CSA-ante was significantly lower in G-aged than in G-young. The maximal power values were significant differences (G-aged < G-young) in Pmax as well as in Fmax and Vmax. Compared with G-young, G-aged showed a greater reduction in Pmax (69.1%) than Fmax (69.5%) … More and Vmax (82.8%) of the plantar-flexors, and also showed a greater reduction in Pmax (69.4%) than Fmax (81.8%) and Vmax (78.9%) of the dorsi-flexors. The ratios of Fmax/CSA-poste, Pmax/CSA-poste and Vmax/lower limb length of the plantar-flexors were significantly lower in G-aged than in G-young. However the ratios of Famx/CSA-poste and Pmax/Csa-poste Vmax/lower limb length of the dorsi-flexors were no significant in G-aged than in G-young. The force-velocity curves of G-aged tended to be lower than that of the G-young. There were significant differences among G-aged and G-young for Vmax, V_<10>, V_<20>, V_<30>, V_<45> and V_<60> in the dorsi-flexors, however, not for under various %Fmax load in the plantar-flexors. The iEMG and %iEMG of agonist and antagonist for the plantar-and dorsi-flexors were no significant between G-aged and G-young.From these results, it was suggested that the ability to develop muscular power may be reduced more functionally than neural factor with increasing age. Less