Characterization of aging-associated deficits of rate of force development of eccentric preloaded concentric torque

Research Objectives: To compare average rate of force development (RFD) of eccentric-preloaded concentric torque (Ecccon-Torque) at 120°/s, 180°/s, and 240°/s for 3 different range of movements (ROMs) (corresponding to muscle length used for walking (small) and balance recovery from moderate (medium) to severe (large) perturbations) at the knee and ankle. Although stretch-shortening induced potentiation of Ecccon-Torque is a positive contributor to physical activity in older adults, a knowledge on joint-specific RFD of the Ecccon-Torque is unknown. Further, it is unknown if movement velocities and ROMs would affect RFD of the Ecccon-Torque.

Design: Cross-sectional study

Setting: University laboratory

Participants: Young adults, n=12; Older adults, n=11

Interventions: Not applicable

Main Outcome Measures: Knee extensors and ankle plantarflexors were assessed in random order for concentric only and eccentric-preloaded concentric muscle strength at 3 different velocities (120°/s, 180°/s, and 240°/s) at 3 different ROMs (small, medium, and large) on Biodex3 device. Average RFD (slope of eccentric-preloaded maximum concentric torque-time curve) was calculated for all the velocities and ROMs

Results: RFD of Ecccon-Torque of older adults was significantly lower than young adults for i) the ankle at all velocities at medium ROMs (p < 0.05, d from 0.8 to 1.8) and 180°/s large ROM (p < 0.05, d = 1); and ii) the knee at 240°/s at all ROMs (p < 0.05, d from 0.3 to 0.6), 180°/s at large ROM (p < 0.05, d = 0.7), and 120°/s at middle ROM (p < 0.05, d = 0.5).

Conclusions: Aging-associated lower RFD of Ecccon-Torque is evident at the ankle and knee. Further, these deficits are movement velocity-, and ROM-specific. Whether RFD of Ecccon-Torque dictates ease, economy, and degree of physical activity in older adults is unknown.

Author(s) Disclosures: No conflict of interest