Force-velocity profiling in older adults: An adequate tool for the management of functional trajectories with aging.

Abstract

The actual mechanisms leading to a reduced muscle power and functional ability in older adults are poorly understood. We investigated the association between different force-velocity (F-V) profiles and impaired muscle power, physical and cognitive function, frailty, and health-related quality of life (HRQoL) in older people. Physical function (habitual gait speed, timed up-and-go test, sit-to-stand and stair-climbing ability), cognitive function, HRQoL and frailty were evaluated in 31 older subjects (70-85 years). The F-V relationship and maximal muscle power (Pmax) were assessed in the leg press exercise. The skeletal muscle index (SMI) and fat index, moderate-to-vigorous physical activity (MVPA) and sedentary time were obtained from DXA scans and accelerometry, respectively. While some subjects showed a force deficit (FDEF), others presented a velocity deficit (VDEF), both leading to an impaired muscle power [Effect size (ES) = 1.30-1.44], and to a likely-very likely moderate harmful effect in their physical and cognitive function, HRQoL and frailty levels (except the VDEF group for cognitive function) [ES = 0.76-1.05]. Leg muscle mass and specific force were similarly associated with force at Pmax, while MVPA but not sedentary time was related to fat index, force at Pmax, and power values (all p < 0.05). A trend was found for the negative association between fat index and relative Pmax (p = 0.075). Older subjects exhibited different mechanisms (force vs. velocity deficits) leading to impaired muscle power. Both deficits were associated with a lower physical function and quality of life, and a higher frailty, whereas only a force deficit was associated with a lower cognitive function. Interventions aimed at reversing age- and/or disuse-related impairments of muscle power might evaluate the specific responsible mechanism and act accordingly.