Knee extension rate of velocity development affects walking performance differently in men and women

Abstract

Purpose: Acceleration capacity affects physical function, but whether it differentially affects men versus women or weak versus strong individuals is less known. We investigated whether knee extension rate of velocity development (RVD, a measure of acceleration) is associated with walking performance independent of peak torque and whether the relationships differ in men versus women and in weak versus strong individuals.

Methods: Relationships of RVD with walking performance were assessed in 326 women and 365 men aged 26-96 years enrolled in the Baltimore Longitudinal Study of Aging. Tests included knee extension peak torque and RVD assessed during a 180°·s^-1 isokinetic strength test and four walking performance measures (usual-paced and fast-paced 6 m walks and 2.5 min usual-paced and 400 m fast-paced walks). Sex-stratified linear regression models were adjusted for age, race, height, appendicular lean mass, fat mass, peak torque, knee pain, and RVD*peak torque interaction.

Results: In men, RVD was not independently associated with any walking performance measure (p > 0.05), and, for the 6 m-usual walk only, there was a significant RVD*peak torque interaction (p < 0.0001). In women, RVD was independently associated with usual-paced walks (p < 0.05) and there were significant RVD ∗ peak torque interactions for all measures. Strength-specific analyses indicated that RVD was most associated with performance among weaker individuals.

Conclusion: RVD is associated with walking performance in women, but less in men, and is most related to performance when strength is low. Strategies to accomplish motor tasks may be sex-specific. Future studies are needed to understand the mechanisms underlying such sex differences.

Keywords: Acceleration; Aging; Gait; Isokinetic dynamometry; Muscle strength; Sex difference.

Figure 1.

An example of isokinetic, concentric knee extension at 180 deg.sec⁻¹ Open circles are torque and filled circles are angular velocity. The dotted horizontal line is angular velocity at 178 deg.sec⁻¹. Rate of velocity development was derived from dividing Δ deg.sec⁻¹ by Δ time between onset of movement and the time point at which angular velocity exceeded 178 deg.sec⁻¹.