Plantarflexor passive-elastic properties related to BMI and walking performance in older women.

Twenty-three older women is a small sample, and the study was cross-sectional, so it can show associations but cannot prove that higher BMI or lower stiffness caused slower walking. All participants could walk independently and had no physical limitations that prevented participation, so findings may not apply to older adults with mobility disability. Only one participant in the overweight/obese group had BMI 30 kg/m^2 or higher, so the study says little about obesity. Only women were studied, so results may not apply to men. The overweight/obese group was younger than the normal-weight group, although age did not significantly affect group differences for passive muscle properties. Muscle stiffness, work absorption, and peak passive torque were measured slowly and in isolation on a dynamometer, not during walking, so they may not fully represent muscle-tendon behaviour during gait. BMI, stiffness, and strength were moderately correlated with one another, which makes it difficult to say which variable is most important for walking performance.

The author reports no conflict of interest.

Do not conclude that increasing ankle plantarflexor stiffness will improve walking speed. This study measured associations in 23 older women, not an intervention, and stiffness, BMI, and strength were correlated.