Fat mass limits lower-extremity relative strength and maximal walking performance in older women.

The purpose of this study was to determine if excess fat negatively affects relative strength and walking gait performance in overweight, older women. Twenty-five older women (65-80 yr) were separated into normal weight (BMI<25 kg m(-2), n=11) and overweight groups (BMI 25 ≥ kg m(-2), n=14). Strength and rate of torque development (RTD) of the knee extensors and flexors, ankle plantarflexors and dorsiflexors were measured. Participants walked at standard and maximal speeds during which muscle activation, spatiotemporal and kinetic gait variables were measured. Relative to mass, overweight older women had 24% lower maximal torque and 38% lower RTD than normal weight women. Maximal walking speed was slower in overweight (1.25±0.22 vs. 1.54±0.25 m s(-1), P=0.004) and was correlated to strength (r=0.53, P<0.01) and fat mass (r=-0.65, P=0.001). At maximal speed, overweight had 11% lower vertical ground reaction force relative to mass, 8% slower stride rate, 12% shorter strides, 13% longer foot-ground contact times, 21% longer double-limb support times, 65% greater knee extensor and 78% greater plantarflexor activation (P<0.05). Overweight, older women demonstrated altered gait and reduced walking performance related to poor relative strength and rate of torque development of lower-extremity muscles.