Objective: To assess the relationship of maximal leg power and its corresponding determinants (eg, optimal velocity and optimal torque) measured during maximal voluntary knee extension to physical functional performance of older women. Design: Descriptive. Setting: Community retirement homes. Participants: Women (N=39) aged 72 to 96 years. Interventions: Not applicable. Main Outcome Measures: Volunteers performed in sitting position maximal knee extensions on an Ergopower dynamometer to calculate maximal leg power, optimal velocity, and optimal torque. Three standardized tests were also performed to evaluate physical performance: walking speed over 6m, time taken to rise 5 times from a chair, and time to climb 6 stairs. Results: On multiple regression analysis, leg power (mean, 1.37±0.80W/kg) significantly correlated with physical performance as measured by 6-m walking speed (mean, .85±.40m/s), chair-stand time (mean, 16.3±7.7s), and stair-climb time (mean, 7±4s), describing 16% to 33% of the variance. Optimal velocity (mean, 1.79±1.20 rad/s) also significantly correlated with 6-m walking speed, chair-stand time, and stair-climb time, describing 46% to 89% of the variance. Optimal torque (50.8±16.9Nm) did not correlate with physical performance. Conclusions: Maximal power and moreover optimal velocity were thus found to be determinants of physical performance, both appearing as significant mobility factors in older adults. This may provide more focus on velocity-oriented training as a means of improving functional status.