80 yr). Subjects were separated into symmetrical strength (SS, n = 13) and asymmetrical strength (SA, n = 11) groups using an asymmetry cutoff of 20%. Subjects walked at a standard speed of 0.8 m·s−1 and at maximal speed on an instrumented treadmill while kinetic and spatiotemporal gait variables were measured. Gait and strength asymmetry were calculated as the percentage difference between legs and gait variability as the coefficient of variation over 20 sequential steps. Results SA had greater strength asymmetry (27.4% ± 5.5%) than SS (11.7% ± 5.4%, P < 0.001). Averaged across speeds, SA had greater single- (7.1% vs. 2.5%) and double-limb support time asymmetry (7.0% vs. 4.3%) than SS and greater single-limb support time variability (9.7% vs. 6.6%, all P < 0.05). Group × speed interactions occurred for weight acceptance force variability (P = 0.02) and weight acceptance force asymmetry (P = 0.017) with greater variability at the maximal speed in SA (5.0% ± 2.4% vs. 3.7% ± 1.2%) and greater asymmetry at the maximal speed in SA (6.4% ± 5.3% vs. 2.5% ± 2.3%). Conclusion Gait variability and asymmetry are greater in older women with strength asymmetry and increase when they walk near their maximal capacities. The maintenance of strength symmetry, or development of symmetry through unilateral exercise, may be beneficial in reducing gait asymmetry, gait variability, and fall risk in older adults....

Historical activity questionnaire, and then they performed a series of maximal, voluntary, isometric knee extensions in a visually cued RT task. Fractionated RT measures were taken using three landmarks in the data: the presentation of the visual stimulus, the beginning of the EMG burst, and the initiation of force development. The rate and magnitude of neural stimulation were taken from surface EMG. Results: Peak torque was 15% greater, rate of torque development was 26% greater, motor time was 17% shorter, rate of EMG rise was 25% faster, and onset EMG magnitude was 15% greater in HA than in LA subjects (P < 0.05). Conclusion: These results indicate that older women with a history of vigorous activity can generate greater force, power, and motor output in comparison with their less active peers. The lower-body mass index of the HA subjects and 310% greater volume of physical activity are likely to account for the enhanced neuromuscular function seen. It is plausible that in addition to aging, physical inactivity is responsible for a large portion of the loss of neuromuscular function seen in older adults....