Increased Motor Time in the Lower Extremity Is Related to Fall History in Older Women

Abstract

Our aim was to determine whether a temporal deterioration in central or peripheral processing was related to a history of falls in older women and observe the relationship between muscular strength in the lower extremity and information processing speed. A population of 34 older women aged 65–84 years were classified into two groups, fallers (n = 15) and non-fallers (n = 19), based on their fall history and fall risk index. Surface EMG was collected from the tibialis anterior (TA), gastrocnemius (GN), and peroneus longus (PL), which were activated in response to postural perturbation. The reaction time was fractionated into the premotor time (PMT) and motor time (MT). Three fast deep squats were performed on a force platform to record peak extensor force in the lower extremity. A 2 (Groups) × 3 (Trials) ANOVA with repeated measures for the trials revealed main group effects of MT on TA [F = 4.59, p < 0.05] and GN [F = 5.01, p < 0.05], and main trial effects of the PMT on TA [F = 3.50, p < 0.05]. A strong negative relationship was found between the motor time and peak extensor force of the left leg or both legs. The peak extensor force of the left leg was a reliable predictor for the motor time. Fallers faced a higher risk of falling and produced a longer motor time in response to the balance perturbation relative to non-fallers. Weaker explosive strength in the lower extremity, especially the non-dominant leg, was highly related to slower neuromuscular recruitment.