Stronger Toes Are Associated With Faster Preferred Walking Speed In Young And Middle-aged Adults

Fall prevalence increases during middle-age alongside declines in balance and strength. Hallux (big toe) strength is a major predictor of fall risk among older adults. Most falls in older adults occur during walking, but it is unknown whether declines in toe strength prior to older age are related to changes in gait parameters commonly associated with stability. PURPOSE: Determine associations between age, foot strength, and spatiotemporal gait parameters. METHODS: Twenty-two adults (9 M/13F; ages 20-62 years, mean + 1 SD: 40.2 ± 14.2 years) completed a barefoot treadmill walking gait analysis at their preferred speed (1.19 ± 0.14 m/s), and toe flexion and pressure strength tests for the hallux and lesser toes on the dominant leg. Toe flexion involved flexion at the metarsophalangeal (MTP) and interphalangeal joints whereas toe pressure involved flexion at the MTP joint only; both measures were normalized to body size (height*mass). Walking speed was normalized to leg length. Gait was measured for 30 seconds using three-dimensional motion capture. Pearson correlation coefficients (r) were calculated to identify associations between age, foot strength, and spatiotemporal gait outcomes (i.e., step width, stride length, stance time). Linear regression models were fit for significant relationships to control for potential confounders. RESULTS: Mean normalized foot strength measures for the hallux and lesser toes were 0.45 ± 0.2 and 0.48 ± 0.2 N/kg*m for flexion tests, and 0.55 ± 0.3 and 0.41 ± 0.2 N/kg*m for pressure tests, respectively; there were no differences in strength between toes or tests (p > 0.05). Age was negatively correlated with hallux flexion strength (r = -0.55, p = 0.01). Only hallux and lesser toes pressure strength, not flexion strength, were associated with preferred walking speed (r = 0.61, p = 0.02-0.03). Speed did not differ by age, but older subjects had shorter step lengths when controlling for speed (p = 0.02). CONCLUSION: Age is related to declines in hallux flexion strength, but not other measures of toe strength, and this decline does not affect spatiotemporal gait parameters in healthy young and middle-aged adults. In this active and highly functional sample, a lack of variation in toe strength outcomes may have precluded the identification of other effects of toe strength on gait.