Variation In Interlimb Coordination Of Healthy Adults At Different Backward Walking Speeds

Abstract

The central pattern generator is demonstrated to produce both rhythmic forward walking (FW) and backward walking (BW). Compared with FW, BW reduces the likelihood of anterior cruciate ligament rupture and osteoarthritis. Because visual feedback is absent in BW, abundant motor units are recruited and interlimb coordination becomes more variable. Walking speed is one of the primary constraints to affect interlimb coordination in FW. However, backward walking speeds that produce the optimal coordination in foot-shank and shank-thigh couplings are unclear in the healthy group. PURPOSE: To explore the effect of different backward walking speeds on the interlimb coordination of healthy adults. METHODS: Forty healthy adults (20 males and 20 females) were recruited, and gait data at preferred backward walking speed (PBWS), maximum backward walking speed (MBWS), 80% MBWS, 60%MBWS and 40% MBWS were collected using a three-dimensional gait analysis system. Continuous relative phase (CRP) method was applied to analyze the interlimb coordination (shank-foot and thigh-shank couplings) at different backward walking speeds and respective CRP was averaged across the subjects. CRPs between the shank-foot and thigh-shank couplings at different speeds were compared using one-way ANOVA. Level of significance was set at 0.05. RESULTS: The average CRP of the shank-foot coupling was the highest at 60% MBWS, reaching 8.61° ± 0.40°, while the average CRP at 80% MBWS was the lowest, which was 6.30° ± 0.11°. The average CRPs of 100% MBWS and 40% MBWS were similar, second only to that of 60% MBWS. For the thigh-shank coupling, the average CRP of 100% MBWS was the largest among five backward walking speeds, while the minimum average CRP was 7. 18° ± 1.27° when BW was performed at 80% MBWS. The interlimb coordination of the thigh-shank and the shank-foot couplings are significantly distinct at different backward walking speeds (P < 0.01). CONCLUSIONS: The interlimb coordination of the shank-foot coupling was the largest when walking backwards at 60% MBWS, while, for the thigh-shank coupling, the largest interlimb coordination was noticed at 100% MBWS. Backward walking speed for optimal locomotion ability varied in different couplings. This study provides a preliminary insight to rehabilitative backward walking training.