Interlimb asymmetry alters walk-run transition speed

asb2015_logo_039th Annual Meeting of the American Society of Biomechanics (August 2015)

Walk-run transitions are dependent on interlimb coupling

Jan Stenum and Julia T. Choi

Department of Kinesiology, University of Massachusetts, Amherst MA

Walk-run transition in adult humans has been studied during forward gaits. However, it is unknown how contralateral leg movement affects walk-run transitions. We examined walk-run transitions on a split-belt treadmill where the speed and direction of each belt can be controlled independently. We hypothesize that walk-run transitions are dependent on contralateral leg movements. A split-belt treadmill was used to test 4 different gait conditions: forward, split-belt (i.e., constant speed difference of 0.5 m/s between belts), hybrid (i.e.,  left leg moved backward and right leg moved forward) and backwards. Here we define preferred walk-run transition speed as the speed where a subject is equally likely to choose walk and run. We found that walk-run transition occurred at different speeds across four conditions. On average, subjects transitioned at 2.00 ± 0.20 m/s in the forward condition. When one leg  moved faster than the other in the split condition, the transition speed on the fast leg increased to 2.36 ± 0.20 m/s. The transition speed was 1.47 ± 0.15 m/s in the backward condition. When one leg walked forward, and one backward in the hybrid condition, both legs transitioned to running together at a lower speed. The average walk-to-run transition speed in hybrid locomotion was 1.17 ± 0.16 m/s. We did not observe walking on one leg, and running on the other leg during hybrid locomotion for the tested speed combinations. In sum, walk-run transition speed is dependent on interlimb speed and direction differences. To our knowledge, this is the first study to investigate the effects of interlimb coupling on human walk-run transitions.