The effect of obstacle height and maximum step length (MSL) on obstacle crossing in healthy adults

In this study, we investigated whether subjects with a Lower Maximum Step Length (MSL) Percentage (LMP) display unstable locomotion while negotiating an obstacle. Data were collected using a three-dimensional motion analysis system. The toe-obstacle clearance of the leading limb was monitored in 10 young adults while stepping over three height obstacles from 30%, 40% and 50% of MSL. The vertical clearance at the time of the obstacle crossing decreased systematically with more complicated experimental set up. In particular, subjects with LMP showed smaller clearances than subjects with a Higher Maximum step length Percentage (HMP). Furthermore, a significant correlation was observed between the toe-obstacle clearance and MSL. The mean of variance value of toe-obstacle clearance of the leading limb differed between the subjects with LMP and those with HMP. Our findings help to explain the relation of MSL and gait adaption ability to negotiate obstacles safely during obstacles crossing.