Three-dimensional motion analysis of the trailing limb in obstacle crossing during gait in young adults: foot trajectory changes with the height of obstacles

[Purpose] We aimed to analyze the kinematic characteristics of the foot trajectory of the trailing limb in a crossing motion during gait when the height of an obstacle is varied. [Participants and Methods] The participants were 12 healthy adult males (age: 24.2 ± 0.9 years). The participants performed 11 tasks: normal gait and crossing an obstacle with a height ranging from 10% to 100% of the height from the floor to the knee joint crease at 10% intervals during gait. The parameters included the clearance height, foot trajectory, swing phase duration, stride, toe distance, and heel distance. [Results] In the crossing condition, the foot trajectory changed with the obstacle height, with some participants showing unimodal trajectories when the obstacle height was ≥30% of the knee joint height. The trend test results show a trend from bimodal to unimodal trajectories with increasing obstacle heights. [Conclusion] The trailing limb of a young participant's crossing motion during gait showed kinematic changes in the foot trajectory, adjusting from bimodal to unimodal as the obstacle height increased, suggesting that this may be a specific strategy for dealing with high obstacles.