Combined Sections Meeting of American Physical Therapy Association

Document Type

Conference Proceeding




Background: Human locomotion is flexible in any environment, and this fact has been proven when walking on different speeds in each leg on the split-belt treadmill. However, during the split-belt walking, participant’s locomotor behaviors are passively adopted by a motor-driven treadmill. Therefore, how humans actively adjust the flexibility of locomotion is still limited by using the split-belt treadmill. Our current study investigated the flexibility of locomotion by using ankle weight on the dominant leg to induce asymmetric walking pattern when walking on a regular treadmill. We hypothesized that the level of active control would increase to adapt the asymmetric walking in all different kinds of inclinations.

Number of Subjects: Twenty healthy young participants (age: 24.7 ± 2.2 years; height: 1.73 ± 0.08 m; mass: 68.92 ± 12.07 kg, 12 females and 8 males) were recruited for this study.

Materials/Methods: Six conditions (walking on the level treadmill, 15% inclined treadmill, 15% declined treadmill with/without wearing 4-lb ankle loading on the dominant leg) were randomly assigned to participants. A motion capture system and reflective markers were used to collect data. The markers were placed on the heel and toe of both legs to measure step length symmetric index (SLS) and step time symmetric index (STS). SLS = (SL_non_dominant_leg - SL_dominant_leg)/(SL_non_dominant_leg + SL_dominant_leg); STS = (ST_non_dominant_leg - ST_dominant_leg)/(ST_non_dominant_leg + ST_dominant_leg). A two-way repeated measures ANOVA was used to investigate interaction between effect of unilateral limb loading and the effect of different locomotor conditions on SLS and STS. The significant level was set at 0.05.

Results: There was a significant interaction between the effect of ankle loading and the effect of inclinations on SLS and STS (p < 0.0001). The post hoc results indicated that unilateral ankle loading caused the asymmetric walking pattern when walking on the level and inclined treadmill but not on the declined treadmill. This phenomenon could be explained by that participants increased their active control of lower leg during declined treadmill walking to eliminate the effect of unilateral ankle loading by reducing the step length and step time.

Conclusions: Walking on the declined surface could induce a higher level of active control than walking on level and an inclined surface.

Clinical Relevance: To our best knowledge, this is the first study to demonstrate that walking on the declined surface eliminated the asymmetric walking pattern in young adults. It has been shown that training patients with stroke on a split-belt treadmill reduced their asymmetric walking pattern during overground walking. However, this learning effect disappeared after approximately ten strides or less due to different levels of active control. The current result illustrates the possibility of training on the declined treadmill to regain symmetric walking pattern in patients who walk asymmetrically.