Age-based comparison of gait asymmetry using unilateral ankle weights.

ABSTRACT

BACKGROUND: The locomotor system is proposed to be able to adapt to asymmetric conditions, which reflects the interaction between interlimb control and task constraints. However, this adaptability may be confounded by intrinsic differences between age groups. RESEARCH QUESTION What are the effects of mechanical asymmetry on kinematic symmetry in healthy younger and older adults? METHODS: Two groups of 10 participants (age 18-25 and 58-65 years) walked (3 km h -1) and ran (9 km h -1) on a treadmill normally, and with unilateral ankle weights (UW). Lower-body kinematic data was collected. Symmetry Index (SI) and bilateral cyclograms were used to evaluate spatiotemporal step-cycle characteristics and joint angles. RESULTS: Step-cycle characteristics were not significantly different between all comparisons. In running gait, asymmetry in range of motion (SI_RoM) of the knee and bilateral cyclogram minimum bounding box length (L) of the ankle was greater with UW compared to the normal condition. Ankle angle characteristics (SI_RoM ankle and minimum ankle angle) were more asymmetrical for older compared to younger adults, regardless of the UW condition. Interaction effects between age and UW were observed. In running gait, L knee and SI_RoM hip were greater with UW for younger adults, and smaller with UW for older adults. In walking gait, ankle angle at touchdown was greater with UW for younger adults, but smaller with UW for older adults. SIGNIFICANCE: For both age groups walking and running with UW, symmetry appears to be preserved in step-cycle characteristics, but not in joint angle measures. While adapting to unilateral perturbation, older adults show greater asymmetry in some ankle kinematic measures compared to younger adults while running, suggesting that some kinematic solutions are altered with age, while the majority of symmetry values about the lower limbs were not.