Relationships between spatiotemporal and kinematic domains during treadmill gait change across adulthood.

Abstract

Spatiotemporal and kinematic variables during gait undergo characteristic changes with aging. However, the relationships between these domains, and how these change with aging, have not been extensively investigated. How does age affect relationships between spatiotemporal and joint/segment range-of-motion variables during treadmill gait? In this cross-sectional study, a motion capture system tracked 60 participants (20-80 years old), walking at self-selected and slow speeds on a treadmill. Spatiotemporal (step length, width, time, velocity) and range-of-motion (ankle, knee, hip, pelvis, trunk) variables were extracted from 50 steps at each speed. Mixed-effects models were used to quantify relationships between spatiotemporal variables and age, range-of-motion, and interactions between age and range-of-motion. Significant relationships with range-of-motion were found for some spatiotemporal variables; the direction of the relationship was most often positive, with several negative relationships. Significant interaction effects were observed for several pairings (ankle range-of-motion-step length, ankle range-of-motion-step velocity, hip range-of-motion-step velocity), with stronger relationships between spatiotemporal and range-of-motion variables as age increased. Stronger relationships at both the ankle and hip in older adults may suggest that older adults rely more on motion at these joints, and constrain other degrees-of-freedom, in an attempt to maintain gait velocity for successful task execution and/or safety on the treadmill. This study statistically quantifies the effects of age on the relationships between spatiotemporal and kinematic domains while accounting for stride-to-stride variations during gait, which provides insight into the control of spatiotemporal variables in healthy individuals across adulthood, and may inform strategies for identifying gait dysfunction with aging.