Lateral body center of mass sway during self-paced versus fixed speed treadmill walking
Treadmill walking has been commonly used for gait training and is a safe and effective approach to assist older adults to improve balance and mobility outcomes. Recent development of self-paced treadmill controllers allow for variations in walking speed and offers the opportunity to better emulate overground walking while on a treadmill. However, how self-paced treadmill condition affects lateral balance stability during walking remains unclear. The primary purposes of this study were to (1) determine whether lateral body center of mass (COM) sway was different between self-paced and fixed speed treadmill conditions in older adults, and (2) identify potential sagittal and frontal plane gait characteristics that predict changes in body lateral sway across treadmill conditions. Seventeen healthy older adults walked at their preferred walking speeds on the fixed speed (FS) treadmill condition and the self-paced (SP) treadmill condition. Our results showed that older adults increased lateral COM sway during the SP condition compared to the FS condition (p < 0.01). In addition, this increase in the lateral COM sway was predicted by changes in medial ground reaction force (β = 0.57), step width (β = 0.39), and anterior-posterior center of mass sway (β = 0.3). These results indicated that walking with adaptive belt speed treadmill affected frontal plane stepping biomechanics that were associated with lateral stability. Findings may provide important information for gait rehabilitation strategy designs that consider adopting self-paced treadmill training for older adults.