Innovative advances in rehabilitation technology have created a split-belt treadmill capable of providing a much needed intervention aimed at limiting mobility disability. When desynchronized, the split-belt treadmill imposes demands on each leg such that the central nervous system must adapt to the challenge. Based on preliminary data from our lab utilizing the split-belt treadmill, the investigators hypothesize this intervention can challenge the locomotor processes required for safe, efficient gait while concurrently providing an aerobic stimulus will produce favorable changes in physical function in older adults at risk for mobility disability.