Motor adaptation during slip-perturbed gait in older adults

[Purpose] The purpose of this study was to investigate adaptations to slip perturbations using a customized separated-belt treadmill in older adults. [Subjects] Forty-five healthy older subjects participated in this study. [Methods] Participants were requested to continue to walk against 20 slip perturbations during a 5-minute period. The magnitudes of the reactive responses were evaluated with the use of a tri-axial accelerometer attached to the subject's pelvis. Also, the latency to the onset of EMG activity and the magnitude of EMG activity were measured using surface electrodes placed on both sides of the erector spinae, rectus abdominis, biceps femoris, vastus medialis (VM), gastrocnemius medialis (GM), and tibialis anterior muscles. [Results] The magnitude of the reactive response in the second half of the perturbed walk was significantly more decreased than during the first half (p < 0.01). Decreases in the magnitude of EMG were also observed from VM and GM muscles (p < 0.01, p < 0.05, respectively), but the latency of each of the muscles was unchanged. [Conclusion] In conclusion, adaptations that may have contributed to the prevention of falls occurred in older adults. These adaptations might have been accomplished by a change in magnitude of muscle activity rather than by a change in timing.