The Time-dependent Changes in EMG Recorded from the Medial Gastrocnemius of Young and Elderly Amputees

[Purpose] Dysfunction of lower extremity muscles is one risk factor of falls for amputee patients. However, the change in muscle activity pattern and balance ability of amputees who have no experience in standing with prosthesis during the period from prosthesis fitting to regaining the ability to walk has never been studied. Therefore, the objectives of the present study were to elucidate changes over time in the muscle activity pattern and walking speed from first prosthesis fitting to hospital discharge. We also investigated the differences of muscle activity during standing between younger and elderly amputee patients. [Methods] Electromyography measurements were performed on the gastrocnemius of the intact leg during standing. The test subjects were asked to shift their center of gravity forward. [Results] Two unique patterns of gastrocnemius activities were observed over time. In a younger patient, the amount of muscular activity of the gastrocnemius gradually increased over time. In an elderly patient, however, the amount of muscular activity of gastrocnemius gradually decreased over time. [Conclusion] The time-dependent changes in gastrocnemius muscle activities are indicative postural control ability. Therefore, understanding the time-dependent changes in muscle activities during rehabilitation and the differences of postural control between younger and elderly patients would contribute to the development of effective rehabilitation programs for each patient.