Surface EMG analysis of tibialis anterior and gastrocnemius activity under different loading positions

Achilles tendon rupture is a common injury during sports activities. In physiotherapy for Achilles tendon ruptures, repair of the tendon must take priority. In addition, because it is necessary to provide proper traction load during the treatment process, it is important to clarify the effect to Achilles tendon by physiotherapy, which is muscle strengthening, stretching and o on. The purpose of this study was to examine the effects of different loading amounts and loading positions on the muscle activity of the ankle plantar flexors and dorsiflexors with a fixed ankle dorsiflexion angle. The ankle joint of the participants was fixed with non-stretch cotton tape so that the ankle joint angle was at 0 degree of dorsiflexion. Surface electromyography of the lower limb muscles was recorded during standing position changed the loading positions and the loading amount. The result, muscle activity in the tibialis anterior was increased by loading to the rearfoot, and that muscle activity in the gastrocnemius was increased by loading to the forefoot. Therefore, it was shown that even if the ankle joint is fixed, muscle activity of the ankle plantar flexor muscle group increases during forefoot loading motion. These results also suggest that in physiotherapy after Achilles tendon rupture, there is a risk of increasing the traction load on the Achilles tendon depending on the loading position, even for partial weight-bearing when the ankle joint is fixed.