Estimation of the kinetic-optimized stimulus intensity envelope for drop foot gait rehabilitation

Abstract

The purpose of present study is to estimate the optimal stimulus intensity envelope for drop foot rehabilitation based on a kinetic perspective. The voluntary and electric-stimulated elicited dorsiflexion torque responses of 11 healthy subjects were measured. During dorsiflexion, we recorded the tibialis anterior (TA) electromyography (EMG) or the stimulation intensity at four angles of the ankle joint. From these measurements, we derived two approximate equations that estimate dorsiflexion produced by either voluntary contraction or by electrical stimulation using a sigmoid function and a stepwise-regression analysis. We then tested the predictive capability of the model using Pearson correlation. Both equations indicated high correlation coefficients. Finally, we derived a relation between the TA EMG amplitude and stimulation intensity. From the obtained equation, we determined the optimal stimulus amplitude. We assume that the derived stimulus intensity envelope, calculated from EMG amplitude and angle of ankle joint, satisfies kinetic demand.

Keywords::

• Functional electrical stimulation
• Tibialis anterior
• Ankle dorsiflexion torque
• Drop foot

Acknowledgements

The study was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No-2070046).

Declaration of interest: The authors report no conflicts of interest.