Joint angle based motor point tracking stimulation for surface FES: A Study on biceps brachii

•A hypothesis is proposed and proven that stimulation efficiency associated with surface FES can be improved by optimizing electrode positions to target the motor point (MP).•Motor point tracking stimulation based on joint angle is proposed based on the relationship between joint angle and MP shift.•Preliminary experimental results on healthy subjects suggest that MP tracking stimulation based on joint angle is effective for the sustainable induction of muscle contraction.•Both tracking selectivity and tracking density are shown to be important factors for improving stimulation efficiency.