Fig. 4. Rectified electromyographic (EMG) signals (after 7 Hz high-pass filter) versus time [normal walking, walking with the leg swing assist (LSA) device] for the rectus femoris (RF) muscle for a representative subject. Vertical dashed lines indicate heel strikes and toe-off for the right leg. Black horizontal bars show the portion of the stride analyzed (between 50–85%). The bar graph on the right depicts mean muscle activity (± s.e.m.) for the burst during swing initiation for all subjects while walking normally (white) and walking with the LSA device (grey). The asterisk denotes a significant difference compared to normal walking (P=0.006).