Fig. 5

a The foot progression angle (FPA) is defined as the angle between the line from the calcaneous to the second metatarsal and the line of progression averaged from heel strike to toe off during the stance phase of walking for each step (toe-in angle is positive and toe-out angle is negative). b Participants were trained to walk with a new gait by adjusting their FPA to fall within the no feedback zone. Medial vibrotactile stimulus was given when FPA was greater than the inward threshold, lateral vibrotactile stimulus was given when FPA was less than the outward threshold, and no stimulus was given when FPA was between the two thresholds