Effect of calf muscle fatigue on person identification using video sequences of body sway

Body sway, which is a slight movement that naturally occurs when a person stands, has attracted attention as an informative cue with which to identify people. In the field of kinematics, analytical studies have revealed that the movement of body sway varies when calf muscles are fatigued. However, the studies have not revealed whether the accuracy of identifying people is reduced by calf muscle fatigue. We investigate the identification accuracy for body sway signals taken from video sequences when fatiguing the target's calves. We find that the power spectral density of each frequency band of body sway is increased by fatigue and that the identification accuracy is significantly decreased. We also find that the magnitude of the velocity of body sway is greater in post-fatigue movement than in pre-fatigue movement.