  Previous research on unstable footwear has suggested that it may induce
plantar mechanical noise during walking. The purpose of this study was to
explore whether unstable footwear could be considered as a noise-based training
gear to exercise body center of mass (CoM) motion during walking or not. Ground
reaction forces were collected among 24 healthy young women walking at speeds
between 3 and 6 km h-1 with control running shoes and unstable rocker-bottom
shoes. The external mechanical work, the recovery of mechanical energy of the
CoM during and within the step cycles, and the phase shift between potential
and kinetic energy curves of the CoM were computed. Our findings support the
idea that unstable rocker-bottom footwear could serve as a speed-dependent
noise- based training gear to exercise CoM motion during walking. At slow
speed, it acts as a stochastic resonance or facilitator, whereas at brisk speed
it acts as a constraint.
