Fig. 6. Instantaneous COM mechanical work rate for each leg over one complete step, measured with arcs of different radii. The trailing leg performed positive work and the leading leg negative work to redirect the COM during the step-to-step transition. Leading leg negative work rate was highest in magnitude for small-radius arcs. Work rate magnitudes decreased with increasing arc radius for the leading leg during double support, and through most of single support. Average rate of negative work was computed by integrating the magnitude of negative regions of instantaneous work rate (shaded areas for 0.40 m arc) and dividing by step period. Data shown are averaged from all subjects and plotted over the mean step period. Blue and green traces indicate work rate of the trailing and leading leg, respectively.