Fig. 4.

Effect of ankle restriction on ground reaction forces and power measures. (A) Vertical ground reaction force and (B) horizontal (fore–aft) ground reaction force versus stride time. (C) Instantaneous COM work rate (dot product of COM velocity with ground reaction force from one leg) versus time. Zero-crossings of COM work rate define collision, middle-stance and push-off phases of stride (CO, MS and PO, respectively). Middle-stance is an interval including both positive rebound and negative pre-load work (RB and PL). (D) Summed joint power (sum of ankle, knee and hip powers) versus time. Left-hand vertical axes show dimensionless units, and right-hand vertical axes show equivalent dimensional SI units. Data are trajectories averaged across subjects (N=8) walking at 1.40 m s⁻¹.