Fig. 2. Mean ground reaction force (GRF) data for steady-speed hopping (gray) and jumping (black). (A) The GRF vector is shown relative to the rock wallaby's average body position, leg angle (broken line) and estimated CoM position during stance. (B) Mean GRF recordings in body weights (BW) plotted against percent of stance. (C) Vertical and horizontal stance impulses. Horizontal impulses are divided in to negative (–), positive (+) and net (patterned bars) impulses. Dotted lines (B) and error bars (C) indicate S.E.M.