Fig. 4. Combined summary results for four walking dogs over a range of speeds. Solid outlines relate to the left axis [compression ratio (CR)] and represent the observed fluctuations in potential energy as a proportion of those calculated from stiff-limbed 4-bar linkage geometry. Symbols with grey outlines relate to the right-hand axis [energy recovery (ER)] and represent the effectiveness of `energy interchange' between kinetic and potential energies (1 being perfect). Lines show quadratic fits.