Fig. 12. Increase in metabolic rate due to distal limb loading in walking and running mammals and guinea fowl. The data were calculated by subtracting the loaded metabolic rate from the unloaded metabolic rate and dividing by the mass of the added load. Closed circles, walking and running humans (Soule and Goldman, 1969; Jones et al., 1984; Martin, 1985; Miller and Stamford, 1987; Claremont and Hall, 1988; Bhambhani et al., 1989). Open squares, trotting dogs (Steudel, 1990a). Open triangles, trotting horses (Wickler et al., 2004). Horse data were calculated from original data provided by S. J. Wickler (personal communication).