Fig. 5. Ratio of lipolytic rate (R_a glycerol) over metabolic rate (_O2) for vertebrates measured to date. Values correspond to vertebrates at rest and during exercise at equivalent intensities (40–70% _O2,max), except for birds, where only data for shivering are available (Vaillancourt and Weber, 2007). Ratios were calculated from the following studies: rat (McClelland et al., 2001), goat (Weber et al., 1993), dog (Issekutz et al., 1967; Issekutz et al., 1975), human (Wolfe et al., 1990), ruff sandpiper (Vaillancourt and Weber, 2007) and trout [present study and Bernard et al. (Bernard et al., 1999) using _O2 values from Burgetz et al. (Burgetz et al., 1998)]. The broken line shows the calculated average ratio for resting and exercising endotherms (0.016).