Fig. 4. The relationship between the total mitochondrial volume of skeletal muscle [V(mt,m)/M_b] and maximum aerobic capacity _O2max in a series of mammalian species. Values for red kangaroo and human are indicated. The values for human and other placental species are from Hoppeler (1990); value for red kangaroo is from Table 4. The addition of the red kangaroo data to the quadruped data does not significantly change the relationship between _O2max and V(mt,m)/M_b.