Running in cheetahs, gazelles, and goats: energy cost and limb configuration.

BAHARAV, AND ARIEH BORUT. Running in cheetahs, gazelles, and goats: energy cost and limb conjguration. Am. J. Physiol. 227(4) : 848-850. 1974.-Functional anatomists have argued that an animal can be built to run cheaply by lightening the distal parts of the limbs and/or by concentrating the muscle mass of the limbs around their pivot points. These arguments assume .that much of the energy expended as animals run at a constant speed goes into alternately accelerating and decelerating the limbs. Gazelles, goats, and cheetahs offer a nice gradation of limb configurations in animals of similar total mass and limb length and, therefore, provide the opportunity to quantify the effect of limb design on the energy cost of running. We found that, despite large differences in limb configuration, the energetic cost of running in cheetahs, gazelles, and goats of about the same mass was nearly identical over a wide range of speeds. Also, the observed energetic cost of running was almost the same as that predicted on the basis of body weight for all three species: cheetah, 0.14 ml 02 (g l km)-’ observed vs. 0.13 ml 02 (g *km)-l predicted; gazelle, 0.16 ml 02 (g *km)-’ observed vs. 0.15 ml 02 (g *km)-’ predicted; and goat, 0.18 ml 02 (g . km)-’ observed vs. 0.14 ml 02 (g *km)-’ predicted. Thus the relationship between body weight and energetic cost of running apparently applies to animals with very different limb configurations and is more general than anticipated. This suggests that most of the energy expended in running at a constant speed is not used to accelerate and decelerate the limbs.