Energy cost of bipedal running.

FEDAK, MICHAEL A., BERRY PINSHOW, AND KNUT SCHMIDTNIELSEN. Energy cost of bipedal running. Am. J. Physiol. 227(5): 1038-1044. 1974.-This study compares the energy cost of running in twoand four-legged animals. In seven species of birds (0.04-22 kg) steady-state oxygen consumption during running at various speeds increased linearly with running speed. The slope (Eru;> of the regression line was a constant for each species, but smaller birds had a steeper slope than larger birds (as previously reported for mammals). brun values for two-legged and fourlegged runners plotted on logarithmic coordinates against body weight fall along two different straight lines. E,,, decreases more rapidly with body weight in four-legged than in two-legged runners. The lines cross at about 1 kg body wt. Thus, for small body size ( < 100 g) the predicted cost of transport is significantly less for two-legged than for four-legged runners. For large body size (>5 kg) theo pposite is true. For an animal the size of man, twolegged running is energetically over twice as expensive as fourlegged running.