Cavagna G A, Heglund N C, Taylor C R
Am J Physiol. 1977 Nov;233(5):R243-61. doi: 10.1152/ajpregu.1977.233.5.R243.
The work done during each step to lift and to reaccelerate (in the forward direction) and center of mass has been measured during locomotion in bipeds (rhea and turkey), quadrupeds (dogs, stump-tailed macaques, and ram), and hoppers (kangaroo and springhare). Walking, in all animals (as in man), involves an alternate transfer between gravitational-potential energy and kinetic energy within each stride (as takes place in a pendulum). This transfer is greatest at intermediate walking speeds and can account for up to 70% of the total energy changes taking place within a stride, leaving only 30% to be supplied by muscles. No kinetic-gravitational energy transfer takes place during running, hopping, and trotting, but energy is conserved by another mechanism: an elastic "bounce" of the body. Galloping animals utilize a combination of these two energy-conserving mechanisms. During running, trotting, hopping, and galloping, 1) the power per unit weight required to maintain the forward speed of the center of mass is almost the same in all the species studied; 2) the power per unit weight required to lift the center of mass is almost independent of speed; and 3) the sum of these two powers is almost a linear function of speed.
在两足动物（美洲鸵鸟和火鸡）、四足动物（狗、短尾猕猴和公羊）以及跳跃动物（袋鼠和跳兔）的运动过程中，已经测量了在每一步中提升、重新加速（向前方向）以及质心所做的功。在所有动物（包括人类）的行走过程中，每一步都涉及重力势能和动能之间的交替转换（就像钟摆一样）。这种转换在中等行走速度时最大，可占一步中总能量变化的70%，仅30%的能量由肌肉提供。在奔跑、跳跃和小跑过程中不发生动能与重力能的转换，但能量通过另一种机制得以守恒：身体的弹性“反弹”。飞奔的动物利用这两种节能机制的组合。在奔跑、小跑、跳跃和飞奔过程中，1）在所研究的所有物种中，维持质心向前速度所需的单位体重功率几乎相同；2）提升质心所需的单位体重功率几乎与速度无关；3）这两种功率之和几乎是速度的线性函数。
