Use and Conserve of Energy by Running Animals Any muscle movements and physical activities require energy. The energetic cost is depends on body size, duration of activity, and speed.  Locomotion is more costly for smaller animals than larger animals relative to their body size. Smaller animals have to take more steps than larger animals for moving same distance Energy can be save in territorial movement in several ways. Small oxygen intake with long distance is more effective than large oxygen intake with short distance. 2 fundamental concepts for  energy conserving mechanism (Ishikawa et al., 2005) "Energy than is stored in the muscle can be used as both gravitational and kinetic energy (spring-like bouncing mechanism)." "Gravitational energy is converted as kinetic energy as legs are swing like pendulum-like mechanism."  Energy consumption is determined by measuring oxygen consumption or calories Larger oxygen and calories usage, more energy is consumed.

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