Revealing the mechanism of high loading capacity of the horse in leg structure

To reveal the mechanism of high loading capacity, the characteristics of the mammalian leg skeletal structure are analyzed, and the horse is chosen as a typical example. The supporting situations of horse standing are presented, including the symmetrical case and the unsymmetrical one. According to the results of animal anatomy, the skeletal structures of the forelimb and the hind limb are appropriately simplified to plane open-chain five-link mechanisms. The force analyses of the five-link mechanisms are presented to explore the variations of joint moments in two aspects: changing the direction of the ground reaction force and changing the posture of the leg. It is concluded that the dead-point supporting effect of the leg skeletal structure help improve the high loading capacity. It means that horses bear loads mainly by bones rather than muscles. Hence horses could carry high loads with little energy consumption of leg muscles.