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Keywords: Ground reaction force; take-off; jump; hind limb; horse EN Ground reaction force take-off jump hind limb horse S516 S518 3 01/29/21 20191002 NES 191002 1. Ground reaction force, take-off, jump, hind limb, horse. [Extracted from the article]

The ability to jump over an obstacle depends upon the generation of work across the joints of the propelling limb(s). The total work generated by one hind limb of a horse and the contribution to the total work by four joints of the hind limb were determined for a jump. It was hypothesized that the hip and ankle joints would have extensor moments performing positive work, while the knee would have a flexor moment and perform negative work during the jump. Ground reaction forces and sagittal plane kinematics were simultaneously recorded during each jumping trial. Joint moment, power and work were determined for the metatarsophalangeal (MP), tarsal (ankle), tibiofemoral (knee) and coxofemoral (hip) joints. The hip, knee and ankle all flexed and then extended and the MP extended and then flexed during ground contact. Consistent with our hypothesis, large extensor moments were observed at the hip and ankle joints and large flexor moments at the knee and MP joints throughout ground contact of the hind limb. Peak moments tended to occur earlier in stance in the proximal joints but peak power generation of the hind limb joints occurred at similar times except for the MP joint, with the hip and ankle peaking first followed by the MP joint. During the first portion of ground contact (≈40%), the net result of the joint powers was the absorption of power. During the remainder of the contact period, the hind limb generated power. This pattern of power absorption followed by power generation paralleled the power profiles of the hip, ankle and MP joints. The total work performed by one hind limb was 0.71 J kg-1. Surprisingly, the knee produced 85% of the work (0.60 J kg-1) done by the hind limb, and the positive work performed by the knee occurred during the first 40% of the take-off. There is little net work generated by the other three joints over the entire takeoff. Velocity of the tuber coxae (a landmark on the pelvis of the animal) was negative (downward) during the first 40% of stance, which perhaps reflects the negative work performed to decrease the potential energy during the first 40% of contact. During the final 60% of contact, the hip, ankle and MP joints generate positive work, which is reflected in the increase of the animal's potential energy. [ABSTRACT FROM AUTHOR]

The dynamics of the hind limbs of the horse and dog at walk are compared. The kinematics were studied by electromyography of animals walking on a moving belt, and by cinephotography in horses walking on the ground and in dogs walking on a moving belt and on the ground. This study reveals that: 1) the retraction of the hoof or foot relative to the hip at the end of the support phase is less in the horse than in the dog; 2) the change in the sense of the movements of the hind limb segments at the end of the support phase and at the beginning of the swing phase occurs earlier in the horse (55-60% of the cycle of a stride) than in the dog (70%); 3) in neither species is there activity in the retractor muscles of the hind limb at the end of the support phase, so that the push-off is effected by the dynamic effect of the load (gravity) and the elastic resilience of the retractor muscles; 4) in the horse, the cannon passes bevond the vertical and makes it necessary to bring the cranial tibial muscle into action to prevent overextension of the hock joint; in the dog, the metatarsus remains in an approximately vertical position and the superficial digital flexor muscle remains active throughout the support phase; 5) at placing, the moment of F(Fig. 1) about the foot provokes a tensile strain on the plantar aspect of the tibia and a compressive strain on its dorsal aspect: the action of the gastrocnemius muscle centres the line of action of the load on the tibia in this phase; 6) at the end of the support phase, the relatively greater moment of Fabout the hoof of the horse makes it necessary to bring the cranial tibial muscle into action to centre the line of action of the load on to the tibia; 7) the tendinous interosseous and superficial digital flexor muscle of the horse store elastic energy at impact and use this energy to stretch the peroneus tertius tendon, the energy ultimately being used to flex the hock at lifting; the superficial digital flexor and the peroneus tertius tendons coordinate the movements of stifle and hock during the swing phases; all the components mentioned save energy: the horse is an animal built for great stamina; 8) in the dog, the analoga of the aforementioned tendons are muscular; consequently the dog is able to dig its digits and claws into the ground for a strong grip and great friction: the digitigrade dog is adapted and for great speed. [ABSTRACT FROM AUTHOR]

The locomotor pattern of the hind limb of seven horses has been studied in intact animals and after transection of the following structures: the peroneus tertius tendon, the cranial tibial muscle, both cranial tibial muscle and peroneus tertius tendon, and the superficial digital flexor tendon. The investigation was carried out by high speed cinematography and electromyography. It is concluded that (1) the muscles and tendons over the cranial aspect of the tibia play an important role during the support phase; (2) the movements of the hind limb may be performed without the action of the cranial tibial and gastrocnemius muscles; (3) the tendons in the shank store elastic energy during the support phase; (4) the gastrocnemius and cranial tibial muscles may centre the force of the load through the long axis of the tibia. [ABSTRACT FROM AUTHOR]

The movements of the right hind limb of horses with normal locomotion were studied using cinephotography and electromyography. A model of the cycle of a stride in the walk and the trot was constructed and the kinetic parameters of the segments of the limb were calculated. A good correlation was obtained between the kinetics and the periods of the cycle of a stride during which individual muscles display activity. The results of this study demonstrate that: [ABSTRACT FROM AUTHOR]

A mare was presented with lameness in left hind limb. Radiographic examination of fetlock revealed presence of numerous radiolucent areas along the planter aspect of sesamoid bones, but only minimal new bone formation on its base. Antiinflammatory drugs, antibiotics and nervine tonics were administered for five days with medium blister application along with rest. Later examination showed recovery with no lameness and animal was put on increasing exercise program till complete recovery. [ABSTRACT FROM AUTHOR]

The article looks at a comparison between vertical impulse and vertical force in hind limbs of horses circling at trot and canter. Topics include lameness' impact on the horses' limbs, dynamometric horseshoe (DHS) composed of triaxial piezoelectric force sensors, and the use of Linear regression models. Also included are details on Fonds Eperon, FEDER, and IFCE's support to the performing research on horses financially.