Jumping Mechanics

In some disciplines modern sports horse are required to jump obstacles. Jumping requires the horse to raise its centre of mass high enough for all of its body parts to successfully clear the height and width of a fence. The jump should be viewed as an increased part of the suspension phase or an elevated canter stride as it occurs between the stance phase of the fore and hind limbs, for this reason jumping is mostly performed whilst cantering. The aim of jumping is to maintain rhythm and balance to encourage a good shape, bascule, over the obstacle. Various fence types are encountered whilst competing which require different riding techniques, though for all the main focus should be on the rhythm and balance of both horse and rider.
 

The jumping process is broken down in to five sections,

• Approach
• Takeoff
• In flight/suspension
• Landing
• Getaway

The last stride before take off tends to be a shorter than the previous stride, the neck is stretched forward and downward in preparation for the take off. This is to help lower the horses' centre of mass. The forelimbs are stretched forward and initiate the upward movement, then the horse is propelled into the air by the hind limbs which have a large stance phase allowing them to generate large impulses of power.



The airborne phase is larger than the initial departure or landing stride according to the width and height of the fence. Once the horse has taken off the body and limb segments are coordinated so that the angular velocity of the trunk remains constant. The fore legs should tucked up in to the under carriage with the hind quarters generating the power. It is widely thought that the rider has limited affect on this angular velocity. However the rider affects the way in which the horse meets the fence which can influence the take off phase. The rider should aim to be in balance with the horse throughout the jumping phases. A poorly balanced rider on take off can be the cause of faults.

The landing and departure strides are as important as the other phases. When the horse lands the leading forelimb is exposed to high forces which can be the cause of mechanical injuries to the tendons and joints. Research has shown that the trailing forelimb has the highest peak forces for both take off and landing, which may explain why some horses have a preferred landing leg or canter strike off. Horses that exhibit signs like this may have a sub clinical lameness or a marked strength asymmetry between their left and right side (Clayton 2000), which can be identified with the Equinalysis system.