Ankle Pronation in High Jumping
by Jesús Dapena
(email: dapena@iu.edu)
This is a biomechanical explanation of the mechanism that can produce ankle pronation and ankle injury in high jumping.
After planting the takeoff foot on the ground, high jumpers push on the ground vertically downward, but also horizontally. The horizontal force that the foot makes on the ground during the takeoff phase points forward, almost in line with the final direction of the run-up, but usually it is also deviated slightly toward the landing pit.
Most high jumpers plant the takeoff foot on the ground with its longitudinal axis pointing in a direction that is not aligned with the final direction of the run-up nor with the horizontal force that the athlete is about to make on the ground. It is more parallel to the bar than either one of them. Since the horizontal reaction force that the foot receives from the ground is not aligned with the longitudinal axis of the foot, this force tends to make the foot roll inward.
In anatomical terminology, this rotation is called “pronation of the ankle joint”. It stretches the medial side of the joint, and compresses the lateral side of the joint. If the pronation is very severe, it can lead to injury of the ankle. It also makes the foot be supported less by the outside edge of the foot, and more by the forward-backward arch of the foot on the medial side. This could lead to injury of the foot itself. Therefore, in high jumping it is important to plant the takeoff foot well aligned with the final direction of the run-up, and definitely never parallel to the bar.
To download a movie showing ankle pronation during the high jump takeoff, please click here: Pronation MOV