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 produces compression in 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 longitudinal (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 movies showing ankle pronation during the high jump takeoff, click below. (These movies were obtained from a high-speed videotape taken during the 1988 International Golden High Jump Gala competition in Genk, Belgium by Dr. Bart Van Gheluwe.)
Negligible pronation AVI (14.4 MB)
Extreme pronation #1 AVI (3.0 MB)
Extreme pronation #2 AVI (17.5 MB)
Please take into account that these movie files are quite large. If you do not have a fast connection, they will take a long time to download.
Last updated: December 2000
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