Kinematics of the take-off phase in barefoot water ski jumping

The purpose of this study was to objectively examine the jumping technique of a group of skilled barefoot water ski jumpers in order to identify the kinematic factors which distinguished between a highly successful jump and a less successful jump. The jumping technique of each subject was filmed during the 1987 Australian Barefoot Water Ski Championships. Results indicated that to jump effectively and safely the barefoot water ski jumper should concentrate on initiating leg extension approximately 2 m before contact with the ramp and continue to push against the ramp in order to maintain an extended body position throughout the jump. This extension allowed the utilisation of the take-off angle and consequent vertical velocity generated by the slope of the ramp, provided the inclination of the trunk and shank were maintained as close to perpendicular to the ramp as possible. Less skilled barefoot water ski jumpers who closed the angle of the hips and delayed or mistimed extension until contact with the ramp were not able to withstand the "crushing" of the body imparted by the slope of the ramp, and placed themselves in a potentially dangerous position where over-rotation into the ramp was possible.