3-D MECHANICS OF THE WRISTS DURING THE GOLF SWING

Abstract

It is generally accepted that the wrists play a critical role during a golf swing. However the precise mechanics involved, and the subject-to-subject variations are not well understood. PURPOSE To determine and analyze the 3-D mechanics of the wrists during a golf swing for various subjects. METHODS A variable full-body computer model of a human was coupled to a flexible model of a golf club to model a golf swing. Data to drive the model were obtained from subject swings recorded with a motion analysis system. The subjects varied in gender, age, size and skill level. All subjects used the same club. RESULTS The computer analysis determined the six components of the paths, velocities, accelerations, and forces/torques of the wrists. In the swing plane, the paths of the wrists are not circular, but move in an ever decreasing radial arc (skill level dependent) to generate club centrifugal acceleration for optimum segmental velocity summation. Delayed wrist uncocking is a factor in generating club head velocity, however a retarding swing torque is not necessary to delay uncocking. The linear velocity profiles of the wrists were consistent among subjects. However, there were marked differences in the magnitude and shape of the club head linear velocity curves (43–51 m/s) with the better players able to generate higher velocities and peak closer to impact. The differences in velocities were primarily the result of swing angular velocities (1600–1950 deg/s), and roll angular velocities (625–1250 deg/s). The better golfers exhibited steeper, greater, and a later application of the roll torque (0.6–2.2 N-M) and swing torque (24–43 N-M). There was a correlation between skill level and the timing of the peaks and zeroes, and the smoothness of the kinematic and kinetic quantities. CONCLUSIONS The wrists play a critical role in the golf swing and in generating club head velocity. The timing of the movement of the wrists, the path of the wrists, and the magnitude and shape of the torques are all important factors. Subject-to-subject variations in wrist mechanics are significant with skill level apparent in many of these quantities. Supported by a grant from the USGA.