The Importance Of Wrist Torque In Driving The Golfball (P6)
Every model is an approximation to the truth, with many variables being neglected that are judged or calculated to be of minor importance to the conclusions reached (Hubbard & Trinkle, 1984). The necessary level of complexity that one builds into a simulation model depends on the question under study. Alexander (1990, 1992) and Hubbard (1993) caution against the use of complex mathematical models whose results become impossible to interpret because of the large number of inextricably intertwined independent variables. From the general agreement of the results with those of a recognized elite professional golfer, it appears that a simple 2-D, three-segment model, using a single activation control strategy with specialized torque generators at the proximal ends, has sufficient modeling detail to predict the optimal timing necessary to achieve maximum clubhead speed at impact.
In recent years there has been conjecture (Jorgensen, 1994) as to whether a good golfer should actively uncock his wrists during the later stages of the golf swing, or whether the release of the clubhead should be allowed to occur naturally as a consequence of the centrifugal pull of the clubhead itself on the arm segment. From our simulation results it is clearly evident that significant gains in clubhead speed (~9%) can be achieved if muscular wrist torque is employed during the later stages of the downward swing just prior to impact. Optimizing the timing of the torque generators used in the model required the use of a proximal to distal muscular activation pattern if maximal clubhead speed was to be achieved.
The simulation results also supported the observation made by Jorgensen (1994) that any active muscular wrist torque must be delayed by the golfer until his/her arms are approximately 30° below a horizontal line through the shoulder joint. Any earlier activation of the muscular wrist torque resulted in a reduction in clubhead speed. Likewise, activation of the torque generators in an order different from proximal to distal resulted in a less than optimal performance as measured by clubhead speed. In fact, a simulation in which the joint torque generators were forced to turn on simultaneously at the start of the downswing produced a clubhead speed of only 30.5 m/s (~68 mph). This value equates to an approximate 30% reduction in clubhead speed from that produced when the timing was optimal.
The SIM-2 simulation condition clearly showed that it is possible to reach the desired impact position with the golfclub without using muscular wrist torque during the downward swing. This result lends support to the contention of such notable golfers as Bobby Jones who felt that during the swing, the club “freewheeled” through the ball (Jones, 1966). However, the simulation results for SIM-1 clearly show that the use of an optimally timed muscular wrist torque during the final phase of the downswing can produce gains of up to 9% in clubhead speed at impact. The implications for hitting the ball further are clear, since this increase in clubhead speed would correspond to an increase in ball speed off the tee of 4.9 m/s (~11 mph; Daish, 1972).