The Importance Of Wrist Torque In Driving The Golfball (End)
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).
Prior to the current study, simulation studies of the golf swing have not incorporated the force-velocity property of muscle into their model’s torque generators. Our results have shown that such an omission will adversely affect the measured optimal timing pattern of segment involvement. Without the constraint imposed by the force-velocity property of muscle, the shoulder and wrist torque generators will be activated earlier in the down swing to take advantage of the additional angular impulse that can be produced by torque output profiles that rise asymptotically to a maximum. The three-segment model used in our study was able to use realistic magnitudes of muscular torques to generate clubhead speeds that are reflective of good golfers. The maximum values for the torques generated by the torso, shoulder, and wrist joints during either SIM-1 and SIM-2 simulation conditions (Figures 3 & 5) were 109 Nm, 96 Nm, and 18.5 Nm, respectively, which agree favorably with the upper values of torque (110, 90, and 30 Nm) measured directly from a of a low handicap amateur golfer using inverse dynamics (Neal et al., 1999).
In comparison, the peak torque values of 339 and 191 Nm reported by Campbell and Reid (1985) for the torso and arm segment generators in their 3 segment model appear to be unrealistically high for a golf swing. Similarly, constant torque values of 200 Nm for the shoulder joint, as used by Lampsa (1975), would appear to be well beyond any golfer’s physical capabilities. Of course with a two-segment model, such as the one used by Lampsa, unrealistically high shoulder torques have to be employed in the simulation model if clubhead speeds at impact are to reach values known to be attainable by good golfers.
One of the obvious disadvantages of two-segment models is that they cannot examine the importance of the torso in generating clubhead speed. The results produced from our three-segment model clearly showed that, for optimal performance, it was the active counter-clockwise rotation of the torso that initiated the downward sequence of the swing. When an active wrist torque was employed by the model, the magnitude of angular displacement that the torso rotated through to impact, increased. It was this strong rotation of the torso segment that was observed to be directly linked to the delay in the uncocking of the wrists that good golfers seek during the downswing.
In conclusion, our simulations have shown that a properly timed wrist torque applied by the golfer to the club’s handle can produce gains of up to 9% in clubhead speed. Our simulation results also show that while muscular wrist torque is desirable for maximizing clubhead speed at impact, it is not a necessary requirement for aligning the clubshaft to the desired vertical position for impact.