ABSTRACT
Several previous studies on golf swing analysis have focused on improving the performance of golfers and golf clubs. It is generally known that professional and expert golfers try to match shaft flexibility with their swing style, and that wrist turns in expert swings tend to appear as a “natural” or “late” release. Jorgensen (1970) obtained numerical solutions for the effect of a delayed wrist turn. Pickering & Vickers (1999) numerically show the effect of “natural release” and “late hit” using a two-dimensional rigid double pendulum model. These results suggest that delaying the wrist turn will enhance the club head speed at impact. Contrary to these reports, the results of the simulation performed by Springs & Mackenzie (2002) indicate that there is only a small advantage in employing the delayed release technique. However, this simulation employs an unrealistic resistive torque of the wrist to delay the wrist turn. The objective of this study is to demonstrate the effect of natural delayed release of the wrist in conjunction with utilizing shaft elasticity, which has not yet been studied. Thus, it is expected that the results of this study will contribute improving the performance of golfers and golf clubs by examining the relationship between the timing of the wrist turn and the shaft vibration. It is demonstrated that “natural release” with no acceleration torque at the shaft’s zero-crossing point for bending vibration and the “late hitting” can efficiently increase the head speed at impact. Furthermore, the skill of the wrist turn for a long drive is experimentally verified by measuring the movement of the wrist and the dynamic deformation of the shaft for various levels of golfers.
