Golfers do not respond to changes in shaft mass properties in a mechanically predictable way

A common belief in the golf community is that a lighter shaft allows the golfer to swing the club faster. From a mechanical point of view, reducing the mass of the shaft would result in a faster swing. However, a golfer is not a purely mechanical system, and so it is simplistic to assume that identical loads will be applied when swinging different clubs. Therefore, the purpose of this study was to test the hypothesis that golfers behave similar to a mechanical model when swinging clubs of varying mass. A torque driven model estimated the effects caused by the addition of 22?g to the shaft. Twelve golfers hit balls with a standard driver as well as a driver fitted with the same 22?g increase in mass. Club kinematics were collected with a high-speed motion capture system. The model predicted a 1.7?% lower club head speed for the club with additional mass. One subject showed a similar reduction (1.4?%), but one subject showed an increase in club head speed by 3.0?%. Ten subjects did not show any significant differences. These results suggest that golfers do not respond to changes in club mass in a mechanically predictable way.