Golf players exhibit changes to grip speed parameters during club release in response to changes in club stiffness

The influence of golf club stiffness on driving performance is currently unclear, and it is possible that this ambiguity is due in part to golfer adaptation to equipment. The purpose of the current study was to elucidate mechanisms of adaptation to club stiffness, during the golf swing, by employing tendon vibration to distort proprioceptive feedback. Vibration (∼50 Hz, ∼1 mm amplitude) was applied to the upper extremities of 24 golfers using DC motors with eccentric weights. Golfers hit golf balls in a laboratory setting using three clubs of varying shaft stiffness, and club kinematics were recorded using high speed (180 Hz) digital cameras. The results demonstrated significant slowing of the club grip during club release for a high-stiffness shaft with vibration. This suggests that, when proprioceptive feedback is available, players adapt to changes in club stiffness by modifying the release dynamics of the club late in the downswing.