The effectiveness of equipment optimization, with regards to shaft stiffness of golf clubs, is questionable. Many players do not exhibit any effect of shaft stiffness on performance, despite the large mechanical influence of the shaft. Based on this counter-intuitive result, it is hypothesized that players are able to sense and adapt to the changes in their equipment. To test this hypothesis, the current research employed tendon vibration to mask sensory feedback from proprioceptors in the upper extremity during a golf swing. It was found that, under these conditions, 46% of players exhibited shaft-specific kinematic changes in their swings. Their swing kinematics revealed systematic changes in peak grip speed, during club release, in response to shaft stiffness. An attempt was made to characterize those players that exhibited shaft-specific changes from those that do not in terms of their sensitivity to external loads;​ however, no distinction could be made between the groups. These findings are discussed in terms of the golf swing, motor control theory, and their implications for the future of equipment optimization.