ABSTRACT
The ability to drive the ball a long distance is a common goal among golfers, and often assumed to be highly dependent on physical size and strength. Hidemichi Tanaka, a well-known Japanese professional golfer, has repeatedly demonstrated this ability, in spite of his small stature. This study was designed to examine factors that may contribute to Tanaka’s ability to achieve this goal. EMG activity, vertical ground reaction forces (VGRF), and video records were taken in order to analyze muscle firing and weight transfer patterns, across multiple trials.
The results indicated that the muscles of the back leg initiated the downswing before the upper body reached the top of the swing. During the downswing there was minimal muscle contraction of the upper body musculature until the left arm reached a horizontal level. Interestingly, at that time total VGRF from both feet decreased to almost half of the subject’s weight. From that point, leg muscle activation preceded left shoulder muscle activation, through ball contact. VGRF varied substantially and reached a peak at ball impact that was 184 percent of bodyweight. The right upper body musculature, with the exception of the pectoralis major and rectus abdominis, did not largely contribute to the swing until the impact. This study demonstrates that the efficiency of Tanaka’s swing for a long drive, appears to be related to a sequential activation of muscle groups that optimizes transfer of momentum throughout the kinetic chain. Further, the end result of a requisite high club head velocity can be achieved in spite of a small body mass.
