Analysis of elite golfers’ kinematic sequence in full and partial shots (P1)
The purposes of the present study were, to determine if partial and full-swing shots performed by skilled golfers were organized in a proximal-to-distal sequencing (PDS) pattern and to examine the speed-summation effect at pelvis, upper torso and hand segments.
Three-dimensional kinematic recordings of pelvis, upper torso, and hand were made while forty-seven skilled golfers stroke three different clubs a range of submaximal and maximal shot distances.
This study showed a clear proximal-to-distal temporal relationship of movement onset and peak angular speed at the pelvis, upper torso and hand segments in the golf swing. The same temporal structure was evident at all test conditions, among different gender and level of expertise. Further, results revealed a summation effect of angular velocity from proximal-todistal, with each succeeding segment generating a larger rotational speed than the proximal segment. However, the increment in speed from proximal-to-distal was different among gender and level of expertise.
The temporal relation of segment kinematics suggests a common PDS organization in partial and full-swing shots for skilled golfers. A speed-summation effect of segmental angular speed indicates that participants did utilize interaction torques in a proximal-to-distal manner. The role of the observed PDS organization and speed-summation effect in partial shots might be to improve accuracy and, potentially, golfers should concentrate on speed initially in learning the golf swing.
Each shot in golf has two requirements – distance and direction. The speed of the club head centre immediately before ball contact is one of the main determinants of ball speed, and ultimately shot distance. Attempts to understand how this speed is generated can be divided into two major approaches. Double and triple pendulum planar models of the golf swing have been used to describe the kinematic and kinetic characteristics of the upper limb that result in a large clubhead speed at ball contact. More recently, the focus of several studies has been the transverse plane rotations of the pelvis and upper torso and their relationship with performance. Aspects of a proximal-to-distal sequencing (PDS) pattern has been observed in these studies as in most throwing and striking skills whose goals are to maximize speed in the most distal segment of an open-link system.
Typical for the kinematics of a PDS pattern is that proximal segments initiate rotation before the distal segments, and that proximal segments begin to slow down before the distal segments have reached peak angular velocity. An immediate mechanical reward for this strategy is that proximal muscle torques creates a dynamic foundation for the entire limb motion and beneficial interaction torques for distal joint rotations. What is important for maximizing speed is that utilization of the interaction torque enables larger joint angular velocity than the muscle torque can produce on its own. For a well-organized PDS motion, increments or carry-over effects of rotational velocity from the proximal to distal segments could be maximized.
Accomplished golf performance requires not only high ball speed but also accuracy. Skilled golf players are able to alter their swings to hit the ball accurately to different submaximal distances with the same club. In other motor skills it has been proposed that motions of different speeds are planned based upon keeping some features invariant in order to reduce storage and computational costs in the central nervous system (CNS). One widely acclaimed invariant feature of movement is relative timing. Abernathy et al examined temporal aspects of swing kinematics in maximal and submaximal shots, but no evidence was found to suggest that subjects maintained the relative duration of subphases invariant across changes in total swing duration. The speed-invariant strategy, in which joint rotations of different speeds have the same joint angles and amplitudes but are scaled in time, has been observed in relatively slow two-joint planar movements. Considering that skilled golf players previously have been found to increase the range of joint motions to hit the ball further, appearance of the speed-invariant strategy in a well-coordinated golf swing is not likely.
Although PDS primarily is associated with mechanical rewards when the speed requirement is high, this temporal order has also been found in relatively slow (peak velocity of the hand 0.3–0.8 m·s-1) multi-joint movements of skilled individuals. It has recently been implicated that PDS can improve accuracy in multi-joint movements of different speeds. Hirashima et al. demonstrated that skilled ball-throwers increase ball speed by increasing beneficial interaction torques at the shoulder, elbow and wrist. This was done by regulating muscle torque at the shoulder and trunk but not at the elbow and wrist. It was concluded that this strategy can be helpful to minimize the consequences of signal-dependent noise in motor command (for review, see Faisal et al. 200820).
Proximal-to-distal sequencing may be important for meeting the mutual requirements of speed and accuracy in golf. However, no research to date have demonstrated whether PDS is a common characteristic in partial and full-swing shots of skilled golf players. The purposes of the present study were, therefore, to determine if the golf swing performed by skilled golfers was organized in a PDS pattern when hitting golf shots to maximal and submaximal distances, and to examine the speed-summation effect (in terms of increment of the peak segmental angular velocity) at pelvis, upper torso and hand segments.