McLaughlin, Patrick (2008) Kinematic and centre of pressure (COP) parameters in golf putting. PhD thesis, Victoria University.

Abstract

The aims of the present study were to: develop a portable and reliable fieldbased system for assessment of centre of pressure movement during the putting task; identify different putting techniques used by experienced golfers; identify the relationship between handicap and putting performance; identify the relationship between putting performance and putting stroke kinematics; identify the relationship between putting performance and movement of the centre of pressure; and to assess the effect of a 3 week balance biofeedback training program on subsequent putting performance and centre of pressure movement during the putting task. In order to enable data collection to occur on the golf course, a portable rubber mat containing 256 individual capacitance pressure sensors (novel pliance®, Munich, Germany) was validated for standing COP output against an AMTI force platform. Assessment of the equality of the output from both systems was assessed using the non-central F test. The peak-to-peak amplitude of movement of COP data in the medio-lateral (COPx, p=0.023) and antero-posterior (COPy, p=0.023) directions were found to be significantly the same. In-field testing required each participant (n=38) to complete five putts at a hole 4m away, and five putts at a hole 8m away. Testing was conducted on the practice putting green of a private golf course. The result of each putt was assessed by recording the distance the ball finished from the hole, as well as other descriptors of direction (left, right, centre) and length (short, long, holed out). Participants (n=38) completed these putts whilst standing on the previously validated mat. Video of each putt was recorded using a 50Hz video camera located perpendicular to the line of the putt. The video was later used to track the path of the putter head. The movement of the putter head was used to establish the key events and phases in the putting stroke – backswing, downswing, ball contact and follow through. Putting performance was assessed using exact putt result, absolute putt result and number of holed out putts. Players were initially grouped according to handicap such that there were low (0-9), middle (10-18) and high handicap groups (19-27). On putting performance, the low handicap group were significantly more likely to achieve a holed out putt at both the 4m and 8m putting tasks (p < 0.05). On the other measures some trends were evident but there were no significant differences between groups. In order to determine whether putting techniques existed, analysis of kinematic and COP data was completed using cluster analysis techniques. Ultimately, a two cluster solution was indicated as optimal for both tasks meaning there are two distinct putting techniques used by the golfers. At the 4m task these two putting techniques were identified as: 1. Less movement (relative to cluster 2) of COPx in the backswing and downswing phases with velocity of COPx at ball contact closer to zero (on average). Low COPx velocity. 2. Larger movement (relative to cluster 1) of COPx in the backswing and downswing phases with velocity of COPx at ball contact non-zero. High COPx velocity. In the 8m putting task, these two techniques were identified as: 1. Short, sharp with minimal COPx movements – a technique that involves comparatively smaller movements of the putter head and the COPx throughout the putting stroke relative to cluster 2. Velocity of the COPx at ball contact is minimal but is a heterogeneous mixture of movements away and towards the hole. Low motion. 2. Long, slow with greater movements of the COPx – a technique that incorporates larger displacements of the putter head and COPx throughout the putting stroke relative to cluster 1. Velocity of the COPx at ball contact is higher than cluster 1 but is homogeneous. High motion. On both tasks, players in cluster 1 had significantly lower handicaps than cluster 2 (4m task – cluster 1 = 12.4±5.9; cluster 2 = 16.4±6.6; p = 0.002; d = 0.63: 8m task – cluster 1 = 11.9±5.5, cluster 2 = 18.3±7.6; p < 0.001; d = 0.91) so would be classified as more skilled, however, no putting technique was significantly better than the other on putting performance. Importantly, all a player’s puttswere not necessarily classified into the same technique grouping. This highlighted the importance of treating each putt as an individual trial rather than using averaged data in the cluster analysis method. At the 4m putting task, the mean putt distance data were not significantly different for both exact putt result (cluster 1 = 14.0±44.5cm; cluster 2 = 25.7±44.5cm; p=0.22; d=0.26) and absolute putt result (cluster 1 = 36.8±28.5cm; cluster 2 = 39.5±32.3cm; p=0.66; d=0.09). Techniques were not significantly different (÷2 = 0.08, p = 0.78) in their ability to produce a holed putt. At the 8m putting task, both the measures of exact putt result (24±77cm vs. 2±71cm; p = 0.7; d = 0.29) and absolute putt result (60±54cm vs. 56±43cm; p = 0.11; d = 0.08) reveal non-significant differences between the techniques. Again, techniques were not significantly different (÷2 = 0.04, p = 0.85) in their ability to produce a holed putt. All players involved in the field based study were offered the opportunity to participate in a follow up study using real time biofeedback training to improve putting technique. Of the current sample, 7 players chose to participate in a three week training program followed by a re-testing session. The biofeedback training was aimed at minimizing COP movement during stance and the putting stroke. On re-testing, the sample of players showed no improvement in putting performance or COP related parameters. The effect of the training program on some players was to, in fact, produce a poorer putting performance and greater movement of the COPx during the stroke. On both putting tasks, there was a significant increase in movement of COPx during the backswing on re-testing. The effect of biofeedback training for improved putting performance was, at best, limited. A new field-based method for assessment of COP has been validated and established. Putting performance data provides evidence to suggest that handicap level and putting performance are related if performance is measured solely by the number of putts holed. Cluster analysis is shown to be a very suitable method for differentiating putting techniques. The movement of the COP was highly influential in distinguishing putting techniques at both tasks, but had no influence on putting performance. Putting techniques have not been described previously in the published scientific literature. Further field-based assessment of putting performance, especially during golf competition is required, along with a more detailed understanding on how far from the hole players of different handicap levels hit their first putts.

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