Performance and Kinematic Differences in Putting Between Healthy and Disabled Elite Golfers

Performance in golf is determined by the accuracy of drives from the tee, accuracy of approach shots from the fairway, short approach shots and putting. Therefore, the most important playing clubs are the driver, wedges and a putter (McLean, 2005). In elite players it was found that about 43% of strokes were performed by the putter (Pelz, 2000). The putting stroke is a specific kind of the golf swing (stroke), which is preferably used on the green, attempting to control both distance and lateral error, to finish either in, or as near as possible the hole. Putting has been considered the ability which determines the amount of prizes on professional tours (PGA Tour et al) (Alexander and Kern, 2005). Sports performance in subjects with disability is influenced by the range of deteriorated movements and body functions, which influence the range of swing motion and other variables, e.g. the information about the weight distribution (weight-shift) between the limbs (Gerych et al., 2013; Jelen et al., 2005), which causes the differences in golf swings (Stastny et al., 2015).

The golf literature gives significant attention to the technique of putting, kinesthetic feel, equipment level (stroke part of putter) and reading the putting green (initial direction choice) as the key abilities leading to successful putting (Wiren, 1990; Woods, 2001). However, an appropriate stable putting technique is the basis for a successful putt (Hurrion, 2008). Successful and consistent putting is based on a stabilized point of rotation, which allows the golfer to putt from a stable position at initial impact (contact between the head of the putter and the ball). Therefore, the golfer needs a stabilized initial position with a fixed centre of rotation to achieve high repeatability of the putting stroke. Weight transfer between both lower limbs will influence the stability or variability in postural integrity during putting (Hurrion, 2009). Although the putting stroke technique differs among players, there are several stabilizing points (mild knee flexion, hip flexion, marginal elbow flexion) aiming to produce positioning of the eyes directly over the ball (Wiren, 1990) allowing for the stroke to be performed with a pendulum movement with the rotation centre in the middle of the shoulder line. Those parameters are different from other golf swings, where the force impulse during the ball impact is reliant upon upper torso–pelvic separation called X-factor (Cheetham et al., 2001; Chu et al., 2010) and plays a crucial role. Therefore, the golfer with disability may complete the putting stroke more effectively or in a different way than with a full swing, e.g. drive.

Besides descriptive information about putting (Hurrion, 2009), there is a lack of literature about different putting approaches and in particular, about putting in golfers with disability. Therefore, the aim of this study was to compare putting stroke performance, kinetic and kinematic consistency between golfers with different disabilities and healthy athletes. Furthermore, we focused on the comparison of the variability of putting to determine which movement pattern was specific to a particular disability.

The CV did not differ between healthy athletes in kinematic variables (Table 3), clubhead speed and total putting accuracy (Table 2); however, there were differences in the depth error and lateral error (Table 2). The T test did not show any significant differences in clubhead speed (Figure 1) and accuracy of the putting stroke (Figure 1). The kinematic variables differed between the healthy athletes and the player with perinatal cerebral palsy (PCP) (p < 0.01), multiple sclerosis (p < 0.05) and the disabled amputee (p < 0.05), (Figure 2). The weight transfer differed significantly between the healthy athletes and players with PCP (p < 0.01), multiple sclerosis (p < 0.01) and the disabled amputee (p < 0.01). The healthy players had greater loading of the left lower limb (Left, 54 ± 4%), which was lower in multiple sclerosis (Left, 51 ± 1%) and below knee amputee (Left, 63 ± 1%). On the other hand, the player with PCP loaded the right leg to a greater extent (Right, 57 ± 1%).

Figure 1

Figure 2

Table 2

Putting accuracy and clubhead speed in healthy and disabled golfers.

Table 3

Kinematic variables of the putting stroke in all study participants

Putting is the least physically demanding golf swing, in which we can observe the highest variation between individual movement technique in professional and amateur golfers. During the putting task, the total distance error from the hole is determined by a combination of the lateral error and depth error. In straight putts, the lateral error is estimated by the initial ball direction and the initial speed of the ball determines the depth error. Initial direction of the ball after impact is dependent on the face angle, stroke path and impact spot (Mackenzie and Evans, 2010). The initial velocity of the ball is determined by the clubhead speed at impact and the impact spot. The similarity in putting clubhead speed between healthy and disabled golfers in our study indicates that they should have similar performances. This is in agreement with a previous study (Pelz, 2000), where the velocity of the ball post impact had four times higher importance than initial ball direction for putting accuracy in breaking putts. Moreover, the putting training intervention by different techniques resulted in lowering the variability of clubhead speed in impact along with putting accuracy (Mackenzie and Evans, 2010; Mackenzie, et al., 2011). Therefore we may assume that low variability in clubhead speed leads to better putting performance.

The finding that CV kinematics during putting did not vary between the golfers with and without disability pointed to a sufficient level of individual technique in disabled golfers (Table 2). The consistency and repeatability of the golf swing has been considered one of the key factors in golf performance (Meister et al., 2011), which was not dependent on the disability level in this study and a previous study performed on a disabled group (Stastny et al., 2015). If the golfers had low swing variability (a fluent and consistent swing), their rotational variables of shoulder and pelvic orientation should correlate with clubhead speed at impact (Meister et al., 2011; Myers et al., 2008), yet this dependence was not confirmed in the study of Kwon et al. (2013) Therefore our study did not analyze this relationship. However, the repeatability of the same clubhead speed and putting performance was similar across all athletes, and the variability in those variables was lowest in the PCP golfer. Therefore, putting performance may be characterized by a technique, where golfers with disability can achieve a high level of efficiency.

The results of kinematic analyses show that disabled players move after impact in the opposite direction of the stroke, which is probably connected to their one limb preference (Figures 3 and 4). This weight-shift was recognized by the right and left foot vertical force ratio throughout the putting stroke, which was influenced by the level and type of disability. Thus, the decreased possibility of proprioception and movement coordination in disabled golfers is evident after the impact rather than set up, back swing and club head impact. Although the importance of weight-shift and the need for its frequent training is one of the foundations of golf (Chu et al., 2010), this variable does not seem to be critical for putting performance. On the other hand, the weight-shift was the most variable parameter among different disabilities during the putting stroke.

Previous studies showed that putting stroke performance and putter movement parameters, such as club head speed variability, could be impacted by specific practice without the need to change technique even in less skilled golfers (Mackenzie and Evans, 2010; Mackenzie et al., 2011). Based on the results of our study, we suggest that different putting techniques in different disabilities do not lead to less accurate putting. Therefore, each player (disabled or healthy) should be looking for their specific repetitive motion of the body, which leads to consistent movement. The consistent body movement should result in repeatable club head movements during the impact in terms of clubhead speed, path and face angle to control initial ball direction and speed, which allows to reach maximal putting performance.

The limitations of the study are in small numbers of participants, as our sample was based on single case studies. The movement variability might have been significantly different if there was comparison of stroke conditions with specially adopted equipment for different kinds of disabilities. This study also did not estimate differences in the force momentum in the knee joints, which might be useful for golf training (McHardy et al., 2006). Since the study sample was low, we did not estimate how the players learned the consistent putting stroke/action (Oliveira et al., 2013).

The fluency and consistency of putting stroke kinematics and accuracy are not dependent on the specific type of disability. The most variable parameter among each disability is weight-shift, where disabled golfers prefer the healthy limb during movement stabilization. The course of stroke movement was performed specifically with individual technique rather than imitation of movement observed in healthy athletes, thus its modification by training is difficult. Therefore, disabled players should find their own putting technique. Putting performance in disabled golfers should be similar to healthy players, which means that partial handicap should be resolved by high reproduction of movement.