Are European and American golf players different? Reply to Engelhardt (1997)

The swing performance Index: Developing a single-score index of golf swing rotational biomechanics quantified with 3D kinematics

Introduction

Golf swing generates power through coordinated rotations of the pelvis and upper torso, which are highly consistent among professionals. Currently, golf performance is graded on handicap, length-of-shot, and clubhead-speed-at-impact. No performance indices are grading the technique of pelvic and torso rotations. As an initial step toward developing a performance index, we collected kinematic metrics of swing rotational biomechanics and hypothesized that a set of these metrics could differentiate between amateur and pro players. The aim of this study was to develop a single-score index of rotational biomechanics based on metrics that are consistent among pros and could be derived in the future using inertial measurement units (IMU).

Methods

Golf swing rotational biomechanics was analyzed using 3D kinematics on eleven professional (age 31.0 ± 5.9 years) and five amateur (age 28.4 ± 6.9 years) golfers. Nine kinematic metrics known to be consistent among professionals and could be obtained using IMUs were selected as candidate variables. Oversampling was used to account for dataset imbalances. All combinations, up to three metrics, were tested for suitability for factor analysis using Kaiser-Meyer-Olkin tests. Principal component analysis was performed, and the logarithm of Euclidean distance of principal components between golf swings and the average pro vector was used to classify pro vs. amateur golf swings employing logistic regression and leave-one-out cross-validation. The area under the receiver operating characteristic curve was used to determine the optimal set of kinematic metrics.

Results

A single-score index calculated using peak pelvic rotational velocity pre-impact, pelvic rotational velocity at impact, and peak upper torso rotational velocity post-impact demonstrated strong predictive performance to differentiate pro (mean ± SD:100 ± 10) vs. amateur (mean ± SD:82 ± 4) golfers with an AUC of 0.97 and a standardized mean difference of 2.12.

Discussion

In this initial analysis, an index derived from peak pelvic rotational velocity pre-impact, pelvic rotational velocity at impact, and peak upper torso rotational velocity post-impact demonstrated strong predictive performance to differentiate pro from amateur golfers. Swing Performance Index was developed using a limited sample size; future research is needed to confirm results. The Swing Performance Index aims to provide quantified feedback on swing technique to improve performance, expedite training, and prevent injuries.

Competitive elite golf: a review of the relationships between playing results, technique and physique

Elite golfers commonly use fitness and technical training to become more competitive. The aim of this paper was to review the literature regarding the relationships between elite golfers' playing results, technique and physique. The competitive outcome is a direct function of the score. The three golf statistical measures that show the strongest correlations to scoring average are greens in regulation (GIR), scrambling, and putts per GIR. However, more detailed game statistics are needed where the distances to the targets are known before and after the strokes. Players affect ball displacement by controlling clubhead velocity and clubface angle during club and ball impact. X-factor studies have produced ambiguous results, possibly caused by different definitions of upper torso, rotation and top of backswing. Higher clubhead speed is generally associated with larger spinal rotation and shoulder girdle protraction at the top of the backswing. It is also associated with higher ground reaction forces and torques, a bottom-up and sequential increase of body segment angular velocities, a rapid increase of spinal rotation and a late adduction of the wrists during the downswing. Players can increase the clubhead speed generated by a swinging motion by actively adding a force couple. Wrist, elbow and shoulder force couple strategies should be differentiated when investigating the technique. Physical parameters such as anthropometrics, strength and flexibility are associated with skill level and clubhead speed. Current studies have investigated the linear correlation between arm and shaft lengths and clubhead speed, but a quadratic relationship may be stronger due to changes in moment of inertia. Fitness training can increase and perhaps decrease the clubhead speed and striking distance, depending on training methods and the player's fitness and level of skill. Future studies may focus on individual training needs and the relationship between physique, execution and its relation to accuracy of impact and ball displacement.

Determinants of PGA tour success: an examination of relationships among performance, scoring, and earnings

Professional Golf Association (PGA) statistics for the 2002 season were analyzed to estimate the relationships between performance variables, scoring, and earnings. Two newly considered variables, Scrambling and Bounce Back percentages, showed meaningful correlation to Simple Scoring Average (rs = -.69 and -.40, respectively), and each made a significant contribution to a regression model. While the full model of performance variables explained most of the variance in Simple Scoring Average (R2 = .94), an adjusted scoring figure, accounting for the performance of the full field of players in each round, better correlated with Earnings over a PGA Tour season (r = .77).

Is American PGA tour more competitive than European tour? Reply to Jiménez and Fierro-Hernández

Analysis of the 1998 European PGA tour yielded four statistically significant differences between the shot-making skills of the top 10 and bottom 10 money winners. Analysis of the 1995 American PGA tour indicated only two skills significantly higher among the 10 top-ranked money winners. The results suggest the American PGA tour may be more competitive.