Variability in clubhead presentation characteristics and ball impact location for golfers' drives

The relationship between skill and ground reaction force variability in amateur golfers

It is accepted that highly skilled golfers are more consistent in their clubhead presentation and shot outcomes than their lesser skilled counterparts. However, the relationships between movement variability, outcome variability and skill in golf are not particularly well understood. This study examined the ground reaction force variability of one-hundred and four amateur golfers for shots with drivers and 5-irons. Principal component analysis was used as a data reduction technique and allowed all three components of ground reaction force to be considered together. There were statistically significant trends for the higher skilled golfers to display lower variability in two of the five principal components (driver) and four of the five principal components (5-iron). A similar trend was also observed in the other principal components, but these trends were not statistically significant. Intra-individual variability was much lower than inter-individual variability across all golfers; the golfers were each relatively consistent in maintaining their own ground reaction force patterns. Lower variability in ground reaction forces may partly explain how highly skilled golfers maintain lower variability in shot outcomes.

Golf Club Selection with AI-Based Game Planning

In the dynamic realm of golf, where every swing can make the difference between victory and defeat, the strategic selection of golf clubs has become a crucial factor in determining the outcome of a game. Advancements in artificial intelligence have opened new avenues for enhancing the decision-making process, empowering golfers to achieve optimal performance on the course. In this paper, we introduce an AI-based game planning system that assists players in selecting the best club for a given scenario. The system considers factors such as distance, terrain, wind strength and direction, and quality of lie. A rule-based model provides the four best club options based on the player's maximum shot data for each club. The player picks a club, shot, and target and a probabilistic classification model identifies whether the shot represents a birdie opportunity, par zone, bogey zone, or worse. The results of our model show that taking into account factors such as terrain and atmospheric features increases the likelihood of a better shot outcome.

Validity and Reliability of the FlightScope Mevo+ Launch Monitor for Assessing Golf Performance

ABSTRACT

Brennan, A, Murray, A, Coughlan, D, Mountjoy, M, Wells, J, Ehlert, A, Xu, J, Broadie, M, Turner, A, and Bishop, C. Validity and reliability of the FlightScope Mevo+ launch monitor for assessing golf performance. J Strength Cond Res 38(4): e174-e181, 2024-The purpose of this study was to (a) assess the validity of the FlightScope Mevo+ against the TrackMan 4 and (b) determine the within-session reliability of both launch monitor systems when using a driver and a 6-iron. Twenty-nine youth golfers, with a minimum of 3 years of playing experience, volunteered for this study. All golfers completed 10 shots with a 6-iron and a driver, with 8 metrics concurrently monitored from both launch monitor systems in an indoor biomechanics laboratory. For both clubs, Pearson's r values ranged from small to near perfect ( r range = 0.254-0.985), with the strongest relationships evident for clubhead speed (CHS) and ball speed ( r ≥ 0.92). Bland-Altman plots showed almost perfect levels of agreement between devices for smash factor (mean bias ≤-0.016; 95% CI: -0.112, 0.079), whereas the poorest levels of agreement was for spin rate (mean bias ≤1,238; 95% CI: -2,628, 5,103). From a reliability standpoint, the TrackMan showed intraclass correlation coefficients (ICCs) ranging from moderate to excellent (ICC = 0.60-0.99) and coefficient of variation (CV) values ranged from good to poor (CV = 1.31-230.22%). For the Mevo+ device, ICC data ranged from poor to excellent (ICC = -0.22 to 0.99) and CV values ranged from good to poor (CV = 1.46-72.70%). Importantly, both devices showed similar trends, with the strongest reliability consistently evident for CHS, ball speed, carry distance, and smash factor. Finally, statistically significant differences ( p < 0.05) were evident between devices for spin rate (driver: d = 1.27; 6-iron: d = 0.90), launch angle (driver: d = 0.54), and attack angle (driver: d = -0.51). Collectively, these findings suggest that the FlightScope Mevo+ launch monitor is both valid and reliable when monitoring CHS, ball speed, carry distance, and smash factor. However, additional variables such as spin rate, launch angle, attack angle, and spin axis exhibit substantially greater variation compared with the TrackMan 4, suggesting that practitioners may wish to be cautious when providing golfers with feedback relating to these metrics.

Evaluation of shaft angle to ball-to-target line as a predictor of horizontal delivery plane angle in the golf swing

The shaft angle to the ball-to-target line at various points in the golf swing is used by coaches as an indication of the horizontal delivery plane angle (HPA). The aim of the current study was to understand to what degree this simplified method of using the shaft orientation can predict the orientation of the HPA. Fifty-two male golfers hit 40 drives each in an indoor biomechanics laboratory. Between-subject regression models were created for the relationship between the HPA and the shaft angle to the ball-to-target line at three different swing positions. Additionally, single subject regression models were created for each subject for the small variables. The only significant between-subjects regression model was for mid-downswing (Adjusted R2 = 89.5%, RMSE = 2.41°); however, this was deemed not accurate enough to distinguish differences between typical driver and wedge HPA. The only shaft position to have significant single-subject regression models for all participants was mid-downswing. The mean RMSE for those models was determined to be low enough to distinguish typical driver and wedge swing planes within individuals. Overall, the shaft angle was only deemed accurate enough to predict the HPA within individual subjects, and only for mid-downswing.

Within- and Between-Session Reliability of Golf Swing Variables Using the TrackMan Launch Monitor in Talented Golfers

ABSTRACT

Shaw, J, Gould, ZI, Oliver, JL, and Lloyd, RS. Within- and between-session reliability of golf swing variables using the TrackMan launch monitor in talented golfers. J Strength Cond Res 37(12): 2431-2437, 2023-The purpose of the current study was to establish the within- and between-session reliability of the TrackMan launch monitor to measure golf swing variables. Twenty-one golfers attended 2 test sessions, with data captured from 3 golf shots using a 6-iron and 3 using a driver. Club head speed (CHS), ball speed, smash factor, attack angle, club path, launch angle, spin rate, spin axis, carry distance, and total distance were determined from data collected using a TrackMan launch monitor. Within- and between-session reliability for each variable was calculated using repeated-measures analysis of variance, intraclass correlation coefficients (ICCs), and coefficients of variation (CVs) with 95% confidence intervals. Within-session measures of CHS, ball speed, carry distance, and total distance were found to be reliable for both 6-iron and driver (CV ≤ 5.8, ICC ≥ 0.87) and launch angle for the 6-iron (CV = 6.7-9.3%, ICC = 0.87-0.92). Between-session measures of CHS, ball speed, smash factor, launch angle, carry distance, and total distance for both 6-iron and driver (CV% = 0.7-9.1%, ICC = 0.5-0.99) and spin rate for 6-iron (CV% = 9.4%, ICC = 0.89) were also shown to be reliable. These findings indicate that the TrackMan launch monitor is a reliable method for measuring CHS, ball speed, carry distance, and total distance in talented golfers, both within and between sessions. Practitioners can confidently use these variables to assess golf swing performance in golfers and evaluate meaningful changes in response to training interventions.

Influence of muscle strength, power, and rapid force capacity on maximal club head speed in male national level golfers

This study investigated the relationships between maximal club head speed (CHS) and physiological and anthropometric parameters in 21 national-level male golfers (age: 21.9 ± 3.9 years; handicap: +1.1 ± 1.7). Maximal isometric strength (MVC) was measured during isometric mid-thigh pull and bench press, while MVC and rate of force development (RFD) were measured during isometric leg press. Power, lower limb stiffness, positive impulse, jump height and RFDdyn were measured during countermovement jump (CMJ). Moreover, rotational trunk power, active range of motion (AROM) and anthropometrics were determined. Comparisons were made between participants with high (FTG) and low (STG) CHS, respectively. FTG demonstrated greater isometric mid-thigh pull and isometric bench press MVC, leg press RFD, rotational trunk power, and CMJ parameters (except RFDdyn) as well as reduced hip AROM compared to STG (P < 0.01). CHS was positively correlated to isometric mid-thigh pull and isometric bench press MVC, leg press RFD, rotational trunk power and CMJ parameters (P < 0.01). In conclusion, strong positive correlations were observed between maximal CHS and maximal strength and power parameters. Consequently, improving maximal neuromuscular strength and power may be considered of importance for golfers, as greater CHS and accompanying driving distance may lead to competitive advantages.

Relationships between highly skilled golfers' clubhead velocity and kinetic variables during a countermovement jump

Previous research has sought to establish the relationship countermovement jump (CMJ) performance has with clubhead velocity (CHV). However, these investigations either assessed lower skilled golfers, or utilised field-based protocols, which are unable to assess a number of biomechanical variables. Fifty highly skilled golfers performed CMJs on Kistler force platforms in laboratory conditions. The CMJ variables included positive impulse, net impulse, average power, peak power, peak force, force at zero velocity and jump height. Clubhead velocity was measured using a TrackMan 3e launch monitor at a driving range. A Pearsons correlation was employed to measure the strength and direction of the relationships between CHV and CMJ derived performance variables. Results indicated strong positive relationships (all p's <0.001) between CHV and positive impulse (r = 0.695), net impulse (r = 0.689), average power (r = 0.645), peak power (r = 0.656), peak force (r = 0.517) and force at zero velocity (r = 0.528) with no significant relationship with jump height. However, if investigators only have access to field-based protocols, it is recommended that they measure jump height and utilise inverse dynamics to calculate take-off velocity. By multiplying take-off velocity by mass, this allows the attainment of net impulse.

Principal Component Analysis can Be Used to Discriminate Between Elite and Sub-Elite Kicking Performance

Contemporary descriptions of motor control suggest that variability in movement can be indicative of skilled or unskilled performance. Here we used principal component analysis to study the kicking performance of elite and sub-elite soldiers who were highly familiar with the skill in order to compare the variability in the first and second principal components. The subjects kicked a force plate under a range of loaded conditions, and their movement was recorded using optical motion capture. The first principal component explained >92% of the variability across all kinematic variables when analyzed separately for each condition, and both groups and explained more of the variation in the movement of the elite group. There was more variation in the loading coefficient of the first principal component for the sub-elite group. In contrast, for the second principal component, there was more variation in the loading coefficient for the elite group, and the relative magnitude of the variation was greater than for the first principal component for both groups. These results suggest that the first principal component represented the most fundamental movement pattern, and there was less variation in this mode for the elite group. In addition, more of the variability was explained by the hip than the knee angle entered when both variables were entered into the same PCA, which suggests that the movement is driven by the hip.

Pedal to the Metal: Velocity and Power in High-Level Golfers

ABSTRACT

Parker, J, and Lundgren, LE. Pedal to the metal: Velocity and power in high-level golfers. J Strength Cond Res 35(12): 3425-3431, 2021-In most rotational power assessments, discrete variables are used for subsequent examination; however, movements are continuous, and data can be collected in time series. The purpose of this investigation was to examine the velocity- and power-time series characteristics of a standing rotation test and identify relationships with golf performance. Thirty-one golfers performed a golf-specific rotation test (GSRT) with 3 different resistances (6, 10, and 14 kg) in a robotic engine system. Time series of velocity and power was calculated from the raw data, and each repetition was then normalized to 0-100%. Principal component analyses (PCAs) were performed on velocity and power waveforms. The PCA used an eigenvalue analysis of the data covariance matrix. The relationship between clubhead speed (CHS) and all principal components (PC) was examined using linear regression. Ten velocity parameters and 6 power parameters explained 80% of the variance in the data. For velocity, the first 2 PCs identified both magnitude and phase shift features while PCs 3-5 identified difference features. For power, the first 2 PCs identified both magnitude and phase shift features, the third PC identified a phase shift feature, and the fourth PC identified a difference feature. The highest relationship with CHS was shown for GSRT with 14 kg in PC2 for power (R2 = 0.48, p < 0.001). The PCA of the GSRT power test could distinguish intraindividual differences, external loads, and sex-based differences. Athletes should focus on accelerating smoothly through the movement, particularly with heavier loads, and not pulling aggressively at the beginning of the rotational movement to achieve maximum power.

Statistical Parametric Mapping Reveals Subtle Gender Differences in Angular Movements in Table Tennis Topspin Backhand

Background: Statistical parametric mapping (SPM) is an innovative method based on the analysis of time series (data series) and is equivalent to statistical methods for numerical (discrete) data series. This study aimed to analyze the patterns of movement in the topspin backhand stroke in table tennis and to use SPM to compare these patterns between advanced female and male players. Methods: The research involved seven advanced male and six advanced female players. The kinematic parameters were measured using an inertial motion analysis system. The SPM was computed using the SPM1D Python package. Results: Our study made it possible to reproduce the pattern of movement in the joints during topspin backhand strokes in the studied athletes. During multiple comparisons, the analysis of variance (ANOVA) SPM test revealed many areas in the studied parameter series with statistically significant differences (p ≤ 0.01). Conclusions: The study presents the movement patterns in the topspin backhand shot and describes the proximal-to-distal sequencing principle during this shot. The SPM study revealed differences between men and women in the contribution of thoracic rotation, external shoulder rotation, dorsal flexion, and supination in the wrist during the hitting phase. These differences may result from the anatomical gender differences or variations in other functionalities of individual body segments between the study groups. Another possible source for these discrepancies may reside in tactical requirements, especially the need for a more vigorous attack in men. The gender differences presented in this study can help in the individualization of the training process in table tennis.

Sport Practitioners as Sport Ecology Designers: How Ecological Dynamics Has Progressively Changed Perceptions of Skill "Acquisition" in the Sporting Habitat

Over two decades ago, Davids et al. (1994) and Handford et al. (1997) raised theoretical concerns associated with traditional, reductionist, and mechanistic perspectives of movement coordination and skill acquisition for sport scientists interested in practical applications for training designs. These seminal papers advocated an emerging consciousness grounded in an ecological approach, signaling the need for sports practitioners to appreciate the constraints-led, deeply entangled, and non-linear reciprocity between the organism (performer), task, and environment subsystems. Over two decades later, the areas of skill acquisition, practice and training design, performance analysis and preparation, and talent development in sport science have never been so vibrant in terms of theoretical modeling, knowledge generation and innovation, and technological deployment. Viewed at an ecological level of analysis, the work of sports practitioners has progressively transitioned toward the facilitation of an evolving relationship between an organism (athlete and team) and its environment (sports competition). This commentary sets out to explore how these original ideas from Davids et al. (1994) and Handford et al. (1997) have been advanced through the theoretical lens of ecological dynamics. Concurrently, we provide case study exemplars, from applied practice in high-performance sports organizations, to illustrate how these contemporary perspectives are shaping the work of sports practitioners (sport ecology designers) in practice and in performance preparation.

Reliability of repeat golf club testing sessions with modified club moment of inertia

The moment of inertia of a golf club, quantified about an axis at the butt of the handle, normal to the swing plane, has the potential to influence both clubhead and ball velocity. The purpose of this study was to assess the reliability of clubhead and ball velocity with changes to moment of inertia over repeat testing sessions and, if reliable, to quantify the effect of modifying moment of inertia. Eleven skilled male golfers hit 20 golf shots with three golf clubs, each with a different moment of inertia achieved through adding mass inside the club shaft and repeated this protocol over three sessions. A commercially available launch monitor was used to measure both velocity variables. Test–retest reliability was assessed via (1) limits of agreement, to determine reliability from a change in magnitude perspective and (2) linear-weighted kappa, to determine reliability from a directional perspective. The effect of moment of inertia on clubhead and ball velocity was determined using one-way, repeated measures analysis of variance tests, with partial eta squared being used to quantify the size of the effect. Increasing golf club moment of inertia reliably decreased clubhead and ball velocity, with fair to substantial kappa results revealed between sessions. The magnitude of decrease in these velocities, however, could not be reliably quantified. Statistically, the influence of moment of inertia was considered large (η2 ≥ 0.662 and 0.404) and significant (p < 0.001 and ≤ 0.006) for both clubhead and ball velocity, respectively.

Differences in kinematics and driver performance in elite female and male golfers

The aim of this study was to compare swing kinematic differences between women and men and investigate which variables predict clubhead speed (CHS) and carry distance (CD) whilst accounting for individual variation.

METHODS

Swing kinematics and driver performance data were collected on 20 (10 women) elite golfers (HCP 0.7 ± 1.4). We used Bayesian T-test for between sex comparison of swing kinematics and Bayesian Analysis of covariance (ANCOVA) to produce general linear models for CHS and carry distance for elite female and male golfers separately.

RESULTS

There was strong evidence that the driver performance variables CHS and CD were decreased in women compared to men, and two kinematic variables; time to arm peak speed downswing and angular wrist peak speed were slower in women. The ANCOVAs identified very strong to overwhelming evidence that participant as a fixed factor was a determinant of CHS for both women and men but was not a determinant of CD.

CONCLUSION

when looking to enhance driver performance among high-level golfers, coaches should be aware that variables that determine CHS and CD differ among women and men and if the aim is to improve CHS coaches should not forget the importance of individual swing characteristics.

A biomechanical approach to investigate swing characteristics in elite golfers

BACKGROUND

The current study aims to compare the variability of positional control of the club in the starting period of downswing and the orientation of the clubface during impact in elite and intermediate golfers.

METHODS

Seven elite and 13 intermediate golfers were recorded by an eight-camera VICON motion capture system while putting with a pitch club. Six retro-reflective markers were attached to the club to build a biomechanical model for analyzing swinging movements. Group comparisons of outcome variables regarding the turning point, sweet spot, elevation angle (EA), and azimuth angle (AA) of the club head were made between the elite and intermediate players.

RESULTS

There were significant differences between groups in SDs of the location of the club tail along the x, y, and z axes at the turning point (x, p = 0.004; y, p = 0.015; and z, p = 0.035); the minimum distance between the center of the sweet spot and the ball at impact (p = 0.007); the EA (p = 0.001); and the AA (p = 0.001) of the club head. Results showed that the elite players displayed more converged locations of turning points, shorter distances between the center of the sweet spot and the ball at impact, greater EAs, and smaller AAs compared with those of the intermediate players.

CONCLUSION

These findings proposed a biomechanical approach of a practical way to observe swing behaviors. These findings suggest that the stability of locations of turning points is a golden reference for differentiating levels of golfers' performance.

Kick impact characteristics of accurate Australian football drop punt kicking

Accurate kicking is essential to team success in Australian football. It is not known how foot-ball impact characteristics influence kicking accuracy, nor is it known if variability in foot-ball impact characteristics is functional or dysfunctional to performance. The aim of this study was to identify the relationship between foot-ball impact characteristics and kicking accuracy and determine if variability in foot-ball impact characteristics influenced performance variability. Ten players performed 30 drop punt kicks toward a target with an Australian football ball. Kicking accuracy (measured as the horizontal distance from the target in the perpendicular direction of the kick), initial ball flight characteristics, and foot-ball impact characteristics, including a novel method to calculate impact location on the ball, were measured. Variability was indicated using standard deviation of foot-ball impact and ball flight characteristics. Multiple linear regression analysis identified azimuth ball flight trajectory as the most important ball flight characteristic influencing kicking accuracy, not ball flight characteristics associated with ball curve. Intra-individual multiple linear regressions identified azimuth ball impact location and foot-ball angle were the two most important factors explaining variance in azimuth ball flight trajectory, the chosen performance measure. Variability existed between and within players. Reduced variability in azimuth ball flight trajectory, the chosen performance measure, was associated with reduced variability in foot-ball impact characteristics. This result indicated variability in foot-ball impact characteristics was dysfunctional for performance in the analysed task. Foot-ball impact characteristics and variability in foot-ball impact characteristics influences accuracy of Australian football drop punt kicking.

Relationships between clubshaft motions and clubface orientation during the golf swing

Since clubface orientation at impact affects ball direction and ball spin, the ability to control clubface orientation is one of the most important skills for golfers. This study presents a new method to describe clubface orientation as a function of the clubshaft motions (i.e., swing plane orientation, clubshaft angle in the swing plane, and clubshaft rolling angle) during a golf swing and investigates the relationships between the clubshaft motions and clubface orientation at impact. The club motion data of driver shots were collected from eight skilled golfers using a three-dimensional motion capture system. The degrees of influence of the clubshaft motions on the clubface orientation were investigated using sensitivity analysis. The sensitivity analysis revealed that the swing plane horizontal angle affected the clubface horizontal angle to an extent of 100%, that the clubshaft angle in the swing plane affected both the clubface vertical and horizontal angles to extents of 74 and 68%, respectively, and that the clubshaft rolling angle affected both the clubface vertical and horizontal angles to extents of -67 and 75%, respectively. Since the method presented here relates clubface orientation to clubshaft motions, it is useful for understanding the clubface control of a golfer.

The relationship between the golf swing plane and ball impact characteristics using trajectory ellipse fitting

The trajectory of the clubhead close to ball impact during the golf swing has previously been shown to be planar. However, the relationship between the plane orientation and the orientation characteristics of the clubhead at ball impact has yet to be defined. Fifty-two male golfers (27 high skilled, 25 intermediate skilled) hit 40 drives each in an indoor biomechanics laboratory. This study successfully fitted the trajectory of the clubhead near impact to an ellipse for each swing for players of different skill levels to help better explain this relationship. Additionally, the eccentricities of the ellipses were investigated for links to skill level. The trajectory of the clubhead was found to fit to an ellipse with RMSE of 1.2 mm. The eccentricity of the ellipse was found to be greater in the high-skilled golfers. The club path and angle of attack generated from the ellipse fitted clubhead trajectory were found to have a normalised bias-corrected RMSE of 2% and 3%, respectively. A set of "rule of thumb" values for the relationship between the club path, angle of attack and delivery plane angle was generated for use by coaches.

Motor abundance and control structure in the golf swing

Variability and control structure are under-represented areas of golf swing research. This study investigated the use of the abundant degrees of freedom in the golf swing of high and intermediate skilled golfers using uncontrolled manifold (UCM) analysis. The variance parallel to (VUCM) and orthogonal to (VOrth) the UCM with respect to the orientation and location of the clubhead were calculated. The higher skilled golfers had proportionally higher values of VUCM than lower skilled players for all measured outcome variables. Motor synergy was found in the control of the orientation of the clubhead and the combined outcome variables but not for clubhead location. Clubhead location variance zeroed-in on impact as has been previously shown, whereas clubhead orientation variance increased near impact. Both skill levels increased their control over the clubhead location leading up to impact, with more control exerted over the clubhead orientation in the early downswing. The results suggest that to achieve higher skill levels in golf may not lie simply in optimal technique, but may lie more in developing control over the abundant degrees of freedom in the body.

Tests examining skill outcomes in sport: a systematic review of measurement properties and feasibility

BACKGROUND

A high level of participant skill is influential in determining the outcome of many sports. Thus, tests assessing skill outcomes in sport are commonly used by coaches and researchers to estimate an athlete's ability level, to evaluate the effectiveness of interventions or for the purpose of talent identification.

OBJECTIVE

The objective of this systematic review was to examine the methodological quality, measurement properties and feasibility characteristics of sporting skill outcome tests reported in the peer-reviewed literature.

DATA SOURCES

A search of both SPORTDiscus and MEDLINE databases was undertaken.

STUDY SELECTION

Studies that examined tests of sporting skill outcomes were reviewed. Only studies that investigated measurement properties of the test (reliability or validity) were included. A total of 22 studies met the inclusion/exclusion criteria.

STUDY APPRAISAL AND SYNTHESIS METHODS

A customised checklist of assessment criteria, based on previous research, was utilised for the purpose of this review.

RESULTS

A range of sports were the subject of the 22 studies included in this review, with considerations relating to methodological quality being generally well addressed by authors. A range of methods and statistical procedures were used by researchers to determine the measurement properties of their skill outcome tests. The majority (95%) of the reviewed studies investigated test-retest reliability, and where relevant, inter and intra-rater reliability was also determined. Content validity was examined in 68% of the studies, with most tests investigating multiple skill domains relevant to the sport. Only 18% of studies assessed all three reviewed forms of validity (content, construct and criterion), with just 14% investigating the predictive validity of the test. Test responsiveness was reported in only 9% of studies, whilst feasibility received varying levels of attention.

LIMITATIONS

In organised sport, further tests may exist which have not been investigated in this review. This could be due to such tests firstly not being published in the peer-review literature and secondly, not having their measurement properties (i.e., reliability or validity) examined formally.

CONCLUSIONS

Of the 22 studies included in this review, items relating to test methodological quality were, on the whole, well addressed. Test-retest reliability was determined in all but one of the reviewed studies, whilst most studies investigated at least two aspects of validity (i.e., content, construct or criterion-related validity). Few studies examined predictive validity or responsiveness. While feasibility was addressed in over half of the studies, practicality and test limitations were rarely addressed. Consideration of study quality, measurement properties and feasibility components assessed in this review can assist future researchers when developing or modifying tests of sporting skill outcomes.

The X-Factor: an evaluation of common methods used to analyse major inter-segment kinematics during the golf swing

A common biomechanical feature of a golf swing, described in various ways in the literature, is the interaction between the thorax and pelvis, often termed the X-Factor. There is no consistent method used within golf biomechanics literature however to calculate these segment interactions. The purpose of this study was to examine X-factor data calculated using three reported methods in order to determine the similarity or otherwise of the data calculated using each method. A twelve-camera three-dimensional motion capture system was used to capture the driver swings of 19 participants and a subject specific three-dimensional biomechanical model was created with the position and orientation of each model estimated using a global optimisation algorithm. Comparison of the X-Factor methods showed significant differences for events during the swing (P < 0.05). Data for each kinematic measure were derived as a times series for all three methods and regression analysis of these data showed that whilst one method could be successfully mapped to another, the mappings between methods are subject dependent (P <0.05). Findings suggest that a consistent methodology considering the X-Factor from a joint angle approach is most insightful in describing a golf swing.