An Investigation of Technique and Equipment Factors Associated with Clubhead Speed in Golf

If golfers achieve long hitting distances whilst maintaining their accuracy they will gain a competitive advantage. To increase hitting distance, faster clubhead speed is required and this can potentially be achieved through a number of factors. Firstly, anthropometric factors such as height and physical factors such as trunk rotational power have been previously considered to be of importance. However, biomechanical factors such as; the X-factor (separation of the trunk-pelvis alignment when viewed in the transverse plane), have been a major focus of recent research. Further, the interaction of the golfer with the implement they hit with i.e. the golf club has also been examined in biomechanical studies. The broad aim of this doctoral research was to investigate how male high-level amateur golfers generate club head speed and this was examined in a series of five studies that examined technical and equipment factors. The first study of this thesis (Study I) developed a valid three-dimensional Cardan / Euler model to examine the kinematics of the trunk and lower trunk during the golf swing. This validation study involved; developing and validating models and related algorithms as well as making comparisons to static and dynamic postures. It was concluded that a lateral bending / flexion-extension / axial rotation (ZYX) order of rotation was the most suitable to quantify the X-factor and lower trunk movement in the golf swing. Previous research has shown conflicting relationships between golf swing kinematics (such as variables related to the X-factor) and clubhead speed, as well as what physical variables assist in generating clubhead speed. The second study of this thesis (Study II) had two aims. The first aim was to determine whether significant between-club (driver and five-iron) differences existed for trunk and lower trunk kinematics as well as launch conditions. The second aim was to determine which anthropometric, physical and trunk and lower trunk kinematic variables were most strongly associated with clubhead speed. Fifteen high level amateur male golfers (2.5 ± 1.9 handicap) had their trunk and lower trunk three-dimensional kinematics data quantified using the methods developed in Study I. Nine significant (p \u3c 0.002) between-club differences in swing kinematics were found; namely trunk and lower trunk flexion and lower trunk axial rotation, as well as ball velocity. Regression analyses explained 33.7 % and 66.7 % of the variance in clubhead speed for the driver and five-iron respectively, with both trunk and lower trunk variables showing associations with clubhead speed. No anthropometric (i.e. height) or physical (i.e. maximum trunk rotational speed) were associated with clubhead speed. The low amount of variance explained by clubhead speed for the driver in Study II stimulated further investigation. Studies III and IV were designed to develop a method to locate the kick point during the golf swing and examine the effect of kick point location on swing parameters and their related launch conditions, respectively. Study III involved two phases, Firstly, the level of agreement between two methods of determining the static kick point was determined. This showed that an algorithm using three-dimensional locations of markers placed on the golf club was a valid method to determine the location of the static kick point. In the second phase of testing, this method was used to determine the location of the dynamic kick point during the golf swing. Excellent between-trial reliability was found for this method. Further, differences were found for the dynamic kick point location when compared to the static kick point location. The main objective of Study IV was to determine whether drivers fitted with shafts having high and low kick points would alter selected swing parameters, and related launch conditions. Twelve high level amateur male golfers (1.2 ± 1.8 handicap) had three shots analysed for each of two drivers fitted with “stiff” shafts but these drivers had differing kick point location. Stiffness profiles of these shafts were also measured. Five swing parameters and their related launch conditions were measured using a real-time launch monitor. The driver fitted with the shaft containing the high kick point displayed a more negative (steeper) angle of attack, a lower launch angle and an increased spin rate when compared to a driver fitted with a low kick point In Study II, a relatively small amount of variance in clubhead speed was explained by the driver and it was the overall intention of the last study of this thesis (Study V) to attempt to explain more of this variance by examining both trunk and wrist kinematics. This was undertaken using two drivers containing differing kick point locations (low and high), with two separate regression models being produced. Twenty high-level amateur male golfers (1.9 ± 1.9 handicap) had their trunk and lower trunk three-dimensional kinematics data quantified as in Study II, but with the addition of a wrist segment. Four significant (p In conclusion, the methods developed for this thesis to analyse golf swing kinematics revealed a greater insight into how highly skilled golfers produce clubhead speed. Particularly, the results from Studies II and V revealed significant associations between lower trunk related variables and clubhead speed when using different clubs (driver vs. fiveiron) and the same club fitted with two shafts of different kick point location (driver). Also, the methods developed in Studies III and IV to investigate dynamic shaft profiles (deflection) in the downswing provided possible explanations as to how shaft performance in the downswing can influence swing parameters and their related launch conditions at ball impact

Coach informed biomechanical analysis of the golf swing

Coach informed biomechanical analysis of the golf swin

Measurement of grip force and evaluation of its role in a golf shot

This study was conducted with the aim of establishing a method to measure time-varying forces at multiple locations at the hand-grip interface, using this method to record how golfers of varying abilities grip the club during a standard tee shot and investigating a potential link between the variations in vibration seen at the grip and the grip force applied near impact. It is hoped that additional knowledge about grip force during a golf shot will lead to improved training techniques and grip design in the future. An assortment of technologies were available for the measurement of grip force, but thinflexible sensors were chosen as they could be applied to the grip or gloves without altering the characteristics of the club. Reliability and performance for these sensors were not well established and, therefore, a novel set of tests were developed to evaluate their capabilities. Thin-film force sensor performance was examined under controlled laboratory conditions to give an indication of each sensor's quasi-static accuracy, hysteresis, repeatability and drift errors, dynamic accuracy and drift errors, and the effects of shear loads and surface curvature. With this newly developed set of tests, five varieties of thin-film force sensor utilizing four different technologies were assessed. The sensors had varying levels of success under the controlled conditions of the evaluation tests. Three of the sensors performed well under static and quasi-static loading conditions, with accuracy errors of 10% or less, hysteresis errors near 6%, repeatability near 6% or below, and drift at 60 s after load application under 15%. Two of these sensors were further tested and demonstrated little change in sensor output to loads applied over curved surfaces, although shear sensitivity and dynamic accuracy errors were more substantial. It was also found that some of the sensors lost sensitivity with repeated loading. Even with these drawbacks, the potential of these sensors to provide useful grip force information was clear. With an understanding of sensor performance in controlled laboratory settings, one sensor type was used to determine regions of peak pressure at the hand-grip interface and three others were used in player tests to obtain time-varying measurements of grip force during a swing. During the player tests, grip force was measured for 10-12 tee shots and impact time was determined Total force was computed for each shot taken by summing the force output of all the sensing elements positioned on either the grip or gloves. When these total force traces were aligned by impact and plotted for each of the golfers tested, an interesting and previously unreported phenomenon became apparent. Each player appeared to have their own grip force 'signature', i.e. total grip force for a particular golfer was very repeatable, but varied considerably between golfers. A grip force signature existed for all players tested regardless of ability, and the level of consistency for an individual golfer and the similarities between golfers was analysed using a cross correlation. It was found that nearly all of the golfers tested had swings that were dominated by the left hand, and that the most notable contributions of the right hand occurred after impact. Variations in grip force were also related to key phases of the swing using high speed video footage. Previously it has been noted that for the same ball, club, and impact location that the vibration on the shaft is remarkably consistent for many different golfers but there is a much greater variation in the vibration at the grip. It was hypothesized that the way a golfer grips the club affects the way vibration is transmitted into their hands and arms. A final set of player tests was therefore conducted with the aim of identifying how grip force affects vibration transmission from the shaft to the hands and the players' perceptions of this vibration. Vibration was measured on the shaft just below the grip and on the golfer'S left thumbnail, force was monitored at 18 locations on the hands, and impact location and clubhead speed were recorded. Each golfer's perceptions of the vibration caused by impact were also noted for two standard drivers. It was found that changes in the amount of vibration travelling from the shaft into the hands is affected by the grip force applied by the golfer. This is the first study to analyse the effects of grip force on vibration transmission into the hands and arms due to a golf impact

Investigating the perceived effectiveness of digital technology for elite athlete support in golf

Digital technologies have enabled vast and varied amounts of data to be captured on elite athletes. The data is intended for use by athletes, coaches and support team e.g. physiotherapists, sports scientists for many purposes including performance development or injury prevention. However, the usefulness of such digital technologies and the information gathered is only beneficial if deemed effective by all those involved. The purpose of this study was to investigate the effectiveness of digital technology for elite athletes’ development and support from athlete, coach and support team perspective in golf. Interviews were conducted with athletes, coaches and support team for a sport where digital technologies were used to facilitate training. The results of the study uncovered four categories that helped to understand how effectiveness was perceived which were “The Influence on Psychological Well-being and Proprioception”, “Measurement Uncertainty”, “Environment” and “Type, Ease and Frequency of Use”. Exploring these categories provided insight into the best practices for digital technology integration into elite athlete support and ultimately can help shape future developments of digital technologies.</div

A behavioural analysis of "choking" in self-paced skills

This thesis is about "choking" in self-paced skills. Choking refers to ''the occurrence of inferior performance despite striving and incentives for superior performance" (Baumeister and Steinhilber, 1986, p. 361). Self-paced skills are skills in which performance is initiated by the athlete. This research set out to investigate the cause of choking in self-paced skills within the theoretical framework of behaviour analysis. The main focus of the research relates to the distinction between behaviour under the control of verbal antecedents (rule-governed behaviour) and behaviour that is shaped by its consequences (contingency-shaped behaviour). It was originally hypothesised that the insensitivity of rule-governed behaviour to changes in the contingencies of reinforcement could he beneficial in situations where these changes led to greater performance pressure. Specifically, it was predicted that performance under the control of verbal antecedents would be less susceptible to choking. In the first experiment, no support was found for the hypothesis and, furthermore, rule-governed performance appeared to be inferior to contingency-shaped performance in the early stages of acquisition. In light of these results, and after a detailed examination of the behaviour analysis distinction between these two forms of behaviour, evidence was presented which suggested that verbal control of the topography, or form, of behaviour would be likely to disrupt performance in self-paced skills. In subsequent experiments, it was found that using simple verbal cues was an effective means of preventing choking under pressure. It was hypothesised that the function of these cues was in preventing reinvestment of too many technical instructions in the moments before performance initiation. The assumptions upon which the reinvestment theory of choking is based were also examined with results providing general support for the theory but also suggesting that it needs to be refined to account for verbal antecedents that do not disrupt performance

How should golfers monitor training load?

Training load monitoring has been integrated into a variety of sports at a high level over the past decade. However, it has been presented by various authors that golfer’s sustain injury caused by overuse of specific sites of the body. This is done without knowledge of golf specific training loads and little academic research into training load monitoring within golf. Therefore, it is reasonable to suggest that the topic of load monitoring in golf should be researched, as load monitoring in other sports has been researched. Such studies have lead to the quantification of load and acute chronic workload ratios by academics. Two literature reviews; one on injury in golf and one investigating training load monitoring in other sports preceded a set of semi structured interviews with subjects working as coaches, doctors, physiotherapists and players within international golf. The purpose of the semi structured interviews was to discuss topics relating to golfing load, summarise the opinions of the experts on those topics and define the importance of each topic relating to a golf specific load monitoring tool

The role of biomechanics in achieving different shot trajectories in golf

In golf, a range of shot types are necessary for successful performance, with driving and iron-play constituting the long-game. It is possible to vary long-game shots through altered trajectory, for example, by utilising right-to-left or left-to-right ball flight curvature, providing course management advantages. However, how golfers vary their biomechanics to achieve different trajectories is not scientifically understood. Therefore, the purpose of this thesis was to biomechanically investigate different trajectories hit with the same club. To investigate shot trajectories, accurate measures of performance were necessary. Launch monitors (TrackMan Pro IIIe and Foresight GC2+HMT) are bespoke technologies capable of tracking the clubhead and ball through impact. However, their accuracy for scientific research has not been independently validated. Therefore, a novel purpose-designed tracking method was developed using a three-dimensional optical tracking system (GOM). The accuracy of this method was validated and the system used as the benchmark to which the two launch monitors were compared through limits of agreement. The results showed, in general, the launch monitors were in closer agreement to the benchmark for ball parameters than clubhead. High levels of agreement were found for ball velocity, ball path, total spin rate and backspin. However, poorer agreement was shown for ball sidespin and spin axis as well as clubhead velocity, clubhead path and clubhead orientation. Consequently, the launch monitors were deemed unsuitable for inclusion in scientific research across a range of impact parameters. Draw and fade trajectories with a driver and draw, fade and low trajectories with a 5-iron were investigated biomechanically. The clubhead and ball were tracked using the optical method developed in this thesis. Key biomechanical variables (address position and whole-swing) were defined based on coaching theory. Statistically, analysis of variance (address) and principal components analysis (whole-swing), were used to compare draw against fade and low against natural trajectories. Multivariate correlation was used to identify swing pattern similarities between golfers. The group-level comparison showed draw-fade address differences whereby for draw trajectories, the ball was positioned further away from the target, the lead hand further towards the target and the pelvis, thorax and stance openness closed relative to the target line. Over the whole-swing, the draw when compared to the fade demonstrated a pelvis rotation, more rotated away from the target with later rotation; lumbar forward flexion, with slower extending in the downswing; lumbar lateral flexion, with more flexion towards the trail throughout and prolonged trail flexing through ball contact; thorax lateral flexion, with greater, slower lead flexing in the backswing and greater, more prolonged trail flexing in the downswing; pelvis translation further towards the target throughout, with earlier forward translation and centre of pressure, with an earlier, quicker, greater forward shift. Cluster differences were evident, with both Clusters I (57% of golfers with the driver) and II (71% of golfers with the 5-iron) showing greater, earlier thorax rotation towards the target and a tendency for greater lumbar forward flexion over the whole-swing (Cluster II) and backswing (Cluster I). For the group-level low-natural comparison, golfers positioned the ball further away from the target and their lead hand further towards the target for low trajectories. Further, Cluster IV (45% of golfers), narrowed their stance width and laterally flexed their thorax towards the lead, for the same trajectories. Over the whole-swing, the low when compared to the natural showed the pelvis translated towards the target throughout, with later, lesser forward shift for the low trajectories. Furthermore, centre of pressure displayed a greater forward shift for the same shots. Finally, both clusters (Cluster III 36% of golfers and Cluster IV) differed in lumbar forward flexion when playing low trajectories; over the backswing, Cluster III extended, whereas Cluster IV flexed. Cluster IV also showed greater extending in the downswing. Finally, Cluster IV showed more lumbar lateral flexion towards the lead throughout. The results of this study have implications for scientific researchers as well as golf coaches, club-fitters and professionals. Commercially available launch monitors appear accurate enough for coaching applications, however caution is needed for scientific research when tracking a range of clubhead and ball parameters. Furthermore, changes in biomechanics when playing different trajectories has implications for future research and interpretation of published work, as well as for coaching theory. Future work following this thesis could utilise the optical tracking method to validate further commercial systems and for more detailed experimental investigation of clubhead-ball impacts. Furthermore, additional biomechanical investigation into a wider range of shot trajectories across more variables could be conducted, with a more in-depth understanding gained from principal components analysis and golfer clustering

Representations of screen heterosexuality in the musicals of Fred Astaire and Vincente Minnelli

This thesis examines the ways in which heterosexuality is rendered in the Hollywood genre where its existence is most privileged: musicals of the studio era (c. 1930 - c. 1960). In this popular film category, heterosexuality is expressed in a framework of "boy-meets-girl" amatory coupling that is remarkably amplified and insistent. In analysis that is at once sympathetic and critical of the subject matter, I show that heterosexuality in the Hollywood musical is constructed in a way that is far from monolithic. On the contrary, I find that there are in fact varieties of heterosexual identity that exist in the genre, and that they are most succinctly revealed through romantic engagement. Yet heterosexuality is depicted along divergent formulations owing to contrasting relational aims and assumptions. Building on Richard Dyer's 1993 essay, "'I Seem to Find the Happiness I Seek': Heterosexuality and Dance in the Musical," I will discuss how the basis of these separate models is traceable to different approaches related to power distributions between men and women. These processes, in turn, arise from different notions concerning masculinity and femininity. In this way, a mix of gender expressions inhabit the Hollywood musical leading to an assortment of heterosexual models. Textually these models become visible not only through an analysis of characterization and the position of the man and woman within the narrative, but in the camera work, all aspects of the mise-en-scene, and most cogently, in the arrangement of the central heterosexual couple in the song-and-dance sequences. For my examination of heterosexuality in the Hollywood musical, I will concentrate on the work of two of its greatest auteurs: Fred Astaire (star) and Vincente Minnelli (director). The impact each man made on this genre is hard to overestimate. In terms of methodology I divide my analysis between these two artists, and ascertain what model(s) of heterosexual identity are communicated by them. Then after establishing what design(s) of heterosexual life each one suggests (for Astaire I analyse Top Hat (1935] as well as Carefree [1938] and The Sky's the Limit [1943], while for Minnelli I look at Meet Me in St. Louis (1944) and The Pirate (1948]), I conclude this thesis by examining their most acclaimed joint effort (The Band Wagon (1953]) to discern what, if any, change one might have had on the other. A phenomenon tied to the US musical (whether stage or screen) is that although it is the most heterosexual of genres, it is also one traditionally both crafted and appreciated by gay men. Though it does not fall within the scope of this thesis, it is worth speculating for future work if Astaire's heterosexuality and Minnelli's homosexuality had any significant bearing on the way they represented the standard boy meets-girl plot device upon which the Hollywood musical relies

Minimising vibration in a flexible golf club during robotic simulations of a golf swing

Robots are widely used as substitutes for humans in situations involving repetitive tasks where a precise and repeatable motion is required. Sports technology is an area which has seen an increase in the implementation of robots which simulate specific human motions required for a sport. One purpose is to test sports equipment, where the requirement is for a motion to be performed with consistent variables. One issue which has arisen frequently in the robot simulation of humans is the inherent presence of vibration excited in a flexible object being manipulated by a robot, and this issue is not unfounded in the situation presented in this research, of a golf robot manipulating a flexible golf club during the simulation of a golf swing. It had been found that during robotic simulations of golf swings performed with the Miyamae Robo V at the Sports Technology Institute at Loughborough University, swing variables such as shaft deformation and clubhead orientation were dissimilar to those measured for human golf swings. Vibrations present in the golf club were identified as the key cause of the disparity between human and robot swing variables. This research sought to address this issue and find a method which could be applied to reduce clubhead vibrations present in robot simulations of a golf swing to improve their similarity to human swings. This would facilitate the use of the golf robot for equipment testing and club fitting. Golf swing variables were studied and measured for 14 human subjects with the aim being to understand the motion that the robot is required to simulate. A vibration damping gripper was then fitted to the robot to test the effect that changing the interface between the robot-excited vibrations and the club would have, this was achieved with a selection of silicone sleeves with differing material properties which could be attached to the club. Preliminary results showed a noticeable reduction in clubhead vibrations and this solution was investigated further. Mathematically modelling the robot was seen as the most suitable method for this as it meant the robot remained functional and allowed a number of solutions to be tested. Several iterations of a mathematical model were developed with the final model being structurally similar to the robot with the addition of a compliant grip and wrist. The method by which the robot is driven was also recognised as having a large effect on the level of vibration excited in the clubhead and the methodology behind generating smooth robot swing profiles is presented. The mathematical model was used to perform 6 swings and the resulting shaft deformation and clubhead vibration were compared with data from human swings. It was found that the model was capable of producing swing variables comparable to human swings, however in the downswing portion of the swing the magnitude of these variables were larger for the simulations. Simulations were made which sought to demonstrate the difference between the model replicating the rigid robot and a compliant system. Reductions in vibration were achieved in all swings, including those driven with robot feedback data which contains oscillations excited by the method with which the robot is driven

El uso de la tecnología de captura de movimiento para el análisis del rendimiento deportivo

In sport performance, motion capture aims at tracking and recording athletes’ human motion in real time to analyze physical condition, athletic performance, technical expertise and injury mechanism, prevention and rehabilitation. The aim of this paper is to systematically review the latest developments of motion capture systems for the analysis of sport performance. To that end, selected keywords were searched on studies published in the last four years in the electronic databases ISI Web of Knowledge, Scopus, PubMed and SPORTDiscus, which resulted in 892 potential records. After duplicate removal and screening of the remaining records, 81 journal papers were retained for inclusion in this review, distributed as 53 records for optical systems, 15 records for non-optical systems and 13 records for markerless systems. Resultant records were screened to distribute them according to the following analysis categories: biomechanical motion analysis, validation of new systems and performance enhancement. Although optical systems are regarded as golden standard with accurate results, the cost of equipment and time needed to capture and postprocess data have led researchers to test other technologies. First, non-optical systems rely on attaching sensors to body parts to send their spatial information to computer wirelessly by means of different technologies, such as electromagnetic and inertial (accelerometry). Finally, markerless systems are adequate for free, unobstructive motion analysis since no attachment is carried by athletes. However, more sensors and sophisticated signal processing must be used to increase the expected level of accuracy.En el ámbito del rendimiento deportivo, el objetivo de la captura de movimiento es seguir y registrar el movimiento humano de deportistas para analizar su condición física, rendimiento, técnica y el origen, prevención y rehabilitación de lesiones. En este artículo, se realiza una revisión sistemática de los últimos avances en sistemas de captura de movimiento para el análisis del rendimiento deportivo. Para ello, se buscaron palabras clave en estudios publicados en los últimos cuatro años en las bases de datos electrónicas ISI Web of Knowledge, Scopus, PubMed y SPORTDiscus, dando lugar a 892 registros. Tras borrar duplicados y análisis del resto, se seleccionaron 81 artículos de revista, distribuidos en 53 registros para sistemas ópticos, 15 para sistemas no ópticos y 13 para sistemas sin marcadores. Los registros se clasificaron según las categorías: análisis biomecánico, validación de nuevos sistemas y mejora del rendimiento. Aunque los sistemas ópticos son los sistemas de referencia por su precisión, el coste del equipamiento y el tiempo invertido en la captura y postprocesado ha llevado a los investigadores a probar otras tecnologías. En primer lugar, los sistemas no ópticos se basan en adherir sensores a zonas corporales para mandar su información espacial a un ordenador mediante distintas tecnologías, tales como electromagnética y inercial (acelerometría). Finalmente, los sistemas sin marcadores permiten un análisis del movimiento sin restricciones ya que los deportistas no llevan adherido ningún elemento. Sin embargo, se necesitan más sensores y un procesado de señal avanzado para aumentar el nivel de precisión necesario