Coach informed biomechanical analysis of the golf swing

Coach informed biomechanical analysis of the golf swin

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

The kinematics of batting against fast bowling in cricket

In cricket, batting against a fast bowler is thought to be one of the most challenging tasks a player must undertake. Despite this, minimal research exists investigating the techniques used by batsmen, with the majority of research focussed on injury mechanisms and pace generation in fast bowlers. The aim of this study was to investigate the techniques used by elite and amateur batsmen in a training environment, such that key aspects of batting technique relating to success could be extracted, and recommendations for future coaching practice and player development could be made. A novel methodology was developed for the collection of full body three-dimensional kinematic data of cricket batsmen in a realistic training environment. Kinematic and high-speed video (250 Hz) data were collected for 31 batsmen, and a three-dimensional full body biomechanical model was developed. Batsmen performed forward drive and pull shots against different delivery methods. Key events and kinematic parameters were defined, and used to produce detailed biomechanical descriptions of the forward drive and pull shots. A curve fitting methodology was developed and validated to determine the impact location of the ball on the bat face, and used to investigate the effects of impact location on shot outcome during a range hitting task. Impacts further from the sweetspot were found to generate lower ball speeds and decrease shot accuracy through bat twist. [Continues.

Movement variability and strength and conditioning in golf

The detrimental nature of movement variability has recently been reconsidered with suggestions that it has a functional role to play in performance. Movements in golf can be attributed to the organismic, task and environmental constraints from which they emerge with these swing movements affecting shot outcomes. A three-dimensional analysis of address position variability revealed that higher skilled golfers present reduced alignment variability in angular relationships between the shoulders and stance compared to less skilled counterparts. Whilst there were no group differences in impact variability, both points in the swing displayed reducing variability from proximal to distal aspects of the kinetic chain. With the popularity of strength and conditioning growing within the golfing world it has become important for coaches to be able to assess golfers’ physical constraints. Two-dimensional analysis, representative of that used in coaching environments, assessed the relationship between the overhead squat and deterioration of posture in the golf swing. Results showed small but significant relationships between this test and golf swing postural kinematics. An 8-week intervention to address overhead squat physical constraints resulted in no change in 3D swing kinematics. Strength and conditioning as a stand-alone intervention provides no benefits to postural kinematics suggesting the need for coaching

Next generation cricket bowling machine

Cricket is a traditional team sport played in over 100 countries around the world. Unlike many mainstream sports, cricket has seen little research and development within the equipment used to play the game. Ball launching machines have been used as a training aid in a number of sports including cricket, however, as with the playing equipment used, these too have seen little development. Current cricket bowling machines enable players to train at a high intensity producing repeatable deliveries for batsmen to hone their skills. A need has been established by the coaching staff of the England and Wales Cricket Board (ECB) for a cricket training system that provides batsmen with a match realistic environment in which to train. Existing cricket bowling machines do not offer batsmen pre-release visual information that they would receive in a match situation and the most popular models release moulded, dimpled balls that do not replicate the performance of cricket balls.... cont'd

The timing and magnitude of muscular activity patterns during a field hockey hit

The field hockey hit is one of the most important skills used in the game. However, due to the paucity of empirical research, little is known about the biomechanics of this movement. Muscular activation patterns have been shown to be major contributing factors to performance variables in similar swinging motions in golf, tennis and baseball but debate remains about which muscles are contributing to and controlling such motions. Moreover, muscle studies have typically neglected the contribution to movement from segmental interactions and have not related muscle activity to the three-dimensional kinematics of the swing. The aim of this study was to investigate the contributions from muscular activity and from segmental interactions to the hits of ten male, university-level field hockey players. The activity of sixteen upper body and trunk muscles was monitored using surface electromyography alongside synchronized three-dimensional kinematics of the upper body and hockey stick motions. Surface electromyographic signals were recorded at 2000Hz bilaterally from the biceps brachii, triceps brachii, the anterior and posterior deltoids, the upper trapezius, the latissimus dorsi and the sternal and clavicular pectoralis major muscles. Three-dimensional kinematic data were collected at 240Hz and each hockey hit was broken down into four phases of the backswing, the early forward swing, acceleration and the early follow-through. These kinematic and electromyographic data were then synchronised and temporally normalised before the electromyographic data were normalised to relative maximal reference contractions. Right anterior deltoid, right pectoralis major and bilateral latissimus dorsi activity initiates the downswing of the hockey hit, causing the early acceleration of the arms. Segmental interactions, due to these accelerations, cause the hockey stick to lag and the wrists to ‘cock’. A combination of left anterior deltoid, left latissimus dorsi and bilateral pectoralis major activity continue to accelerate the shoulders during the downswing whilst elbow musculature appears to control the effects of segmental interactions. These segmental interactions then become involved in wrist ‘uncocking’ as the stick accelerates towards impact with the ball. The effects of muscular activity and segmental interactions cause the right elbow to flex then extend, whereas the left elbow demonstrates a more constant degree of extension throughout the hit. Both wrists display the same pattern of ‘cocking’ then ‘uncocking’. These combined patterns lead the left arm and stick system to function as a double pendulum whilst the right arm and stick more closely resemble a triple pendulum

Action recognition based on joint trajectory maps using convolutional neural networks

Recently, Convolutional Neural Networks (ConvNets) have shown promising performances in many computer vision tasks, especially image-based recognition. How to effectively use ConvNets for video-based recognition is still an open problem. In this paper, we propose a compact, effective yet simple method to encode spatiotemporal information carried in 3D skeleton sequences into multiple 2D images, referred to as Joint Trajectory Maps (JTM), and ConvNets are adopted to exploit the discriminative features for realtime human action recognition. The proposed method has been evaluated on three public benchmarks, i.e., MSRC-12 Kinect gesture dataset (MSRC-12), G3D dataset and UTD multimodal human action dataset (UTD-MHAD) and achieved the state-of-the-art results

Temporal Motion Models for Monocular and Multiview 3–D Human Body Tracking

We explore an approach to 3D people tracking with learned motion models and deterministic optimization. The tracking problem is formulated as the minimization of a differ- entiable criterion whose differential structure is rich enough for optimization to be accom- plished via hill-climbing. This avoids the computational expense of Monte Carlo methods, while yielding good results under challenging conditions. To demonstrate the generality of the approach we show that we can learn and track cyclic motions such as walking and running, as well as acyclic motions such as a golf swing. We also show results from both monocular and multi-camera tracking. Finally, we provide results with a motion model learned from multiple activities, and show how this models might be used for recognition

Bridging the Gap between Detection and Tracking for 3D Human Motion Recovery

The aim of this thesis is to build a system able to automatically and robustly track human motion in 3–D starting from monocular input. To this end two approaches are introduced, which tackle two different types of motion: The first is useful to analyze activities for which a characteristic pose, or key-pose, can be detected, as for example in the walking case. On the other hand the second can be used for cases in which such pose is not defined but there is a clear relation between some easily measurable image quantities and the body configuration, as for example in the skating case where the trajectory followed by a subject is highly correlated to how the subject articulates. In the first proposed technique we combine detection and tracking techniques to achieve robust 3D motion recovery of people seen from arbitrary viewpoints by a single and potentially moving camera. We rely on detecting key postures, which can be done reliably, using a motion model to infer 3D poses between consecutive detections, and finally refining them over the whole sequence using a generative model. We demonstrate our approach in the cases of golf motions filmed using a static camera and walking motions acquired using a potentially moving one. We will show that this approach, although monocular, is both metrically accurate because it integrates information over many frames and robust because it can recover from a few misdetections. The second approach is based on the fact that the articulated body models used to represent human motion typically have many degrees of freedom, usually expressed as joint angles that are highly correlated. The true range of motion can therefore be represented by latent variables that span a low-dimensional space. This has often been used to make motion tracking easier. However, learning the latent space in a problem independent way makes it non trivial to initialize the tracking process by picking appropriate initial values for the latent variables, and thus for the pose. In this thesis, it will be shown that by directly using observable quantities as latent variables, this issue can be eliminated