The influence of tracking marker locations on three-dimensional wrist kinematics
Turner J, Forrester SE, Mears AC and Roberts JR
To determine the influence of tracking marker locations on wrist kinematics during free movements and the golf swing, with the intention of recommending a solution that generates meaningful three-dimensional wrist kinematics.
Golf Swing Segmentation from a Single IMU Using Machine Learning
Kim M and Park S
Golf swing segmentation with inertial measurement units (IMUs) is an essential process for swing analysis using wearables. However, no attempt has been made to apply machine learning models to estimate and divide golf swing phases. In this study, we proposed and verified two methods using machine learning models to segment the full golf swing into five major phases, including before and after the swing, from every single IMU attached to a body part. Proposed bidirectional long short-term memory-based and convolutional neural network-based methods rely on characteristics that automatically learn time-series features, including sequential body motion during a golf swing. Nine professional and eleven skilled male golfers participated in the experiment to collect swing data for training and verifying the methods. We verified the proposed methods using leave-one-out cross-validation. The results revealed average segmentation errors of 5-92 ms from each IMU attached to the head, wrist, and waist, accurate compared to the heuristic method in this study. In addition, both proposed methods could segment all the swing phases using only the acceleration data, bringing advantage in terms of power consumption. This implies that swing-segmentation methods using machine learning could be applied to various motion-analysis environments by dividing motion phases with less restriction on IMU placement.
The effects of strength and conditioning interventions on golf performance: A systematic review
Ehlert A
There is a growing body of literature on strength and conditioning (S&C) interventions for golfers of various skill levels. The aim of this systematic review was to evaluate the effects of S&C interventions on measures of golf performance (clubhead speed, ball speed, distance, etc.). Three databases (PubMed, SPORTDiscus, Web of Science) were searched and twenty-five studies identified that evaluated the effects of a S&C intervention on at least one golf performance measure compared to a control or comparison group. Most studies used combinations of strength training, plyometrics, stretching or core exercise, with many finding a benefit. Though it varied across studies and outcomes, average increases in clubhead speed, ball speed and distance measures were 4-6.4% when significant findings were synthesized. Four studies also found significant changes to golf swing kinematics, while three others found positive effects on measures of accuracy or consistency. Future research should compare different S&C interventions, explore the role of training status, skill level and intervention duration on the effects of S&C interventions, and report individual responses in addition to group data. Further, research should continue to evaluate effects on swing kinematics, accuracy and direct golf performance measures (e.g., handicap index).
Could knee joint mechanics during the golf swing be contributing to chronic knee injuries in professional golfers?
Carson H, Richards J and Coleman SGS
Full three-dimensional movements and external moments in golfers' knees and the possible involvement in injuries have not been evaluated using motion capture at high sample frequencies. This study measured joint angles and external moments around the three anatomical axes in both knees of 10 professional golfers performing golf drives whilst standing on two force plates in a motion capture laboratory. Significant differences were found in the knee joint moments between the lead and trail limbs for the peak values and throughout all stages during the swing phase. A significantly higher net abduction moment impulse was seen in the trail limb compared with the lead limb (-0.518 vs. -0.135, indicating greater loading over the whole swing, which could contribute to knee lateral compartment or anterior cruciate ligament injuries. A significant correlation (= -0.85) between clubhead speed at ball contact and maximum joint moment was found, with the largest correlations being found for joint moments at the top of the backswing event and at the end of the follow-through. Therefore, although knee moments can contribute to high clubhead speeds, the large moments and impulses suggest that they may also contribute to chronic knee injuries or exacerbate existing conditions.
Partial swing golf shots: scaled from full swing or independent technique?
Todd SD, Wiles JD, Coleman DA and Brown MB
During practice and competition, golfers are required to use submaximal effort to hit the ball a given distance, i.e., perform a partial shot. While the full golf swing has undergone extensive research, little has addressed partial shots and the biomechanical modifications golfers employ. This study investigates the biomechanical changes between full and partial swings, and determines if the partial swing is a scaled version of the full swing. Using a repeated measures design, 13 male golfers completed a minimum of 10 swings in the full and partial swing conditions, whilst club, ball, kinematic, and kinetic parameters were recorded. Large and statistically significant reductions in body motion (centre of pressure ellipse: 33.0%,  = 0.004,  = 2.26), combined with moderate reductions in lateral shift (25.5%,  = 0.004,  = 0.33) and smaller reductions in trunk rotation (arm to vertical at top of backswing: 14.1%,  = 0.002,  = 2.58) indicate golfers favour larger reductions in proximal measures, combined with diminished reductions as variables moved distally. Furthermore, the partial swing was not found to be a scaled version of the full swing implying a new approach to coaching practices might be considered.
Chemical Meningitis after a Golf Swing-induced Dermoid Cyst Rupture
Takahashi M, Tanabe M, Inaba A and Orimo S
A 51-year-old man developed a sudden headache during golf practice, followed by a high fever. He was admitted with suspected neutrophilic meningitis and was diagnosed with chemical meningitis caused by a dermoid cyst rupture based on the characteristic magnetic resonance imaging (MRI) findings, which showed multiple lipid droplets in his ventricle and cistern. His repetitive golf-swing motion was suggested to be the cause of his dermoid cyst rupture. On MRI, the lipid droplets appeared to have migrated by gravity because of the body position. Therefore, the body position should be considered to prevent obstructive hydrocephalus by lipid droplets after a dermoid cyst rupture.
Three Dimensional Upper Limb Joint Kinetics of a Golf Swing with Measured Internal Grip Force
Choi H and Park S
The biomechanics of a golf swing have been of interest to golfers, instructors, and biomechanists. In addition to the complexity of the three-dimensional (3D) dynamics of multi-segments of body, the closed-chain body posture as a result of both hands holding a club together makes it difficult to fully analyze the 3D kinetics of a golf swing. To identify the hand-grip joint force and torque applied by each hand, we directly measured the 3D internal grip force of nine registered professional golfers using an instrumented grip. A six-axis force-torque sensor was connected to a custom-made axially separated grip, which was then connected to a driver shaft using a manufactured screw thread. Subjects participated in two sessions of data collection featuring five driver swings with both a regular and customized sensor-embedded grip, respectively. Internal grip force measurement and upper limb kinematics were used to calculate the joint force and torque of the nine-linkage closed-chain of the upper limb and club using 3D inverse dynamics. Direct measurement of internal grip forces revealed a threefold greater right-hand torque application compared to the left hand, and counterforce by both hands was also found. The joint force and torque of the left arm tended to precede that of the right arm, the majority of which had peaks around the impact and showed a larger magnitude than that of the left arm. Due to the practical challenge of measuring internal force, heuristic estimation methods based on club kinematics showed fair approximation. Our results suggest that measuring the internal forces of the closed-chain posture could identify redundant joint kinetics and further propose a heuristic approximation.
Dynamic task observation: A gaze-mediated complement to traditional action observation treatment?
D'Innocenzo G, Nowicky AV and Bishop DT
Action observation elicits changes in primary motor cortex known as motor resonance, a phenomenon thought to underpin several functions, including our ability to understand and imitate others' actions. Motor resonance is modulated not only by the observer's motor expertise, but also their gaze behaviour. The aim of the present study was to investigate motor resonance and eye movements during observation of a dynamic goal-directed action, relative to an everyday one - a reach-grasp-lift (RGL) action, commonly used in action-observation-based neurorehabilitation protocols. Skilled and novice golfers watched videos of a golf swing and an RGL action as we recorded MEPs from three forearm muscles; gaze behaviour was concurrently monitored. Corticospinal excitability increased during golf swing observation, but it was not modulated by expertise, relative to baseline; no such changes were observed for the RGL task. MEP amplitudes were related to participants' gaze behaviour: in the RGL condition, target viewing was associated with lower MEP amplitudes; in the golf condition, MEP amplitudes were positively correlated with time spent looking at the effector or neighbouring regions. Viewing of a dynamic action such as the golf swing may enhance action observation treatment, especially when concurrent physical practice is not possible.
Sonification of Golf Putting Gesture Reduces Swing Movement Variability in Novices
O'Brien B, Juhas B, Bieńkiewicz M, Buloup F, Bringoux L and Bourdin C
: To study whether novices can use sonification to enhance golf putting performance and swing movements. : Forty participants first performed a series of 2 m and 4 m putts, where swing velocities associated with successful trials were used to calculate their mean velocity profile (MVP). Participants were then divided into four groups with different auditory conditions: static pink noise unrelated to movement, auditory guidance based on personalized MVP, and two sonification strategies that mapped the real-time error between observed and MVP swings to modulate either the stereo display or roughness of the auditory guidance signal. Participants then performed a series of 2 m and 4 m putts with the auditory condition designated to their group. : In general our results showed significant correlations between swing movement variability and putting performance for all sonification groups. More specifically, in comparison to the group exposed to static pink noise, participants who were presented auditory guidance significantly reduced the deviation from their average swing movement. In addition, participants exposed to error-based sonification with stereo display modulation significantly lowered their variability in timing swing movements. These results provide further evidence of the benefits of sonification for novices performing complex motor skill tasks. : More importantly, our findings suggest participants were able to better use online error-based sonification rather than auditory guidance to reduce variability in the execution and timing of their movements.
Effects of pelvis-shoulders torsional separation style on kinematic sequence in golf driving
Han KH, Como C, Kim J, Hung CJ, Hasan M and Kwon YH
The golfer's body (trunk/arms/club) can be modeled as an inclined axle-chain system and the rotations of its parts observed on the functional swing plane (FSP) can represent the actual angular motions closely. The purpose of this study was to investigate the effects of pelvis-shoulders torsional separation style on the kinematic sequences employed by the axle-chain system in golf driving. Seventy-four male skilled golfers (handicap ≤ 3) were assigned to five groups based on their shoulder girdle motion and X-factor stretch characteristics: Late Shoulder Acceleration, Large Downswing Stretch, Large Backswing Stretch, Medium Total Stretch, and Small Total Stretch. Swing trials were captured by an optical system and the hip-line, thorax, shoulder-line, upper-lever, club, and wrist angular positions/velocities were calculated on the FSP. Kinematic sequences were established based on the timings of the peak angular velocities (backswing and downswing sequences) and the backswing-to-downswing transition time points (transition sequence). The backswing and transition sequences were somewhat consistent across the groups, showing full or partial proximal-to-distal sequences with minor variations. The downswing sequence was inconsistent across the groups and the angular velocity peaks of the body segments were not significantly separated. Various swing characteristics associated with the separation styles influenced the motion sequences.
Physical Determinants of Golf Swing Performance: A Review
Sheehan WB, Bower RG and Watsford ML
Sheehan, WB, Bower, RG, and Watsford, ML. Physical determinants of golf swing performance: A review. J Strength Cond Res XX(X): 000-000, 2019-Traditionally, golf practice has primarily focused on the mental, technical, and skill aspects as the primary means to improve performance. Only recently has a greater emphasis been placed on the physical components with balance, muscular strength, power, and specific muscle-tendon properties demonstrating positive associations with club head speed and carry distance. Accordingly, this review will explore the influence of these physical components on measures of golf swing performance. Superior balance may allow players to effectively deal with the need to shift weight during the swing as well as different stance positions, whereas superior lower-body muscular strength, power, and stiffness may allow more mechanical work to be performed on the club during the swing per unit of time, consequently increasing club head speed. Alternatively, flexibility may also contribute to enhanced force production with a greater range of motion, particularly when generating the "X-factor," allowing for a longer backswing and more time to produce higher angular velocities and forces. Furthermore, training intervention studies focusing on the aforementioned components have demonstrated enhancements in swing performance. Targeting multiple muscle groups, including those implicated via electromyography activation, and utilizing multiple modalities have proven effective at increasing club head speed. However, such multifaceted programs have made it difficult to determine the mechanisms that specifically contribute to performance gains. Despite these limitations, strength, power, and musculotendinous stiffness, particularly in the lower body, seem to be stronger determinants of club head speed and carry distance than flexibility. Furthermore, acute improvements can be induced using resistance-orientated warm-ups.
Differences in kinematics and driver performance in elite female and male golfers
Parker J, Hellström J and Olsson MC
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.
Motor control of practice and actual strokes by professional and amateur golfers differ but feature a distance-dependent control strategy
Hasegawa Y, Fujii K, Miura A, Yokoyama K and Yamamoto Y
We explored how practice and actual putting strokes differed between professionals and high-level golf amateurs, and how practice strokes reflected subtle differences in putting distances. We analysed swing amplitude, impact velocity, and acceleration profile of the club-head. The acceleration profiles showed that the motor control pattern of the practice stroke differed from that of the actual stroke. To clarify the effects of different putting distances on the practice stroke and to analyse how much the actual stroke could be explained by the practice stroke, we conducted individual regression analyses. The practice strokes of all participants could be divided into three strategies and five types by the coefficient of determination and the slope. This implies that the purpose of the practice stroke varied among golfers. Most golfers used the individual velocity criteria in their practice strokes, which resulted in different putting distances based on their criteria. Unexpectedly, we found no significant difference in skill level between professionals and high-level amateurs. The results of this study imply that the practice stroke does not duplicate the actual stroke, even for professional golfers with excellent skills. However, most high-level golfers adopted distance-dependent control strategies for slightly different putting distances.
The effect of alterations in foot centre of pressure on lower body kinematics during the five-iron golf swing
Faux L, Carlisle A, Vickers J and Diss C
The research aimed to evaluate the effects of an intervention aimed at altering pressure towards the medial aspect of the foot relating to stability mechanisms associated with the golf swing. We hypothesised that by altering the position of the foot pressure, the lower body stabilisation would improve which in turn would enhance weight distribution and underpinning lower body joint kinematics. Eight professional golf association (PGA) golf coaches performed five golf swings, recorded using a nine-camera motion analysis system synchronised with two force platforms. Following verbal intervention, they performed further five swings. One participant returned following a one-year intervention programme and performed five additional golf swings to provide a longitudinal case study analysis. Golf performance was unchanged evidenced by the velocity and angle of the club at ball impact (BI), although the one-year intervention significantly changed the percentage of weight experienced at each foot in the final 9% of downswing, which provided an even weight distribution at BI. This is a highly relevant finding as it indicates that the foot centre of pressure was central to the base of support and in-line with the centre of mass (CoM), indicating significantly increased stability when the CoM is near maximal acceleration.
Visual dependency and postural control on swing performance in golf players
Micarelli A, Viziano A, Lanzillotta A, Ruscello B, D'Ottavio S and Alessandrini M
Individuals have to reweight the respective contribution of the different sources of sensorial information for regulating posture and balance, especially during fine task execution. Given the evidences indicating strategy during swing performance as associated with prioritization of task-relevant visuospatial information for skill execution, the aim of the present work is to assess differences in visual dependency (VD) and postural control in a population of expert (EXP) and non-expert (NEXP) golfers when compared with healthy subjects (HC) and to discover possible relationships between these outcomes and swing performance. Thus, 15 golfers (EXP = 7; NEXP = 8) and 32 matched HC underwent otoneurological testing including video Head Impulse Test, posturography and Rod and Disk Test (RDT). Golf players also underwent a swing session procedure, which performance was measured by means of the Flightscope X2 Doppler-radar launch monitor system. EXP subjects demonstrated significant ( < 0.05) lower values in i) counter-clockwise (CCW) and clockwise (CW) dynamic conditions when compared with both NEXP and HC subjects RDT outcome measures and ii) surface and length posturography values as compared with HC subjects. When treating golf players outcomes as 'a continuum', CCW and CW scores were found to positively correlate with both lateral distance and horizontal launch angle and to negatively correlate with spin rpm. In conclusion, the present study suggests that the high-level of visual-independency demonstrated by EXP subjects may be functionally related in expert golfers to an effective motor strategy preferentially not referring to an inappropriate reliance on visual input.
Three-dimensional kinematics in healthy older adult males during golf swings
Severin AC, Tackett SA, Barnes CL and Mannen EM
The biomechanics of the golf swing have received considerable attention in previous research. However, existing studies have focused on young athletes, while the kinematics of older golfers remain poorly documented. This study presents kinematic data for healthy senior golfers during swings performed with a driver and six-iron. Seventeen male golfers (62.2 ± 8.8 years) volunteered for participation and a 10-camera Vicon system (Oxford, UK) recorded kinematic data (500 Hz). A launch monitor (TrackMan, Vedbæk, Denmark) recorded club head speed and initial ball speed. Joint angles and peak velocities of the trunk and lower body were extracted at the top of the backswing, ball contact, and end of the swing. Intraclass correlations and standard error of measurement determined reliability, and pairwise statistics determined between-club differences. Swings with the driver had 7.3° less trunk extension and 4.3° less X-factor at backswing, and 10.5° less trunk flexion and 3.2° less X-factor at ball impact. Older adults portray several differences in lower body kinematics between a six-iron and driver but maintain good to excellent reliability (0.728-0.997) during the swings. Comparisons with previous research also showed senior athletes produce slower club head and ball speeds than younger golfers, and that kinematic differences exist between the populations.
A biomechanical approach to investigate swing characteristics in elite golfers
Fuyu M, Lee HM, Chen PY, Chou LW and Wei SH
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.
The effect of uphill and downhill slopes on centre of pressure movement, alignment and shot outcome in mid-handicap golfers
Hiley MJ, Bajwa Z, Liang Y and Blenkinsop GM
The aim of the study was to examine changes in centre of pressure (COP) movement, alignment and shot outcome during golf shots from flat, uphill, and downhill slopes by mid-handicap golfers. Twelve male golfers hit balls with a six-iron from the flat and 5° slopes while kinematics and kinetics of the swing were collected. A launch monitor measured performance outcomes. A shift in the COP was found during the backswing when playing on a slope, but disappeared during the downswing. Golfers attempted to align the body perpendicular to the slope at the start of the swing resulting in COP movement towards the lower foot, but were not able to maintain this throughout the swing, like low handicap golfers. There was no significant difference in stance width, but golfers placed the ball closer to the uphill foot on a slope. Ball speed was not significantly affected by the slope, but launch angle and ball spin were. Golfers were more likely to hit shots to the left from an uphill slope and to the right for a downhill slope. No consistent compensatory adjustments in alignment at address were found, with differences in final ball position due to lateral spin.
Kinematic determinants of performance parameters during golf swing
Khuyagbaatar B, Purevsuren T and Kim YH
In golf, the trunk and pelvis kinematic variables are often related to measures of performance due to the highly complex and multi-joint movements involved in swings. However, it is unclear how specific body segments or joints contributed to the golf performance parameters. Therefore, the purpose of this study was to identify the key joints, including those of the upper and lower trunk, that are associated with golf performance parameters, such as X-Factor and pelvis motion. A motion capture system was used to obtain three-dimensional kinematics of golf swings performed by 10 low handicap male golfers. Based on regression analysis, right knee adduction, right shoulder external rotation and left elbow extension in ball address to top of the backswing and left knee adduction and lower trunk right bending with left rotation in top of the backswing to end of follow-through were presented as predictor variables for the X-Factor. For pelvis movement, a greater number of joint angles were associated with pelvis posterior tilt during backswing and pelvis motion to target with right rotation during downswing/follow-through. This study provides fundamental details of the movement mechanisms of major joints, as well as their relationships with performance parameters. Such understanding can be combined with training to improve the golfing skill and prevent possible injuries.
Examining the influence of grip type on wrist and club head kinematics during the golf swing: Benefits of a local co-ordinate system
Carson HJ, Richards J and Mazuquin B
Wrist movements have been identified as an important factor in producing a successful golf swing, with their complex motion influencing both club head velocity and orientation. However, a detailed analysis of wrist angles is lacking in the literature. The purpose of this study was to determine kinematics across wrists and club head characteristics during the golf swing under weak, neutral and strong grip conditions. Twelve professional male golfers executed 24 shots using a driver under three grip conditions. A six degrees of freedom analysis of the hand with respect to the distal forearm was performed using a 10-camera three-dimensional motion capture system. Differences in joint angles were explored using repeated measures ANOVAs at key swing events (onset, top of backswing and impact), in addition club head velocity and clubface angle at impact were also explored. Main findings revealed significant differences in flexion/extension and internal/external rotation for both wrists at all swing events, whereas fewer significant interactions were found in ulnar/radial deviation across grips for both wrists at all events. Clubface angle only differed significantly between the weak and the strong and neural grips, presenting a more 'open' clubface to the intended hitting direction. This study is the first to explore tri-planar wrist movement and the effect of different grips, such analysis has implications for coaching knowledge and practice and should inform future research into different aspects of skill, technique analysis and may inform injury mechanisms/prevention.
Effects of the golfer-ground interaction on clubhead speed in skilled male golfers
Han KH, Como C, Kim J, Lee S, Kim J, Kim DK and Kwon YH
The purposes of this study were to characterise the golfer-ground interactions during the swing and to identify meaningful associations between the golfer-ground interaction force/moment parameters and the maximum clubhead speed in 63 highly skilled male golfers (handicap ≤ 3). Golfers performed shots in 3 club conditions (driver, 5-iron and pitching wedge) which were captured by an optical motion capture system and 2 force plates. In addition to the ground reaction forces (GRFs), 3 different golfer-ground interaction moments (GRF moments, pivoting moments and foot contact moments) were computed. The GRF moment about the forward/backward (F/B) axis and the pivoting moment about the vertical axis were identified as the primary moments. Significant (p < 0.05) correlations of peak force parameters (all components in the lead foot and F/B component in the trail foot) and peak moment parameters (lead-foot GRF moment and trail-foot pivoting moment) to clubhead speed were found. The lead-foot was responsible for generating the GRF moment, while the trail foot contributed to the pivoting moment more. The instant the lead arm becomes parallel to the ground was identified as the point of maximum angular effort, and the loading onto the lead-foot near this point was critical in generating both peak moments.
Dynamics of pelvis rotation about its longitudinal axis during the golf swing
Takagi T, Murata M, Yokozawa T and Shiraki H
The purpose of this study was to identify the dynamic factors contributing to pelvis angular velocity about its longitudinal axis (pelvis axial angular velocity) during the golf swing. Thirty-one right-handed skilled golfers (handicap, 3.5 ± 1.8) performed swings with a driver. The kinematic and kinetic data were collected using an optical motion analysis system and two force platforms. The dynamic factors (i.e., joint torque, gravitational force, motion-dependent forces and inertia forces) contributing to pelvis axial angular acceleration were calculated. The present study revealed that the left (lead) hip flexor and adductor torques as well as the right (trail) hip extensor and abductor torques were identified as the main contributors to pelvis axial angular velocity. These hip joint torques contributed not synchronously but sequentially to the pelvis. Although the knee joint torques contributed little to pelvis axial angular velocity directly, the knee joint torques might support the generation of large hip joint torques by regulating joint postures. These findings indicate that the functional coordination of the lower limb segments as well as the magnitude of the joint torques play an important role in rotating the pelvis.
Acute effects of different warm-up protocols on highly skilled golfers' drive performance
Langdown BL, Wells JET, Graham S and Bridge MW
Previous research has highlighted the positive effect that different warm-up protocols have on golf performance (e.g. Sorbie et al., 2016; Tilley & Macfarlane, 2012) with the design of warm-ups and programmes targeting and improving golf performance through the activation and development of specific muscle groups. This study aimed to examine the acute effects of two warm-up protocols on golf drive performance in comparison to a control condition. Using a randomised counterbalanced design over three testing sessions, twenty-three highly skilled golfers completed the control, dynamic and resistance-band warm-up conditions. Following each condition, a GC2 launch monitor was used to record ball velocity and other launch parameters of ten shots hit with the participants' own driver. A repeated-measures ANOVA found significant increases in ball velocity (η = .217) between the control and both the dynamic and resistance-band warm-up conditions but no difference between these latter two, and a reduction in launch angle between control and dynamic conditions. The use of either a dynamic stretching or resistance-band warm-up can have acute benefits on ball velocity but golfers should liaise with a PGA Professional golf coach to effectively integrate this into their golf driving performance.
The evaluation of foot pressure and postural structure of national golfers
İlhan Odabaş H, Bulgan Ç, Bingül BM and Sarpyener K
The aim of this study was to perform the static and dynamic biomechanical assessment of postural structure and analyze variations of foot pressure in elite golfers.
The Relationship Between the Golf Specific Movement Screen and Golf Performance
Speariett S and Armstrong R
Golf requires effective movement patterns to produce an effective swing and performance.
Biomechanics of the golf swing using OpenSim
Mahadas S, Mahadas K and Hung GK
A study was conducted to investigate the underlying mechanisms involved in the dynamics of body motions during the golf swing. A series of model simulation programs were developed in OpenSim to control the characteristics of the biomechanical model of the body. The resultant model parameters were put in an Excel file, which allowed these parameters to be modified. OpenSim model simulation run was paused at various points of the golf swing and screenshots were taken. MATLAB was used to find the positional value of the center of clubface for each screenshot and the Euclidean distances of the clubhead position between poses. A series of simulation trials were then conducted using various time increments between the poses in order to calculate the clubhead velocities. Three of these trials were selected to illustrate the swing patterns of players of varying skill levels ranging from basic beginner to highly-skilled. These simulations using OpenSim can serve as a platform for understanding the dynamics of body motions in sports and biomedicine.
Test-retest reliability of segment kinetic energy measures in the golf swing
Outram T and Wheat J
Analyses of segment kinetic energy (KE) can provide the most appropriate means of exploring sequential movements. As the reliability associated with its measurement has not been reported, the aim of this study was to examine the test-retest reliability of segment KE measures in the golf swing. On two occasions, seven male golfers hit five shots with three different clubs. Body segment inertia parameters were estimated for 17 rigid bodies and 3D kinematic data were collected during each swing. The magnitude and timing of peak total, linear and angular kinetic energies were then calculated for each rigid body and for four segment groups. Regardless of club type, KE was measured with high reliability for almost all rigid bodies and segment groups. However, significantly larger magnitudes of peak total (p = 0.039) and linear (p = 0.021) lower body KE were reported in test 2 than in test 1. The high reliability reported in this study provides support for the use of analyses of segment kinetic energy. However, practitioners should pay careful attention to the identification of anatomical landmarks which define the thigh, pelvis and thorax as this was the main cause of variability in repeated measures of segment kinetic energy.
Examination of the neuromechanical factors contributing to golf swing performance
Sheehan WB, Watsford ML and Pickering Rodriguez EC
This study investigated the relationship between a range of neuromechanical variables in the lower- and upper-body, and golf performance. Participants were assessed for individual muscle stiffness, vertical stiffness (Kvert), flexibility, power and maximal isometric strength. Furthermore, golf performance was determined by handicap and club head speed. Pearson's correlations quantified the relationships between neuromechanical variables and performance measures. Participants were also separated into relatively high club head speed (HC) and low club head speed (LC) groups and compared for physical characteristics. Club head speed showed positive relationships with Kvert and power and a negative relationship with hip mobility. The HC group exhibited superior Kvert and power, while strength and flexibility measures were not related to performance. Higher levels of lower-body stiffness, rate of force development and power output appear to be beneficial for generating superior club head speed. A stiffer system may reduce the time needed to remove the "slack" from the series elastic component therefore, reducing electromechanical delay and enhancing rate of force development. The positive association with rate of force development suggests that increasing this component, along with power production may be superior focal components for training in golfers due to the short duration of the downswing.
Movement Modifications Related to Psychological Pressure in a Table Tennis Forehand Task
Sekiya H and Tanaka Y
Although many studies on choking under pressure used closed skills, such as golf putting, we examined the influence of pressure on movement during a dynamic skill by studying participants' kinematic and kinetic changes during a table tennis forehand task under pressure. Thirty novice table tennis players hit forehand shots toward a target for 135 practice trials and then performed 10 no-pressure and 10 pressure trials. We added psychological pressure by instructing participants they could earn monetary rewards for successful performance and by cancelling accumulated scores for a poor performance. We measured racket head and ball movements as kinematic variables and grip force as a kinetic variable. We also measured state anxiety and heart rate as checks on our manipulation of psychological pressure. In the pressure condition, both state anxiety and heart rate increased significantly ( p < .025), though the pressure level was relatively small. Analysis of kinematic measures revealed that back swing and forward swing were reduced in length; speed of forward swing and ball speed decreased significantly ( p < .008) under pressure. Also, under pressure, ball and racket contact point shifted forward significantly ( p < .008) to reduce the distance between impact and target locations, and performance declined as the ball-landing locations shifted leftward ( p < .007). Grip force showed no significant change. We conclude that, under pressure, movement was modified toward reduced displacement and lower speed in an apparent risk-aversive hitting strategy; these modifications resulted in a performance decrement.
The required number of trials for biomechanical analysis of a golf swing
Severin AC, Barnes SG, Tackett SA, Barnes CL and Mannen EM
The increasing interest in the biomechanical analysis of the golf swing warrants establishing the minimum number of trials required to obtain reliable data. Several such methods have been suggested previously for other movement tasks, and it has been shown that the number of required trials depends on the method used and on the task examined. This study aimed to compare three methods of reliability: a sequential average, intraclass correlations, and a modified version of the standard error of measurement (SEM). Kinematic and kinetic data of 10 recreational golfers performing 15 shots with both a six-iron and a driver was collected using a ten-camera motion capture system and force platforms. Range-of-motion, velocity, joint moments, and ground reaction forces were extracted and analysed using the three methods. The sequential average method yielded the highest number of required trials (12), while the intraclass correlations and SEM both resulted in lower numbers of required trials (4). Considering the variability between participants and strengths and limitations of the various methods, we conclude that 8 trials is sufficient for biomechanical analyses of a golf swing and recommend the SEM method for determining how many swings should be collected.
Vertebral artery dissection and golf swing: a paradigmatic new case
Civardi C, Collini A, Genovese E, Lucchini C, Maggio M and Geda C
Biomechanical Effects of Ball Position on Address Position Variables of Elite Golfers
Kim SE, Koh YC, Cho JH, Lee SY, Lee HD and Lee SC
The purpose of this study was to investigate address position variables in response to changes in ball position in golfers. Eleven male professional golfers were instructed to perform their golf swing. A three-dimensional motion analysis system, with eight infrared cameras and two force platforms, was used to capture the address positions. A golf ball has a diameter of 4.27 cm, and a radius of 2.14 cm. Even small movements of ball position in the mediolateral (M-L) and anteroposterior (A-P) directions significantly changed the address position. When the ball was moved to the left, the shoulder rotation and club-face aim rotated toward the left of the target, and the left vertical ground reaction force increased. When the ball was moved to the right, the opposite findings were observed. When the ball was moved closer, the trunk, hip, knee, ankle, and absolute arm angle extended; the lie angle of the golf club increased; and the center of pressure moved toward the posterior direction. These changes were reversed when the ball was moved further away. The M-L ball position critically changed the address positions of the upper extremities in the horizontal plane, and the A-P ball position critically changed the angles of whole body parts in the sagittal plane. Furthermore, club-head kinematics at impact such as club-face aim, club path, and angle of attack were significantly changed in the M-L ball position; and club-head speed and angle of attack were significantly changed in the A-P ball position. This in-depth understanding of the address position in association with the ball position could provide valuable data for swing coaches when finding a golfer's optimal address position.
Editorial Commentary: When Your Golf Game Is Handicapped by Your Hip
Faucett SC
Golf is a common recreational and competitive sport that requires full hip rotation to allow for a smooth and effective swing. Therefore hip impingement and hip osteoarthritis, by limiting rotation, could cause pain in golfers and even encourage them to discontinue the sport. In my opinion, the lead hip in golfers is likely what generally drives the symptoms in the hip, back, or knee. After surgical correction, golfers are able to get back to golf and many experience improved performance.
Lumbar Spine Injuries: Primary Prevention in Amateur and Professional Golf Players
Goebel D, Drollinger F and Drollinger A
In the sport of golf, there is no standard teaching method or swing technique even though golf is known for overuse injuries. This prospective study was to analyze classic swing kinematics in comparison with the Free-Release method and to define a physiological golf swing. Two hundred eighty-three players, age 50-59 years, were included in the study. For both swing techniques, examination addressed swing visualization, center of pressure (COP), center of mass (COM), as well as pelvic movement in relationship to different standing widths. The position of the spine was evaluated in the frontal and lateral planes. Using the classic technique, no golfer was able to describe his swing parameters, which would be necessary for visualization and to tolerate physiological range of movement, whereas players using the Free-Release method were able to provide such a description. COP and COM showed pathological swing mechanics for the classic technique, whereas for the Free-Release method mechanics were physiological. We conclude that to prevent lumbar spine injury, the classic swinging technique, which is characterized by lateral shear forces, static and dynamic pelvic side bending while rotating with high force against the spine, and an unbalanced COM and COP, should be substituted by the Free-Release technique as a new physiological guideline.
Golf Swing Rotational Velocity: The Essential Follow-Through
Steele KM, Roh EY, Mahtani G, Meister DW, Ladd AL and Rose J
To evaluate if shoulder and pelvic angular velocities differ at impact or peak magnitude between professional and amateur golfers. Golf swing rotational biomechanics are a key determinant of power generation, driving distance, and injury prevention. We hypothesize that shoulder and pelvic angular velocities would be highly consistent in professionals.
The role of pelvis-thorax coupling in controlling within-golf club swing speed
Lamb PF and Pataky TC
Pelvis-thorax coordination has been recognised to be associated with swing speed. Increasing angular separation between the pelvis and thorax has been thought to initiate the stretch shortening cycle and lead to increased clubhead speed. The purpose of this study was to determine whether pelvis-thorax coupling played a significant role in regulating clubhead speed, in a group of low-handicap golfers (mean handicap = 4.1). Sixteen participants played shots to target distances determined based on their typical 5- and 6-iron shot distances. Half the difference between median 5- and 6-iron distance for each participant was used to create three swing effort conditions: "minus", "norm", and "plus". Ten shots were played under each swing effort condition using both the 5-iron and 6-iron, resulting in six shot categories and 60 shots per participant. No significant differences were found for X-factor for club or swing effort. X-factor stretch showed significant differences for club and swing effort. Continuous relative phase (CRP) results mainly showed evidence of the stretch shortening cycle in the downswing and that it was more pronounced late in the downswing as swing effort increased. Substantial inter-individual CRP variability demonstrated the need for individual analyses when investigating coordination in the golf swing.
Development, content validity and test-retest reliability of the Lifelong Physical Activity Skills Battery in adolescents
Hulteen RM, Barnett LM, Morgan PJ, Robinson LE, Barton CJ, Wrotniak BH and Lubans DR
Numerous skill batteries assess fundamental motor skill (e.g., kick, hop) competence. Few skill batteries examine lifelong physical activity skill competence (e.g., resistance training). This study aimed to develop and assess the content validity, test-retest and inter-rater reliability of the "Lifelong Physical Activity Skills Battery". Development of the skill battery occurred in three stages: i) systematic reviews of lifelong physical activity participation rates and existing motor skill assessment tools, ii) practitioner consultation and iii) research expert consultation. The final battery included eight skills: grapevine, golf swing, jog, push-up, squat, tennis forehand, upward dog and warrior I. Adolescents (28 boys, 29 girls; M = 15.8 years, SD = 0.4 years) completed the Lifelong Physical Activity Skills Battery on two occasions two weeks apart. The skill battery was highly reliable (ICC = 0.84, 95% CI = 0.72-0.90) with individual skill reliability scores ranging from moderate (warrior I; ICC = 0.56) to high (tennis forehand; ICC = 0.82). Typical error (4.0; 95% CI 3.4-5.0) and proportional bias (r = -0.21, p = .323) were low. This study has provided preliminary evidence for the content validity and reliability of the Lifelong Physical Activity Skills Battery in an adolescent population.
Training effects of Interactive Metronome® on golf performance and brain activity in professional woman golf players
Kim JH, Han JK and Han DH
During putting in golf, the direction and velocity of the club head should be consistent across swings. In order to maintain consistency in swing timing, the cerebellum provides temporal information, motor timing, control of rhythm, and timing of movements. We utilized Interactive Metronome (IM), a brain training software program that combines the concepts of neurotechnology with the abilities of a computer, to improve an individual's rhythm and timing. We propose that IM would activate neural networks involved in decreasing variation in putt swing. Twenty professional female golfers (KLPGA) were randomly assigned to either an IM training group (n = 10, 35-40 min per session, twice a week for 6 weeks) or a control group (n = 10). The golf putting movements and brain activity were analyzed using Kinovea Software and resting state functional MRI, respectively. Consistency was measured as the standard deviation of mean swing speed (SSD) during three sections of the swing: backswing (AD-BS), backswing-impact (BS-IMP), and impact-finish (IMP-FIS). Our results show that the consistency of the IM group improved in the time between the back swing and impact in the 2 m putt and 5 m putt compared to the control group. Using functional MRI, after the training period, the IM group showed increased functional connectivity from the superior cerebellar vermis to the right medial frontal gyrus, left superior temporal gyrus, right middle occipital gyrus, right middle temporal gyrus, right cingulate gyrus, and right supramarginal gyrus (uncorrected p < 0.001, voxels > 40). These findings suggest that IM training in professional female golf players may improve consistency in putt timing. In addition, IM training may increase brain connectivity from the cerebellum to the frontal cortex, which plays an important role in motor control and timing.
The Effect of Uphill and Downhill Slopes on Weight Transfer, Alignment, and Shot Outcome in Golf
Blenkinsop GM, Liang Y, Gallimore NJ and Hiley MJ
The aim of the study was to examine changes in weight transfer, alignment, and shot outcome during golf shots from flat, uphill, and downhill slopes. Twelve elite male golfers hit 30 shots with a 6-iron from a computer-assisted rehabilitation environment used to create 5° slopes while collecting 3-dimensional kinematics and kinetics of the swing. A launch monitor measured performance outcomes. A shift in the center of pressure was found throughout the swing when performed on a slope, with the mean position moving approximately 9% closer to the lower foot. The golfers attempted to remain perpendicular to the slope, resulting in weight transfer toward the lower foot. The golfers adopted a wider stance in the sloped conditions and moved the ball toward the higher foot at address. Ball speed was not significantly affected by the slope, but launch angle and ball spin were. As the coaching literature predicted, golfers were more likely to hit shots to the left from an uphill slope and to the right from a downhill slope. No consistent compensatory adjustments in alignment at address or azimuth were found, with the change in final shot dispersion resulting from the lateral spin of the ball.
Injuries among Korean Female Professional Golfers: A Prospective Study
Joeng HS, Na YM, Lee SY and Cho YJ
This study aims to analyze the incidence, location, type, and mechanisms of injuries and possible injury risk factors among all levels of Korean female professional golfers. This was a prospective study with a follow-up period of 24 months. A total of 363 members of the Korean Ladies Professional Golf Association (KLPGA), who competed in tournaments during the 2015 and 2016 seasons, took part in the study. The incidence of injury varied by tournament level and was significantly higher in Division II (11.1/1000AEs) and Division III (13.4/1000AEs) than in Division I (5.6/1000AEs) (p < 0.05). The most common location and type of injury were the shoulder/clavicle (Division I: 14.1%, Division II: 15.7%, Division III: 17.3%) and the tendinosis or tendinopathy (21.2%) (Division I: 23.7%, Division II: 21.2%, Division III: 18.5%), respectively. The most common mechanism of injury was the golf swing (47.9%-51.6% for the three divisions), and the most frequent specific phase of injury was upon ball impact (23.5%-30.9%). Multivariate analysis revealed that body mass index and the number of previous season competitions were significantly associated with injury risk in female golfers. The other factors examined did not have a significant association with golf-related injuries. In conclusion, KLPGA golfers were commonly exposed to injuries and showed a higher rate of injuries in competitions than practices, with significantly higher in Division II, III than Division I. However, overall, there was no significant difference in the location, type, mechanism and risk factors for injuries among the division level of KLPGA.
Regulation of Linear and Angular Impulse during the Golf Swing with Modified Address Positions
Peterson TJ and McNitt-Gray JL
Golf shots off uneven terrain often require modifications in address position to complete the swing successfully. This study aimed to determine how golf players coordinate the legs to regulate linear and angular impulse (about an axis passing vertically through the center of mass) while modifying the lower extremity address position during the swing. Nine highly skilled golf players performed swings with a 6-iron under the Normal, Rear Leg Up and Target Leg Up conditions. Components of linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force, resultant horizontal reaction force angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse did not change between conditions. Target leg angular impulse was greater in the Target Leg Up condition than Rear Leg Up condition. Regulation of linear and angular impulse generation occurred while increasing stance width and redirecting resultant horizontal reaction forces to be more parallel to the target line under modified address positions. Net linear impulse perpendicular to the target was near zero or slightly posterior. Net linear impulse parallel to the target was less toward the target in the Target Leg Up condition compared to Normal and Rear Leg Up conditions. These results indicate individuals utilized player specific mechanisms to coordinate the legs and regulate impulse generation during the golf swing under modified address positions.
Coordination of lower extremity multi-joint control strategies during the golf swing
Peterson TJ and McNitt-Gray JL
This study aimed to understand how players coordinate the multi-joint control strategies of the rear and target legs to satisfy the lower extremity and whole-body mechanical objectives during the golf swing when hitting shots with different clubs. Highly skilled golf players (n = 10) performed golf swings with a 6-iron and a driver. Joint kinetics were calculated using ground reaction forces and segment kinematics to determine net joint moments (NJMs) during the interval of interest within the downswing. Between club difference in NJMs and 3D support moments were compared across the group and within a player. Although player-specific multi-joint control strategies arose, players generally increased target leg ankle, knee, and hip NJMs when hitting with the driver while maintaining the relative contribution to the 3D support moment. Multi-joint control strategies used to control the target and rear legs were found to be different, yet the majority of the 3D support moment was produced by NJMs about an axis perpendicular to the leg planes. These results emphasize the importance of recognizing how an individual player coordinates multi-joint control from each leg, and highlights the need to design interventions that are player and leg specific to aid in improving player performance.
Hooker QL, Shapiro R, Malone T and Pohl MB
The knee joint is one of the most frequently injured regions in the game of golf, and the loads experienced by the knee during the golf swing are typically greater than during other activities of daily living. Altering movement patterns is a common strategy that can be used to reduce loading on the knee joint but has received little attention during studies of the golf swing. The primary aim of this study was to examine the effect altering golf stance has on the lead limb peak external knee adduction moment.
The Golf Movement Screen Is Related to Spine Control and X-Factor of the Golf Swing in Low Handicap Golfers
Gould ZI, Oliver JL, Lloyd RS, Neil R and Bull M
Gould, ZI, Oliver, JL, Lloyd, RS, Neil, R, and Bull, M. The golf movement screen is related to spine control and x-factor of the golf swing in low handicap golfers. J Strength Cond Res XX(X): 000-000, 2018-The aim of the study was to investigate the association between the golf movement screen (GMS), x-factor, which is the separation between the upper torso and pelvis rotation, and biomechanical movements of the pelvis, thorax, and spine during the backswing and impact of a golf shot in low handicap golfers. In total, 62 golfers were involved in this study (n = 40 male, n = 22 female); the mean age of the sample was 15.4 ± 2.4 years. For the GMS, all participants were assessed on their movement ability over a total of 10 different exercises. After a thorough warm-up routine of practice swings, each golfer then performed a single trial for biomechanical analysis. Biomechanical data were collected using an electromagnetic tracking system. Four of the 10 exercises had a significant correlation with x-factor (r = 0.25-0.33; p < 0.05). Four exercises had moderate correlations with spine rotation at the top of backswing. Spine side bend had a significant correlation with 9 of the 10 exercises and total GMS score (r = 0.26-0.53, p < 0.05). Movements of the pelvis and thorax at the top of backswing had minimal associations with the GMS. At impact, trunk inclination, thoracic rotation, and squat had small to moderate significant relationships with biomechanical movements (p < 0.05). Movement competency, as measured by the GMS, is associated with important aspects of swing mechanics. In particular, golfers who achieve better scores in the GMS have better spine control and can create a greater x-factor during the golf swing.
Effect of shoulder model complexity in upper-body kinematics analysis of the golf swing
Bourgain M, Hybois S, Thoreux P, Rouillon O, Rouch P and Sauret C
The golf swing is a complex full body movement during which the spine and shoulders are highly involved. In order to determine shoulder kinematics during this movement, multibody kinematics optimization (MKO) can be recommended to limit the effect of the soft tissue artifact and to avoid joint dislocations or bone penetration in reconstructed kinematics. Classically, in golf biomechanics research, the shoulder is represented by a 3 degrees-of-freedom model representing the glenohumeral joint. More complex and physiological models are already provided in the scientific literature. Particularly, the model used in this study was a full body model and also described motions of clavicles and scapulae. This study aimed at quantifying the effect of utilizing a more complex and physiological shoulder model when studying the golf swing. Results obtained on 20 golfers showed that a more complex and physiologically-accurate model can more efficiently track experimental markers, which resulted in differences in joint kinematics. Hence, the model with 3 degrees-of-freedom between the humerus and the thorax may be inadequate when combined with MKO and a more physiological model would be beneficial. Finally, results would also be improved through a subject-specific approach for the determination of the segment lengths.
Electromyographic analyses of the erector spinae muscles during golf swings using four different clubs
Sorbie GG, Grace FM, Gu Y, Baker JS and Ugbolue UC
The purpose of this study was to compare the electromyography (EMG) patterns of the thoracic and lumbar regions of the erector spinae (ES) muscle during the golf swing whilst using four different golf clubs. Fifteen right-handed male golfers performed a total of twenty swings in random order using the driver, 4-iron, 7-iron and pitching-wedge. Surface EMG was recorded from the lead and trail sides of the thoracic and lumbar regions of the ES muscle (T8, L1 and L5 lateral to the spinous-process). Three-dimensional high-speed video analysis was used to identify the backswing, forward swing, acceleration, early and late follow-through phases of the golf swing. No significant differences in muscle-activation levels from the lead and trail sides of the thoracic and lumbar regions of the ES muscle were displayed between the driver, 4-iron, 7-iron and pitching-wedge (P > 0.05). The highest mean thoracic and lumbar ES muscle-activation levels were displayed in the forward swing (67-99% MVC) and acceleration (83-106% MVC) phases of the swing for all clubs tested. The findings from this study show that there were no significant statistical differences between the driver, 4-iron, 7-iron and pitching-wedge when examining muscle activity from the thoracic and lumbar regions of the ES muscle.
Estimating Putting Outcomes in Golf: Experts Have a Better Sense of Distance
Tanaka H and Iwami M
In putting, golfers require an internal forward sense of the causal relationship between putting actions and outcomes-a sense of distance-to decide appropriate impact intensity. As no previous work has shown such a cognitive ability in skilled golfers, we sought to quantify sense-of-distance skill differences between experts and novice golfers in both putting-swing consistency and accuracy of outcome estimation. We compared nine expert and nine novice golfers on putting-outcome estimation by having them putt a golf ball to a target located at three distances (1.2, 2.4, and 3.6 m), and then, after automatic closure of their electric-shutter spectacles immediately following putter impact with the ball, they gave their best estimate of where the ball stopped. We assessed outcome-estimation accuracy by calculating the absolute error between the stopped ball's actual and estimated positions. We also measured and analyzed putter head-swing movements during the task using a motion-capture system. Two-way, mixed-design analysis of variance tests revealed that expert golfers achieved both significantly lower variability in putter-head kinematics and higher accuracy at outcome estimation than the novices. Linear partial correlation analyses with target distance as the control variable tested the relationship between outcome-estimation performance and putter-head variability kinematic measurements. There were no significant correlations between them for experts and novices in separate databases, while medium correlations were found in a collective database. Thus, swing consistency and a sense of distance are independent skills that both account for putting expertise, and specific training is required for each to improve putting skills.
Golf Injuries: Epidemiology, Pathophysiology, and Treatment
Zouzias IC, Hendra J, Stodelle J and Limpisvasti O
Increasing numbers of people are playing golf. Golf is a unique sport in that the ability to participate at a high level is not limited by age. In addition, participants tend to play more rather than less as they grow older. Injuries can occur at any point during the golf swing, from takeaway through follow-through. Upper extremity injuries can affect the hands, elbow, and shoulder and are usually a result of the golf swing at impact. Injuries are also common in the lower back as well as the lower extremities. Most injuries are the result of overuse and poor swing mechanics. When treating golfers, it is important to have a good understanding of the biomechanics and forces of the golf swing to diagnose and manage the vast spectrum of injuries incurred in this sport.
The relationship between the golf swing plane and ball impact characteristics using trajectory ellipse fitting
Morrison A, McGrath D and Wallace ES
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.
An unusual mechanism of coracoid fracture in a beginner golfer
Lee JH, Kim JR and Wang SI
Golfers may injure themselves as a result of repetitive asymmetrical loads exerted on the body by poor swing mechanics. If the repetitive sub-maximal loading is not removed, this repetitive loading will exceed the adaptive capacity of bone, eventually resulting in a stress fracture. Stress fracture of the scapula due to golfing is extremely rare. Only two cases of acromion fracture have been reported. A rare case of nontraumatic coracoid fracture in a 50-year-old female beginner golfer is reported here. The mechanism of injury is also discussed. Level of evidence Level IV.
Effects of Fat Grip Training on Muscular Strength and Driving Performance in Division I Male Golfers
Cummings PM, Waldman HS, Krings BM, Smith JW and McAllister MJ
Cummings, PM, Waldman, HS, Krings, BM, Smith, JW, and McAllister, MJ. Effects of fat grip training on muscular strength and driving performance in division I male golfers. J Strength Cond Res 32(1): 205-210, 2018-Fat grip (FG) training is implemented into strength and conditioning programs with the overall goal of increasing grip strength. Previous research assessing the effect of training with increased grip diameters compared with standard Olympic bar diameters has mainly been in acute settings. Therefore, the purpose of this study was to examine to effects FG training compared with normal diameter grip (CON) training during an 8-week periodized resistance training (RT) program in division I male golfers. Subjects (n = 10) were randomly assigned into 2 groups: the FG group (n = 5, scoring average: 75.4 ± 2.0) and CON group (n = 5, scoring average: 75.0 ± 0.5). Both groups participated in 8 weeks of RT (3 d·wk). The FG group completed every lift and repetition using FG, compared with the CON training group which used normal diameter bars. Pretraining and posttraining performance variables included swing speed, ball speed, driving distance, driving carry, maximum pull-ups to failure, right and left hand grip strength, and 1 repetition max trap-bar deadlift. The FG group demonstrated significant increases (p ≤ 0.05) in ball speed, carry, drive distance, and left hand grip strength after 8 weeks of RT. In a population, such as low-handicap division I male golfers, FG training may allow for athletes to increase golf-specific performance after 8 weeks of periodized RT. Strength and conditioning coaches may use FG training over the course of a training program with athletes who require adequate grip strength to further elicit training adaptations.
Analysis of Movement Acceleration of Down's Syndrome Teenagers Playing Computer Games
Carrogi-Vianna D, Lopes PB, Cymrot R, Hengles Almeida JJ, Yazaki ML and Blascovi-Assis SM
This study aimed to evaluate movement acceleration characteristics in adolescents with Down syndrome (DS) and typical development (TD), while playing bowling and golf videogames on the Nintendo Wii™.
Risk Factors for Knee Injury in Golf: A Systematic Review
Baker ML, Epari DR, Lorenzetti S, Sayers M, Boutellier U and Taylor WR
Golf is commonly considered a low-impact sport that carries little risk of injury to the knee and is generally allowed following total knee arthroplasty (TKA). Kinematic and kinetic studies of the golf swing have reported results relevant to the knee, but consensus as to the loads experienced during a swing and how the biomechanics of an individual's technique may expose the knee to risk of injury is lacking.
Performance and Kinematic Differences in Putting between Healthy and Disabled Elite Golfers
Gryc T, Stastny P, Zahálka F, Smółka W, Żmijewski P, Gołaś A, Zawartka M and Malý T
Golfers with disability are limited in the execution of the full golf swing, but their performance in putting may be comparable because this stroke does not demand significant strength, balance and range of motion. Therefore, the aim of this study was to compare putting performance, kinetic and kinematic consistency between golfers with different disabilities and healthy athletes. The participants consisted of three disabled athletes (perinatal cerebral palsy, multiple sclerosis, below knee lower limb amputee) and three healthy golfers (age 34 ± 4.5 years, body height 178 ± 3.3 cm, body mass 83 ± 6.2 kg). The golfers' movements were recorded by active 3D markers for kinematic analyses; the subjects performed 10 trials of a 6 m putting task while standing on separate force platforms placed under each lower limb. Putting performance was measured by the distance of the final ball position to the centre of the hole. ANOVA analyses did not show any differences in clubhead speed and total ball distance from the hole. The consistency of those two parameters expressed by the coefficient of variation (CV) was CV = 0.5% or better in both groups for clubhead speed and ranged from CV = 0.40 to 0.61% in healthy and CV = 0.21 to 0.55% in disabled athletes for total error distance. The main effect ANOVA showed differences in weight shift, hip and shoulder kinematics (p < 0.05) between healthy players and all players with disability. All disabled athletes shifted their weight toward the healthy side (towards the healthy lower limb) and alternated the end of the swing. The player with below knee amputation had the lowest range of motion in the shoulder joint during the putting stroke. The players with perinatal cerebral palsy and multiple sclerosis had the largest range of motion in the hips. Putting performance of disabled golfers was similar to healthy athletes. During training of disabled players, coaches should pay attention to the specificity of a particular disability when focused on putting performance. However, individual technique should achieve the same consistency as observed in healthy players.
A laceration of left internal mammary artery caused by an amateur golfer's swing
Cho DG, Chang YJ and Cho KD
We report the rare case of a patient presenting with a spontaneous laceration of left internal mammary artery (LIMA) after playing golf. The patient had no specific history except for cardiac surgery, and there were no results that caused bleeding on preoperative examination. A computed tomography (CT) scan of the chest demonstrated an anterior mediastinal hematoma and a left hemothorax with active extravasation close to LIMA. Through thoracotomy, hematoma evacuation and clipping for lacerated artery were performed. The patient was discharged in stable condition on the sixteenth postoperative day. This is the first reported case of a spontaneous laceration of internal mammary artery (IMA) after playing golf.
Contribution of vertical and horizontal components of ground reaction forces on global motor moment during a golf swing: a preliminary study
Bourgain M, Sauret C, Rouillon O, Thoreux P and Rouch P
Determination of the intervertebral spinal axial rotation in a golf player population: a preliminary study
Prum G, Bourgain M, Sauret C, Rouillon O, Rouch P and Thoreux P
An examination of the correlation amongst trunk flexibility, x-factor and clubhead speed in skilled golfers
Joyce C
Skilled golfers are reported to be more flexible than lesser able golfers, which may assist in increased x-factor (shoulder-pelvis separation) at the top of the backswing. However, it is unknown if increased flexibility produces faster clubhead speed. The aim of this study was to investigate the correlations amongst trunk flexibility and x-factor, as well as the association between flexibility and clubhead speed in low handicap golfers. Fifteen low handicap male golfers who displayed a modern swing, had their trunk static anatomical end-range of motion (flexibility) and driver swing kinematics were measured. Although Pearson correlations revealed trunk extension and lateral bending were moderately related to x-factor, axial rotation flexibility was not. A generalised linear model (GLM) reported three axial rotation flexibility variables, and six golf swing kinematic variables were associated with faster clubhead speed. The Pearson correlation results suggest that skilled golfers who have increased axial rotation flexibility do not necessarily utilise it to increase x-factor, and the GLM results support the importance of multisegment flexibility and interaction for improving golf performance with skilled golfers.
How to quantify the transition phase during golf swing performance: Torsional load affects low back complaints during the transition phase
Sim T, Choi A, Lee S and Mun JH
The transition phase of a golf swing is considered to be a decisive instant required for a powerful swing. However, at the same time, the low back torsional loads during this phase can have a considerable effect on golf-related low back pain (LBP). Previous efforts to quantify the transition phase were hampered by problems with accuracy due to methodological limitations. In this study, vector-coding technique (VCT) method was proposed as a comprehensive methodology to quantify the precise transition phase and examine low back torsional load. Towards this end, transition phases were assessed using three different methods (VCT, lead hand speed and X-factor stretch) and compared; then, low back torsional load during the transition phase was examined. As a result, the importance of accurate transition phase quantification has been documented. The largest torsional loads were observed in healthy professional golfers (10.23 ± 1.69 N · kg), followed by professional golfers with a history of LBP (7.93 ± 1.79 N · kg), healthy amateur golfers (1.79 ± 1.05 N · kg) and amateur golfers with a history of LBP (0.99 ± 0.87 N · kg), which order was equal to that of the transition phase magnitudes of each group. These results indicate the relationship between the transition phase and LBP history and the dependency of the torsional load magnitude on the transition phase.
The most important "factor" in producing clubhead speed in golf
Joyce C
Substantial experiential research into x-factor, and to a lesser extent crunch-factor has been undertaken with the aim of increasing clubhead speed. However, a direct comparison of the golf swing kinematics associated with each 'factor' has not, and possible differences when using a driver compared to an iron. Fifteen low handicap male golfers who displayed a modern swing had their golf swing kinematic data measured when hitting their own driver and five-iron, using a 10-camera motion analysis system operating at 250Hz. Clubhead speed was collected using a validated launch monitor. No between-club differences in x-factor and crunch-factor existed. Correlation analyses revealed within-club segment (trunk and lower trunk) interaction was different for the driver, compared to the five-iron, and that a greater number of kinematic variables associated with x-factor, compared to crunch-factor were shown to be correlated with faster clubhead speeds. This was further explained in the five-iron regression model, where a significant amount of variance in clubhead speed was associated with increased lower trunk x-factor stretch, and reduced trunk lateral bending. Given that greens in regulation was shown to be the strongest correlated variable with PGA Tour earnings (1990-2004), the findings suggests a link to player performance for approach shots. These findings support other empiric research into the importance of x-factor as well as anecdotal evidence on how crunch-factor can negatively affect clubhead speed.
Relationships between clubshaft motions and clubface orientation during the golf swing
Takagi T, Yokozawa T, Inaba Y, Matsuda Y and Shiraki H
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.
Enhancement of motor skill learning by a combination of ideal model-observation and self-observation
Nishizawa H and Kimura T
[Purpose] In sports physical therapy, video of a patient's movement or of a skilled model's movement has been used as observational learning methods for injury prevention and movement modification. Positive effects of model video observation have been reported. This study aimed to clarify the effect on motor skill learning using a combination of model-observation and self-observation, which is thought to act as an enhanced method for active error detection by comparing model-observation and self-observation alone for acquisition of correct sports movement. [Subjects and Methods] Forty-five healthy females were randomly allocated into three groups comprising model- and self-observation, model-observation, and self-observation. The motor task performed was a half golf swing using an elastic club. Shoulder grip angle between both shoulder lines and the acromia grip strength were measured as an index of body rotation using a three-dimensional motion analyzer. Change in the shoulder grip angle in the three groups was analyzed at pre-, immediate delayed retention, and delayed retention tests. [Results] A significant difference in shoulder grip angle was observed among the three groups for the immediate delayed retention test. The combined model and self-observation group had a value closer to 90 degrees compared to the other two groups. [Conclusion] Observation combining model and self-observation exerted a positive effect on short-term motor skill learning.
Comparison of Thoracic and Lumbar Erector Spinae Muscle Activation Before and After a Golf Practice Session
Sorbie GG, Grace FM, Gu Y, Baker JS and Ugbolue UC
Lower back pain is commonly associated with golfers. The study aimed: to determine whether thoracic- and lumbar-erector-spinae muscle display signs of muscular fatigue after completing a golf practice session, and to examine the effect of the completed practice session on club head speed, ball speed and absolute carry distance performance variables. Fourteen right-handed male golfers participated in the laboratory-based-study. Surface electromyography (EMG) data was collected from the lead and trail sides of the thoracic- and lumbar-erector-spinae muscle. Normalized root mean squared (RMS) EMG activation levels and performance variables for the golf swings were compared before and after the session. Fatigue was assessed using median frequency (MDF) and RMS during the maximum voluntary contraction (MVC) performed before and after the session. No significant differences were observed in RMS thoracic- and lumbar-erector-spinae muscle activation levels during the five phases of the golf swing and performance variables before and after the session (p > .05). Significant changes were displayed in MDF and RMS when comparing the MVC performed before and after the session (p < .05). Fatigue was evident in the trail side of the erector-spinae muscle after the session.
Wide-area measurement system-based supervision of protection schemes with minimum number of phasor measurement units
Gajare S, Rao JG, Naidu OD and Pradhan AK
Cascade tripping of power lines triggered by maloperation of zone-3 relays during stressed system conditions, such as load encroachment, power swing and voltage instability, has led to many catastrophic power failures worldwide, including Indian blackouts in 2012. With the introduction of wide-area measurement systems (WAMS) into the grids, real-time monitoring of transmission network condition is possible. A phasor measurement unit (PMU) sends time-synchronized data to a phasor data concentrator, which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for a slower form of protection. In this work, a method to identify the faulted line using synchronized data from strategic PMU locations is proposed. Subsequently, a supervisory signal is generated for specific relays in the system for any disturbance or stressed condition. For a given system, an approach to decide the strategic locations for PMU placement is developed, which can be used for determining the minimum number of PMUs required for application of the method. The accuracy of the scheme is tested for faults during normal and stressed conditions in a New England 39-bus system simulated using EMTDC/PSCAD software. With such a strategy, maloperation of relays can be averted in many situations and thereby blackouts/large-scale disturbances can be prevented.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'.
Features of Golf-Related Shoulder Pain in Korean Amateur Golfers
Lee CH, Hong JY, Jeon PS, Hwang KH, Moon WS, Han YH and Jeong HJ
To investigate the causes and characteristics of golf-related shoulder injuries in Korean amateur golfers.
Suitability of Strain Gage Sensors for Integration into Smart Sport Equipment: A Golf Club Example
Umek A, Zhang Y, Tomažič S and Kos A
Wearable devices and smart sport equipment are being increasingly used in amateur and professional sports. Smart sport equipment employs various sensors for detecting its state and actions. The correct choice of the most appropriate sensor(s) is of paramount importance for efficient and successful operation of sport equipment. When integrated into the sport equipment, ideal sensors are unobstructive, and do not change the functionality of the equipment. The article focuses on experiments for identification and selection of sensors that are suitable for the integration into a golf club with the final goal of their use in real time biofeedback applications. We tested two orthogonally affixed strain gage (SG) sensors, a 3-axis accelerometer, and a 3-axis gyroscope. The strain gage sensors are calibrated and validated in the laboratory environment by a highly accurate Qualisys Track Manager (QTM) optical tracking system. Field test results show that different types of golf swing and improper movement in early phases of golf swing can be detected with strain gage sensors attached to the shaft of the golf club. Thus they are suitable for biofeedback applications to help golfers to learn repetitive golf swings. It is suggested that the use of strain gage sensors can improve the golf swing technical error detection accuracy and that strain gage sensors alone are enough for basic golf swing analysis. Our final goal is to be able to acquire and analyze as many parameters of a smart golf club in real time during the entire duration of the swing. This would give us the ability to design mobile and cloud biofeedback applications with terminal or concurrent feedback that will enable us to speed-up motor skill learning in golf.
Immediate Effects of Sports Taping Applied on the Lead Knee of Low- and High-Handicapped Golfers During Golf Swing
Kim TG, Kim EK and Park JC
Kim, T-G, Kim, E-K, and Park, J-C. Immediate effects of sports taping applied on the lead knee of low- and high-handicapped golfers during golf swing. J Strength Cond Res 31(4): 981-989, 2017-Elite golf athletes suffer from various musculoskeletal injuries due to repeated golf swings. Repetitive varus moment during golf swing has been suggested as a possible cause of injuries to the lead knee. The aim of this study was to objectively and quantitatively evaluate the immediate effects of sports taping on the lead knee of elite golfers to restrict varus moment. Thirty-one elite golfers were assigned to the low- (LHG, n = 15) or high-handicapped group (HHG, n = 16). Using 3-dimensional motion analysis, the lead knee position on the frontal plane with and without rigid taping (RT), elastic taping (ET), and placebo taping was identified in 4 separate phases by the 5 events of golf swing as follows: the peak of the backswing (E1), parallel to the ground during downswing (E2), ball impact (E3), parallel to the ground during follow-through (E4), and finish (E5). The LHG when using a driver club had decreased movement toward knee varus with RT and ET than that without it from E1 to E2 (p = 0.001). The LHG when using a 5-iron club decreased movement toward knee varus with RT than that without it from E1 to E2 (p = 0.006) and from E2 to E3 (p = 0.019). The HHG when using a driver club had decreased movement toward knee varus with RT from E1 to E2 (p = 0.014). Sports taping may be helpful for elite golfers in terms of reducing varus moment of the lead knee during the downswing and be useful for the development of preventive strategies for golf-related knee injuries.
Comparison of centre of gravity and centre of pressure patterns in the golf swing
Smith AC, Roberts JR, Kong PW and Forrester SE
Analysing the centre of pressure (COP) and centre of gravity (COG) could reveal stabilising strategies used by golfers throughout the golf swing. This study identified and compared golfers' COP and COG patterns throughout the golf swing in medial-lateral (ML) and anterior-posterior (AP) directions using principal component analysis (PCA) and examined their relationship to clubhead velocity. Three-dimensional marker trajectories were collected using Vicon motion analysis and force plate data from two Kistler force plates for 22 low-handicap golfers during drives. Golfers' COG and COP were expressed as a percentage distance between their feet. PCA was performed on COG and COP in ML and AP directions. Relationships between principal component (PC) scores were examined using Pearson correlation and regression analysis used to examine the relationship with clubhead velocity. ML COP movements varied in magnitude (PC1), rate of change and timing (PC2 and PC3). The COP and COG PC1 scores were strongly correlated in both directions (ML: r = 0.90, P < .05; AP: r = 0.81, P < .05). Clubhead velocity, explained by three PCs (74%), related to timing and rate of change in COP near downswing (PC2 and PC3) and timing of COG late backswing (PC2). The relationship between COP and COG PC1 scores identified extremes of COP and COG patterns in golfers and could indicate a golfer's dynamic balance. Golfers with earlier movement of COP to the front foot (PC2) and rate of change (PC3) patterns in ML COP, prior to the downswing, may be more likely to generate higher clubhead velocity.
Using visual guidance to retrain an experienced golfer's gaze: A case study
Bishop DT, Addington N and D'Innocenzo G
Eye movements are essential for both predictive and reactive control of complex motor skills such as the golf swing. We examined the use of a visually guided learning protocol to retrain an experienced golfer's point-of-gaze immediately prior to execution of the full golf swing; his swing, and his gaze behaviour, had become established over more than a decade of practice and competition. Performance and eye movement data were obtained, from baseline, through intervention, to retention, for a total of 159 shots struck at a target 200 yards away. Results show that, at baseline, not only was the golfer's point-of-gaze not at the intended/predicted location, at the top-rear of the ball, but there was also high trial-to-trial variability. A bespoke visual guidance protocol improved his gaze behaviour considerably, in terms of accuracy and consistency - and this was reflected in accuracy and consistency of his shots. Implications of oculomotor interventions for the relearning of established motor skills are discussed.
Hand and Wrist Injuries in Golfers and Their Treatment
Woo SH, Lee YK, Kim JM, Cheon HJ and Chung WH
A thorough understanding of the swing phases and mechanisms of injury in golf allows accurate diagnosis, treatment, and future prevention of injuries. Recommended initial treatment starts with cessation of practice to rest the wrist, a splint or orthotic brace, and nonsteroidal antiinflammatory drug medication with corticosteroid injection and swing modification. Pisiform excision is the best treatment of the most severe chronic cases of pisiform ligament complex syndrome. Delayed diagnosis of hook of hamate fracture may lead to complications, including flexor tendon rupture. Prompt surgical resection is recommended to hasten return to sport and to prevent further complications.
Fatigue injury risk in anterior cruciate ligament of target side knee during golf swing
Purevsuren T, Kwon MS, Park WM, Kim K, Jang SH, Lim YT and Kim YH
A golf-related ACL injury can be linked with excessive golf play or practice because such over-use by repetitive golf swing motions can increase damage accumulation to the ACL bundles. In this study, joint angular rotations, forces, and moments, as well as the forces and strains on the ACL of the target-side knee joint, were investigated for ten professional golfers using the multi-body lower extremity model. The fatigue life of the ACL was also predicted by assuming the estimated ACL force as a cyclic load. The ACL force and strain reached their maximum values within a short time just after ball-impact in the follow-through phase. The smaller knee flexion, higher internal tibial rotation, increase of the joint compressive force and knee abduction moment in the follow-through phase were shown as to lead an increased ACL loading. The number of cycles to fatigue failure (fatigue life) in the ACL might be several thousands. It is suggested that the excessive training or practice of swing motion without enough rest may be one of factors to lead to damage or injury in the ACL by the fatigue failure. The present technology can provide fundamental information to understand and prevent the ACL injury for golf players.
Return to Golfing Activity After Joint Arthroplasty
Papaliodis DN, Photopoulos CD, Mehran N, Banffy MB and Tibone JE
Many patients who are considering total joint arthroplasty, including hip, knee, and shoulder replacement, are concerned with their likelihood of returning to golf postoperatively as well as the effect that surgery will have on their game.
Parallel streams versus integrated timing in multilimb pattern generation: A test of Korte's Third Law
Jagacinski RJ, Rizzi E, Kim TH, Lavender SA, Speller LF and Klapp ST
Skilled drummers performed a 4:3:2 polyrhythm with 2 hands and 1 foot. For each pair of limbs patterns of temporal covariation were used to infer relatively independent parallel streams versus integrated timing relationships. Parallel timing was more prevalent between hand and foot than between the 2 hands, and parallel timing generally increased with tapping rate. Different combinations of integrated and parallel timing were found among the 3 limbs. A second experiment used a wider range of tapping rates and explored 3:2 tapping with 2 hands, 2 feet, or hand and foot. The latter 2 limb pairs resulted in greater prevalence of parallel timing. These results can be interpreted in terms of a Gestalt principle of grouping known as Korte's Third Law, which can be extended from the perceptual domain to the perceptual-motor domain. This principle indicates that perceived velocity is a key factor in determining whether a sequence of events is represented as a single integrated pattern or as multiple parallel patterns. The present results put disparate previous findings on bimanual polyrhythmic tapping and rhythmic aspects of the golf swing under a common theoretical perspective. (PsycINFO Database Record
A randomized trial of traditional and golf-specific resistance training in amateur female golfers: Benefits beyond golf performance
Hegedus EJ, Hardesty KW, Sunderland KL, Hegedus RJ and Smoliga JM
Compare golf-specific resistance training (GSRT) with traditional resistance training (TRAD) with regard to golf performance and other outcome measures.
The short-term effects of trigger point therapy, stretching and medicine ball exercises on accuracy and back swing hip turn in elite, male golfers - A randomised controlled trial
Quinn SL, Olivier B and Wood WA
This study aimed to compare the effect of myofascial trigger point therapy (MTPT) and stretching, MTPT and medicine ball exercises, and no intervention, on hip flexor length (HFL), golf swing biomechanics and performance in elite, male golfers.
Improving the ground reaction force prediction accuracy using one-axis plantar pressure: Expansion of input variable for neural network
Joo SB, Oh SE and Mun JH
In this study, we describe a method to predict 6-axis ground reaction forces based solely on plantar pressure (PP) data obtained from insole type measurement devices free of space limitations. Because only vertical force is calculable from PP data, a wavelet neural network derived from a non-linear mapping function was used to obtain 3-axis ground reaction force in medial-lateral (GRF), anterior-posterior (GRF) and vertical (GRF) and 3-axis ground reaction moment in sagittal (GRF), frontal (GRF) and transverse (GRF) data for the remaining axes and planes. As the prediction performance of nonlinear models depends strongly on input variables, in this study, three input variables - accumulated PP with respect to time, center of pressure (COP) pattern, and measurements of the opposite foot, which are calculable only with a PP device - were considered in order to improve prediction performance. To conduct this study, the golf swing motions of 80 subjects were characterized as unilateral movement and GRF patterns as functions of individual characteristics. The prediction model was verified with 5-fold cross-validation utilizing the measured values of two force plates. As a result, prediction model (correlation coefficient, r=0.73-0.97) utilized accumulated PP and PP data of the opposite foot and showed the highest prediction accuracy in left-foot GRF, GRM, GRM and right-foot GRF, GRF, GRM, GRM. Likewise, another prediction model (r=0.83-0.98) utilized accumulated PP and COP patterns as input and showed the best accuracy in left-foot GRF, GRF, GRM and right-foot GRF, GRM. New methods based on the findings of the present study are expected to help resolve problems such as spatial limitation and limited analyzable motions in existing GRF measurement processes.
Multi-segment trunk models used to investigate the crunch factor in golf and their relationship with selected swing and launch parameters
Joyce C, Chivers P, Sato K and Burnett A
The use of multi-segment trunk models to investigate the crunch factor in golf may be warranted. The first aim of the study was to investigate the relationship between the trunk and lower trunk for crunch factor-related variables (trunk lateral bending and trunk axial rotation velocity). The second aim was to determine the level of association between crunch factor-related variables with swing (clubhead velocity) and launch (launch angle). Thirty-five high-level amateur male golfers (Mean ± SD: age = 23.8 ± 2.1 years, registered golfing handicap = 5 ± 1.9) without low back pain had kinematic data collected from their golf swing using a 10-camera motion analysis system operating at 500 Hz. Clubhead velocity and launch angle were collected using a validated real-time launch monitor. A positive relationship was found between the trunk and lower trunk for axial rotation velocity (r(35) = .47, P < .01). Cross-correlation analysis revealed a strong coupling relationship for the crunch factor (R(2) = 0.98) between the trunk and lower trunk. Using generalised linear model analysis, it was evident that faster clubhead velocities and lower launch angles of the golf ball were related to reduced lateral bending of the lower trunk.
Hip morphology in elite golfers: asymmetry between lead and trail hips
Dickenson E, O'Connor P, Robinson P, Campbell R, Ahmed I, Fernandez M, Hawkes R, Charles H and Griffin D
During a golf swing, the lead hip (left hip in a right-handed player) rotates rapidly from external to internal rotation, while the opposite occurs in the trail hip. This study assessed the morphology and pathology of golfers' hips comparing lead and trail hips.
Electromyographic Analysis of the Lower Limb Muscles in Low- and High-Handicap Golfers
Marta S, Silva L, Vaz JR, Castro MA, Reinaldo G and Pezarat-Correia P
The aim of this study was to compare the electromyographic patterns of the lower limb muscles during a golf swing performed by low- and high-handicap golfers.
Angular Impulse and Balance Regulation During the Golf Swing
Peterson TJ, Wilcox RR and McNitt-Gray JL
Our aim was to determine how skilled players regulate linear and angular impulse while maintaining balance during the golf swing. Eleven highly-skilled golf players performed swings with a 6-iron and driver. Components contributing to linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force [RFh], RFh-angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse generated by both the rear and target legs was greater for the driver than the 6-iron. Mechanisms used to regulate angular impulse generation between clubs varied across players and required coordination between the legs. Increases in net angular impulse with a driver involved increases in target leg RFh. Rear leg RFh-angle was maintained between clubs whereas target leg RFh became more aligned with the target line. Net linear impulse perpendicular to the target line remained near zero, preserving balance, while net linear impulse along the target line decreased in magnitude. These results indicate that the net angular impulse was regulated between clubs by coordinating force generation of the rear and target legs while sustaining balance throughout the task.
Dynamic Hip Kinematics During the Golf Swing After Total Hip Arthroplasty
Hara D, Nakashima Y, Hamai S, Higaki H, Ikebe S, Shimoto T, Yoshimoto K and Iwamoto Y
Although most surgeons allow their patients to play golf after total hip arthroplasty (THA), the effect on the implant during the golf swing is still unclear.
Effects of core and non-dominant arm strength training on drive distance in elite golfers
Sung DJ, Park SJ, Kim S, Kwon MS and Lim YT
Various training schemes have sought to improve golf-related athletic ability. In the golf swing motion, the muscle strengths of the core and arms play important roles, where a difference typically exists in the power of arm muscles between the dominant and non-dominant sides. The purposes of this study were to determine the effects of exercises strengthening the core and non-dominant arm muscles of elite golf players (handicap < 3) on the increase in drive distance, and to present a corresponding training scheme aimed at improving golf performance ability.
Spine biomechanics associated with the shortened, modern one-plane golf swing
Dale RB and Brumitt J
The purpose of this study was to compare kinetic, kinematic, and performance variables associated with full and shortened modern backswings in a skilled group of modern swing (one-plane) golfers. Shortening the modern golf backswing is proposed to reduce vertebral spine stress, but supporting evidence is lacking and performance implications are unknown. Thirteen male golfers performed ten swings of each swing type using their own 7-iron club. Biomechanical-dependent variables included the X-Factor kinematic data and spine kinetics. Performance-related dependent variables included club head velocity (CHV), shot distance, and accuracy (distance from the target line). Data were analysed with repeated measures ANOVA with an a priori alpha of 0.05 (SPSS 22.0, IBM, Armonk, NY, USA). We found significant reductions for the X-Factor (p < 0.05) between the full and shortened swings. The shortened swing condition ameliorated vertebral compression force from 7.6 ± 1.4 to 7.0 ± 1.7 N (normalised to body weight, p = 0.01) and significantly reduced CHV (p < 0.05) by ~2 m/s with concomitant shot distance diminution by ~10 m (p < 0.05). Further research is necessary to examine the applicability of a shortened swing for golfers with low back pain.
Electromyographic Patterns during Golf Swing: Activation Sequence Profiling and Prediction of Shot Effectiveness
Verikas A, Vaiciukynas E, Gelzinis A, Parker J and Olsson MC
This study analyzes muscle activity, recorded in an eight-channel electromyographic (EMG) signal stream, during the golf swing using a 7-iron club and exploits information extracted from EMG dynamics to predict the success of the resulting shot. Muscles of the arm and shoulder on both the left and right sides, namely flexor carpi radialis, extensor digitorum communis, rhomboideus and trapezius, are considered for 15 golf players (∼5 shots each). The method using Gaussian filtering is outlined for EMG onset time estimation in each channel and activation sequence profiling. Shots of each player revealed a persistent pattern of muscle activation. Profiles were plotted and insights with respect to player effectiveness were provided. Inspection of EMG dynamics revealed a pair of highest peaks in each channel as the hallmark of golf swing, and a custom application of peak detection for automatic extraction of swing segment was introduced. Various EMG features, encompassing 22 feature sets, were constructed. Feature sets were used individually and also in decision-level fusion for the prediction of shot effectiveness. The prediction of the target attribute, such as club head speed or ball carry distance, was investigated using random forest as the learner in detection and regression tasks. Detection evaluates the personal effectiveness of a shot with respect to the player-specific average, whereas regression estimates the value of target attribute, using EMG features as predictors. Fusion after decision optimization provided the best results: the equal error rate in detection was 24.3% for the speed and 31.7% for the distance; the mean absolute percentage error in regression was 3.2% for the speed and 6.4% for the distance. Proposed EMG feature sets were found to be useful, especially when used in combination. Rankings of feature sets indicated statistics for muscle activity in both the left and right body sides, correlation-based analysis of EMG dynamics and features derived from the properties of two highest peaks as important predictors of personal shot effectiveness. Activation sequence profiles helped in analyzing muscle orchestration during golf shot, exposing a specific avalanche pattern, but data from more players are needed for stronger conclusions. Results demonstrate that information arising from an EMG signal stream is useful for predicting golf shot success, in terms of club head speed and ball carry distance, with acceptable accuracy. Surface EMG data, collected with a goal to automatically evaluate golf player's performance, enables wearable computing in the field of ambient intelligence and has potential to enhance exercising of a long carry distance drive.
The relationships of waist and mid-thigh circumference with performance of college golfers
Son S, Han K and So WY
[Purpose] Our aim was to evaluate the relationships between waist and mid-thigh circumference, used as proxy measures of trunk and lower limb strengths, respectively, and selected parameters of driver and putting performance in Korean college golfers. [Subjects and Methods] The participants were 103 college golfers (81 male, 20 to 27 years old). Measurements of body composition, waist and mid-thigh circumference, and grip strength, as well as assessment of golf performance, including driver distance, driver swing speed, putting accuracy, and putting consistency, were performed at the golf performance laboratory at Konkuk University in Chungju-si, Republic of Korea. Average round score was obtained from 10 rounds of golf completed during the study period. The relationships between strength measures and golf performance were evaluated by partial correlation analysis, with adjustment for age, golf experience, and body mass index. [Results] Waist circumference did not correlate with any of the performance variables in both males and females. Mid-thigh circumference correlated with putting consistency (r = 0.364) in males and with putting consistency (r = 0.490) and accuracy (r = 0.547) in females. No other significant correlations between waist and mid-thigh circumference and golf performance were identified. [Conclusion] Lower limb strength may be an important component of putting performance. Further studies are needed to fully characterize the contributions of trunk strength to performance.
Looking to Learn: The Effects of Visual Guidance on Observational Learning of the Golf Swing
D'Innocenzo G, Gonzalez CC, Williams AM and Bishop DT
Skilled performers exhibit more efficient gaze patterns than less-skilled counterparts do and they look more frequently at task-relevant regions than at superfluous ones. We examine whether we may guide novices' gaze towards relevant regions during action observation in order to facilitate their learning of a complex motor skill. In a Pre-test-Post-test examination of changes in their execution of the full golf swing, 21 novices viewed one of three videos at intervention: i) a skilled golfer performing 10 swings (Free Viewing, FV); ii) the same video with transient colour cues superimposed to highlight key features of the setup (Visual Guidance; VG); iii) or a History of Golf video (Control). Participants in the visual guidance group spent significantly more time looking at cued areas than did the other two groups, a phenomenon that persisted after the cues had been removed. Moreover, the visual guidance group improved their swing execution at Post-test and on a Retention test one week later. Our results suggest that visual guidance to cued areas during observational learning of complex motor skills may accelerate acquisition of the skill.
A preliminary investigation of trunk and wrist kinematics when using drivers with different shaft properties
Joyce C, Burnett A, Cochrane J and Reyes A
It is unknown whether skilled golfers will modify their kinematics when using drivers of different shaft properties. This study aimed to firstly determine if golf swing kinematics and swing parameters and related launch conditions differed when using modified drivers, then secondly, determine which kinematics were associated with clubhead speed. Twenty high level amateur male golfers (M ± SD: handicap = 1.9 ± 1.9 score) had their three-dimensional (3D) trunk and wrist kinematics collected for two driver trials. Swing parameters and related launch conditions were collected using a launch monitor. A one-way repeated measures ANOVA revealed significant (p ≤ 0.003) between driver differences; specifically, faster trunk axial rotation velocity and an early wrist release for the low kick point driver. Launch angle was shown to be 2° lower for the high kick point driver. Regression models for both drivers explained a significant amount of variance (60-67%) in clubhead speed. Wrist kinematics were most associated with clubhead speed, indicating the importance of the wrists in producing clubhead speed regardless of driver shaft properties.
Biomechanical analysis of the golf swing: methodological effect of angular velocity component on the identification of the kinematic sequence
Marsan T, Thoreux P, Bourgain M, Rouillon O, Rouch P and Sauret C
The golf swing is a complex whole-body motion for which a proximal-to-distal transfer of the segmental angular velocities from the pelvis to the club is believed to be optimal for maximizing the club head linear velocity. However, previous experimental results about such timing (or kinematic sequence) are contradictory. Nevertheless, methods that were used in these studies differed significantly, in particular, those regarding the component of the angular velocity vector selected for the identification of the kinematic sequence. Hence, the aim of this study was to investigate the effect of angular velocity vector component selection on the identified kinematic sequence.
Effects of nine weeks isokinetic training on power, golf kinematics, and driver performance in pre-elite golfers
Parker J, Lagerhem C, Hellström J and Olsson MC
It has previously been shown that isotonic strength training can improve driver performance among golfers, though few studies have investigated effects of strength training on swing kinematics together with driver performance. In this study we investigated whether isokinetic rotational training could improve driver performance and swing kinematic variables amongst elite golfers.
Correction of a Technical Error in the Golf Swing: Error Amplification Versus Direct Instruction
Milanese C, Corte S, Salvetti L, Cavedon V and Agostini T
Performance errors drive motor learning for many tasks. The authors' aim was to determine which of two strategies, method of amplification of error (MAE) or direct instruction (DI), would be more beneficial for error correction during a full golfing swing with a driver. Thirty-four golfers were randomly assigned to one of three training conditions (MAE, DI, and control). Participants were tested in a practice session in which each golfer performed 7 pretraining trials, 6 training-intervention trials, and 7 posttraining trials; and a retention test after 1 week. An optoeletronic motion capture system was used to measure the kinematic parameters of each golfer's performance. Results showed that MAE is an effective strategy for correcting the technical errors leading to a rapid improvement in performance. These findings could have practical implications for sport psychology and physical education because, while practice is obviously necessary for improving learning, the efficacy of the learning process is essential in enhancing learners' motivation and sport enjoyment.
The Effects of Increased Body Temperature on Motor Control during Golf Putting
Mathers JF and Grealy MA
This study investigated the effect of increased core temperature on the performance outcome and movement kinematics of elite golfers during a golf putting task. The study aimed to examine individual differences in the extent to which increased temperature influenced the rate of putting success, whether increased temperature speeded up the timing of the putting downswing and whether elite golfers changed their movement kinematics during times of thermal stress. Six participants performed 20 putts to each of four putt distances (1, 2, 3, and 4 m) under normal temperature conditions and when core body temperature was increased. There was no significant difference in the number of successful putts between the two temperature conditions, but there was an increase in putterhead velocity at ball impact on successful putts to distances of 1 and 4 m when temperature was elevated. This reflected an increase in swing amplitude rather than a reduction in swing duration as hypothesized. There were individual differences in the motor control response to thermal stress as three of the golfers changed the kinematic parameters used to scale their putting movements to achieve putts of different distances at elevated temperatures. Theoretical implications for these findings and the practical implications for elite golfers and future research are discussed.
Risk Factors Associated With Low Back Pain in Golfers: A Systematic Review and Meta-analysis
Smith JA, Hawkins A, Grant-Beuttler M, Beuttler R and Lee SP
Low back pain is common in golfers. The risk factors for golf-related low back pain are unclear but may include individual demographic, anthropometric, and practice factors as well as movement characteristics of the golf swing.
An electromyographic study of the effect of hand grip sizes on forearm muscle activity and golf performance
Sorbie GG, Hunter HH, Grace FM, Gu Y, Baker JS and Ugbolue UC
The study describes the differences in surface electromyography (EMG) activity of two forearm muscles in the lead and trail arm at specific phases of the golf swing using a 7-iron with three different grip sizes among amateur and professional golfers. Fifteen right-handed male golfers performed five golf swings using golf clubs with three different grip sizes. Surface EMG was used to measure muscle activity of the extensor carpi radialis brevis (ECRB) and flexor digitorum superficialis (FDS) on both forearms. There were no significant differences in forearm muscle activity when using the three golf grips within the group of 15 golfers (p > 0.05). When using the undersize grip, club head speed significantly increased (p = 0.044). During the backswing and downswing phases, amateurs produced significantly greater forearm muscle activity with all three grip sizes (p < 0.05). In conclusion, forearm muscle activity is not affected by grip sizes. However, club head speed increases when using undersize grips.
Analysis of Pelvis-Thorax Coordination Patterns of Professional and Amateur Golfers during Golf Swing
Sim T, Yoo H, Choi A, Lee KY, Choi MT, Lee S and Mun JH
The aim of this research was to quantify the coordination pattern between thorax and pelvis during a golf swing. The coordination patterns were calculated using vector coding technique, which had been applied to quantify the coordination changes in coupling angle (γ) between two different segments. For this, fifteen professional and fifteen amateur golfers who had no significant history of musculoskeletal injuries. There was no significant difference in coordination patterns between the two groups for rotation motion during backswing (p = 0.333). On the other hand, during the downswing phase, there were significant differences between professional and amateur groups in all motions (flexion/extension: professional [γ] = 187.8°, amateur [γ] = 167.4°; side bending: professional [γ] = 288.4°, amateur [γ] = 245.7°; rotation: professional [γ] = 232.0°, amateur [γ] = 229.5°). These results are expected to be a discriminating measure to assess complex coordination of golfers' trunk movements and preliminary study for interesting comparison by golf skilled levels.
Comparison of Muscle Onset Activation Sequences between a Golf or Tennis Swing and Common Training Exercises Using Surface Electromyography: A Pilot Study
Vasudevan JM, Logan A, Shultz R, Koval JJ, Roh EY and Fredericson M
Aim. The purpose of this pilot study is to use surface electromyography to determine an individual athlete's typical muscle onset activation sequence when performing a golf or tennis forward swing and to use the method to assess to what degree the sequence is reproduced with common conditioning exercises and a machine designed for this purpose. Methods. Data for 18 healthy male subjects were collected for 15 muscles of the trunk and lower extremities. Data were filtered and processed to determine the average onset of muscle activation for each motion. A Spearman correlation estimated congruence of activation order between the swing and each exercise. Correlations of each group were pooled with 95% confidence intervals using a random effects meta-analytic strategy. Results. The averaged sequences differed among each athlete tested, but pooled correlations demonstrated a positive association between each exercise and the participants' natural muscle onset activation sequence. Conclusion. The selected training exercises and Turning Point™ device all partially reproduced our athletes' averaged muscle onset activation sequences for both sports. The results support consideration of a larger, adequately powered study using this method to quantify to what degree each of the selected exercises is appropriate for use in both golf and tennis.
Pronator Teres Myotendinous Tear
Qayyum U, Villacis D and Jobin CM
Pronator teres muscle strain is a rare sporting injury reported thus far only in cricket and golf players. The injury appears to occur when the sporting club or racket strikes the ground during a forceful swing and causes the elbow to experience an eccentric force during resisted elbow flexion and pronation. On initial presentation, this injury can be mistaken for injury to the medial ulnar collateral ligament, or exacerbation of medial epicondylitis. On examination, bruising and tenderness distal to the elbow over the course of the pronator teres are often present. Advanced imaging confirms the diagnosis and can help in grading injury severity. In this article, we report the case of a patient who was conservatively treated, and returned to function and sport by 6 weeks after a period of rest and restricted activities. The prognosis is excellent for even high-grade strains. Complete return to sporting function without residual weakness is expected.
Effects of Flexibility and Balance on Driving Distance and Club Head Speed in Collegiate Golfers
Marshall KJ and Llewellyn TL
Good balance, flexibility, and strength are all required to maintain a steady stance during the kinematic chain to produce successful golf shots. When the body can produce more power, more club head speed is generated. This formation of power translates into greater distance and accuracy. Athletes today are seeking exercise programs to enhance these qualities of their golf swing. The purpose of this study is to investigate the correlations between flexibility and balance with club head speed and driving distance in the golf swing of male and female collegiate golfers. Five male and five female collegiate golfers participated in the study. They completed multiple range of motion tests, the Balance Error System Test, and multiple flexibility tests. Subjects then participated in a short hitting session. Ten shots were hit with the subject's own driver. The Optishot simulator measured distance and club head speed generated. There was a significant negative correlation between the BESS test score and average distance for male subjects (r=-0.850, p=0.034). There were also a few trends between the balance, flexibility, and club head speed findings of both male and female subjects. This data shows there is a significant relationship between better balance and driving the ball farther. Other trends show better balance and flexibility will result in greater driving distance and club head speed. Balance and flexibility exercises should be incorporated into a golfer's practice or workout regiment.
Comparison of knee characteristics between professional and amateur golfers during the downswing
Kim TG and So WY
Evaluating the biomechanical and performance factors of the knee joint during golf swing can provide objective and quantitative information about improving the performance and development of efficient physical training, as the legs are important for achieving an efficient swing and maximum speed of the club head in golf. In the present study, kinematic movements of the knee joint were identified during the downswing by using 3-dimensional motion analysis, and isokinetic strength was measured with driver and 5-iron clubs in 15 professional (PRO) golfers and 10 amateur (AMA) golfers. Results showed that PRO golfers had a narrower minimal angle between the thigh and lower leg in the trail knee than the AMA golfers, regardless of the club used, and the angular velocity of the lead knee was faster during the downswing with a 5-iron club in the AMA golfers than in the PRO golfers. The PRO and AMA golfers had a wider minimal angle between the thigh and lower leg, smaller total range of movement, and slower angular velocity of the trail knee when swinging a 5-iron club than when swinging a driver club. These results are expected to provide useful information to prevent golf-related injuries that usually arise in the knee joint and help improve the golf performance of amateur golfers.
Focus of Attention in Children's Motor Learning: Examining the Role of Age and Working Memory
Brocken JE, Kal EC and van der Kamp J
The authors investigated the relative effectiveness of different attentional focus instructions on motor learning in primary school children. In addition, we explored whether the effect of attentional focus on motor learning was influenced by children's age and verbal working memory capacity. Novice 8-9-year old children (n = 30) and 11-12-year-old children (n = 30) practiced a golf putting task. For each age group, half the participants received instructions to focus (internally) on the swing of their arm, while the other half was instructed to focus (externally) on the swing of the club. Children's verbal working memory capacity was assessed with the Automated Working Memory Assessment. Consistent with many reports on adult's motor learning, children in the external groups demonstrated greater improvements in putting accuracy than children who practiced with an internal focus. This effect was similar across age groups. Verbal working memory capacity was not found to be predictive of motor learning, neither for children in the internal focus groups nor for children in the external focus groups. In conclusion, primary school children's motor learning is enhanced by external focus instructions compared to internal focus instructions. The purported modulatory roles of children's working memory, attentional capacity, or focus preferences require further investigation.

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