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Taxonomy of golf putting: Do different golf putting techniques exist?
Journal of Sports Sciences
Abstract
Abstract This study is a preliminary investigation into the use of cluster analysis to determine if different putting techniques existed in a group of club level golfers. Putting at a hole 4 m away, the performances of 34 experienced golfers (age 55.3 ± 17.8 years and handicap 15.3 ± 6.9, range 3-27) were analysed using putter head kinematic and centre of pressure data. Two distinct putting techniques were identified (named as Arm putting and Body putting), this being the first time different putting techniques have been reported in the research literature. These techniques were defined by parameters related solely to movement of the centre of pressure along the line of the putt. Some players (17 of 34) moved between techniques when performing their putting trials. Neither technique produced more accurate putt results (P = 0.783). Putting technique was further analysed after grouping players according to handicap (similar skill level) or accuracy (similar putting performance). The lack of significant findings when players were re-analysed according to handicap or accuracy highlights the importance of the correct methodological approach to detecting technique differences.
... high McLaughlin & Best (2013) This study investigated the use of cluster analysis to determine if different putting techniques existed in a group of club level golfers by using kinematics. ...
Introduction: The purpose of this study was to evaluate whether kinematic assessments help to improve golf putting accuracy and precision, and increase the success rate of golf putts. Specifically, this study also investigated the differences in club head velocity and putter face angle at impact (°) between elite and amateur golfers. Methods: A total of 25 articles were used in this review. An initial, broad search of electronic databases including PubMed, SPORT discus, Scopus, Science Direct and Google Scholar was conducted for literature using the keywords “biomechanics” AND “golf putting”. The total number of studies screened for this review was n = 897. Among these articles, only n = 63 were assessed for eligibility. The number of articles were reduced further to n = 25 and included in the qualitative and quantitative synthesis. Results: Out of the initial n = 897, n = 834 records were excluded. After the articles were assessed for eligibility, n = 17 articles were excluded for not meeting the inclusion criteria. The studies included demonstrated that kinematic approaches can help improve accuracy and precision of golf putts which help to increase the success rate of putts and reduce overall scoring. Elite golfers have a more accurate direction and face angle when compared to amateur golfers. Conclusion: This systematic review and meta-analysis suggests that kinematic assessments of face angle at impact, putter path, the vertical spot and backswing are critical determinants of a golfer’s success and are useful indicators to help improve accuracy and precision of golf putts. This study also noted that elite golfers had slightly less velocity but more precise putter face angles at impact which increased their accuracy in completing more successful putts than amateur golfers.
... Different aspects like green reading, putter geometry and movement execution determine putt distance and direction accuracy and therefore the outcome of the putt [4]. Coaches especially struggle to completely assess the movement solely by visual inspection due to the precise nature of the putting movement, individual technique variations [5] and the high number of parameters that determine the success of the putt [6]. Biomechanical analysis is needed to understand the key aspects of putting and meaningful quantitative measures are needed for efficient coaching and training. ...
A mobile system for real-time golf putt analysis and augmented feedback is of high interest for technique training and research. Recently, instrumented golf clubs comprising inertial measurement units were introduced as a suitable modality for mobile putt analysis. The high level of sensor integration and its mobile nature enable the unobtrusive and mobile collection of a high amount of data. We developed such a mobile analysis system with feedback capabilities using off-the-shelf components with a removable sensor. The main features are an automatic putt detection with machine learning methods and the real-time parameter calculation in the club coordinate system. In a validation study, the system detected more than 83 % of the putts for 8 out of 11 subjects while maintaining a false-positive rate of 2.4 %. Thus, it is a suitable tool to analyze putting strokes in real time and enables feedback intervention applications. As an application example for research, the collected kinematic data of eight players (1,946 putts) were used to analyze training progress. Compared to the common analysis of expert and novice differences, the presented results provide a first insight in the motor learning path of inexperienced golfers. In principle, the presented system can be used to realize mobile data analysis systems for various sports disciplines beyond golf putting. It furthermore provides an innovative tool to analyze motor learning processes in more detail.
Movement variability has been considered important to execute an effective golf swing yet is comparatively unexplored regarding the golf putt. Movement variability could potentially be important considering the small margins of error between a successful and a missed putt. The aim of this study was to assess whether variability of body segment rotations influence putting performance (ball kinematic measures). Eight golfers (handicap range 0–10) performed a 3.2 m level putt wearing retro-reflective markers which were tracked using a three-dimensional motion analysis system sampling at 120 Hz. Ball roll kinematics were recorded using Quintic Ball Roll launch monitor. Movement (segment) variability was calculated based on a scalene ellipsoid volume concept and correlated with the coefficient of variation of ball kinematics. Statistical analysis showed no significant relationships between segment variability and putting proficiency. One significant relationship was identified between left forearm variability and horizontal launch angle, but this did not result in deficits in putting success. Results show that performance variability in the backswing and downswing is not related to putting proficiency or the majority of ball roll measures. Differing strategies may exist where certain golfers may have more fluid movement patterns thereby effectively utilising variability of movement. Therefore, golf instructors should consider movement variability when coaching the golf putt.
„Drive for the show, putt for the dough” is a common proverb which means golfers can only be successful, if they not only hit their long distance shots but also hole their putts on the greens. This applies to golf professionals as well as amateur players, because on average about 40 % of all strokes are putts (independent of the playing ability). Besides a proper technique, confidence and mental fitness are the success factors for successful putting.
This master thesis examines the mental states, collected using a low-cost EEG device, of seven amateur players during putting execution. Out of numerous consumer devices available, the Emotiv EPOC headset was chosen for collecting EEG data. The Emotiv EPOC device is bundled with a software development kit, which interprets collected EEG signals to estimate the extent of mental states like engagement, excitement, frustration, and meditation.
In this paper, the mental states are recorded during putts from varying distances to evaluate if state values differ for near/far or successful/unsuccessful putts. The results show that the mental state calculation of the Emotiv EPOC SDK is not suitable for the analysis of such a short action like putting, because values are changing too seldom and too little.
Wearable athlete support systems are a popular technology for performance enhancement in sports. The complex signal and data analysis on these systems is often tackled with pattern recognition techniques like classification. The implementation of classification algorithms on mobile hardware is called embedded classification. Thereby, technical challenges arise from the restricted computational power, battery capacity and size of such mobile systems. The accuracy-cost tradeoff describes the two conflicting design goals of embedded classification systems; the accuracy and the computational cost of a classifier. A data analysis system should be as accurate as possible and, at the same time, as cheap as required for an implementation on a mobile system with restricted resources. Thus, accuracy and cost have to be simultaneously considered in the design phase of the algorithms. Furthermore, an accurate modeling of classification systems, a precise estimation of the expected accuracy and energy efficient algorithms are needed. The first main goal of this thesis was to develop design considerations to support the solution of the accuracy-cost tradeoff that occurs during embedded classification system design. The success of wearable technology in sports originates in several application opportunities. A wearable system can collect data in the field without the restrictions of a lab environment or capture volume. Data with realistic variation and a high number of trials can be used to analyze the true field performance as well as its long-term progress over time. Real-time data processing allows to support athletes and coaches with augmented feedback in the field. Therefore, wearable systems enable new opportunities for the analysis of athletic performance. The second main goal of this thesis was to illustrate the benefits and opportunities of wearable athlete support systems with three application examples. This thesis presents applications for plyometric training, golf putting and swimming. The applications were realized as body sensor networks (BSNs) and analyzed kinematic data that were acquired with inertial measurement units (IMUs). The plyometric training application targeted the ground contact time calculation in drop jump exercises. The presented algorithm used a hidden markov model to calculate the ground contact with high accuracy. The ground contact time is an important training parameter to assess athlete performance and cannot be visually assessed. The golf putt application realized a system for technique training in the field. It featured an algorithm for automatic putt detection and parameter extraction as a basis for augmented feedback training applications. Long-term kinematic golf training data provided new insights in the progress of golf putting. The swimming application realized an unobtrusive swimming exercise tracker. The system was able to classify the four swimming styles, turns and breaks based on the head kinematics. Furthermore, an algorithm to classify long-term fatigue that occurs in a 90 min swimming exercise was presented. The swimming style, turn and break classification was implemented as embedded classification system on a BSN sensor node. This application underlines the applicability of the presented design considerations for solving the accuracy-cost tradeoff. The contributions of this thesis are considerations for the design of embedded classification systems and application examples that illustrate the benefits of wearable athlete support systems. The focus was to provide practical support for the solution of the accuracy-cost tradeoff and to present the technical realization of wearable athlete support systems. The findings of this thesis can be beneficial for research as well as industrial applications in the sport, health and medical domain.
In golf, play on the green has a large impact on final score and a great amount of time is spent on coaching and practice greens to improve putting performance. The study purpose was to measure putting outcome performance when different length putters were used with an anchoring mechanism. Seventy-two skilled golfers each executed a total of 60 putts using standard, belly and long putters from two distances. Putting mechanics were assessed using SAM PuttLab™. From 1.83 m (6 ft) participants holed 80.3% of putts with a standard length putter, dropping to 78.6 and 75.3% for belly and long-handled putters. At 3.66 m (12 ft) participants holed 51.7% of putts with a standard length putter, and 50.8 and 46.9% for belly and long-handled putters. Shot performance showed no significant differences between or within clubs. There were significant (p < 0.05) but small effect size between-club differences for swing time, putter head rotation and putter face impact spot. Results show that while anchoring may reduce putter head rotation it does not prevent rotation. It has been ascertained for a large cohort of different handicap golfers not accustomed to using longer putters that using an anchored putter will not necessarily provide a scoring advantage over using a standard putter without an anchoring system. Practice may better focus on the individual golfer’s specific technical weaknesses identified by the performer or by a coach.
The purpose of this study was to determine the effects of two putting stances (conventional versus side-saddle) and two points of aim (ball versus hole) on putting accuracy. Subjects (12 men, 4 women) were taught to putt using four methods: (a) conventional stance, eyes on the ball; (b) conventional stance, eyes on the hole; (c) side-saddle stance, eyes on the ball; and (d) side-saddle stance, eyes on the hole. Each subject practiced each method for 2 wk., after which they were tested for purring accuracy by counting putts made, determining constant error, and by calculating variable error. Accuracy was assessed at 5 and 15 ft. A 2 by 2 repeated-measures analysis of variance showed that there was no single combination of stance and point of aim that was significantly better than another at either distance. This suggests that, contrary to popular opinion, the traditional method of putting is not the best method for putting; other methods are equally as good and could be used if individually desired.
Numerical classification or “cluster” analysis was selected to determine whether or not there were generic characteristics which could distinguish various classification levels of weightlifters as they executed the jerk portion of the clean and jerk lift. Forty-five jerks (by 27 weightlifters) were compared across 27 kinematic variables, as well as height of the athlete and the number of years in competition. Master, Classes 1 and 2, Class 3, and athletes ranked below Class 4 each formed distinct groups. Master weightlifters generally performed the jerks with a shallower squat and a shorter braking phase than the other groups. Master and Class 1 weightlifters showed less horizontal displacement of the barbell during the squat than lifters ranked Class 2 and below. Few of the lifts approximated the characteristics of elite athletes.
A method for identifying clusters of points in a multidimensional Euclidean space is described and its application to taxonomy considered. It reconciles, in a sense, two different approaches to the investigation of the spatial relationships between the points, viz., the agglomerative and the divisive methods. A graph, the shortest dendrite of Florek etal. (1951a), is constructed on a nearest neighbour basis and then divided into clusters by applying the criterion of minimum within cluster sum of squares. This procedure ensures an effective reduction of the number of possible splits. The method may be applied to a dichotomous division, but is perfectly suitable also for a global division into any number of clusters. An informal indicator of the "best number" of clusters is suggested. It is a"variance ratio criterion" giving some insight into the structure of the points. The method is illustrated by three examples, one of which is original. The results obtained by the dendrite method are compared with those obtained by using the agglomerative method or Ward (1963) and the divisive method of Edwards and Cavalli-Sforza (1965).
A graph-theoretic paradigm is used to generalize the common measures of categorical clustering in free recall based on the number of observed repetitions. Two graphs are defined: Graph G, which characterizes the a priori structure of the item set defined by a researcher; and Graph R, which characterizes an S's protocol. Two indices of clustering, denoted by Gamma and Omega, are obtained by evaluating the sum of the pair-wise products of the weights on the corresponding edges of the 2 graphs. It is observed that the Gamma statistic is a direct generalization of the commonly used clustering indices and reduces to the number of repetitions whenever G represents a standard categorical decomposition of a stimulus list. The Omega statistic, on the other hand, extracts more information from the protocol graph, R, than does Gamma and incorporates a distance measure based on the number of intervening items in an S's recall sequence. (19 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
This study examined the set-up position of 30 elite PGA professional golfers (2007 Season), in comparison with 30 amateur golfers (Handicap +3 to 9) while attempting the same putt of 25ft on a flat surface with a stimpmeter reading of 12. Video analysis at 50 frames per second was used to record kinematic parameters of the golfers' set-up and posture. All golfers performed their typical putting action while standing on an RSscan International 1.0 m × 0.4 m pressure platform. The RSscan Footscan® and Quintic Biomechanics 9.03 v14 software were synchronised to enable key positions of the putting stroke to be identified. Each golfer used their own personal putter. The main difference between the amateur and professional golfers was in set-up. This was found to be significant with amateurs' weight distribution 59.60% Right and 40.40% Left while the Professional Group was 48.34% Left and 51.66% Right, much closer to a balanced set-up. Students' t-test was used to compare the group means for each parameter with a level of significance set at p < 0.05. There is a trend to suggest that the wider the stance, the smaller the centre of pressure movement during the putting stroke. Although there was no significant difference in stance width, there was a significant difference in the total amount of centre of pressure movement (p < 0.05) between the two groups of golfers.
The purpose was to evaluate the traditional method, of visually focusing on the ball, in comparison to focusing on the hole, during the putting stroke. The study design consisted of a pretest, a 4-week practice period, and a posttest. Participants (n = 31, handicap: 18.7 ± 10.4) practised using only one of the two gaze techniques. Testing consisted of having all participants putt using both gaze techniques from both a 1.22 m and a 4 m distance. Five putts were executed for each gaze technique/putt length combination for a total of 20 putts in each testing session per participant. The kinematics of every putting stroke executed during testing (1240 strokes) were captured using a TOMI® system. There was a significant improvement in putting success for both groups following practice (P = 0.001). Practising while visually focusing on the hole, resulted in a statistically significant reduction in putter speed variability in comparison to practising while visually focusing on the ball (P = 0.017). Visually focusing on the hole did not meaningfully (nor statistically) affect the quality of impact as assessed by the variability in face angle, stroke path, and impact spot at the precise moment the putter head contacted the ball.
The authors examined the patterns of expert and less skilled golfers in putting on an indoor surface to 1 of 3 circular targets (1, 3, and 5 m away) in trials with a ball present (and putted) or not present (a practice stroke). As expected, the experts performed better than the less skilled golfers on a large number of outcome and kinematic measures. Displacement and velocity profiles of the head and putter revealed high positive correlations for the less skilled golfers, indicating a dominant allocentric coordination pattern, but high negative correlations for the expert golfers, indicating a dominant egocentric coordination pattern. The observed coordination patterns did not interact with the distance of the intended putt or the presence/absence of a ball. These findings offer preliminary evidence that, although contrary to traditional beliefs, fundamental differences exist in putting coordination modes between expert and less skilled golfers.
The primary purpose of the present study was to examine kinematic characteristics and force control during a golf-putting task under a pressure condition. The secondary purpose was to provide an exploratory investigation of the relationship between changes in behavior (kinematics and force control) and performance on the one hand, and psychological (attention and affect) and physiological (arousal level) changes on the other hand. Twenty male novices performed 150 acquisition trials, followed by 10 test trials during a pressure condition induced by performance-contingent distracters: a cash reward or punishment. A three-dimensional motion analysis revealed that, during the pressure test, angular displacements of rotational movements at the horizontal plane and movement time of the arms and club during the backswing and downswing phases all decreased, while acceleration of the elbows during the downswing phase increased. Mean performance indices in all participants' were unchanged in spite of the kinematic changes under the pressure condition. Multiple regression analyses indicated that the decrement in performance, as well as increased variability of movement time and speed, were more likely to increase when participants shifted their attention to movements. Furthermore, changes in heart rate and negative affect were related to both the increase in movement acceleration and a decrease in grip force. These findings suggest that performance and behavioral changes during golf-putting under pressure can be associated with attentional changes, along with the influences of physiological-emotional responses.
The purpose of this study was to determine the validity and reliability of a new method for measuring three-dimensional (3D) putting stroke kinematics using the TOMI device. A putting robot and a high-speed camera were used to simultaneously collect data for the validity evaluation. The TOMI device, when used in conjunction with standard 3D coordinate data processing techniques, was found to be a valid and reliable method for measuring face angle, stroke path, putter speed, and impact spot at the moment of ball contact. The validity of the TOMI(R) measurement system was quantified using the 95% limits of agreement method for each aforementioned variable. The practical significance of each validity score was assessed by incorporating the maximum estimated measurement error into the stroke of the putting robot for 10 consecutive putts. All putts were executed from a distance of 4 m on a straight and flat synthetic putting surface. Since all putts were holed successfully, the measurement error for each variable was deemed to be negligible for the purposes of measuring putting stroke kinematics. The influence of key kinematic errors, at impact, on the outcome of a putt was also determined.
The aims of the present study were to: develop a portable and reliable fieldbased system for assessment of centre of pressure movement during the putting task; identify different putting techniques used by experienced golfers; identify the relationship between handicap and putting performance; identify the relationship between putting performance and putting stroke kinematics; identify the relationship between putting performance and movement of the centre of pressure; and to assess the effect of a 3 week balance biofeedback training program on subsequent putting performance and centre of pressure movement during the putting task. In order to enable data collection to occur on the golf course, a portable rubber mat containing 256 individual capacitance pressure sensors (novel pliance®, Munich, Germany) was validated for standing COP output against an AMTI force platform. Assessment of the equality of the output from both systems was assessed using the non-central F test. The peak-to-peak amplitude of movement of COP data in the medio-lateral (COPx, p=0.023) and antero-posterior (COPy, p=0.023) directions were found to be significantly the same. In-field testing required each participant (n=38) to complete five putts at a hole 4m away, and five putts at a hole 8m away. Testing was conducted on the practice putting green of a private golf course. The result of each putt was assessed by recording the distance the ball finished from the hole, as well as other descriptors of direction (left, right, centre) and length (short, long, holed out). Participants (n=38) completed these putts whilst standing on the previously validated mat. Video of each putt was recorded using a 50Hz video camera located perpendicular to the line of the putt. The video was later used to track the path of the putter head. The movement of the putter head was used to establish the key events and phases in the putting stroke – backswing, downswing, ball contact and follow through. Putting performance was assessed using exact putt result, absolute putt result and number of holed out putts. Players were initially grouped according to handicap such that there were low (0-9), middle (10-18) and high handicap groups (19-27). On putting performance, the low handicap group were significantly more likely to achieve a holed out putt at both the 4m and 8m putting tasks (p < 0.05). On the other measures some trends were evident but there were no significant differences between groups. In order to determine whether putting techniques existed, analysis of kinematic and COP data was completed using cluster analysis techniques. Ultimately, a two cluster solution was indicated as optimal for both tasks meaning there are two distinct putting techniques used by the golfers. At the 4m task these two putting techniques were identified as: 1. Less movement (relative to cluster 2) of COPx in the backswing and downswing phases with velocity of COPx at ball contact closer to zero (on average). Low COPx velocity. 2. Larger movement (relative to cluster 1) of COPx in the backswing and downswing phases with velocity of COPx at ball contact non-zero. High COPx velocity. In the 8m putting task, these two techniques were identified as: 1. Short, sharp with minimal COPx movements – a technique that involves comparatively smaller movements of the putter head and the COPx throughout the putting stroke relative to cluster 2. Velocity of the COPx at ball contact is minimal but is a heterogeneous mixture of movements away and towards the hole. Low motion. 2. Long, slow with greater movements of the COPx – a technique that incorporates larger displacements of the putter head and COPx throughout the putting stroke relative to cluster 1. Velocity of the COPx at ball contact is higher than cluster 1 but is homogeneous. High motion. On both tasks, players in cluster 1 had significantly lower handicaps than cluster 2 (4m task – cluster 1 = 12.4±5.9; cluster 2 = 16.4±6.6; p = 0.002; d = 0.63: 8m task – cluster 1 = 11.9±5.5, cluster 2 = 18.3±7.6; p < 0.001; d = 0.91) so would be classified as more skilled, however, no putting technique was significantly better than the other on putting performance. Importantly, all a player’s puttswere not necessarily classified into the same technique grouping. This highlighted the importance of treating each putt as an individual trial rather than using averaged data in the cluster analysis method. At the 4m putting task, the mean putt distance data were not significantly different for both exact putt result (cluster 1 = 14.0±44.5cm; cluster 2 = 25.7±44.5cm; p=0.22; d=0.26) and absolute putt result (cluster 1 = 36.8±28.5cm; cluster 2 = 39.5±32.3cm; p=0.66; d=0.09). Techniques were not significantly different (÷2 = 0.08, p = 0.78) in their ability to produce a holed putt. At the 8m putting task, both the measures of exact putt result (24±77cm vs. 2±71cm; p = 0.7; d = 0.29) and absolute putt result (60±54cm vs. 56±43cm; p = 0.11; d = 0.08) reveal non-significant differences between the techniques. Again, techniques were not significantly different (÷2 = 0.04, p = 0.85) in their ability to produce a holed putt. All players involved in the field based study were offered the opportunity to participate in a follow up study using real time biofeedback training to improve putting technique. Of the current sample, 7 players chose to participate in a three week training program followed by a re-testing session. The biofeedback training was aimed at minimizing COP movement during stance and the putting stroke. On re-testing, the sample of players showed no improvement in putting performance or COP related parameters. The effect of the training program on some players was to, in fact, produce a poorer putting performance and greater movement of the COPx during the stroke. On both putting tasks, there was a significant increase in movement of COPx during the backswing on re-testing. The effect of biofeedback training for improved putting performance was, at best, limited. A new field-based method for assessment of COP has been validated and established. Putting performance data provides evidence to suggest that handicap level and putting performance are related if performance is measured solely by the number of putts holed. Cluster analysis is shown to be a very suitable method for differentiating putting techniques. The movement of the COP was highly influential in distinguishing putting techniques at both tasks, but had no influence on putting performance. Putting techniques have not been described previously in the published scientific literature. Further field-based assessment of putting performance, especially during golf competition is required, along with a more detailed understanding on how far from the hole players of different handicap levels hit their first putts.
The aim of this study was to test the conflicting predictions of processing efficiency theory (PET) and the conscious processing hypothesis (CPH) regarding effort's role in influencing the effects of anxiety on a golf putting task. Mid-handicap golfers made a series of putts to target holes under two counterbalanced conditions designed to manipulate the level of anxiety experienced. The effort exerted on each putting task was assessed though self-report, psychophysiological (heart rate variability) and behavioural (pre-putt time and glances at the target) measures. Performance was assessed by putting error. Results were generally more supportive of the predictions of PET rather than the CPH as performance was maintained for some performers despite increased state anxiety and a reduction in processing efficiency. The findings of this study support previous research suggesting that both theories offer useful theoretical frameworks for examining the relationship between anxiety and performance in sport.
Biomechanical studies have been published which investigate techniques of performing skills by measuring characteristics associated with predefined phases of movement. In this study cluster analysis is used to describe the movement patterns adopted by subjects performing a backstroke swim start. Ten skilled male backstroke swimmers (17-22 yr of age) were used as subjects. Subjects performed a FINA backstroke swim start and sprint to 10 m. Postures, the angular positions adopted by subjects in each film frame of the start, were grouped using an agglomerative hierarchical clustering method. Student-t and chi square tests were used to assist in assessing the appropriateness of cluster separation between trials and subjects. The movement of all but 1 subject could be represented by 6 clusters of posture groups with each cluster being represented by a modal action pattern (MAP). Thus, movement, was described as a time sequence of significantly different MAPs. Significant differences between trials and subjects were noted. The cluster procedure appears to be an objective procedure for describing phases of movement and differences between trials and subjects.
Handspring to forward somersaults performed by three advanced level gymmnasts were analysed using high speed cinematography. Kinematic variables were calculated for the hurdle to support, flight and somersault take-off phases. Spatial and temporal differences between subjects were analysed using a cluster analysis technique. It was found that a successful handspring to front somersault required maximum horizontal amplitude with minimal upward displacement of the whole body centre of mass (WBCM) during the support phase. The flight phase was characterised by being short in duration with minimal upward displacement of the WBCM. Transfer of angular motion was noted between limb and trunk segments during these phases. Cluster analysis demonstrated differences between the subjects for each phase of the handspring, in particular those associated with poorer performance. Cluster analysis proved to be a useful technique for analysing spatial and temporal differences between the movement patterns of a dynamic skill.
The purpose of the paper was to determine if more than one gait pattern exists in able-bodied young men, by analyzing the dissimilarities in the three-dimensional (3-D) muscle powers, developed at the joints of the right lower limb. The subjects were members of the general community and they were evaluated in an attempt to extract normative data. Nineteen young male volunteers participated in the study, all of them were able-bodied, right-sided, they did not have any orthopedic or neurological disorders which could affect their walking pattern. Multiple gait trials were used for the classification of the peak muscle powers using cluster analysis. The detailed description of the clusters was based on a multivariate general linear model. The peak values of the 3-D muscle power patterns for each of the lower extremity joints were determined by the inverse dynamic approach. Five distinct able-bodied gait patterns were identified by means of the cluster analysis classification method of 56 trials from the 19 subjects. The principal gait parameters identified in the classification process were: (a) at heel-strike, the sagittal and frontal peak hip powers, (b) at mid-stance, the sagittal and frontal knee peak powers, and (c) at push-off, all sagittal peak powers as well as the frontal hip peak powers. The variability observed in able-bodied gait may be the result of multiple normal dynamic strategies employed by the different subjects.
The purpose of the study was to understand how force is controlled for impact movements such as golf putting. Expert players (10) and control subjects (10) executed a putt as accurately as possible, in order to reach a target distance of 1, 2, 3, or 4 m. Movements of the club were recorded at 200 Hz via a SELSPOT system. Overall, the results showed that, in order to increase club velocity at the moment of contact with the ball with increasing distance of the target, subjects increased the downswing (DS) amplitude maintaining DS movement time constant. The change in force required to reach the different distances seemed to rely on an adjustment of the magnitude of the motor command within the same time period. Furthermore, our results showed that the movement of putting consists primarily in specifying the amplitude of the Backswing (BS) as a function of the distance of the target. This gives rise to a motor impulse originating the force-time function required for an adequate DS movement.
Researchers have suggested that skill performance deteriorates when people try to exert conscious control over automatic actions. Unfortunately, little is known about the effects of different types of conscious processing on skilled performance by expert athletes. We conducted two experiments to address this issue. Experiment 1 investigated the influence of a specific form of conscious control (making technical adjustments to a stroke) on the putting skills of expert golfers. The expert golfers maintained putting proficiency (i.e. number of putts holed) when making technical adjustments. However, this form of conscious processing altered the timing and consistency of golfers' putting strokes. Experiment 2 compared the influence of technical adjustments and conscious monitoring (paying attention to the execution of the stroke) on expert golfers' putting skills. Technical adjustments had no disruptive influence on expert golfers' putting proficiency but did reduce the consistency of their strokes. However, conscious monitoring was found to impair putting proficiency. The implications of the work for theory and future work are discussed.
Although it is well established that performance is influenced by competitive pressure, our understanding of the mechanisms which underlie the pressure-performance relationship is limited. The current experiment examined mediators of the relationship between competitive pressure and motor skill performance of experts. Psychological, physiological, and kinematic responses to three levels of competitive pressure were measured in 50 expert golfers, during a golf putting task. Elevated competitive pressure increased putting accuracy, anxiety, effort, and heart rate, but decreased grip force. Quadratic effects of pressure were noted for self-reported conscious processing and impact velocity. Mediation analyses revealed that effort and heart rate partially mediated improved performance. The findings indicate that competitive pressure elicits effects on expert performance through both psychological and physiological pathways.
In this study, golf-putting movements were examined under three goal distances (short, 1.7m; middle, 3.25m; long, 6m), two different putter weights (500g, 750g), and two levels of expertise (5 experts, 5 novices). The study's aim was to identify differences in kinematics and accuracy between expert and novice golfers. The results demonstrated that experts achieved higher accuracy with lower impact velocity than novices. In addition, while novices showed symmetrical movements, experts exhibited asymmetrical movements, which were achieved by modulating their movement time and amplitude differently from novices. These results demonstrated differences in relative timing, relative amplitude and velocity, but no difference in time-to-contact between novices and experts. The results reaffirmed the role of prior learning and supported the hypothesis of Manoel and Connolly (1995) that motor learning is a hierarchical process organized at both macroscopic and microscopic levels.
Incluye bibliografía e índice v.1. Regression and experimental design.-- v.2. Categorical and multivariate methods
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
It is well established that performance is influenced by pressure, but the underlying mechanisms of the pressure-performance relationship are poorly understood. To address this important issue, the current experiment evaluated psychological, physiological, and kinematic factors as mediators of the pressure-performance relationship. Psychological, physiological, and kinematic responses to three levels of competitive pressure were measured in 23 males and 35 females during a golf putting task. Pressure manipulations impaired putting performance. Self-reported anxiety, effort, and perceived pressure were increased. Heart rate, heart rate variability, muscle activity, and lateral clubhead acceleration were also elevated. Mediation analyses revealed that effort, muscle activity, and lateral acceleration partially mediated the decline in performance. Results confirmed that pressure elicits effects on performance through multiple pathways.
For the Time-Use survey conducted by Insee in 1999 data was gathered from seven-day diaries in which working people noted their working hours for one week. Different types of working weeks were categorized by applying a two-stage optimal matching method, firstly for working days, then for simplified weeks using day types. The days differ greatly according to socio-professional category, the type of job, sector, but also gender. Pronounced regularities also emerge at a weekly level. Generally speaking, the better ones position in the economic system, the more independent time-management one has and the more working weeks are standard or long. Meanwhile, less skilled workers have working weeks which are shorter on average, but have staggered and fragmented schedules and a very low degree of control over their working time. For couples less independent time-management leads to their work schedules becoming more desynchronized and this creates new inequalities between households.
Weight transfer research in the golf swing has produced conflicting and inconclusive results. A limitation of previous studies is the assumption that only one swing "style" exists within the golf swing. If different styles, or movement strategies, exist and if the different styles are analysed together in a single group, statistical errors will result. The aim of this study was to determine if different weight transfer styles exist in the golf swing by applying cluster analysis to centre of pressure (CP) patterns in the direction of hit (CPy) and to evaluate cluster analysis issues. Sixty-two professional to high handicap golfers performed simulated drives, hitting a golf ball into a net, while standing on two force plates. Centre of pressure position relative to the feet (CPy%) was quantified at eight swing events identified from 200-Hz video. Cluster analysis identified two major CPy% styles: a "Front Foot" style and a "Reverse" style. Both styles began with CPy% positioned evenly between the feet, moved to the back foot during backswing, and then forward during early downswing. Beyond early downswing, the Front Foot group continued to move CPy% to the Front Foot through to ball contact, while the Reverse group moved CPy% towards the back foot through ball contact and follow-through. Both weight transfer styles were evident across skill levels from professional to high handicap golfers, indicating that neither style was a technical error. Cluster analysis should include hierarchical and non-hierarchical clustering and use objective measures combined with theoretical assessment to determine the optimal number of clusters. Furthermore, a number of validation procedures should always be used to validate the solution.
A technique for automatically clustering linear envelopes of EMGs (electromyograms) during gait has been developed. It uses a temporal feature representation and a maximum peak matching scheme. This technique provides a viable way to define compact and meaningful EMG waveform features. The envelope matching is performed by dynamic programming, providing qualitatively the largest number of matched peaks and quantitatively a minimum distance measurement. The resulting averaged EMG profiles have low statistical variation and can serve as templates for EMG comparison and further classification.
Seeking Nicklaus-Like consistency in put-ting: An experiment for the BBC. Retrieved from http://www. coaches-info.com
- R G Sanders
Sanders, R. G. (n.d.). Seeking Nicklaus-Like consistency in put-ting: An experiment for the BBC. Retrieved from http://www. coaches-info.com. Accessed January 2005.
Effects of foot orthotics on ground reac-tion forces during running
- R Kawamoto
- Y Ishige
- T Mochida
- T Yoshihisa
- S Fukashiro
Kawamoto, R., Ishige, Y., Mochida, T., Yoshihisa, T., & Fukashiro, S. (2003). Effects of foot orthotics on ground reac-tion forces during running. Japanese Journal of Biomechanics, Sports and Exercise, 7, 272–278.
Dave Pelz's putting bible
- D T Pelz
- J A Frank
Pelz, D. T., & Frank, J. A. (2000). Dave Pelz's putting bible. New York, NY: Doubleday.
Best Downloaded by [Michigan State University
- R Mclaughlin
McLaughlin & R. Best Downloaded by [Michigan State University] at 21:34 05 March 2015