Could knee joint mechanics during the golf swing be contributing to chronic knee injuries in professional golfers?

ABSTRACT

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 Nms.kg^?1), indicating greater loading over the whole swing, which could contribute to knee lateral compartment or anterior cruciate ligament injuries. A significant correlation (r = ?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.     

The expected value of possession in professional rugby league match-play

This study estimated the expected point value for starting possessions in different field locations during rugby league match-play and calculated the mean expected points for each subsequent play during the possession. It also examined the origin of tries scored according to the method of gaining possession. Play-by-play data were taken from all 768 regular-season National Rugby League (NRL) matches during 2010–2013. A probabilistic model estimated the expected point outcome based on the net difference in points scored by a team in possession in a given situation. An iterative method was used to approximate the value of each situation based on actual scoring outcomes. Possessions commencing close to the opposition’s goal-line had the highest expected point equity, which decreased as the location of the possession moved towards the team’s own goal-line. Possessions following an opposition error, penalty or goal-line dropout had the highest likelihood of a try being scored on the set subsequent to their occurrence. In contrast, possessions that follow an opposition completed set or a restart were least likely to result in a try. The expected point values framework from our model has applications for informing playing strategy and assessing individual and team performance in professional rugby league.     

The kinematic differences between off-spin and leg-spin bowling in cricket

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.     

Recovery from the overexpectation effect: Contrasting performance-focused and acquisition-focused models of retrospective revaluation

In four Pavlovian conditioned lick-suppression experiments, rats had two conditioned stimuli (CSs X and A) independently paired with footshock, followed by pairings of a compound of A and X with the footshock. On subsequent tests with CS X, less conditioned suppression was observed than in control subjects that lacked the compound AX→footshock trials. Thisoverexpectation effect was reversed through posttraining extinction of CS A, a result consistent with both performance- and acquisition-focused models of retrospective revaluation. However, only performance-focused models could account for how posttraining increases or decreases in the A-footshock temporal interval attenuate the overexpectation effect.     

Imagining the Singapore “Nation” and “Identity”: The role of the media and National Education

This article presents an analysis of two state ideological apparatuses in Singapore to understand how the city-state constructs its sense of nationhood and national identity. The analysis shows how Singapore uses the media to represent its impoverished national identity, and through a state-led curriculum intervention, uses National Education to re-mediate its lack of a national identity. The conclusion points to the difficulties and paradoxes of Singapore's national project of constructing a preferred (national) identity over other identities.     

Organizational effectiveness in education: Its measurement and enhancement

This study is concerned with the nature of organizational goals, and ways of measuring goal achievement. It is intended to provide administrators with some new ways of conceptualizing the evalution of effectiveness in educational systems. The paper points out the desirability of involving professionals in the setting of goals, proposes a three-tier system of goals for educational systems, and suggests some of the reasons for the frequent failure to achieve organizational goals. Additionally, a comprehensive approach to the goals of organizations, adapted from Gross's matrix of purposes, is proposed, on the grounds that only such an inclusive approach to organizational goals is entirely satisfactory. Finally, the paper takes issue with the notion that freedom for organization members equals absence of organizational controls. The sense of power for organization members increases with participation in control, as does effectiveness. Thus, particularly for organizations with large numbers of professionals as members, it is not absence of control but rather participation in control that is the vital factor in both freedom and effectiveness. The final conclusion of the paper is that attempts to improve the effectiveness of educational systems or institutions must be in the future more inclusive, and that the matrix of purposes approach is one possible line of development.

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Résumé Cette étude porte sur la nature des objectifs des plans d'organisation et des méthodes servant à mesurer le degré de réussite dans la poursuite de ces objectifs. L'auteur se propose de fournir aux administrateurs un certain nombre de nouveaux critères pour concevoir l'évaluation de l'efficacité des systèmes éducatifs. Soulignant l'opportunité de confier à des professionnels l'établissement des objectifs, cette étude propose un système à trois paliers et tente d'expliquer les échecs fréquents auxquels aboutissent les objectifs des plans d'organisation. Par ailleurs, en ce qui concerne les objectifs des organisations, elle propose une attitude globale adaptée de l'étude de Gross intitulée matrix of purposes (matrice des objectifs), étant donné qu'une telle attitude est la seule qui soit satisfaisante à tous points de vue. Enfin l'auteur dénonce la notion selon laquelle la liberté accordée aux membres des organisations équivaut à une absence de contrôle sur ces dernières. En participant au contrôle de leurs organisations, les membres prennent en effet de plus en plus conscience de leur pouvoir et l'efficacité s'en trouve accrue. C'est ainsi que lorsqu'il s'agit, en particulier, d'organisations comptant de nombreux membres des professions libérales, ce n'est pas l'absence de contrôle mais plutôt la participation au contrôle qui représente le facteur capital à la fois de la liberté et de l'efficacité. En conclusion finale, cette étude affirme qu'à l'avenir, les tentatives d'amélioration des systèmes éducatifs ou des institutions devront avoir un caractère plus global et que la matrice des objectifs représente l'une des méthodes possibles à adopter dans ce domaine.