Somersaulting techniques used in high-scoring and low-scoring Roche vaults performed by male Olympic gymnasts     

Takei Y  Dunn JH  Blucker EP 《Journal of sports sciences》2007,25(6):673-685

The aim of this study was to compare the somersaulting techniques used in the 16 highest-scoring and 16 lowest-scoring Roche vaults. Our hypothesis was that the gymnasts performing the highest-scoring Roche vaults would demonstrate a better technique than those performing the lowest-scoring Roche vaults while on the horse (pushing off the horse more effectively), somersaulting (executing most of the required somersaults higher in flight), and landing (showing a greater control). A 16-mm motion picture camera, operating at 100 Hz, recorded the vaults during the official competition. The two-dimensional direct linear transformation was used for spatial reconstruction. The results of t-tests (P < 0.05) indicated that, compared with the low-scoring gymnasts, the high-scoring gymnasts had: (1) greater height of body centre of mass and a more fully extended body position at the horse take-off; (2) greater height of body centre of mass at the peak of post-flight, knee release, and touchdown on the mat; (3) greater horizontal and vertical displacements of body centre of mass, greater somersaulting rotation, and longer time from the knee release to mat touchdown; and (d) markedly smaller landing point deductions. In conclusion, a successful Roche vault is likely when the focus is on: (a) leaving the horse with a large vertical velocity in an extended body position to achieve a high trajectory of centre of mass by first extending the legs, then immediately pushing off the horse vigorously, using the muscles of the upper extremity; (b) grasping the knees immediately after the take-off from the horse, achieving the tightly tucked body position early during the ascent to the peak, and completing two-thirds of the required somersaults at a great height; (c) releasing the knees and extending the body above the top level of the horse; and (d) contacting the mat with a high body centre of mass position.  相似文献   

Helsen, Gilis and Weston (2006) err in testing the optical error hypothesis     

Oudejans RR  Bakker FC  Beek PJ 《Journal of sports sciences》2007,25(9):987-990

In this commentary, we react to the recent study by Helsen, Gilis and Weston (2006) on judging offside in football. Helsen et al. claim that their data falsify the optical error hypothesis presented by Oudejans et al. (2000). However, as we will elucidate here, they misinterpret this hypothesis and present a data set that is seriously flawed, and hence not suited to test it. Therefore, their conclusions regarding the optical error hypothesis are in error.  相似文献   

Different centre of pressure patterns within the golf stroke I: Cluster analysis   总被引：1，自引：0，他引：1  

Ball KA  Best RJ 《Journal of sports sciences》2007,25(7):757-770

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.  相似文献   

The mediating role of intention and stages of change in physical activity among adults with physical disabilities: an integrative framework     

Kosma M  Ellis R  Cardinal BJ  Bauer JJ  McCubbin JA 《运动与训练心理学杂志》2007,29(1):21-38

The study's purpose was to identify the mediating role of intention and the stages of change (SOC) in physical activity (PA) over a 6-month period using two models (theory of planned behavior [TPB] and TPB/SOC). Participants were 143 adults with physical disabilities (70.68% response rate; M age = 46.03). The TPB constructs, SOC (time 1), and PA (time 2) were assessed using standardized self-report questionnaires. Based on path analyses, attitude had the highest effect on intention and SOC followed by perceived behavioral control within both well-fit models. The variance in PA explained by the first (TPB) and second (TPB/SOC) models was 16% and 28% respectively. In the just identified model of TPB/SOC, the direct effect of SOC on physical activity remained strong (gamma(soc.pa) = .45) and SOC approached full mediation through attitude. Health promotion interventions need to include both intention and behavior elements (SOC) reinforcing increased PA value and barrier elimination.  相似文献   

Biomechanics of aggressive inline skating: landing and balancing on a grind rail     

Major MJ  Beaudoin AJ  Kurath P  Hsiao-Wecksler ET 《Journal of sports sciences》2007,25(12):1411-1422

Currently, only epidemiological injury data have been reported for the new extreme sport of aggressive inline skating, or trick skating. No studies have examined the biomechanics of this sport, which involves repetitive jumping and landing from railings, ramps, and ledges, often over 1 m in height. We present results of a pilot study that examined the effect of skater experience and lower extremity biomechanics on energy absorption ability, and observed balance strategies used during two basic tricks. In these tricks, the skater jumps onto an elevated rail and maintains balance while standing in a single position (stall) or sliding along the rail (grind). Lower extremity joint kinematics, impact force characteristics, and general movement behaviours were examined during landing and balance phases. Ten male skaters performed ten stalls and ten frontside grinds on an instrumented grind rail, capable of measuring vertical force. Vertical impact force was found to decrease with increasing skater experience in stalls (r = -0.84, P = 0.002) and grinds (r = -0.84, P = 0.009). This might imply that less-experienced skaters are (subconsciously) more concerned about maintaining balance than refining technique to minimize impact force. Similar to drop landing experiments, peak impact force decreased with increasing knee flexion during stalls (r = -0.65, P = 0.04). During stalls, skaters demonstrated classic balance maintenance strategies (ankle, hip, or multi-joint) depending on trick length. During grinds, skater centre of mass never passed over the rail base of support, suggesting the use of momentum produced from obliquely approaching the rail.  相似文献   

Validation of self-report measures of physical activity: a case study using the New Zealand Physical Activity Questionnaire     

Mackay LM  Schofield GM  Schluter PJ 《Research quarterly for exercise and sport》2007,78(3):189-196

Accurate measurement of physical activity is fundamentally important in epidemiological research of physical activity behavior A widely used telephone-based physical activity questionnaire was compared with other methods of administration and objective measures (pedometers and accelerometers) among 80 adults (43 women). The telephone questionnaire was comparable to both the self-administered form and international telephone-administered equivalent. Although moderate correlation coefficients with objective measures supported the use of the questionnaire, wide prediction intervals generated using Bland Altman methods highlighted large discrepancies between the measures, particularly in the moderate intensity category. These findings illustrate the limitations of correlation coefficients in validation studies and the inaccuracy of self-report questionnaires in measuring physical activity.  相似文献   

They Sang for Roosevelt: Songs of the People in the Age of FDR     

Patrick J. Maney 《Journal of American culture (Malden, Mass. : 2003)》2000,23(1):85-89

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East Asian pop culture and the trajectory of Asian consumption     

C. J. W.-L. Wee 《Inter-Asia Cultural Studies》2016,17(2):305-315

This article focuses on Chua Beng Huat’s work on the East Asian pop culture that became more prominent in East and Southeast Asia from the 1990s, when the circulation of multilingual and multi-format pop culture started to exceed linguistic, ethnic and national boundaries. It argues that Chua’s work indicates that the pop-cultural production and innovation that support the globalisation and regionalisation processes in East Asia need not be national in origin but can hail from different national origins – and this despite the existing political realities of the region and its history of political fractures. Chua Beng Huat cautions, though, that the national popular can also be marshalled to defeat the border-crossing potential of an inter-Asian pop culture. What is the “Asia” imagined or being represented in such cultural production? Chua’s work is also distinctive in that it deals with the political and economic conditions that underpin mainstream pop consumption as a socio-cultural phenomenon, instead of examining consumption as identity politics. The article concludes by noting the significance that Chua as an institutional builder has played in enabling the study of East Asian pop culture in the region.  相似文献   

Film Criticism,the Cold War,and the Blacklist: Reading the Hollywood Reds Jeff Smith. Berkeley: University of California Press, 2014.          下载免费PDF全文

Martin J. Manning 《Journal of American culture (Malden, Mass. : 2003)》2016,39(3):361-362

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Humility & Humiliation: The Transformation of Franciscan Humour,c.1210–1310     

Peter J. A. Jones 《Cultural and Social History》2018,15(2):155-175

Humiliation and self-ridicule worked as surprisingly important tools of evangelical outreach in the first decades of the Franciscan Order (c.1210–50). According to early Franciscan texts such as the Assisi Compilation (c.1240s) and Jordan of Giano’s Chronica (c.1260), St Francis and his earliest followers sought to win supporters by stripping naked in public, mocking learned preachers and ludicrously imitating animals. Yet within a few decades of the founder’s death this type of humour had been erased from Franciscan texts. Chronicles now omitted references to Francis’s laughter, while humiliating behaviour came to be condemned by Franciscan preachers, chroniclers and theologians alike. From being a means of undermining dignity and reason, joking was now instead celebrated as a tool of upholding these very same values. Describing the nature of this shift, and contextualising it within the evolving institutional priorities of the Franciscans under the leadership of Bonaventure (d.1274), this article will complicate debates about the development of medieval humour, while also reflecting on laughter’s role as a means of resistance to the significant social and cultural upheavals of the 1200s.  相似文献