Time-motion analysis of Test and One-Day international cricket centuries     

Duffield R  Drinkwater EJ 《Journal of sports sciences》2008,26(5):457-464

The aim of this study was to quantify movement patterns of batsmen scoring 100 runs (century), including analysis at 50, 80, and 100 runs, in Test and One-Day international (one-day) matches and between the first and second 50 within a Test century. Test centuries (n = 13) and one-day scores above 80 (n = 12) filmed during the 2005 - 2006 Australian international season were analysed for movement patterns of standing, walking, jogging, striding, sprinting, shot playing, and turning. At each run target, differences in total time, duration of individual movement pattern, movement pattern frequency, and number of balls faced were determined between Test and one-day matches (analysis of variance). Differences within Test centuries were assessed using paired t-tests. A similar fractional predominance of time spent in low-intensity activity (standing and walking) between Test and one-day matches at each run target (94 and 96% respectively) was observed, with no differences in duration of striding or sprinting (Test: 1.1 min, s = 0.5; one-day: 0.9 min, s = 0.5 for sprinting: P = 0.28). A 37% longer total duration occurred in Tests, resulting in longer recovery bouts between high-intensity efforts. There were no differences between the first and second 50 runs of a Test century for any measure (P at best = 0.34). In summary, Test and one-day centuries are characterized by much low-intensity activity and patterns of high-intensity activity similar to many repeat-sprint team sports and greater recovery breaks in longer matches.  相似文献   

Elite tennis player sensitivity to changes in string tension and the effect on resulting ball dynamics     

Rob Bower  Rod Cross 《Sports Engineering》2008,11(1):31-36

Eighteen elite male tennis players were tested to determine their ability to identify string tension differences between rackets strung from 210 N (47 lb) to 285 N (64 lb). Each player impacted four tennis balls projected from a ball machine before changing rackets and repeating the test. Eleven participants (61%) could not correctly detect a 75 N (17 lb) difference between rackets. Only two participants (11%) could correctly detect a 25 N (6 lb) difference. To establish whether varying string tensions affected ball rebound dynamics, the ball’s rebound speed and landing position were analysed. The mean rebound ball speed was 117 km h⁻¹, with only the trials from the 210 N racket producing significantly lower (P < 0.05) rebound speeds than the 235 N and 260 N rackets. This is contrary to previous laboratory-based tests where higher rebound speeds are typically associated with low-string tensions. The anomaly may be attributable to lower swing speeds from participants as they were not familiar with such a low string tension. Ball placement did not appear related to string tension, with the exception of more long errors for the 235 N racket and fewer long errors for the 285 N racket. It was concluded that elite male tennis players display limited ability to detect changes in string tension, impact the ball approximately 6% faster than advanced recreational tennis players during a typical rallying stroke, and that ball placement is predominantly unrelated to string tension for elite performers.  相似文献   

Indigenous Digital Art as Politics in Australia     

Judith Bessant  Rob Watts 《Culture, Theory & Critique》2017,58(3):306-319

This essay contributes to discussions about Indigenous politics and debates about contemporary democracy. It uses a case study of video art produced by young indigenous people and a community development organisation in the Pilbara, Australia. Those involved in the project use digital media under the auspices of the Big hART Yijala Yala Project to produce an interactive comic series. The essay addresses the following questions: Do contemporary community development projects play a conservatising role serving the interests of a neoliberal polity? Given the long-standing practice of representing modern media as a vehicle for western domination what, if anything, do these projects imply about the political relations between Aboriginal and non-indigenous Australians? Are Indigenous media and cultural work inherently political? What conceptions of the political are at stake in such arguments? We focus on how certain groups of young people use new media, and how their activities are political. The argument is that Indigenous media like these are ‘inherently political’ because they are about efforts to reclaim the images of indigenous peoples for themselves.  相似文献   

The Acute Exercise-Induced Inflammatory Response: A Comparison of Young-Adult Smokers and Nonsmokers     

Tegan E. Kastelein  Cheyne E. Donges  Amy E. Mendham  Rob Duffield 《Research quarterly for exercise and sport》2017,88(1):15-25

Purpose: This study examined postexercise inflammatory and leukocyte responses in smokers and nonsmokers, as well as the effects of cigarette smoking on the acute postexercise inflammatory and leukocyte response in habitual smokers. Method: Eleven recreationally active male smokers and 11 nonsmokers matched for age and aerobic fitness were familiarized and underwent baseline fitness testing. Participants then completed 40 min of cycling at 50% peak aerobic workload. Smokers performed 2 randomized exercise sessions, including an acute postexercise smoking condition (2 cigarettes in 15 min of 12 mg tar and 1 mg nicotine) and a no-smoking condition, while nonsmokers performed 1 exercise session without smoking. Venous blood was obtained preexercise and postexercise for analysis of interleukin (IL)-6, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha (TNF-α), and c-reactive protein (CRP). Results: No differences existed between groups for resting CRP (d = 0.25–0.46; p = .374–.617). Despite no baseline difference (d = 0.03–0.07; p = .141–.70), exercise-induced increases were observed for IL-1 ra in smokers (d = 0.50; p = .024–.033), which was not observed in the never-smoker group. No between-group difference was observed for IL-6 across all points (d = 0.09–0.5; p = .102–.728); however, all groups observed significant within-group change (d = 0.27–1.09; p = .001–.042). Further, TNF-α for smokers smoking was elevated above both smokers not smoking and nonsmokers at baseline and across the protocol (d = 1.20–1.80; d = 0.20–1.0; p = .001–.035). Additionally, a marked postexercise increase in leukocyte and neutrophil concentrations was evident in smokers smoking compared with nonsmokers and smokers not smoking as indicated by a moderate-to-large effect size (d = 0.72; d = 0.78). Conclusion: Consequently, male smokers exhibit an altered postexercise proinflammatory profile compared with age- and fitness-matched nonsmokers.  相似文献   

Grassroots Football Development in Japan     

Masahiro Sugiyama  Rob Hess 《国际体育史杂志》2017,34(17-18):1854-1871

Abstract

The history and issues surrounding elite football in Japan have been addressed by a number of scholars. However, grassroots football, although fundamental to the development of the code, has rarely been explored in the academic literature. In Japan, the importance of grassroots football has received heightened attention by the Japanese Football Association (JFA) since 2003, with 20% growth in the number of registered players under 12 years old from 2003 (262,956 players) to 2014 (315,178 players) a result of the JFA’s initiatives in this area. Japan is currently one of the most successful countries in Asia in terms of grassroots football development and the JFA won the Asian Football Confederation’s award, namely ‘The Best Member Association of the Year 2013 for Grassroots Football’. This paper explores the key driver behind the development of grassroots football development, namely the 47 Prefectural Football Associations, which provide programmes and technical, physical and promotional services which include activities to increase opportunities, facilities, coach education, elite pathways, and competitions for grassroots football. The paper concludes that the factors which have resulted in the success of Japan’s grassroots football revolve around governance of Prefectural Football Associations, coach education programmes, increased opportunities by clubs, leagues and schools, and collaboration with stakeholders within and outside of Prefectural Football Associations.  相似文献   

Effects of focus of attention on baseball batting performance in players of differing skill levels     

Castaneda B  Gray R 《运动与训练心理学杂志》2007,29(1):60-77

This study addressed the question, what should baseball players focus their attention on while batting? Less-skilled and highly skilled (college) baseball players participated in four dual-task conditions in a baseball batting simulation: two that directed attention to skill execution (skill/internal [movement of the hands] and skill/external [movement of the bat]) and two that directed attention to the environment (environmental/irrelevant [auditory tones] and environmental/external [the ball leaving the bat]). Batting performance for highly skilled players was best in the environmental/external condition and worst in the skill/internal condition. Performance of less-skilled batters was significantly better in the two skill conditions than in either of the two environmental conditions. We conclude that the optimal focus of attention for highly skilled batters is one that does not disrupt proceduralized knowledge and permits attention to the perceptual effect of the action, whereas the optimal focus of attention for less-skilled batters is one that allows attention to the step-by-step execution of the swing.  相似文献   

What We Know (and What We Don't Know) About Training for Problemsolving: An Update     

Rob Fosbay 《Performance Improvement》1997,36(3):40-45

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