Physiological responses and bowling performance during repeated spells of medium-fast bowling     

Duffield R  Carney M  Karppinen S 《Journal of sports sciences》2009,27(1):27-35

The aim of the present study was to investigate the relationship between physiological and performance responses during repeated 6-over fast-bowling spells. Six, first-class, medium-fast bowlers performed 2x6-over spells separated by 45 min of light activity. The 6-over spells were based on the Cricket Australia fast bowling skills test that is a set order of deliveries at a grid-based target. Ball speed, accuracy and full and final 5-m run-up speed were measured on each ball. Nude mass, heart rate, core temperature, capillary blood lactate, pH and glucose, perceptual measures of RPE and muscle soreness (MS) and repeated vertical jump efforts were measured prior to, during and following each spell. Results indicated no decrement (P=0.41) and small effect sizes (d<0.2) in bowling speed (125.7+/-5.1 and 125.4+/-4.5 km.h(-1)) or accuracy (40.4+/-16.1 and 41.6+/-18.0 AU) between spells 1 and 2. No differences (P=0.6-0.8) were present between spells for heart rate, core temperature, lactate, pH, glucose, RPE, MS or vertical jump. Only final 5-m run-up speed showed a large correlation with ball speed (r=0.70), while accuracy and speed were not correlated (r=0.05). In conclusion, repeated 6-over spells in well-trained bowlers results in minimal performance decrement in mild conditions (22 degrees C). As faster bowlers had faster final 5-m run-up speeds, the maintenance of high final 5-m run-up speeds might be important to maintaining bowling speed. Future research should also include a third bowling spell and warmer environmental conditions.  相似文献   

教育：青年与青年奥运会          下载免费PDF全文

Rob  KOEHLER  加拿大 《体育科研》2008,29(5):9-10

有人把体育运动中的兴奋剂归咎于参赛运动员违背了体育运动精神的价值取向,从不太严格的意义上讲,体育精神可以这样来描述,即运动员通过努力的训练及顽强的意志（而不是使用违禁物质与方法）,来实现对体育运动的热爱、卓越的追求,并由此获取相应的物质回报。另一方面,运动员是否以为他（她）的对手在使用兴奋剂也会影响他们的态度,因为他们往往会为了取得同等的竞争条件而做同样的事情;另外一些影响运动员是否使用兴奋剂的因素来自于他（她）的同伴、支持者、赞助商、媒体、公众舆论等,这些因素都有可能左右他（她）们的决定,即在比赛当中是否应使用提高运动成绩的违禁药物或措施。  相似文献   

The physical demands of elite English rugby union   总被引：1，自引：1，他引：0  

Roberts SP  Trewartha G  Higgitt RJ  El-Abd J  Stokes KA 《Journal of sports sciences》2008,26(8):825-833

The aim of this study was to assess the physical demands of elite English rugby union match-play. Player movements were captured by five distributed video cameras and then reconstructed on a two-dimensional plane representing the pitch. Movements based on speeds were categorized as standing, walking, jogging, and medium-intensity running (low-intensity activity), and high-intensity running, sprinting, and static exertion (scrummaging, rucking, mauling, and tackling) (high-intensity activity). Position groups were defined as forwards (tight and loose) and backs (inside and outside). Backs travelled more total distance than forwards (6127 m, s=724 vs. 5581 m, s=692; P<0.05) and greater distances in walking (2351 m, s=287 vs. 1928 m, s=2342; P<0.001) and high-intensity running (448 m, s=149 vs. 298 m, s=107; P<0.05). Forwards performed more high-intensity activity than backs (9:09 min:s, s=1:39 vs. 3:04 min:s, s=1:01; P<0.001), which was attributable to more time spent in static exertion (7:56 min:s, s=1:56 vs. 1:18 min:s, s=0:30; P<0.001), although backs spent more time in high-intensity running (0:52 min:s, s=0:19 vs. 1:19 min:s, s=0:26; P=0.004). Players travelled a greater distance in the first 10 min compared with 50-60 and 70-80 min, but there was no difference in the amount of high-intensity activity performed during consecutive 10-min periods during match-play. These results show the differing physical demands between forwards and backs with no evident deterioration in high-intensity activity performed during match-play.  相似文献   

Changes in respiratory muscle and lung function following marathon running in man     

Ross E  Middleton N  Shave R  George K  Mcconnell A 《Journal of sports sciences》2008,26(12):1295-1301

Respiratory muscle fatigue has been reported following short bouts of high-intensity exercise, and prolonged, moderate-intensity exercise, as evidenced by decrements in inspiratory and expiratory mouth pressures. However, links to functionally relevant outcomes such as breathing effort have been lacking. The present study examined dyspnoea and leg fatigue during a treadmill marathon in nine experienced runners. Maximal inspiratory and expiratory pressure, peak inspiratory and expiratory flow, forced vital capacity, and forced expiratory volume in one second were assessed before, immediately after, and four and 24 hours after a marathon. During the run, leg effort was rated higher than respiratory effort from 18 through 42 km (P < 0.05). Immediately after the marathon, there were significant decreases in maximal inspiratory pressure and peak inspiratory flow (from 118 +/- 20 cm H(2)O and 6.3 +/- 1.4 litres x s(-1) to 100 +/- 22 cm H(2)O and 4.9 +/- 1.5 litres x s(-1) respectively; P < 0.01), while expiratory function remained unchanged. Leg maximum voluntary contraction force was significantly lower post-marathon. Breathing effort correlated significantly with leg fatigue (r = 0.69), but not inspiratory muscle fatigue. Our results confirm that prolonged moderate-intensity exercise induces inspiratory muscle fatigue. Furthermore, they suggest that the relative intensity of inspiratory muscle work during exercise makes some contribution to leg fatigue.  相似文献   

Energy system contribution to 1500- and 3000-metre track running   总被引：1，自引：0，他引：1  

Duffield R  Dawson B  Goodman C 《Journal of sports sciences》2005,23(10):993-1002

The aim of the present study was to quantify the contributions of the aerobic and anaerobic energy systems to 1500- and 3000-m track running events during all-out time-trials performed individually on a synthetic athletic track. Ten 3000-m (8 males, 2 females) and fourteen 1500-m (10 males, 4 females) trained track athletes volunteered to participate in the study. The athletes performed a graded exercise test in the laboratory and two time-trials over 1500 or 3000 m. The contributions of the energy systems were calculated by measures of race oxygen uptake, accumulated oxygen deficit (AOD), race blood lactate concentration, estimated phosphocreatine degradation and some individual muscle metabolite data. The relative aerobic energy system contribution (based on AOD measures) for the 3000 m was 86% (male) and 94% (female), while for the 1500 m it was 77% (male) and 86% (female). Estimates of anaerobic energy expenditure based on blood lactate concentrations, while not significantly different (P > 0.05), were generally lower compared with the AOD measures. In conclusion, the results of the present study conform with some recent laboratory-based measures of energy system contributions to these events.  相似文献   

Learning About Information Technologies and Social Change: The Contribution of Social Informatics   总被引：5，自引：0，他引：5  

Rob Kling 《The Information Society》2000,16(3):217-232

Social informatics is the body of research that examines the design, uses, and consequences of information and communication technologies in ways that take into account their interaction with institutional and cultural contexts. This article serves as a brief introduction to social informatics. Examples such as computer networks, scientific communication via electronic journals, and public access to the Internet are used to illustrate key ideas from social informatics research. Some of the key themes include the importance of social contexts and work processes, sociotechnical networks, public access to information, and social infrastructure for computing support. The article draws upon 25 years of systematic analytical and critical research about information technology and social change.  相似文献   

Learning places and ‘little volunteers’: an assessment of place- and community-based education in China     

Rob Efird 《Environmental Education Research》2015,21(8):1143-1154

  相似文献   

Negotiating the challenge of collaborative writing: learning from one writing group's mutiny     

Karen Nairn  Jenny Cameron  Megan Anakin  Adisorn Juntrasook  Rob Wass  Judith Sligo 《高等教育研究与发展》2015,34(3):596-608

With continuing pressure to publish or perish, interventions such as writing groups are increasingly part of the academic landscape. In this paper, we discuss our writing group's experiment with collaborative writing, which came unstuck as simmering concerns led to a mutiny within the group. The mutiny provided insights into tensions that are inevitably present in writing groups and collaborative writing exercises but are seldom written about. We explore these tensions via a collaborative autoethnography, drawing on published literature on writing groups and collaborative writing. The mutiny revealed three key dynamics. Experienced voices can have an important role to play but these voices need to be moderated so that other voices might be recognised and valued. Pleasure and productivity are two necessary components for sustaining writing groups and writing collaborations. Finally, hierarchies in the academic context are inescapable but they can be renegotiated so that more enabling power relations can be generated.  相似文献   

Science friction: data, metadata, and collaboration     

Edwards PN  Mayernik MS  Batcheller AL  Bowker GC  Borgman CL 《Social studies of science》2011,41(5):667-690

  相似文献   

Playing With "patriotic fire": women and football in the Antipodes during the Great War     

Hess R 《国际体育史杂志》2011,28(10):1388-1408

The revelation that women first played Australian Rules football during the period of the Great War is an important element in overall understandings of how both masculine and feminine ideals were challenged and redefined by sporting practices in a time of general social flux. This paper reveals that the genesis of the women's code was in Western Australia, where contests occurred as early as 1915. Three years later, with the war nearing its conclusion, the template of women's involvement in charity matches with strong military and patriotic overtones was adopted in the state of Victoria, the code's heartland. Investigations such as this one, indicative of the complex relationships between sport and gender during the First World War, offer scope for deeper comprehension of a much-studied military conflict, and point the way forward for those that bemoan the static agenda of research into women's football.  相似文献