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Abstract In this study, we used recently developed technology to determine the force–time profile of elite swimmers, which enabled coaches to make informed decisions on technique modifications. Eight elite male swimmers with a FINA (Federation Internationale de Natation) rank of 900+ completed five passive (streamline tow) and five net force (arms and leg swimming) trials. Three 50-Hz cameras were used to video each trial and were synchronized to the kinetic data output from a force-platform, upon which a motorized towing device was mounted. Passive and net force trials were completed at the participant's maximal front crawl swimming velocity. For the constant tow velocity, the net force profile was presented as a force–time graph, and the limitation of a constant velocity assumption was acknowledged. This allowed minimum and maximum net forces and arm symmetry to be identified. At a mean velocity of 1.92 ± 0.06 m · s?1, the mean passive drag for the swimmers was 80.3 ± 4.0 N, and the mean net force was 262.4 ± 33.4 N. The mean location in the stroke cycle for minimum and maximum net force production was at 45% (insweep phase) and 75% (upsweep phase) of the stroke, respectively. This force–time profile also identified any stroke asymmetry. 相似文献
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Danielle P. Formosa Mark G.L. Sayers Brendan Burkett 《Journal of sports sciences》2013,31(18):1729-1737
AbstractThis study used both an instantaneous net drag force profile and a symmetry timing to evaluate the effect of the breathing action on stroke coordination. Twenty elite swimmers completed a total of six randomised front-crawl towing trials: (i) three breathing trials and (ii) three non-breathing trials. The net drag force was measured using an assisted towing device mounted upon a Kistler force platform, and this equipment towed the swimmer at a constant speed. The net drag force profile was used to create a stroke symmetry index for each swimming trial. Analysis using the symmetry indices identified that the majority of participants demonstrated an asymmetrical instantaneous net drag force stroke profile in both the breathing and non-breathing conditions, despite no significant differences in the time from finger-tip entry to finger-tip exit. Within the breathing condition, the faster swimmers compared to the slower swimmers demonstrated a lesser percentage of overlap between stroke phases on their breathing stroke side. During the non-breathing condition, the faster participants compared to the slower swimmers recorded a reduction in the percentage of overlap between stroke phases and less duration in the underwater stroke on their breathing stroke side. This study identified that the majority of participants demonstrated an asymmetrical net drag force profile within both conditions; however, asymmetry was less prevalent when examining with only the timing symmetry index. 相似文献
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Ellie Burkett 《Educational Action Research》2013,21(4):481-493
This article explores the experiences of students who used interactive learning material on handheld computers in a gallery to support their understanding and appreciation of artwork. The article considers the wider implications of using technology to change relationships between teacher, learners and subject matter, and attempts to offer positive and pragmatic recommendations about the implementation of new technology into established educational contexts. Research was undertaken as part of the ICT Test Bed Project, set up by the DfES (UK Department for Education and Science) and funded by Becta (British Education Communications Technology Agency). Initial findings from this project are likely to be of interest to those exploring how mobile technology can be used to support the Government’s wider agenda for educational reform and offer a practitioner’s critical perspective on the possibilities and challenges offered by their use. 相似文献
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Brendan Burkett Mark Connick Mark Sayers Luke Hogarth Tom Stevens Mike Hurkx Sean Tweedy 《Sports Engineering》2017,20(2):163-170
In Paralympic seated throwing events, the athlete can throw with and without an assistive pole. This study aimed to identify and compare performance-related kinematic variables associated with both seated throwing techniques. Twenty-nine non-disabled males (21.9 ± 2.6 years) performed 12 maximal throws using a 1-kg ball in two conditions (no-pole and pole). Automatic 3D-kinematic tracking (150 Hz) and temporal data were acquired. There was no significant difference between ball speeds at the point of release between conditions (no-pole = 12.8 ± 1.6 m/s vs. pole = 12.9 ± 1.5 m/s). There were four kinematic variables that were strongly correlated with ball speed when throwing with or without an assistive pole. These variables were elbow flexion at the start phase (pole r = .39 and no-pole r = .41), maximum shoulder external rotation angular velocity during the arm cocking phase (pole r = .42), maximum shoulder internal rotation angular velocity during the arm acceleration phase (pole r = .47), and should internal rotation angular velocity at the instant of ball release (pole r = .40). The pole clearly influenced the throwing technique with all four strongly correlated variables identified in this condition, compared to only one during the no-pole condition. When using the pole, participants produced significantly higher shoulder internal rotation angular velocities during the arm acceleration phase (pole = 367 ± 183°/s vs. no-pole = 275 ± 178°/s, p < .05) and at the instant of ball release (pole = 355 ± 115°/s vs. no-pole = 264 ± 120°/s, p < .05), compared to throwing without the pole. These findings have implications for the development of evidence-based classification systems in Paralympic seated throwing, and facilitate research that investigates the impact of impairment on seated throwing performance. 相似文献
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Barbara Spector Ruth S. Burkett Cyndy Leard 《Journal of Science Teacher Education》2007,18(2):185-208
This is the report of a qualitative emergent-design study of 2 different Web-enhanced science methods courses for preservice
elementary teachers in which an experiential learning strategy, labeled “using yourself as a learning laboratory,” was implemented.
Emergent grounded theory indicated this strategy, when embedded in a course organized as an inquiry with specified action
foci, contributed to mitigating participants’ resistance to learning and teaching through inquiry. Enroute to embracing inquiry,
learners experienced stages resembling the stages of grief one experiences after a major loss. Data sources included participant
observation, electronic artifacts in WebCT, and interviews. Findings are reported in 3 major sections: “Action Foci Common
to Both Courses,” “Participants’ Growth and Change,” and “Challenges and Tradeoffs.” 相似文献
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