Changes in swimming technique during time to exhaustion at freely chosen and controlled stroke rates     

Morgan Alberty  François Potdevin  Jeanne Dekerle  Patrick Pelayo  Philippe Gorce  Michel Sidney 《Journal of sports sciences》2013,31(11):1191-1200

Abstract

The aim of this study was to assess technical changes during constrained swimming in time-to-exhaustion tests. Ten swimmers of national standard performed a maximal 400-m front crawl and two sets of exhaustion tests at 95%, 100%, and 110% of mean 400-m speed. In the first set (free), swimmers had to maintain their speeds until exhaustion and mean stroke rate was recorded for each test. In the second set (controlled), the same speed and individual corresponding stroke rate were imposed. The durations of the exhaustion tests, relative durations of the stroke phases, and arm coordination were analysed. For each speed in the “controlled” set, the exhaustion tests were shorter. Moreover, variables were consistent, suggesting a stabilization of stroke technique. Under the free condition, stroke rate increased to compensate for the decrease in stroke length. At the same time, swimmers reduced the relative duration of their non-propulsive phases in favour of the propulsive phases. Thus, swimmers changed their arm coordination, which came close to an opposition mode. These two constraints enable swimmers both to maintain their stroking characteristics and develop compensatory mechanisms to maintain speed. Moreover, stroke rate can be seen as a useful tool for controlling arm technique during paced exercise.  相似文献   

Interrater Objectivity for Field-Based Fundamental Motor Skill Assessment     

Lisa Barnett  Eric van Beurden  Philip J. Morgan  Doug Lincoln  Avigdor Zask  John Beard 《Research quarterly for exercise and sport》2013,84(2):363-368

We recently published an article on arm coordination and performance level in 400-m front-crawl swimming in Research Quarterly for Exercise and Sport (Schnitzler, Seifert, &; Chollet, 2011). The index of coordination (IdC) was used to quantify interarm coordination. Our results showed that expert swimmers exhibited lower IdC than recreational swimmers over a 400-m trial. In addition to criticizing various methodological points, Havriluk (2012) challenged our conclusion that catch-up could be an efficient model of coordination and instead suggested that it might lead to injuries. An important point in this debate, however, is that our definition of catch-up coordination may differ from the one proposed by Havriluk (2012), which would explain why we consider catch-up coordination to be the dominant mode of coordination used by expert swimmers during training sessions.  相似文献   

Testing Social-Cognitive Theory to Explain Physical Activity Change in Adolescent Girls From Low-Income Communities     

Deborah L. Dewar  Ronald C. Plotnikoff  Philip J. Morgan  Anthony D. Okely  Sarah A. Costigan 《Research quarterly for exercise and sport》2013,84(4):483-491

Purpose

The aim of this study was to test the hypothesized structural paths in Bandura's social-cognitive theory (SCT) model on adolescent girls' physical activity following a 12-month physical activity and dietary intervention to prevent obesity.

Method

We conducted a 12-month follow-up study of 235 adolescent girls (M _age = 13.2 years, SD = 0.4) from 12 secondary schools located in low-income communities. At baseline, participants completed SCT scales related to physical activity (i.e., self-efficacy, intention, parental support, and outcome expectations). At baseline and 12-month follow-up (postintervention), participants wore accelerometers for 7 days. Structural equation modeling was used to determine if Time 1 measures predicted physical activity at 12-month follow-up after adjusting for baseline activity.

Results

The model explained 28% and 34% of the variance in physical activity and intention, respectively. Model fit indexes indicated the data were a good fit to the model; however, only self-efficacy was associated with physical activity at 12 months. There was no support for intention or outcome expectations as proximal determinants of behavior. Self-efficacy was associated with outcome expectations and parental support; however, only outcome expectations predicted intention.

Conclusions

Current findings indicate a large proportion of the variance for physical activity and intention remains unexplained and that the proposed pathways in the SCT model were not fully supported. Future model testing may need to consider augmentation or integration of theoretical models, which may include ecological components if we are to advance our understanding of physical activity behavior in this subgroup of the adolescent population.  相似文献   

The relationship between PE biographies and PE teaching practices of classroom teachers     

Philip J. Morgan  Vibeke Hansen 《Sport, Education and Society》2013,18(4):373-391

The current study sought to explore the relationship between personal school physical education (PE) experiences and current PE teaching practices of classroom teachers. Questionnaires were completed by 189 teachers from 38 randomly selected schools. Additionally, semi-structured interviews of 31 classroom teachers were conducted. The results indicated that many teachers had negative memories of school PE and believed that they were not taught anything. Interestingly, teachers involved in the study held reasonably positive attitudes towards teaching PE but examination of their current teaching practices indicated that little ‘teaching’ was evident in their PE programmes. A hierarchical regression model was used to examine key predictors of PE programme quality and accounted for 32% of the variance. Personal school experiences in primary school PE, quality of preservice education and attitudes to teaching PE were established as significant predictors. A key finding of the current study was the significant relationship evident between personal school experiences in PE and current PE teaching practices which has not been previously established with classroom teachers. The implications of these findings for preservice education and professional development will be discussed.  相似文献   

Information behaviour of Canadian pharmaceutical policy makers     

Greyson DL  Cunningham C  Morgan S 《Health information and libraries journal》2012,29(1):16-27

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Influence of kick frequency on metabolic efficiency and performance at a severe intensity in international monofin-swimmers     

Vercruyssen F  Boitel G  Alberty M  Nesi X  Bourdon L  Brisswalter J 《Journal of sports sciences》2012,30(10):1055-1061

The aim of this study was to examine the effect of kick frequency on metabolic efficiency and performance in elite monofin-swimmers at the surface. Seven participants of international calibre were requested to perform three separate time limit exercises conducted at an intensity corresponding to 97.5% of the velocity at the maximal oxygen uptake. The first Time Limit exercise was systematically conducted at a freely chosen kick frequency (FCK(F)) and the other Time Limit exercises were performed in random order at FCK(F)-10% and FCK(F) + 10%. The slow component of oxygen uptake (VO2sc) was identified independently of the Time Limit exercise (ranging from 180 to 243 ml · min(-1), P < 0.05). No significant change in energy cost of aquatic locomotion (ranging from 565 to (596 J · m(-1)) and [VO2sc) responses was observed between the three Time Limit exercises. An increase or decrease of 10% of the FCK(F) was associated with a significant reduction in Time Limit of -47.3% and -49.1%, respectively (P < 0.05). The analysis of the Time Limit exercise indicates that the selection of kick frequency other than FCK(F) is detrimental to overall monofin-swimming performance. Furthermore, the study results showed that the indicators of metabolic efficiency such as energy cost or [VO2sc) do not determine the performance response in elite monofin-swimmers at a severe intensity.  相似文献   

The role and impact of the internet on library and information services: edited by Lewis-Guido Liu. Westport, CT: Greenwood Press, 2001. 334p. $67.95. ISBN 0-313-30920-5. (Contributions in Librarianship and Information Science Series, No. 96)     

John A. Shuler  Associate Professor/Documents Librarian  Documents  Maps  Microforms  Curriculum Department  Richard J. Daley Library  S. Morgan St.  University of Illinois at Chicago  Chicago  IL - alfred@uic.edu. 《The Journal of Academic Librarianship》2002,28(6):436

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Ethnocentrism and the Social Criticism of Sports: A Response to Roberts     

William J. Morgan 《体育哲学杂志》2013,40(1):81-102

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Anti Racism and Language Diversity: Raising Meta Linguistic Awareness to Combat Racism     

Graham Morgan 《Literacy》1990,24(3):192-203

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Help for employers considering child care     

Gwen Morgan 《Early Childhood Education Journal》1981,9(1):7-9

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