Explaining differences in the metabolic cost and efficiency of treadmill locomotion in children     

Frost G  Bar-Or O  Dowling J  Dyson K 《Journal of sports sciences》2002,20(6):451-461

The metabolic cost of locomotion at any given speed, when expressed per kilogram of body mass, is greater for children than for older individuals. Incomplete explanations for the age-related difference motivated this study, which used a multidisciplinary method to examine metabolic, kinematic and electromyographic data from three maturational groups of children. Thirty children aged 7-8 (n = 10), 10-12 (n = 10) and 15-16 (n = 10) years completed 4 min bouts of submaximal treadmill exercise at six speeds--two walking and four running--assigned in random order. Metabolic (net VO2), kinematic (total body mechanical power, energy transfer rates, stride rate) and electromyographic (co-contraction of agonist and antagonist muscles in thigh and leg segments) data were collected. Multiple regression analysis was performed with net VO2 or efficiency as the dependent variable and mechanical power, thigh and leg co-contraction, stride rate and age as independent variables. It was possible to explain up to 77% of the age-related variance in net VO2 and 62% of the variation in efficiency using combinations of these variables. Age was the best single predictor of both VO2 and efficiency. Co-contraction, possibly used to enhance joint stability, was an important component of the observed age-related differences, although mechanical power was not. Additional variance might be explained as specific growth-related factors affecting the metabolic cost of locomotion are identified, as mechanical work models improve, and as methods are developed to measure the effects of stored elastic energy and the metabolic cost of isometric muscle actions.  相似文献   

Habituation of 10-year-old hockey players to treadmill skating     

Kelly L. Lockwood  Gail Frost 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):145-154

This study assessed changes in selected physiological and kinematic variables over 6 weeks of treadmill skating in an effort to understand the process of habituation to this novel training modality. Seven male, Atom-A hockey players who were injury-free and had no previous treadmill skating experience participated in the study. Players performed four 1-min skating bouts at progressively increasing speeds, each week, for 6 weeks. One speed (10.5 km/h) was repeated weekly to allow for assessment of the habituation process. Our criteria for habituation were: a decrease in stride rate, heart rate and rating of perceived exertion, and an increase in stride length, trunk angle and vertical movement of the centre of mass, leading to a plateau, over the course of the 6-week study. Significant decreases were seen in stride rate, heart rate and ratings of perceived exertion, and significant increases were found in stride length. Some of these changes were evident after only one week of training and all were present by week 4. After 6 weeks (24 min) of exposure to treadmill skating, all participants displayed a visibly more efficient skating style.  相似文献   

The influence of resistance bands on frontal plane knee mechanics during body-weight squat and vertical jump movements     

Tyson A.C. Beach  David M. Frost 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):438-439

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Expanding assessment methods and moments in history     

Jennifer Frost  Genevieve de Pont  Ian Brailsford 《Assessment & Evaluation in Higher Education》2012,37(3):293-304

History courses at The University of Auckland are typically assessed at two or three moments during a semester. The methods used normally employ two essays and a written examination answering questions set by the lecturer. This study describes an assessment innovation in 2008 that expanded both the frequency and variety of activities completed by 182 undergraduates taking a course on the history of African‐American freedom struggles. All week‐by‐week tutorial assignments were collected for textual analysis to see if students were moving beyond the recollection and regurgitation of facts (surface learning) and instead were dealing with the deeper historical issues. The quality of student work coupled with our own classroom observations indicate that innovative assessment methods at regular moments during the semester made a positive difference to the student learning experience.  相似文献   

Researching Work and Learning: A Bird's Eye View     

Keith Forrester  Nick Frost  Kevin Ward 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》2000,46(6):483-489

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Clarity, charity and criticism, wit, wisdom and worldliness: Avoiding intellectual impositions     

David Turnbull  Henry Krips  Val Dusek  Steve Fuller  Alan Sokal  Jean Bricmont  Alan Frost  Alan Chalmers  Anna Salleh  Alfred I. Tauber  Yvonne Luxford  Nicolaas Rupke  Steven French  Peter G. Brown  Hugh LaFollette  Peter Machamer  Nicolas Rasmussen  Andy J. Miller  Marya Schechtman  Ross S. West  John Forge  David Oldroyd  Nancy Demand  Darrin W. Belousek  Warren Schmaus  Sungook Hong  Alan Chalmers  Rachel A. Ankeny  Peter Anstey  Jeremy Butterfield  Harshi Gunawardena 《Metascience》2000,9(3):347-498

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