Influence of upright versus time trial cycling position on determination of critical power and W′ in trained cyclists     

Mehdi Kordi  Chris Fullerton  Louis Passfield  Len Parker Simpson 《European Journal of Sport Science》2019,19(2):192-198

Body position is known to alter power production and affect cycling performance. The aim of this study was to compare mechanical power output in two riding positions, and to calculate the effects on critical power (CP) and W′ estimates. Seven trained cyclists completed three peak power output efforts and three fixed-duration trial (3-, 5- and 12-min) riding with their hands on the brake lever hoods (BLH), or in a time trial position (TTP). A repeated-measures analysis of variance showed that mean power output during the 5-min trial was significantly different between BLH and TTP positions, resulting in a significantly lower estimate of CP, but not W′, for the TTP trial. In addition, TTP decreased the performance during each trial and increased the percentage difference between BLH and TTP with greater trial duration. There were no differences in pedal cadence or heart rate during the 3-min trial; however, TTP results for the 12-min trial showed a significant fall in pedal cadence and a significant rise in heart rate. The findings suggest that cycling position affects power output and influences consequent CP values. Therefore, cyclists and coaches should consider the cycling position used when calculating CP.  相似文献   

Estimating fat-free mass in elite-level male rowers: a four-compartment model validation of laboratory and field methods     

Kristina L. Kendall  David H. Fukuda  Parker N. Hyde  Abbie E. Smith-Ryan  Jordon R. Moon  Jeffrey R. Stout 《Journal of sports sciences》2017,35(7):624-633

The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. METHODS: Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM.  相似文献   

Guideposts and Roadblocks to the Career-Long Scholarly Engagement of Physical Education Teacher Education Faculty     

Catherine P. Berei  Erica Pratt  Melissa Parker  Kevin Shephard  Tanjian Liang  Udon Nampai 《Research quarterly for exercise and sport》2017,88(4):455-467

Purpose: Scholarship is essential for the growth and development of the physical education field. Over time, scholarship expectations have changed, forcing faculty members to alter time spent for research, teaching, and service. Social-cognitive career theory (SCCT) presents a model for understanding performance and persistence in an occupational environment. The interconnected aspects of SCCT have different emphasis related to self-efficacy, outcome expectations, or personal goals pursuit. This study explored physical education teacher education (PETE) faculty members’ continuing engagement in scholarly activity through SCCT. Method: Data collection included interviews with 9 senior PETE faculty members who met the criteria for “productive scholars over time.” Curriculum vitae were collected to verify productivity. Results: Data analysis revealed guidepost themes that included collaborating, finding balance, defining a research process, and maintaining a strong work ethic. Roadblocks encountered included other obligations and lack of support for research. Conclusions: Participants demonstrated strong self-efficacy; held high, positive expectations for success; and set very specific, clear, and deliberate goals. Participant behavior was moderated by their personal attributes (capacity to build relationships, set goals, and maintain interest and passion) and was tempered by the environments in which they worked. Fostering similar behaviors has the potential to guide future and current PETE faculty members in creating supportive and encouraging atmospheres for sustained productivity. The lack of literature relating to this topic warrants the need for more research exploring the influential factors and benefits gained from sustained scholarly productivity over time for PETE faculty members.  相似文献   

Relational Database Technology     

Sandra Parker 《Curator: The Museum Journal》1987,30(2):124-130

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The problem of coal supply     

Edward W Parker 《Journal of The Franklin Institute》1918,185(4):445-460

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Book reviews     

Sixten Marklund  Franz Hilker  Marjorie L. Jenkins  Franklin Parker  Gustav Jahoda  M. J. Langeveld  Karl Henrik Eriksson  Nicholas Hans  Gilbert de Landsheere  Leslie D. Mclean  J. Cambon  A. St. Langeland  S. Wiegersma  Richard F. Goodings  J. B. Biggs 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1966,12(2):221-251

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Predicting vertical ground reaction force during running using novel piezoresponsive sensors and accelerometry     

Matthew K. Seeley  Alyssa Evans-Pickett  Gavin Q. Collins  James B. Tracy  Noelle J. Tuttle  Parker G. Rosquist 《Journal of sports sciences》2020,38(16):1844-1858

ABSTRACT

Running is a common exercise with numerous health benefits. Vertical ground reaction force (vGRF) influences running injury risk and running performance. Measurement of vGRF during running is now primarily constrained to a laboratory setting. The purpose of this study was to evaluate a new approach to measuring vGRF during running. This approach can be used outside of the laboratory and involves running shoes instrumented with novel piezoresponsive sensors and a standard accelerometer. Thirty-one individuals ran at three different speeds on a force-instrumented treadmill while wearing the instrumented running shoes. vGRF was predicted using data collected from the instrumented shoes, and predicted vGRF were compared to vGRF measured via the treadmill. Per cent error of the resulting predictions varied depending upon the predicted vGRF characteristic. Per cent error was relatively low for predicted vGRF impulse (2–7%), active peak vGRF (3–7%), and ground contact time (3–6%), but relatively high for predicted vGRF load rates (22–29%). These errors should decrease with future iterations of the instrumented shoes and collection of additional data from a more diverse sample. The novel technology described herein might become a feasible way to collect large amounts of vGRF data outside of the traditional biomechanics laboratory.  相似文献   

Curriculum reform and choice of science: Consequences for balanced and equitable participation and achievement     

Lonie J. Rennie  Lesley H. Parker 《科学教学研究杂志》1993,30(9):1017-1028

In 1988, most schools in Western Australia adopted a Unit Curriculum structure in the first three years of high school, following piloting of the scheme in seven schools in 1987. The goais of the Unit Curriculum are stated to be excellence, equity, and relevance, and one of its key features is the increased flexibility students have in making their subject selection. This article reviews the science enrollment and achievement patterns of males and females studying in the pilot schools in 1987, and for the first three years of the operation of the Unit Curriculum in 1988, 1989, and 1990. The data indicate that lowering the age for subject choice is associated with a reduction in the amount of science studies, especially by females, and with the early manifestation of sex-stereotyped subject selection. It appears that if early sex stereotyping is to be avoided, then students need to be provided with more structure in their selection of units. This article emphasizes the need for all involved in system-wide curriculum change to be fully informed of the potential benefits and dangers of curriculum models which allow wide flexibility, especially where curriculum change affects students' “choice point”.  相似文献   

A framework for considering educational and non-educational influences on the attainments of deaf persons     

J J DeCaro  E R Stuckless  J R Clarcq  C A Parker 《American annals of the deaf》1985,130(3):206-211

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Future war: Armed conflict in the next decade: Edited by Frank Barnaby New York and Bicester,England: Facts on File Publications, 1984, 192 pages, $16.50. ISBN 0-87196-892-4. LC 84-1593     

Susan E. Parker 《Government Information Quarterly》1985,2(2):218-219

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