Step width alters iliotibial band strain during running     

Stacey A. Meardon  Samuel Campbell  Timothy R. Derrick 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):464-472

This study assessed the effect of step width during running on factors related to iliotibial band (ITB) syndrome. Three-dimensional (3D) kinematics and kinetics were recorded from 15 healthy recreational runners during overground running under various step width conditions (preferred and at least ± 5% of their leg length). Strain and strain rate were estimated from a musculoskeletal model of the lower extremity. Greater ITB strain and strain rate were found in the narrower step width condition (p < 0.001, p = 0.040). ITB strain was significantly (p < 0.001) greater in the narrow condition than the preferred and wide conditions and it was greater in the preferred condition than the wide condition. ITB strain rate was significantly greater in the narrow condition than the wide condition (p = 0.020). Polynomial contrasts revealed a linear increase in both ITB strain and strain rate with decreasing step width. We conclude that relatively small decreases in step width can substantially increase ITB strain as well as strain rates. Increasing step width during running, especially in persons whose running style is characterized by a narrow step width, may be beneficial in the treatment and prevention of running-related ITB syndrome.  相似文献   

Scapulohumeral kinematic assessment of the forward kayak stroke in experienced whitewater kayakers     

Craig A. Wassinger  Joseph B. Myers  Timothy C. Sell  Sakiko Oyama  Elaine N. Rubenstein  Scott M. Lephart 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):98-109

By understanding the normal humeral and scapular kinematics during the kayak stroke, inferences about the relationship of kayaking technique and shoulder injury may be established. The purpose of this study was to describe scapular and humeral kinematics and to compare dominant versus non-dominant symmetry in healthy whitewater kayakers performing the forward stroke. Twenty-five competent whitewater kayakers (mean age: 34.1 ± 9.4 years, mean height: 1.768 ± 0.093 m, mean mass: 78.2 ± 13.0 kg) underwent humeral and scapular kinematic assessment, using an electromagnetic tracking device, while kayaking on a kayak ergometer. Paired t-tests were used to determine symmetry. Scapular and humeral kinematic means and standard deviations at six time points during the kayak stroke were described. Scapular and humeral kinematics were shown to be similar upon bilateral comparison. The greatest potential for injury during the forward stroke may be at thrust paddle shaft vertical when the humerus is maximally elevated in internal rotation and adduction as subacromial structures may be mechanically impinged. The relationship between scapulohumeral kinematics related to injury at other time points are also described.  相似文献   

The Variability of Practice Hypothesis: Further Tests and Methodological Discussion     

Craig A. Wrisberg  Timothy P. Winter  Jolynn S. Kuhlman 《Research quarterly for exercise and sport》2013,84(4):369-374

Abstract

In the present study experimental subjects practiced variations in movement distance and/or movement time during training trials on a closed timing task. Control subjects trained with single distance-time combinations. During transfer trials all subjects attempted (without knowledge of results) a distance-time combination that was different (except in the case of one control condition) from any performed during training. The results revealed that the timing accuracy of the two experimental conditions that practiced a variety of times was significantly poorer than that of most of the other conditions during the training phase. However, transfer analyses revealed several significant differences between the performance of variable-trained and constant-trained conditions, in all cases favoring the former. It was concluded that the transfer benefits of variable practice are (a) not due to the particular movement component selected for variation during training, and (b) to some extent always determined by the similarity of training and transfer conditions experienced by constant-practice subjects.  相似文献   

Accuracy of Step Recording in Free-Living Adults     

Timothy K. Behrens  Mary K. Dinger  Sara K. Vesely  David A. Fields 《Research quarterly for exercise and sport》2013,84(5):542-547

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Evaluation of Low-Cost,Objective Instruments for Assessing Physical Activity in 10–11-Year-Old Children     

Teresa L. Hart  Timothy Brusseau  Pamela Hodges Kulinna  James J. McClain  Catrine Tudor-Locke 《Research quarterly for exercise and sport》2013,84(4):600-609

This study compared step counts detected by four, low-cost, objective, physical-activity-assessment instruments and evaluated their ability to detect moderate-to-vigorous physical activity (MVPA) compared to the ActiGraph accelerometer (AG). Thirty-six 10–11-year-old children wore the NL-1000, Yamax Digiwalker SW 200, Omron HJ-151, and Walk4Life MVP concurrently with the AG during school hours on a single day. AG MVPA was derived from activity count data using previously validated cut points. Two of the evaluated instruments provided similar group mean MVPA and step counts compared to AG (dependent on cut point). Low-cost instruments may be useful for measurement of both MVPA and steps in children's physical activity interventions and program evaluation.  相似文献   

Deconstructing Delphinium: Violence and Flowers in Rousseau’s émile and Henke’s Chrysanthemum     

Timothy A. Kinard 《Children‘s Literature in Education》2012,43(4):303-322

This article is an attempt to contribute to the conversation about “go[ing] beyond all kinds of binary thinking” (Lenz Taguchi, Going beyond the theory/practice divide in early childhood education: introducing an intra-active pedagogy, 2010, p. 50), especially the binary which positions “adults” and “children” as being powerful and powerless, respectively, in educational settings. It is also a personal reflection on “naming.” At the center of the reflection are two literary works, the picture book by Henkes, Chrysanthemum (1991), and the novel by Rousseau, émile, ou l’education (1762a). The central metaphor of émile—that of the developing child as organically unfolding, like a flower—is deconstructed by the plot involving two flower-named characters in Chrysanthemum. These characters are the protagonist, Chrysanthemum, and her music teacher, Delphinium Twinkle. Two acts of “naming” are considered: the literal act of naming a newborn baby and the abstract concept of “naming” [or labeling] a particular time in the life of a human being: “Childhood” (Cannella, Deconstructing early childhood education: social justice and revolution, 1997).  相似文献   

Transactional sex as a form of child sexual exploitation and abuse in Rwanda: implications for child security and protection     

Williams TP  Binagwaho A  Betancourt TS 《Child abuse & neglect》2012,36(4):354-361

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Outcomes assessment: an examination of the ETS major field test and the comprehensive business exam     

William Hahn  Lyle L. Bowlin  Timothy Welch 《Assessment & Evaluation in Higher Education》2012,37(2):259-271

This study is the first to examine student performance differences between the major field test in business (MFTB) and the comprehensive business exam (CBE). Results reveal students performed at a statistically significant 50.8 percentile ranking on the CBE compared to a 38.0 percentile ranking on the MFTB. Additionally, this study finds that students transferring business core courses with a grade point average (GPA) of 2.5 or lower perform at a statistically significant lower level on both the MFTB and the CBE than those transferring business core courses with GPAs higher than 2.5. These findings have important implications for assessment of learning purposes.  相似文献   

Earnings benefits of Tulsa's pre-K program for different income groups     

Timothy J. Bartik  William Gormley  Shirley Adelstein 《Economics of Education Review》2012

This paper estimates future adult earnings effects associated with a universal pre-K program in Tulsa, Oklahoma. These projections help to compensate for the lack of long-term data on universal pre-K programs, while using metrics that relate test scores to social benefits. Combining test-score data from the fall of 2006 and recent findings by Chetty et al. (2011) on the relationship between kindergarten test scores and adult earnings, we generate projections of adult earnings effects and a partial cost–benefit analysis of the Tulsa pre-K program. For both half-day and full-day programs, benefits are similar across program participants of different income, with benefit-to-cost ratios of 3- or 4-to-1. Because we only consider adult earnings benefits, actual benefit–cost ratios are likely higher, especially for disadvantaged children.  相似文献   

The implications of an across-the-board salary increase     

Timothy J. Keaveny  Robert E. Allen 《Research in higher education》1983,19(1):11-24

The implications of an across-the-board salary increase for selected outcomes are assessed. While such an approach to employee compensation is easily administered, the results of this analysis suggest that such an approach has some long-run costs. Those perceiving themselves as high performers and as putting forth greater effort felt undercompensated. Those with feelings of being undercompensated, relative to those feeling equitably compensated, anticipated a reduction in their job performance during the coming year, and perceived a deterioration in the association between performance and compensation. Differences in intentions to search for alternative employment are statistically significant.  相似文献