The dynamic control ratio at the equilibrium point (DCRe): introducing relative and absolute reliability scores     

Tobias Alt  Axel J. Knicker  Heiko K. Strüder 《Journal of sports sciences》2017,35(7):688-693

Analytical methods to assess thigh muscle balance need to provide reliable data to allow meaningful interpretation. However, reproducibility of the dynamic control ratio at the equilibrium point has not been evaluated yet. Therefore, the aim of this study was to compare relative and absolute reliability indices of its angle and moment values with conventional and functional hamstring–quadriceps ratios. Furthermore, effects of familiarisation and angular velocity on reproducibility were analysed. A number of 33 male volunteers participated in 3 identical test sessions. Peak moments (PMs) were determined unilaterally during maximum concentric and eccentric knee flexion (prone) and extension (supine position) at 0.53, 1.57 and 2.62 rad · s^–1. A repeated measure, ANOVA, confirmed systematic bias. Intra-class correlation coefficients and standard errors of measurement indicated relative and absolute reliability. Correlation coefficients were averaged over respective factors and tested for significant differences. All balance scores showed comparable low-to-moderate relative (<0.8–0.9) and good absolute reliability (<10%). Relative reproducibility of dynamic control equilibrium parameters augmented with increasing angular velocity, but not with familiarisation. At 2.62 rad · s^–1, high (moment: 0.906) to moderate (angle: 0.833) relative reliability scores with accordingly high absolute indices (4.9% and 6.4%) became apparent. Thus, the dynamic control equilibrium is an equivalent method for the reliable assessment of thigh muscle balance.  相似文献   

Evidence for data missing at random in youth physical activity monitoring research     

P. F. Saint-Maurice  Y. Kim  G. J. Welk 《Journal of sports sciences》2017,35(5):484-490

This study examined whether or not activity monitor data collected as part of a typical 7-day physical activity (PA) measurement protocol can be expected to be missing at random. A total of 315 participants (9–18 years) each wore a SenseWear Armband monitor for 7 consecutive days. Participants were classified as “compliant” (86 boys and 124 girls) if they had recorded accelerometer data during 70% or more of the predefined awake time (7 AM–10 PM) on four different days; and “non-compliant” (44 boys and 51 girls) when not meeting these criteria. Linear mixed models were used to examine differences in energy expenditure (EE) levels by compliance across 10 different time periods. The results indicated that non-compliant girls were older (13.4 ± 2.9 vs. 12.2 ± 2.5) and taller (156.8 ± 10.3 vs. 152.8 ± 11.3) than their same gender compliant peers (P < .05). Comparisons of EE rates at segmented portions of the day revealed no differences between compliant and non-compliant groups (P ≥ .05). Differences in EE ranged from ?0.32 kcal · kg^?1 · h^?1 (before school time) to 0.62 kcal · kg^?1 · h^?1 (physical education class) in boys and ?0.39 kcal · kg^?1 · h^?1 (transportation from school) to 0.37 kcal · kg^?1 · hour^?1 (recess) in girls. The results showed that compliant and non-compliant individuals differed in a few demographic characteristics but exhibited similar activity patterns. This suggests that data were considered to be missing at random, but additional work is needed to confirm this observation in a representative sample of children using other types of activity monitors and protocols.  相似文献   

基于对应分析模型原理的户外运动安全风险研究     

欧雅怡  刘〓亚  马逢伯 《广州体育学院学报》2017,37(2):43-48

通过对我国2001年至2014年期间,258个户外运动安全事故案例的统计和分析,结合国内外相关研究,建立户外运动安全风险分析框架,将户外运动安全风险划分为4个维度,18个因素指标.根据对应分析模型原理,深入研究户外运动中季节、月份与时段风险的对应性关系,R(3.2.0)软件运行结果显示:户外运动中,凌晨和晚上的风险指数最高;春季、秋季的上午和下午时段,可能存在的伤亡风险几率较高;5月、9月、10月的上午和晚上,3月、6月、11月、12月的下午,1月和4月的凌晨时段,可能存在的伤亡风险几率更高.使用Minitab软件,根据累积贡献率80％以上为主要因素的帕累托原则得到8个主要风险因素和7个次要风险因素.  相似文献   

Comfort,Class and Climate Change: The Rise of Glass in Late Medieval and Early Modern Domestic Architecture     

Daniel Jütte 《Cultural and Social History》2013,10(5):621-641

ABSTRACT

In the modern world, glass windows are considered an indispensable element of the built environment. Throughout premodern times, however, glass was not universally used in European architecture. This article argues that the rise of glass in Western architecture was neither an inevitable nor a linear process, but rather a response to certain social, cultural and environmental factors that gained increasing relevance from the late medieval period onwards. In other words, glass windows are a cultural convention, reflecting some of the wide-ranging and transformative challenges that Europeans faced in the late medieval and early modern period.  相似文献   

Erfahrungsbasierte Bildung im Spiegel der Standardisierungsdebatte DGfE-Tagung der Kommission Sportpädagogik     

Ilka Lüsebrink 《Sportwissenschaft》2008,38(2):240-245

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Statistical modelling of knee valgus during a continuous jump test     

Nagano Y  Sakagami M  Ida H  Akai M  Fukubayashi T 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(3):342-350

Landing with the knee in a valgus position is recognized as a risk factor for anterior cruciate ligament (ACL) injury. Using linear and non-linear regression analyses, the purpose of this study was to examine the correlation between two-dimensional (2D) knee valgus and three-dimensional (3D) knee kinematics measured during a jump landing task. Twenty-eight female collegiate athletes participated. All participants were required to perform a continuous jump test. The average maximum angles of abduction and internal tibial rotation during landing were measured using the Point Cluster Technique. Average peak knee valgus angle was measured using a 2D approach. Linear and non-linear regression analyses between 2D valgus and 3D knee abduction, and between 2D valgus and 3D internal tibial rotation, were performed. The R2 value between 2D valgus and 3D knee abduction was significantly different from zero and had a moderate correlation for all models, whereas the R2 value between 2D valgus and 3D internal tibial rotation was not significantly different from zero. The 2D approach could be used to screen a specific group of individuals for risk of ACL injury; however, using frontal plane 2D analysis of valgus motion to evaluate internal tibial rotation is not advised.  相似文献   

Book reviews     

Walter Hahn  Helmut Skowronek  H. J. Butcher  Hans-Martin Müller-Wolf  J. C. Cairns  Michael Angermaier  Maureen Woodhall  Ha Wun Sung  Oskar Anweiler  John A. Smyth  Gilbert de Landsheere  Gaby Venstermans  Erika Voigt  Anza Amen Lema  David Wolsk  Robert O. Berdahl 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1974,20(1):83-107

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Stability analysis of nonlinear control systems with characteristics equations having complex coefficients     

Y.T. Tsay  B.C. Wang  K.W. Han 《Journal of The Franklin Institute》1974,297(3):179-186

In this paper, the stability equation method is applied to the analysis of nonlinear systems with characteristics equations having complex coefficients. Three types of systems are studied: those with unstable open-loop poles, unstable characteristics roots or an equal number of open-loop poles and zeros.  相似文献   

Book reviews     

J. Bruce Francis  Michalina Vaughan  Colin Flood Page  Sally Tomlinson  R. A. Becher  Margaret C. Ives  John Urry  K. G. Collier  Meir Zadok  Charles Carter  Jürgen Schramm  Jean Barry  Graeme C. Moodie  Donald Bligh  R. A. King  D. G. Mulcahy  Peter Scott  F. R. Charmer  T. R. Bone  John A. Hughes  Roger Greenhough  Alec M. Ross  John Wakeford  Joyce Skinner  Duncan B. Nimmo  Cedric Cullingford  L. R. B. Elton 《Higher Education》1979,8(6):709-744

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Nach dem Spiel ist vor dem Spiel     

Prof. Dr. M. Krüger  E. Emrich 《Sportwissenschaft》2009,39(1):5-6

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