Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training     

Liang-Ching Tsai  Yi-An Ko  Kyle E. Hammond  John W. Xerogeanes  Gordon L. Warren  Christopher M. Powers 《Journal of sports sciences》2017,35(24):2405-2411

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.  相似文献   

Annual bibliography of publications on the history of sport in Britain, 1982/83     

Richard W. Cox 《国际体育史杂志》2013,30(3):318-334

  相似文献   

A critical analysis of the conceptualisation of ‘coaching philosophy’     

Christopher Cushion 《Sport, Education and Society》2016,21(6):851-867

The aim of this paper was to critically review existing literature relating to, and critically analyse current conceptualisations of, ‘coaching philosophy’. The review reveals a bewildering approach to definitions, terms and frameworks that have limited explanation and reveal a lack of conceptual clarity. It is argued that rather than provide clarification and understanding the existing literature conflates coaching rhetoric and ideology with coaching philosophy and serves to reproduce existing coaching discourse rather than explain coaching practice. The paper problematises the unquestioned assumptions currently underpinning ‘coaching philosophy’; namely the overemphasis of coaches' agency and reflexivity, the downplaying of the significance of social structure on coaches' dispositions and the acceptance that coaching practice is an entirely conscious activity. The paper argues for an alternative philosophy of coaching that uses philosophic thinking to help coaches question existing ideology, and critically evaluate the assumptions and beliefs underpinning their practice.  相似文献   

Effect of repeat-sprint training in hypoxia on post-exercise interleukin-6 and F2-isoprostanes     

Paul S. R. Goods  Brian Dawson  Grant J. Landers  Christopher J. Gore  Kevin Croft  Peter Peeling 《European Journal of Sport Science》2016,16(8):1047-1054

This investigation examined the oxidative stress (F₂-Isoprostane; F₂-IsoP) and inflammatory (interleukin-6; IL-6) responses to repeat-sprint training in hypoxia (RSH). Ten trained male team sport athletes performed 3(sets)*9(repetitions)*5?s cycling sprints in simulated altitude (3000?m) and sea-level conditions. Mean and peak sprint power output (MPO and PPO) were recorded, and blood samples were collected pre-exercise, and again at 8 and 60?min post-exercise. Both MPO and PPO were significantly reduced in hypoxia (compared to sea-level) in the second (MPO: 855?±?89 vs. 739?±?95?W, p?=?.006; PPO: 1024?±?114 vs. 895?±?112?W, p?=?.010) and third (MPO: 819?±?105 vs. 686?±?83?W, p?=?.008; PPO: 985?±?125 vs. 834?±?99?W, p?=?.008) sets, respectively. IL-6 was significantly increased from pre- to 1?h post-exercise in both hypoxia (0.7?±?0.2 vs. 2.4?±?1.4?pg/mL, p?=?.004) and sea-level conditions (0.7?±?0.2 vs. 1.6?±?0.3?pg/mL, p?d?=?0.80) suggesting higher IL-6 levels of post-hypoxia. F₂-IsoP was significantly lower 1?h post-exercise in both the hypoxic (p?=?.005) and sea-level (p?=?.002) conditions, with no differences between trials. While hypoxia can impact on exercise intensity and may result in greater post-exercise inflammation, it appears to have little effect on oxidative stress. These results indicate that team sport organisations with ready access to hypoxic training facilities could confidently administer RSH without significantly increasing the post-exercise inflammatory or oxidative stress response.  相似文献   

Recognition of facial emotions among maltreated children with high rates of post-traumatic stress disorder     

Masten CL  Guyer AE  Hodgdon HB  McClure EB  Charney DS  Ernst M  Kaufman J  Pine DS  Monk CS 《Child abuse & neglect》2008,32(1):139-153

OBJECTIVE: The purpose of this study is to examine processing of facial emotions in a sample of maltreated children showing high rates of post-traumatic stress disorder (PTSD). Maltreatment during childhood has been associated independently with both atypical processing of emotion and the development of PTSD. However, research has provided little evidence indicating how high rates of PTSD might relate to maltreated children's processing of emotions. METHOD: Participants' reaction time and labeling of emotions were measured using a morphed facial emotion identification task. Participants included a diverse sample of maltreated children with and without PTSD and controls ranging in age from 8 to 15 years. Maltreated children had been removed from their homes and placed in state custody following experiences of maltreatment. Diagnoses of PTSD and other disorders were determined through combination of parent, child, and teacher reports. RESULTS: Maltreated children displayed faster reaction times than controls when labeling emotional facial expressions, and this result was most pronounced for fearful faces. Relative to children who were not maltreated, maltreated children both with and without PTSD showed enhanced response times when identifying fearful faces. There was no group difference in labeling of emotions when identifying different facial emotions. CONCLUSIONS: Maltreated children show heightened ability to identify fearful faces, evidenced by faster reaction times relative to controls. This association between maltreatment and atypical processing of emotion is independent of PTSD diagnosis.  相似文献   

Latent Profiles of Reading and Language and Their Association With Standardized Reading Outcomes in Kindergarten Through Tenth Grade     

Barbara R. Foorman  Yaacov Petscher  Christopher Stanley  Adrea Truckenmiller 《Journal of research on educational effectiveness》2017,10(3):619-645

The objective of this study was to determine the latent profiles of reading and language skills that characterized 7,752 students in kindergarten through tenth grade and to relate the profiles to norm-referenced reading outcomes. Reading and language skills were assessed with a computer-adaptive assessment administered in the middle of the year and reading outcome measures were administered at the end of the year. Three measures of reading comprehension were administered in third through tenth grades to create a latent variable. Latent profile analysis (LPA) was conducted on the reading and language measures and related to reading outcomes in multiple regression analyses. Within-grade multiple regressions were subjected to a linear step-up correction to guard against false-discovery rate. LPA results revealed five to six profiles in the elementary grades and three in the secondary grades that were strongly related to standardized reading outcomes, with average absolute between-profile effect sizes ranging from 1.10 to 2.53. The profiles in the secondary grades followed a high, medium, and low pattern. Profiles in the elementary grades revealed more heterogeneity, suggestive of strategies for differentiating instruction.  相似文献   

A review of ‘psychology and the study of education: critical perspectives on developing theories’     

Christopher P. Dwyer 《Irish Educational Studies》2019,38(2):213-217

This review examines Psychology and the Study of Education: Critical Perspectives on Developing Theories, a collection of academic articles edited by Cathal Ó Siochrú. The collection comprehensively considers wide-ranging topics pertinent to the psychology of education, with a target audience of educators and students wishing to learn more about psychology. The review evaluates the collection as an integrated work of entries and analyses each component chapter; recognising the success of the collection with respect to its aim of challenging readers to critically reflect upon and consider the value of psychology in both understanding and influencing education. The book transcends the common formula of academic article collections in this area by being presented in a somewhat conversational manner, making it both interesting and accessible. The book is recommended for anyone interested in the psychology of education and for anyone who values the advancement of learning and teaching.  相似文献   

Classifications of college students’ protean and boundaryless orientation to work     

Jay W. Rojewski  Christopher Pisarik  Hyojung Han 《International Journal for Educational and Vocational Guidance》2017,17(3):329-346

Increasingly, individuals navigate their own careers in self-directed (protean) and boundaryless contexts. These concepts have been applied to adult employees but have seen limited application with young adults. Therefore, 205 college students were assessed on the Protean and Boundaryless Career Attitudes scales (Briscoe, Hall, and DeMuth, 2006); i.e., self-directed career management, values-driven, boundaryless mindset, and organizational mobility preferences. Scale items were reworded to focus on college experience. Cluster analysis organized respondents into five distinct protean-boundaryless career types. Three types were similar to those hypothesized for adults, while two types were unique to our sample.  相似文献   

Optimal Design for Two-Level Random Assignment and Regression Discontinuity Studies     

Christopher H. Rhoads  Charles Dye 《Journal of Experimental Education》2016,84(3):421-448

An important concern when planning research studies is to obtain maximum precision of an estimate of a treatment effect given a budget constraint. When research designs have a multilevel or hierarchical structure changes in sample size at different levels of the design will impact precision differently. Furthermore, there will typically be differential costs of enrolling additional units at different levels of the hierarchy. The optimal design problem in multilevel research studies involves determining the optimal sample size at each level of the design given specified design parameters and a specified marginal cost of recruitment at each level. The current work extends existing results by considering optimal design for (a) unbalanced random assignment designs and (b) regression discontinuity designs.  相似文献   

A cross-cultural investigation of students' preferences for lecturers' personalities in Britain, Malaysia and the United States     

Viren Swami  Adrian Furnham  Ismail Maakip  Sharani Ahmad  Nurul Hudani  Peter S.K. Voo  Andrew N. Christopher  Jeanette Garwood 《Learning and individual differences》2007,17(4):307-315

  相似文献