A comparison of methods to determine bilateral asymmetries in vertical leg stiffness     

Sean J. Maloney  Iain M. Fletcher  Joanna Richards 《Journal of sports sciences》2016,34(9):829-835

Whilst the measurement and quantification of vertical leg stiffness (K_vert) asymmetry is of important practical relevance to athletic performance, literature investigating bilateral asymmetry in K_vert is limited. Moreover, how the type of task used to assess K_vert may affect the expression of asymmetry has not been properly determined. Twelve healthy males performed three types of performance tasks on a dual force plate system to determine K_vert asymmetries; the tasks were (a) bilateral hopping, (b) bilateral drop jumping and (c) unilateral drop jumping. Across all the three methods, K_vert was significantly different between compliant and stiff limbs (P < 0.001) with a significant interaction effect between limb and method (P = 0.005). Differences in K_vert between compliant and stiff limbs were ?5.3% (P < 0.001), ?21.8% (P = 0.007) and ?15.1% (P < 0.001) for the bilateral hopping, bilateral drop jumping and unilateral drop jumping methods, respectively. All the three methods were able to detect significant differences between compliant and stiff limbs, and could be used as a diagnostic tool to assess K_vert asymmetry. Drop jumping tasks detected larger K_vert asymmetries than hopping, suggesting that asymmetries may be expressed to a greater extent in acyclic, maximal performance tasks.  相似文献   

Perception of sign language and its application to visual communications for deaf people   总被引：1，自引：0，他引：1  

Muir LJ  Richardson IE 《Journal of deaf studies and deaf education》2005,10(4):390-401

Video communication systems for deaf people are limited in terms of quality and performance. Analysis of visual attention mechanisms for sign language may enable optimization of video coding systems for deaf users. Eye-movement tracking experiments were conducted with profoundly deaf volunteers while watching sign language video clips. Deaf people are found to fixate mostly on the facial region of the signer to pick up small detailed movements associated with facial expression and mouth shapes. Lower resolution, peripheral vision is used to process information from larger, rapid movements of the signer in the video clips. A coding scheme that gives priority to the face of the signer may be applied to improve perception of video quality for sign language communication.  相似文献   

The impact of collective efficacy beliefs on effort and persistence in a group task   总被引：4，自引：0，他引：4  

Greenlees IA  Graydon JK  Maynard IW 《Journal of sports sciences》1999,17(2):151-158

Collective efficacy is an important determinant of the motivation of individuals within groups, with increases in collective efficacy producing more effort in a task and greater persistence when faced with failure. To test hypotheses concerning the impact of collective efficacy on effort and persistence, participants (n = 22) were assigned to triads (consisting of the participant and two confederates) and performed three time trials on cycle ergometers. After trial 1, the participants were assigned to either a high or low collective efficacy condition, receiving appropriate bogus performance feedback. All groups received failure feedback after trial 2. Effort was assessed by performance time and maximum heart rate (HRmax) achieved during performance. A 2 (collective efficacy condition) x 3 (trials) analysis of variance with repeated measures on trials revealed significant interaction effects for both performance time and HRmax. Fisher's least significant difference post-hoc tests indicated that, following efficacy manipulation, groups low in collective efficacy significantly reduced both their performance time and HRmax, whereas groups high in collective efficacy maintained performance and HRmax. However, predictions concerning the impact of failure on persistence were not supported. Our results provide partial support for the role of collective efficacy in team sports.  相似文献   

Stressors in elite sport: a coach perspective   总被引：1，自引：1，他引：0  

Thelwell RC  Weston NJ  Greenlees IA  Hutchings NV 《Journal of sports sciences》2008,26(9):905-918

We examined the varying performance and organizational stressors experienced by coaches who operate with elite athletes. Following interviews with eleven coaches, content analysis of the data revealed coaches to experience comparable numbers of performance and organizational stressors. Performance stressors were divided between their own performance and that of their athletes, while organizational stressors included environmental, leadership, personal, and team factors. The findings provide evidence that coaches experience a variety of stressors that adds weight to the argument that they should be labelled as "performers" in their own right. A variety of future research topics and applied issues are also discussed.  相似文献   

Teacher Appraisal,Professional Development and School Improvement: a case study     

David Hopkins  Julie Howard  Iain Johnston  Barbara Glover  Sue Woodburn 《School Leadership & Management》2013,33(1):37-53

The paper argues that in respect of the day‐to‐day work activities required in being a headteacher, and in the work relationships involved in running schools, the occupational culture of headship has changed fundamentally. Using the accounts of 20 headteachers, interviewed in respect of their career histories in 1990 and followed up by means of a postal questionnaire in 1992, the paper illustrates the changes experienced and identified by this group of heads. It is argued that a new headteacher is required; that aspects of educational leadership have diminished dramatically in the work culture of headship.  相似文献   

Computer Aided Assessment and Development of Basic Skills∗     

Iain Macleod  Don Overheu 《International Journal of Disability, Development & Education》1977,24(1):18-35

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Relationships between highly skilled golfers’ clubhead velocity and force producing capabilities during vertical jumps and an isometric mid-thigh pull     

Jack E. T. Wells  Andrew C. S. Mitchell  Laura H. Charalambous  Iain M. Fletcher 《Journal of sports sciences》2018,36(16):1847-1851

Whilst previous research has highlighted significant relationships between golfers’ clubhead velocity (CHV) and their vertical jump height and maximum strength, these field-based protocols were unable to measure the actual vertical ground reaction force (vGRF) variables that may correlate to performance. The aim of this study was to investigate relationships between isometric mid-thigh pull (IMTP), countermovement jump (CMJ), squat jump (SJ) and drop jump (DJ) vGRF variables and CHV in highly skilled golfers. Twenty-seven male category 1 golfers performed IMTP, CMJ, SJ and DJ on a dual force platform. The vertical jumps were used to measure positive impulse during different stretch-shortening cycle velocities, with the IMTP assessing peak force (PF) and rate of force development (RFD). Clubhead velocity was measured using a TrackMan launch monitor at a golf driving range. Pearsons correlation coefficient analyses revealed significant relationships between peak CHV and CMJ positive impulse (r = 0.788, p < 0.001), SJ positive impulse (r = 0.692; p < 0.001), DJ positive impulse (r = 0.561, p < 0.01), PF (r = 0.482, p < 0.01), RFD from 0–150 ms (r = 0.343, p < 0.05) and RFD from 0–200 ms (r = 0.398, p < 0.05). The findings from this investigation indicate strong relationships between vertical ground reaction force variables and clubhead velocity.  相似文献   

Examining the capacity of a sport for development programme to create social capital     

Andrew Adams  Kevin Harris  Iain Lindsey 《Sport in Society》2018,21(3):558-573

Robert Putnam’s conceptualization of social capital has been commonly associated with, and used to analyse, sport-for-development programmes. This paper bucks this trend and uses James Coleman’s rational strain of social capital to examine the use of sport as a component part of a programme to support male adults in addressing connected problems of substance misuse, homelessness and other forms of social exclusion. Using a qualitative research strategy, in-depth and longitudinal data were collected using individual interviews and focus groups with programme participants and key stakeholders over a three-year period. The results suggest the importance of unintentionality for the formation and use value of social capital; indicating that social capital created through this programme was individual, contingent on interactional context and benefited individuals in line with Coleman’s six aspects of social capital.  相似文献   

Running economy,mechanics, and marathon racing shoes     

Iain Hunter  Aubree McLeod  Dru Valentine  Tyler Low  Jared Ward  Ron Hager 《Journal of sports sciences》2013,31(20):2367-2373

ABSTRACT

The choice of marathon racing shoes can greatly affect performance. The purpose of this study is to metabolically and mechanically compare the consumer version of the Nike Vaporfly 4% shoe to two other popular marathon shoes, and determine differences in running economy. Nineteen subjects performed two 5-minute trials at 4.44m/s wearing the Adidas Adios Boost (AB), Nike Zoom Streak (ZS), and Nike Vaporfly 4% (VP) in random order. Oxygen uptake was recorded during minutes 3–5 and averaged across both shoe trials. On a second day, subjects wore reflective markers, and performed a 3-minute trial in each shoe. Motion and force data were collected over the final 30 seconds of each trial. VP oxygen uptake was 2.8% and 1.9% lower than the AB and ZS. Stride length, plantar flexion velocity, and center of mass vertical oscillation were significantly different in the VP. The percent benefit of the VP over AB shoe was predicted by subject ground time. These results indicate that use of the VP shoe results in improved running economy, partially due to differences in running mechanics. Subject variation in running economy improvement is only partially explained by variation in ground time.  相似文献   

Team-Referent Attributions Among Sport Performers     

Iain Greenlees  Andrew Lane  Richard Thelwell  Tim Holder  Gina Hobson 《Research quarterly for exercise and sport》2013,84(4):477-487

Abstract

The aim of this study was to develop and validate a team-referent attribution scale. Conducted over three studies, Study 1 modified items from McAuley, Duncan, and Russell's (1992) Causal Dimension Scale II by rewording items to reflect team attributions and adding one item per factor. This led to the development of a 16-item scale (Causal Dimension Scale-T, CDS-T). Study 2 tested competing models of attribution theory among a sample of 433 team sport players. Confirmatory factor analysis indicated strongest support for a four-factor model (robust comparative fit index = .961; root mean squared error of approximation = .054). Study 3 tested the predictive validity of the scale among a sample of 201 team players. Results indicated that winners reported more internal and stable attributions than losers. Further, performances perceived as successful were associated with stable attributions. The results of the study, therefore, suggest that the CDS-T provides a valid measure of team-referent attributions in sport.  相似文献