Reliability of arterial spin labelling measurements of perfusion within the quadriceps during steady-state exercise     

Jonathan Fulford  Anni Vanhatalo 《European Journal of Sport Science》2016,16(1):80-87

Arterial spin labelling (ASL) provides a potential method to non-invasively determine muscle blood flow and examine the impact of interventions such as supplementation and training. However, it's a method with intrinsically low signal, leading to limitations in accuracy and temporal resolution. To examine these limitations, the current study measured perfusion via ASL on three occasions in the rectus femoris of 10 healthy adults, during light and moderate exercise, over three different exercise durations. For data sampled over 9 min, light intensity exercise gave an average perfusion of 35.0 ± 5.1 ml/min.100g^?1 with a coefficient of variation (COV) of 16% and single intraclass correlation coefficient (ICC) of 0.67. For the moderate bout, perfusion was 51.3 ± 5.6 ml/min.100g^?1 (COV 10%, ICC 0.82). When the same data were analyzed over 5 min 24 s, perfusion was 37.8 ± 11.13 (COV 30%, ICC 0.13) during light and 49.5 ± 8.8 ml/min.100g^?1 (COV 18%, ICC 0.52) during moderate exercise. When sampling was reduced to 1 min 48 s, perfusion was 41.2 ± 13.7 (COV 33%, ICC 0.26) during light and 49.5 ± 13.6 ml/min.100g^?1 (COV 28%, ICC 0.04) during moderate exercise. For 9 min a significant perfusion difference was found between the exercise intensities; however, this was not the case for sampling over 5 min 24 s or 1 min 48 s. Such findings illustrate the potential of ASL to non-invasively monitor muscle perfusion under steady-state conditions, but highlight that extended exercise protocols are necessary in order to generate date of sufficient reliability to be able to discriminate intervention dependent perfusion differences.  相似文献   

A kinematic analysis of the spine during rugby scrummaging on natural and synthetic turfs     

Ramesh Swaminathan  Jonathan M. Williams  Michael D. Jones 《Journal of sports sciences》2016,34(11):1058-1066

Artificial surfaces are now an established alternative to grass (natural) surfaces in rugby union. Little is known, however, about their potential to reduce injury. This study characterises the spinal kinematics of rugby union hookers during scrummaging on third-generation synthetic (3G) and natural pitches. The spine was sectioned into five segments, with inertial sensors providing three-dimensional kinematic data sampled at 40 Hz/sensor. Twenty-two adult, male community club and university-level hookers were recruited. An equal number were analysed whilst scrummaging on natural or synthetic turf. Players scrummaging on synthetic turf demonstrated less angular velocity in the lower thoracic spine for right and left lateral bending and right rotation. The general reduction in the range of motion and velocities, extrapolated over a prolonged playing career, may mean that the synthetic turf could result in fewer degenerative injuries. It should be noted, however, that this conclusion considers only the scrummaging scenario.  相似文献   

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes     

Cheng-Shiun He  William D. Fraser  Jonathan Tang  Kirsty Brown  Stephen Renwick  Jay Rudland-Thomas 《Journal of sports sciences》2016,34(1):67-74

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D₃ supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D₃ supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D₃ group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D₃ group was higher than in the placebo group (P = 0.025). Only in the vitamin D₃ group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D₃ supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.  相似文献   

Explaining match outcome in elite Australian Rules football using team performance indicators     

Sam Robertson  Nicole Back  Jonathan D. Bartlett 《Journal of sports sciences》2016,34(7):637-644

The relationships between team performance indicators and match outcome have been examined in many team sports, however are limited in Australian Rules football. Using data from the 2013 and 2014 Australian Football League (AFL) regular seasons, this study assessed the ability of commonly reported discrete team performance indicators presented in their relative form (standardised against their opposition for a given match) to explain match outcome (Win/Loss). Logistic regression and decision tree (chi-squared automatic interaction detection (CHAID)) analyses both revealed relative differences between opposing teams for “kicks” and “goal conversion” as the most influential in explaining match outcome, with two models achieving 88.3% and 89.8% classification accuracies, respectively. Models incorporating a smaller performance indicator set displayed a slightly reduced ability to explain match outcome (81.0% and 81.5% for logistic regression and CHAID, respectively). However, both were fit to 2014 data with reduced error in comparison to the full models. Despite performance similarities across the two analysis approaches, the CHAID model revealed multiple winning performance indicator profiles, thereby increasing its comparative feasibility for use in the field. Coaches and analysts may find these results useful in informing strategy and game plan development in Australian Rules football, with the development of team-specific models recommended in future.  相似文献   

The effects of physical contact type on the internal and external demands during a rugby league match simulation protocol     

Jonathan P. Norris  Jamie Highton  Stephen F. Hughes  Craig Twist 《Journal of sports sciences》2016,34(19):1859-1866

The aim of this study was to investigate how the type of contact influences physiological, perceptual and locomotive load during a simulated rugby league match. Eleven male university rugby league players performed two trials of the rugby league movement simulation protocol for interchange forwards with a traditional soft tackle bag and a weighted tackle sled to replicate contact demands. The interchange forward-specific simulation was chosen given the contact frequency is higher for this group of players compared to whole match players. Locomotive rate, sprint speed, tackle intensity, heart rate (HR) and rating of perceived exertion were analysed during the first and second bouts that replicated two ~23 min on-field passages. Countermovement jump (CMJ) was measured before and immediately after each trial. More time was spent in heart rate zone between 91 and 100% HR_peak during the first (effect size ± 90% confidence interval: 0.44 ± 0.49) and second bouts (0.44 ± 0.43), and larger (0.6 ± 0.69) decrements in CMJ performance were observed during the sled trial (5.9, s = 4.9%) compared to the bag trial (2.6, s = 5.4%). Changing the type of contact during the match simulation subtly altered both the internal and external loads on participants. Using a standard tackle bag results in faster sprint speed to contact, but lower overall high-intensity running. Conversely, a heavier tackle object increases the internal load and results in greater lower limb neuromuscular fatigue as reflected by the decrease in CMJ performance.  相似文献   

International Review     

Olugbemiro J. Jegede  Barry Fraser  Darrell Fisher Curtin 《Educational technology research and development : ETR & D》1995,43(1):89-90

  相似文献   

Foreword     

Jonathan D. Fife 《ASHE Higher Education Report》1990,19(2):xvii-xviii

  相似文献   

Examining the effect of positive behaviour support on academic achievement of students with disabilities     

Morgan Chitiyo  Plaxedes Makweche‐Chitiyo  Meungguk Park  Lawrence K Ametepee  Jonathan Chitiyo 《Journal of Research in Special Educational Needs》2011,11(3):171-177

Students who engage in challenging behaviour compromise the fundamental ability of schools to educate children. Consequently, teachers face the daunting task of designing effective strategies to promote positive educational outcomes for their students. Since the 1997 Individuals with Disabilities Education Act amendments, the use of positive behaviour supports (PBS) to address the behavioural needs of children challenged by disabilities has expanded. There is evidence to support the utility of PBS in reducing challenging behaviour among students. However, successful schools are also gauged by the academic achievement of their students. Hence, it is important to examine the extent to which behavioural outcomes are related to academic outcomes. The purpose of this paper is to examine the extent to which PBS interventions aimed at reducing challenging behaviour result in corresponding improvement in academic achievement. A meta‐analysis of extant research indicated a positive correlation of 0.40 between improvement in problem behaviour and academic achievement. A video abstract of this article can be viewed at: http://youtu.be/c9OUU0GkGrw .  相似文献   

The impact of ASEP on pupil learning and classroom climate     

Barry J. Fraser 《Research in Science Education》1975,5(1):1-12

  相似文献   

THE INADEQUACY OF VERBAL TEACHING     

Mowat G. Fraser 《Educational theory》1955,5(1):53-55

  相似文献