Acute responses of soccer match play on hip strength and flexibility measures: potential measure of injury risk

Abstract

Regular measurements of groin risk factors may offer a preventive measure against injury. Therefore, the aim of this study was to (1) determine minimal detectable change (MDC) and reliability of hip flexibility and strength measures and to (2) identify the effect soccer match play load has on these measures. Reliability was determined for bent knee fall out test, hip abduction and adduction (hand-held dynamometry (HHD)) in 20 trained youth male soccer players. Reliability was evaluated with the intra-class correlation coefficient (ICC_[2,1]), 95% confidence intervals (CI). Hip strength and flexibility measures were taken before and after an international friendly match. Intra-rater reliability ICC ranges were bent knee fall out (0.75–0.90), abduction (0.83–0.90) and adduction (0.72–0.96). Inter-rater ICCs (95% CI) were bent knee fall out test [0.75 (0.39–0.90) right, 0.71 (0.27–0.89) left hip]; abduction [0.80 (0.50–0.92) right, 0.81 (0.53–0.92) left hip] and adduction [0.72 (0.31–0.89) right, 0.70 (0.26–0.88) left hip]. MDCs were as low as 20.7% of the mean for hip flexibility and 12.5% for strength. In conclusion, HHD and the bent knee fall out test are reliable tools to measure changes in hip strength and flexibility. Finally, a threshold may exist in which match play load negatively impacts hip flexibility.     

高强度间歇训练的科学与实践:应用考量与关键指标

高强度间歇训练(HIIT)是以≥无氧阈或最大乳酸稳态的负荷强度进行多次持续时间为几秒到几分钟的练习,并且每 2.次练习之间安排不足以使练习者完全恢复的静息或低强度练习的训练方法。进入2 1.世纪以来,HIIT受到了训练科学与实践领域的密切关注,越来越多的教练员在训练实践中开始采用HIIT来提升运动员的竞技表现。然而,HIIT不只是“高强度”和“间歇”这么简单,其效果和价值的发挥需要考虑诸多因素。本文基于《高强度间歇训练的科学与应用:训练安排的解决方案》一书内容,分别从形式和目标类型、应用的整体框架、应用情境、同期化训练、关键指标 5.个方面对HIIT进行了论述,旨在为教练员和科研人员在训练实践当中应用HIIT并发挥HIIT的价值提供参考     

Temporal aspects of the VO2 response at the power output associated with VO2peak in well trained cyclists--implications for interval training prescription

The power output achieved at peak oxygen consumption (VO2peak) and the time this power can be maintained (i.e., Tmax) have been used in prescribing high-intensity interval training. In this context, the present study examined temporal aspects of the VO2 response to exercise at the cycling power that output well trained cyclists achieve their VO2peak (i.e., Pmax). Following a progressive exercise test to determine VO2peak, 43 well trained male cyclists (M age = 25 years, SD = 6; M mass = 75 kg, SD = 7; M VO2peak = 64.8 ml x kg(-1) x min(-1), SD = 5.2) performed two Tmax tests 1 week apart. Values expressed for each participant are means and standard deviations of these two tests. Participants achieved a mean VO2peak during the Tmax test after 176 s (SD = 40; M = 74% of Tmax, SD = 12) and maintained it for 66 s (SD = 39; M = 26% of Tmax, SD = 12). Additionally, they obtained mean 95% of VO2peak after 147 s (SD = 31; M = 62% of Tmax, SD = 8) and maintained it for 95 s (SD = 38; M = 38% of Tmax, SD = 8). These results suggest that 60-70% of Tmax is an appropriate exercise duration for a population of well trained cyclists to attain VO2peak during exercise at Pmax. However, due to intraparticipant variability in the temporal aspects of the VO2 response to exercise at Pmax, future research is needed to examine whether individual high-intensity interval training programs for well trained endurance athletes might best be prescribed according to an athlete's individual VO2 response to exercise at Pmax.     

Temporal changes in home advantage in English football since the Second World War: what explains improved away performance?

This study examined temporal trends in home advantage in the top two English football divisions and used change point analysis to test the hypothesis that home advantage has not remained constant over time. Regression analysis was used to model the impact of substitutions (a proxy for "information transfer") and the points system on home advantage. The results suggest that changing from two points for a win to three points for a win has led to a 0.39 reduction (95% confidence interval=0.21 to 0.56) in the ratio of home wins to away wins. Increasing the number of substitutions is associated with a small increase in the ratio of home wins to away wins, although this is not statistically significant. The evidence indicates that, in this particular context, the extent of home advantage has diminished. This contradicts most other published work, which suggests that home advantage is stable over time. I argue that this reduction is more likely to be the result of the introduction of three points for a win, which has lessened the incentives for away teams to settle for a draw, than an increase in "information transfer". Research into temporal trends in home advantage is interesting in its own right but might, in addition, shed light on determinants of the home advantage phenomenon.     

A protocol for measuring the direct effect of cycling on neuromuscular control of running in triathletes

Abstract

The direct effects of cycling on movement and muscle recruitment patterns (neuromuscular control) during running are unknown but critical to success in triathlon. We outline and test a new protocol for investigating the direct influence of cycling on neuromuscular control during running. Leg movement (three-dimensional kinematics) and muscle recruitment (surface electromyography, EMG) were compared between a control run (no prior exercise) and a 30-min transition run that was preceded by 20 min of cycling. We conducted three experiments investigating: (a) the repeatability (between-day reliability) of the protocol; (b) the ability of the protocol to investigate, in highly trained national or international triathletes, the direct influence of cycling on neuromuscular control during running independent of neuromuscular fatigue; and (c) the ability of the protocol to provide a control, or baseline, measure of neuromuscular control (determined using a measure of stability) without causing fatigue. Kinematic and EMG measures of neuromuscular control during running showed moderate to high repeatability: mean coefficients of multiple correlation for repeatability of EMG and kinematics were 0.816 ± 0.014 and 0.911 ± 0.031, respectively. The protocol provided a robust baseline measure of neuromuscular control during running without causing neuromuscular fatigue (coefficients of multiple correlation for stability of EMG and kinematics were 0.827 ± 0.023 and 0.862 ± 0.054), while EMG and force data provided no evidence of fatigue. The protocol outlined here is repeatable and can be used to measure any direct influence of cycling on neuromuscular control during running.     

Variation in Students’ Experiences of the ‘Oxford Tutorial’

This paper examines Oxford University students’ conceptions of the role of the tutorial in their learning. An analysis of interviews with 28 students constituted four qualitatively different conceptions of the ‘Oxford Tutorial’. These ranged from the tutorial involving the tutor explaining to the student what the student did not know, to the tutorial involving the tutor and the student in exchanging different points of view and both coming to a new understanding of the topic under discussion. These different conceptions also appeared to be related to variations in students’ views of the role of the work done in preparation for the tutorial, their view of the student’s and tutor’s roles in the tutorial, and the conception of knowledge that students adopted in relation to the tutorial. The implications of this study are discussed in terms of the relations between students’ conceptions of tutorials and their anticipated learning outcomes and its implications for contexts outside of Oxford in terms of students’ conceptions of academic tasks.     

College/University Counseling Centers Supporting Study Away: Challenges and Opportunities

Research points to significant numbers of students on college campuses experiencing mental health distress and an ever increasing number of college students who are choosing to make an off-campus educational experience a part of their college careers. When we consider both of these trends together, it is quite apparent that a significant number of students with mental health concerns will spend periods of time studying away from campus, with converging concerns among college mental health and study away professionals about how to best support these students. This article seeks to outline both challenges and opportunities inherent in the collaboration between campus professionals in supporting students with mental health issues before and during their study away experiences.     

Within‐High‐School Versus Across‐High‐School Scaling of Admissions Assessments: Implications for Validity and Diversity Effects

Previous research has established that SAT scores and high school grade point average (HSGPA) differ in their predictive power and in the size of mean differences across racial/ethnic groups. However, the SAT is scaled nationally across all test takers while HSGPA is scaled locally within a school. In this study, the researchers propose that this difference in how SAT scores and HSGPA are scaled partially explains differences in validity and subgroup differences. Using a large data set consisting of 170,390 students each of whom matriculated at one of 114 separate colleges, the researchers find that awarding SAT scores by ranking SAT within a high school generally results in substantial reduction in the size of subgroup mean differences for this predictor. However, validity for predicting first‐year GPA is also reduced by a small amount. Conversely, placing HSGPA onto a nationally normed metric through the use of multiple regression procedures results in a moderate increase in the size of subgroup mean differences, while also producing a small increase in validity. Taken together, these findings suggest that differences in predictor scaling can partially explain differences in the size of subgroup mean differences between HSGPA and SAT scores and have implications for predictive power.