An exercise protocol that simulates the activity patterns of elite junior squash

Abstract

Squash is a popular racket sport that requires intermittent activity with frequent bursts of near maximal-intensity exercise. Consequently, effective physiological and thermoregulatory responses are important contributors to performance during squash match-play. Controlled field-based simulation protocols have been introduced in a growing number of sports, which allow sports scientists to investigate changes in physiology and the efficacy of various interventions in sport-specific contexts. This study aimed to develop an exercise protocol that simulates the physiological requirements of elite squash match-play. Eight elite junior squash players (age 16.2 ± 0.8 years, height 1.76 ± 0.06 m, body mass 61.3 ± 5.9 kg; mean ± s) completed the following in a randomized order: (1) a squash match against a player of similar standard and (2) a squash-specific incremental exercise protocol (multistage squash test [MST]) followed by the squash simulation protocol (SSP). The multistage squash test was continued for 18.0 ± 1.0 min and elicited near maximal post-MST heart rates, blood lactate concentrations and ratings of perceived exertion (198 ± 9 beats · min^?1, 5.7 ± 1.7 mmol · l^?1 and 18 ± 1, respectively). The SSP was 12.2 min in length compared with mean game length during competitive matches of 10.0 ± 1.6 min (P = 0.27). Peak heart rates were similar during the SSP and match-play (192 ± 11 and 189 ± 6 beats · min^?1, respectively; P = 0.44). Mean exercising heart rates were similar during the SSP (180 ± 8 beats · min^?1) and match-play (179 ± 13 beats · min^?1; P = 0.73). Peak blood lactate concentrations during the SSP and match-play were 3.5 ± 1.5 and 2.4 ± 1.2 mmol · l^?1 (P = 0.07), respectively. Peak ratings of perceived exertion during the SSP and match-play were similar (17 ± 2 and 17 ± 2, respectively; P = 0.64). It was concluded that the SSP closely replicated the demands of squash match-play in elite junior squash players. Furthermore, the SSP provides coaches and scientific support staff with a controlled squash-specific exercise protocol that has potential application in the objective investigation of a range of interventions such as training programmes, nutritional supplements and strategies to maintain core body temperature.     

The effect of knee angle on the external validity of isometric measures of lower body neuromuscular function

The aim of this study was to evaluate the effect of varying knee angle (120° and 90°) on the external validity of an isometric leg press test with reference to vertical jump performance. Isometric peak force (PF 120 and PF 90 ), rate of force development (RFD 120 and RFD 90 ), and maximum height reached with a squat jump and counter-movement jump were measured in 14 males. Although RFD 120 was significantly correlated with squat jump and counter-movement jump performance ( r = 0.71 and 0.69), and the correlations with PF 120 approached statistical significance ( r = 0.53 and 0.50), neither PF 90 nor RFD 90 was significantly related to vertical jump performance. Furthermore, although both RFD 120 and PF 120 were significantly different between the best five and the worst five jumpers, RFD 90 and PF 90 did not differentiate between individuals' vertical jump performance. We conclude that the choice of joint angle affects the external validity of isometric strength testing. Based on our results, we recommend accurate control of biomechanical specificity and assessment at different angles to find the position at which isometric strength testing is most comfortable.     

New evidence on the validity of the Arnett Caregiver Interaction Scale: Results from the Early Childhood Longitudinal Study-Birth Cohort

The Arnett Caregiver Interaction Scale (CIS) has been widely used in research studies to measure the quality of caregiver–child interactions. The scale was modeled on a well-established theory of parenting, but there are few psychometric studies of its validity. We applied factor analyses and item response theory methods to assess the psychometric properties of the Arnett CIS in a national sample of toddlers in home-based care and preschoolers in center-based care from the Early Childhood Longitudinal Study-Birth Cohort. We found that a bifactor structure (one common factor and a second set of specific factors) best fits the data. In the Arnett CIS, the bifactor model distinguishes a common substantive dimension from two methodological dimensions (for positively and negatively oriented items). Despite the good fit of this model, the items are skewed (most teachers/caregivers display positive interactions with children) and, as a result, the Arnett CIS is not well suited to distinguish between caregivers who are “highly” versus “moderately” positive in their interactions with children, according to the items on the scale. Regression-adjusted associations between the Arnett CIS and child outcomes are small, especially for preschoolers in centers. We encourage future scale development work on measures of child care quality by early childhood scholars.     

Validity and quality in action research

The early childhood–school relationship is reported as having points of separation and difference. In particular, early childhood teachers located in a school setting report experiencing a push-down effect. This paper reports on a participatory action research project involving three early childhood teachers working within an independent school. Using lyric poetry as a method of data (re)presentation, the paper argues this method allowed for multiple layers of politics within this context to emerge. Because of this, a more nuanced account of the early childhood–school relationship is uncovered. The paper concludes by arguing that this method offers the possibility of narrating participatory action research in a powerful and respectful form.     

准实验研究在教育技术领域的应用

论文首先介绍了准实验研究中的多种实验方法,按照实验对象将其分成单组实验和多组实验,并使用案例分析法分析、介绍其在教育技术领域内的应用,接着论述了几种提高准实验研究效度的方法,最后,对准实验研究在教育技术领域中的应用进行了总结。     

夸张辞格的认知阐释

从认知的角度探讨夸张的定义、成立条件和有效性条件,认为夸张是指故意用话语表述出一种不符合基础认知的虚拟认知,通过形成认知距离而突显对象属性的一种表达手段。夸张成立必须满足两个条件：一是基础认知程度值必须为真,二是认知距离必须大于零。夸张要有效,其言辞传达出的情感值就不能超过人们认知中限定的情感最大值。     

利用统计软件SPSS进行试卷质量分析

试卷质量分析是教学中的一项重要任务,也是教学效果检查的重要依据.质量好的试卷才能准确地反映出学校的教学水平和学生的学习效果.本文抽取我校2007级国际贸易专业两个班级共90份<统计学>考卷作为样本,利用统计软件SPSS13.0来分析试卷的质量,重点演示包括数据录入、分析成绩分布、试卷难度、区分度、信度及效度等内容,从而科学地进行试卷质量分析,提高教学质量和效率.     

Validity and reliability of measures assessing social-cognitive determinants of physical activity in low-active Australian adults

This cross-sectional study of 504 community-dwelling Australian adults (328 females, 176 males, mean age 50.8 ± 13.0 years) sought to examine the reliability and validity of measurement scales for physical activity (PA) self-efficacy and outcome expectations. Participants completed demographic and anthropometric measurements, and a 23-item psychosocial questionnaire pertinent to an intervention target of 10,000 steps per day. Exploratory (n = 252) and confirmatory (n = 252) factor analyses were conducted to determine psychometric properties of the measures. Based on theory and goodness-of-fit indices, six factors were extracted from the questionnaire: PA self-efficacy; PA barriers self-efficacy (including general, personal, and conflict); and physical and mental outcome expectations. From confirmatory factor analysis, the model demonstrated good data fit in four out of five indices: CFI = 0.99; TLI = 0.99; SRMR = 0.03; RMSEA = 0.03, 90%CI = 0.01–0.05, χ² = 113.14 (88), p = 0.04; including good fit by sex, age, weight status, education, and birth country. PA interventions can employ our psychometrically sound social cognitive measures.     

违反法律、行政法规的强制性规定合同的效力

适用《合同法》第52条第五项规定时,应对强制性规定作限定性的解释和具体分析,真正从尊重当事人的意思自治、维护合同自由、鼓励市场交易出发,结合具体案情,综合各种因素去设定合同的效力,应尽量减少无效合同的认定,以最大限度地实现私法精神。