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Ryan S. Sacko Danielle Nesbitt Kerry McIver Ali Brian Farid Bardid David F. Stodden 《Journal of sports sciences》2019,37(15):1755-1761
Objective: To examine children’s energy expenditure (EE) during object projection skill performance at three intensity intervals. Methods: Children’s (42, Mage = 8.1) average metabolic equivalents of task (METs) were calculated using a COSMED K4b2 while they repeatedly performed blocks of kicking, throwing (overhand), and striking (two-handed) during 6, 12, and 30-s interval conditions. A repeated-measures analysis of covariance examined differences in METs while controlling for skill level. Results: Data indicated a main effect for interval condition (df = 2, 123, F = 94.36, p <.001, η2 = .605). Post hoc t-tests demonstrated decreasing performance interval times yielded progressively higher METs (p <.001) across the three conditions (30s = 4.5±0.8 METs, 12s = 6.3±1.3, 6s = 8.3±1.6). There also was a main effect for sex (df = 1,120, F = 52.28, p <.001 η2 = .305). Boys demonstrated higher METs at each performance interval (p <.001). Conclusion: Skill practice with a maximum of one trial every 30s resulted in the equivalent of at least moderate physical activity (>4.0 METs) and intervals of 6s demonstrated vigorous physical activity (>7.0 METs). Practicing/performing object projection skills, even at intervals that allow for adequate instruction and feedback (i.e., 1 trial/30s), promotes MVPA in children. 相似文献
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Dan K. Ramsey Ryan L. Crotin 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(5):553-570
Propulsion and bracing ground reaction force (GRF) in overhand throwing are integral in propagating joint reaction kinetics and ball velocity, yet how stride length effects drive (hind) and stride (lead) leg GRF profiles remain unknown. Using a randomised crossover design, 19 pitchers (15 collegiate and 4 high school) were assigned to throw 2 simulated 80-pitch games at ±25% of their desired stride length. An integrated motion capture system with two force plates and radar gun tracked each throw. Vertical and anterior–posterior GRF was normalised then impulse was derived. Paired t-tests identified whether differences between conditions were significant. Late in single leg support, peak propulsion GRF was statistically greater for the drive leg with increased stride. Stride leg peak vertical GRF in braking occurred before acceleration with longer strides, but near ball release with shorter strides. Greater posterior shear GRF involving both legs demonstrated increased braking with longer strides. Conversely, decreased drive leg propulsion reduced both legs’ braking effects with shorter strides. Results suggest an interconnection between normalised stride length and GRF application in propulsion and bracing. This work has shown stride length to be an important kinematic factor affecting the magnitude and timing of external forces acting upon the body. 相似文献
926.
中国和世界金融市场的发展 总被引:1,自引:0,他引:1
罗伯特·J·希勒 《河南师范大学学报(哲学社会科学版)》2004,31(3)
对于每一个成功的国家来说,一个有效的金融市场是其成功的必要条件.所有的经济活动都会面临风险,如何处理这些风险也就成了一个非常重要的问题.如果金融市场设计得比较合理,就能够保持经济增长的动力.由于我们面临的风险环境不断变化,因此金融体系也需要不断革新,以应对金融风险的改变. 相似文献
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Gilbert's (1978/1996) Behavior Engineering Model (BEM) can enable the success of novice performance engineers by prompting appropriate front‐end analysis. This paper describes the third author's first performance improvement project conducted in the customer service department at an insurance agency. Front‐end performance analysis informed the design of an intervention package that addressed particular environment and person variables. This package included task clarification, employee self‐monitoring, and public posting of group performance. A multiple baseline design across behaviors was used to assess the effects of the intervention. The performance targets were: 1) the percentage of transactions where Customer Service Representatives (CSRs) used customer names, and 2) the percentage of transactions where CSRs suggested additional services available to customers. Average performance during intervention was more than 50% better than average baseline performance for both targets. Results are discussed in terms of the utility of the BEM as a front‐end analysis tool that can guide novice performance engineers to build simple and inexpensive, yet effective, performance improvement interventions. 相似文献
928.
Correlations between the WISC-R Full, Verbal, Performance, and Freedom from Distractibility Scale IQs, WISC-R subtest scaled scores, and Wide Range Achievement Test Reading, Spelling, and Arithmetic standard scores were computed for a sample of 114 children (64 boys, 50 girls), aged 6 to 16 years, who were referred for psychological evaluation because of academic or learning difficulties. The Full Scale IQ, Verbal Scale IQ, and Freedom from Distractibility IQ correlated moderately with the three achievement area standard scores (rs of .48 to .59). However, the Performance Scale IQ correlated minimally with reading and spelling scores (rs of .26 and .27), but moderately with arithmetic scores (r = .40). The results support the concurrent validity of the WISC-R. 相似文献
929.
Popular belief in alternative assessment procedures suggests that the use of student portfolios can help learners successfully organize and integrate newly acquired scientific knowledge. This two-group comparison study documents the use of student created portfolios in an algebra-based, college-level, introductory physics course. Sixteen students were assessed primarily using a portfolio-style assessment procedure. Nineteen students were assessed primarily using traditional, objective examinations. Both groups were given the same cumulative, multiple-choice final examination. All students completed a pre- and post-self-report survey of achievement in physics. There were no significant differences in learner achievement between the two groups on the final examination or on the self-report of achievement given before and after instruction. Analysis of two focus group discussions did, however, suggest that students assessed by portfolios feel less anxious about learning physics, devote considerable time to reading and studying outside of class, internalize and personalize the content material, and enjoy the learning experience. The results of this study suggest that portfolio-style assessment procedures support student achievement at least at the same level as traditional assessment procedures and appear to have additional benefits. © 1997 John Wiley & Sons, Inc. J Res Sci Teach 34: 255–271, 1997. 相似文献
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