Power training in elite young soccer players: Effects of using loads above or below the optimum power zone     

Irineu Loturco  Lucas A. Pereira  Valter P. Reis  Chris Bishop  Vinicius Zanetti  Pedro E. Alcaraz 《Journal of sports sciences》2020,38(11-12):1416-1422

ABSTRACT

This study aimed to examine the effects of two jump squat (JS) training programs involving different loading ranges in under-20 soccer players during a preseason period. Twenty-three elite young soccer players performed sprint speed (at 5-, 10-, and 20-m), change-of-direction (COD) speed, JS peak-power (PP), and countermovement jump (CMJ) tests pre and post four weeks of training. Athletes were pair-matched in two groups according to their optimum power loads (OPL) as follows: lower than OPL (LOPL; athletes who trained at a load 20% lower than the OPL) and higher than OPL (HOPL; athletes who trained at a load 20% higher than the OPL). Magnitude-based inferences were used to compare pre- and post-training measures. Meaningful increases in the PP JS were observed for both groups. Likely and possible improvements were observed in the 5- and 10-m sprint velocity in the LOPL group. Meanwhile, possible and likely improvements were observed in the CMJ, 5- and 10-m sprint velocity, and COD speed in the HOPL group. Overall, both training schemes induced positive changes in athletic performance. Soccer coaches and sport scientists can implement the JS OPL-based training schemes presented here, either separately or combined, to improve the physical performance of youth soccer players.  相似文献   

我国专利联盟特质对专利联盟市场绩效影响研究     

郑栋之  张同建 《科技管理研究》2018,(11)

以实证性的检验揭示专利联盟特质对联盟市场绩效影响的微观机理,发现我国专利联盟建设中的成效与不足,提出专利联盟建设的改进方向,以进一步促进我国专利联盟的成长。  相似文献   

Effect of different velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles     

Alejandro Pérez-Castilla  Paulino Padial  Antonio J. Morales-Artacho  Belén Feriche 《Journal of sports sciences》2018,36(12):1331-1339

This study compared the effects of two velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles. Twenty men were counterbalanced in two groups (VL10 and VL20) based on their maximum power capacity. Both groups used the same exercises, relative intensity and repetition volume, only differing in the velocity loss threshold of each set (VL10: 10% vs. VL20: 20%). Pre- and post-training assessments included an incremental loading test and a 15-m linear sprint to assess the force- and load-velocity relationships and athletic performance variables, respectively. No significant between-group differences (P > 0.05) were observed for the force-velocity relationship parameters (ES range = 0.15–0.42), the MPV attained against different external loads (ES range = 0.02–0.18) or the 15-m sprint time (ES = 0.09). A high between-participants variability was reported for the number of repetitions completed in each training set (CV = 30.3% for VL10 and 29.4% for VL20). These results suggest that both velocity loss thresholds induce similar changes on the lower-body function. The high and variable number of repetitions completed may compromise the velocity-based approach for prescribing and monitoring the repetition volume during a power-oriented resistance training program conducted with the countermovement jump exercise.  相似文献   

高中立定三级跳远教学与训练策略     

林池森 《当代体育科技》2020,(12):93-94

在高考制度深化改革的背景下,高中阶段的学科教学越来越注重学生身体素质的培养,体育成为高考必考的一门科目。为了强化高中生的锻炼身体意识,使其拥有健康的心态和强健的体魄,高中体育课堂上出现了越来越多的运动项目与教学内容,如立定三级跳远等,有利于丰富课堂内容,锻炼学生的各种运动能力。本文针对高中立定三级跳远教学与训练策略展开分析。  相似文献   

“翻转课堂教学模式”在小学体育教学改革实践中的运用研究--以小学三年级《立定跳远》教学为例     

桂洁 《当代体育科技》2020,(12):11-13

立定跳远,在小学三年级的体育教材中被列为学习跳跃的主要教学内容,为了提高了教学的效率和质量,教师经过多次教学改革实践,从传统的"挤牙膏式"的教学,再到套入情境的教学,最后运用翻转课堂教学模式进行教学,一步步地实践并对比和反思,发现运用"翻转课堂教学模式"的立定跳远课不但有趣还有效,教学效果得到明显提高。  相似文献   

海绵城市、城市公园、城市建筑与绿色城市     

曹婷  连之伟  周武忠 《中国名城》2021,(4):8-14

“绿色”作为现代城市主题,将“城市种进大自然”成为由城市建设不当导致生态问题的核心解决策略。依据设计实践和相关案例分析,可提出:(1)海绵城市的核心治理理念和目前建筑能耗相关概念结合,以“削峰填谷”解决环境、城市内涝问题。(2)城市公园设计必须从生态的丰富内涵出发,尊重城市地格,同时注意整个城市的公园联络性,形成城市空间内的自然轴线.。(3)垂直绿化不仅是单一的绿色外观建筑设计形式,还需要和建筑功能空间、理念结合,让自然这个元素由外向内渗透到建筑内部、人居环境、人们健康饮食以及健康生活方式甚至是思想观念,从建筑外观或者城市形象来增添城市与自然的相关性。  相似文献   

Effects of timing of signal indicating jump directions on knee biomechanics in jump-landing-jump tasks     

Mitchell L. Stephenson  Taylour J. Hinshaw  Haley A. Wadley  Qin Zhu  Margaret A. Wilson  Mark Byra 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(1):67-82

A variety of the available time to react (ATR) has been utilised to study knee biomechanics during reactive jump-landing tasks. The purpose was to quantify knee kinematics and kinetics during a jump-land-jump task of three possible directions as the ATR was reduced. Thirty-four recreational athletes performed 45 trials of a jump-land-jump task, during which the direction of the second jump (lateral, medial or vertical) was indicated before they initiated the first jump, the instant they initiated the first jump, 300 ms before landing, 150 ms before landing or at the instant of landing. Knee joint angles and moments close to the instant of landing were significantly different when the ATR was equal to or more than 300 ms before landing, but became similar when the ATR was 150 ms or 0 ms before landing. As the ATR was decreased, knee moments decreased for the medial jump direction, but increased for the lateral jump direction. When the ATR is shorter than an individual’s reaction time, the movement pattern cannot be pre-planned before landing. Knee biomechanics are dependent on the timing of the signal and the subsequent jump direction. Precise control of timing and screening athletes with low ATR are suggested.  相似文献   

能实现垂直缠绕攀爬的蛇形机器人     

孙洪 《苏州市职业大学学报》2020,(2):6-9

垂直缠绕攀爬的蛇形机器人是基于模块化的P_R(pitch_roll)关节,以串行总线舵机作为关节驱动装置,其控制系统采用协调级和执行级配合的二级结构,以空间三连杆组成的蠕动爬行作为基本步态,实现了蛇形机器人具有垂直缠绕攀爬的功能。  相似文献   

Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent,male players     

Aaron T Scanlan  Jordan L Fox  Nattai R Borges  Anne Delextrat  Tania Spiteri  Vincent J Dalbo 《Journal of sports sciences》2018,36(8):852-860

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.  相似文献   

跨年级小学生数学学力认知诊断测验的IRT垂直等值分析     

王欣瑜 《中国考试》2021,(2)

本研究采用“共同题?锚测验”设计,使用R语言ltm程序包中的IRT两参数模型进行各年级小学生数学学力认知诊断测验和被试参数的估计,并使用equateIRT程序包进行跨年级小学生数学学力认知诊断测验各项参数的等值转换。结果表明,等值转换后各年级测验的题目难度和小学生数学学力均随年级增长而逐渐递增,不同学校、民族、性别学生的数学学力发展差异性特征均与理论假设相符。本研究验证了采用IRT垂直等值方法构建跨年级小学生数学学力发展水平垂直量表的可行性,为制定系统性补救教学方案和自适应题库建设提供了必要的实证证据。  相似文献