The reliability of linear position transducer,force plate and combined measurement of explosive power-time variables during a loaded jump squat in elite athletes     

Keir T. Hansen  John B. Cronin  Michael J. Newton 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):46-58

The purpose of this study was to determine the between day reliability of power-time measures calculated with data collected using the linear position transducer or the force plate independently, or a combination of the two technologies. Twenty-five male rugby union players performed three jump squats on two occasions one week apart. Ground reaction forces were measured via a force plate and position data were collected using a linear position transducer. From these data, a number of power-time variables were calculated for each method. The force plate, linear position transducer and a combined method were all found to be a reliable means of measuring peak power (ICC = 0.87‐0.95, CV = 3.4%‐8.0%). The absolute consistency of power-time measures varied between methods (CV = 8.0%‐53.4%). Relative consistency of power-time measures was generally comparable between methods and measures, and for many variables was at an acceptable level (ICC = 0.77‐0.94). Although a number of time-dependent power variables can be reliably calculated from data acquired from the three methods investigated, the reliability of a number of these measures is below that which is acceptable for use in research and for practical applications.  相似文献   

The effects of load on system and lower-body joint kinetics during jump squats     

Gavin L. Moir  Jared M. Gollie  Shala E. Davis  John J. Guers  Chad A. Witmer 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):492-506

To investigate the effects of different loads on system and lower-body kinetics during jump squats, 12 resistance-trained men performed jumps under different loading conditions: 0%, 12%, 27%, 42%, 56%, 71%, and 85% of 1-repetition maximum (1-RM). System power output was calculated as the product of the vertical component of the ground reaction force and the vertical velocity of the bar during its ascent. Joint power output was calculated during bar ascent for the hip, knee, and ankle joints, and was also summed across the joints. System power output and joint power at knee and ankle joints were maximized at 0% 1-RM (p < 0.001) and followed the linear trends (p < 0.001) caused by power output decreasing as the load increased. Power output at the hip was maximized at 42% 1-RM (p = 0.016) and followed a quadratic trend (p = 0.030). Summed joint power could be predicted from system power (p < 0.05), while system power could predict power at the knee and ankle joints under some of the loading conditions. Power at the hip could not be predicted from system power. System power during loaded jumps reflects the power at the knee and ankle, while power at the hip does not correspond to system power.  相似文献   

基于FPGA空调控制系统设计     

贺婷 《茂名学院学报》2012,22(4):43-45

本控制系统利用FPGA技术,结合模块化设计方法,将控制系统分为分频、温度调节、定时、主控制中心和显示五个模块,采用Verilog语言来分别实现各模块功能。所设计的系统不仅开发周期短,开发费用低,同时还具有低功耗,高稳定性等优点。  相似文献   

System design and analysis of the trans-critical carbon-dioxide automotive air-conditioning system   总被引：1，自引：0，他引：1  

穆景阳  陈江平  陈芝久 《Journal of Zhejiang University. Science. B》2003,(3)

INTRODUCTIONAftertheKyotoProtocolwassigned ,theworldwiderefrigerationandair conditioningin dustryfaceduptogreatchangesintheenviron mentalproblem .Forautomotiveair conditioning(AAC) ,thecurrentrefrigerant,R 13 4a ,hasbeenregardedasrestricted use refrigeran…  相似文献   

肢体间不对称对运动表现的影响及干预手段     

李丹阳  程序  阙怡琳  倪丽丽 《武汉体育学院学报》2021,55(8):94-100

肢体间不对称是当前国际体能训练研究领域的热点问题。梳理国际权威研究成果,厘清肢体间不对称的概念和内涵,探究肢体间不对称与运动表现的关系、肢体不对称的评估方式、肢体间不对称的干预方法。主要结论：第一,肢体间不对称主要是指身体左右两侧肢体结构、动作模式、运动能力和运动技能的差异;第二,肢体间不对称直接影响爆发力输出、多向速度、离心-向心能力、平衡能力,潜在影响运动经济性、动作模式及专项运动技能的发挥;第三,肢体间不对称的干预方式为力量和爆发力训练（双侧和单侧）、快速伸缩复合训练、核心区训练、平衡能力训练等。建议在训练实践中应将肢体不对称与基础力量、爆发力等测评结合起来,以优化精英运动员的评估体系;应对运动员的肢体间不对称进行持续的动态监控,探索肢体间不对称与多种运动能力、神经肌肉疲劳等多种能力的交互影响,为调控训练计划提供指南。  相似文献   

基于S161车型的汽车电子空调控制器开发     

林巧婷  邓盈  郑昕斌 《闽江学院学报》2013,34(2):63-67

S161是上海汽车集团自主品牌的乘用车公司的以荣威品牌命名的第三款轿车,市场定位在A级别,是一款新型数字化轿车.结合该车型,主要针对汽车电子空调控制器控制问题,以及实际的使用效果根据项目需求来划分系统的架构,并介绍了创新点和优势以及实际的使用效果.  相似文献   

务实性价值取向下的高职教材编写探索--以《通风与空调工程》为例     

周舟  陆兰晶 《高教论坛》2013,(9)

文章主要介绍了在务实性价值取向的指导下,《通风与空调工程》课程教材的选题基本思路、特点与优势,并具体阐述了该课程教材建设的内容与应用价值。  相似文献   

Part I: Biomechanics     

T. Asai  H. Nunome  S. S. Matsubara  M. Lake 《Journal of sports sciences》2013,31(6):485-500

The purpose of this study was to determine whether the sequence of strength training before endurance training (ST/ET) is more or less effective than endurance training followed by strength training (ET/ST). Twenty‐three females and 11 males were assigned to one of three groups: ST/ET (n= 15), ET/ST (n= 15) or control (n = 4). The 7‐week training programme consisted of strength training using 10 exercises for two sets of 3–12 repetitions and running for 20–25 min at 60–90% of heart rate reserve. Maximal oxygen uptake (VO₂ max) was measured during a graded treadmill test, and muscular strength was assessed using one‐repetition maximum tests for the bench press (BP), shoulder press (SP), arm curl (AC) and leg press (LP). The VO₂ max significantly (P < 0.05) increased 6.7 and 6.2% for the ST/ET and ET/ST groups, respectively. There was no significant (P > 0.05) difference between the two experimental groups. Muscular strength significantly (P <0.05) improved by 15.2% (BP), 16.6% (SP), 17.2% (AC) and 11.9% (LP) for the ST/ET group and 19.9% (BP), 24.1% (SP), 20.9% (AC) and 14.0% (LP) for the ET/ST group. There were no significant (P > 0.05) differences between the two experimental groups for the BP, AC and LP; however, the ET/ST group increased (P < 0.05) SP strength more than the ST/ET group. In conclusion, adaptations to a combination of short‐term endurance and strength training as assessed by VO₂ max and BP, AC and LP strength appear to be independent of whether endurance training occurs prior to or following strength training.  相似文献   

Not quite so fast: effect of training at 90% sprint speed on maximal and repeated-sprint ability in soccer players     

Thomas Haugen  Espen Tonnessen  Svein Leirstein  Erlend Hem  Stephen Seiler 《Journal of sports sciences》2014,32(20):1979-1986

Abstract

The aim of the present study was to investigate the effect of training at an intensity eliciting 90% of maximal sprinting speed on maximal and repeated-sprint performance in soccer. It was hypothesised that sprint training at 90% of maximal velocity would improve soccer-related sprinting. Twenty-two junior club-level male and female soccer players (age 17 ± 1 year, body mass 64 ± 8 kg, body height 174 ± 8 cm) completed an intervention study where the training group (TG) replaced one of their weekly soccer training sessions with a repeated-sprint training session performed at 90% of maximal sprint speed, while the control group (CG) completed regular soccer training according to their teams’ original training plans. Countermovement jump, 12 × 20-m repeated-sprint, VO_2max and the Yo-Yo Intermittent Recovery Level 1 test were performed prior to and after a 9-week intervention period. No significant between-group differences were observed for any of the performance indices and effect magnitudes were trivial or small. Before rejecting the hypothesis, we recommend that future studies should perform intervention programmes with either stronger stimulus or at other times during the season where total training load is reduced.  相似文献   

汽车空调系统故障诊断研究     

鲍晓东 《北京工业职业技术学院学报》2009,8(2):37-39,51

由于汽车空调工作条件较恶劣,极易发生故障,从汽车空调制冷系统的结构、原理入手,并根据实践经验,总结出对空调制冷系统故障进行诊断方法,同时详细介绍了常见故障排除方法。  相似文献