青春期笨拙是否存在——青春期不同阶段青少年动作表现的比较研究

目的:分析青春期前期、中期和后期三个阶段青少年动作发展的趋势及性别差异,验证"青春期笨拙"现象是否存在,为青少年动作表现准确评估与有效训练提供依据。方法:选取处于青春期前期、中期和后期三个阶段的共302名青少年,采用BOT-2SF分别对其动作表现进行测试。测试包含4个维度8个指标:精细动作控制(精细动作准确性、精细动作整合)、手部协调(手灵巧度、上肢协调)、躯干协调(两侧协调、平衡)、力量与敏捷(速度和敏捷、力量)。结果:(1)测试总得分和具体指标(除平衡能力外)得分,阶段主效应显著,且青春期中期优于青春期前期;(2)性别主效应显著的指标有精细动作准确性、手灵巧度、上肢协调和力量;(3)性别和阶段交互效应显著的指标包含手灵巧度、跑步速度和灵敏性。结论:(1)整个青春期阶段男生、女生的动作表现均未呈现出暂时下降的现象,"青春期笨拙"现象并不存在;(2)动作表现在部分阶段的部分指标上存在性别差异。力量和上肢协调性方面,青春期三个阶段中男生都优于女生;精细动作准确性方面,青春期三个阶段中女生优于男生;手灵巧度方面,青春期中期女生优于男生;速度与敏捷方面,青春期后期男生优于女生;手灵巧度方面,青春期后期男生优于女生;(3)性别差异引起的动作表现随青春期的发展而逐渐增大。     

不同界面上“Plyometric”训练对运动表现与肌肉损伤的研究进展及对运动训练的启示

采用文献资料法、逻辑分析法等探究硬地面与非硬地(水中、沙地)界面上进行“plyometric”训练对运动表现与肌肉损伤的影响,并提出运动训练实践建议。研究发现:硬地与水中plyometric训练均可以提高运动表现,且干预效果相似;硬地与沙地进行plyometric训练,均可以提高运动表现,不同的测试指标反向纵跳、蹲跳、垂直跳的干预效果存在异同。水中和沙地相对于硬地面进行plyometric训练可以明显较少训练后肌肉酸痛程度,降低运动损伤风险。硬地面适应机制:肌腱复合体和关节的训练适应机制;神经-肌肉对训练的适用机制等。水中和沙地的适应机制:“离心-向心”转化速度;神经冲动与适应机制等。对运动训练的建议:在水中进行plyometric训练时,水面一般在身体的腰部-胸部位置,水温的选择一般在27°C左右;水中、硬地plyometric训练的干预周期介于6-10周之间,每周干预频率介于2-3次之间;组合界面plyometric训练的相关研究文献较少,需进一步研究论证;当在硬界面时,中等负荷量可诱导出最佳的效果;在进行Plyometric训练时,强度比量更重要,且小强度优于大强度;不同年龄、性别进行Plyometric训练时,要选择适应的训练手段,水中和沙地面可以作为传统训练的替换手段。     

声音反馈对高尔夫挥杆训练效果的生物力学影响

目的:从生物力学角度探究声音反馈训练(teaching with acoustical guidance,TAGteachTM)和传统训练方法对高尔夫初学者击球效果和挥杆动作的影响。方法:21名无高尔夫训练基础的大学生受试者随机分为声音反馈训练组(clicker training group,CG,n=11)和传统训练组(traditional training group,TG,n=10),由一名韩国职业高尔夫教练员进行5周的高尔夫挥杆动作教学训练,使用7号铁杆。训练后,对受试进行挥杆动作生物力学测试,对比两组受试者的击球效果和挥杆动作。结果:5周声音反馈训练后,CG杆速、球速、杆面角度、击球距离等击球表现指标显著优于TG(P<0.01)。挥杆动作方面,CG从上杆阶段到随挥初期挥杆时间显著小于TG(P<0.05),骨盆转动速度显著大于TG(P<0.05);CG骨盆转动角度和COM-COP倾角的标准化角加速度变化率显著小于TG(P<0.05)。结论:声音反馈是一种有效的训练辅助手段,可提升高尔夫初学者的挥杆练习效果。     

我国马拉松赛事发展动力机制模型构建与实证研究

运用文献资料法、德尔菲法和数理统计法等,以2013—2018年我国举办的马拉松赛事为研究对象,基于对我国马拉松赛事发展影响因素的系统分析,以理论力学理论为指导,构建我国马拉松赛事发展动力评价指标体系和动力机制理论模型,并对动力机制理论模型进行实证研究。结果表明:1)我国马拉松赛事发展动力评价指标体系,包含4个一级指标、8个二级指标、26个三级指标;2)我国马拉松赛事发展动力的测量指标、影响因素均与综合指数呈正相关关系(R>0.45);3)我国马拉松赛事发展不同年度的综合动力值之间不存在显著性差异(F=0.284,P>0.05);4)我国马拉松赛事发展不同影响因素和动力要素的动力值存在显著性差异(F=30.504,P<0.01)。我国马拉松赛事需要从协同发展、市场化运作、赛事创新、政策落实等视角进行不断的调整和完善,才能更好地促进我国马拉松赛事的健康与良性发展。     

不锈钢耐蚀层冷焊与热焊的研究

带极电渣堆焊广泛应用于核反应堆压力容器内壁大面积的不锈钢耐蚀层堆焊。文章针对不锈钢耐蚀层带极电渣堆焊时采用冷焊与热焊两种控温方式制备实验试件,分别进行弯曲、金相等项目的性能检验。结果表明:不锈钢耐蚀层采用冷焊与热焊方式均能满足技术条件的要求,但热焊的实验结果更优于冷焊。     

基于GT-DRIVE的AT车匹配仿真研究

根据AT车动力学方程,在GT-DRIVE6.1.0环境下建立某B级5AT整车模型,并仿真计算不同变矩器和主减速比下整车动力性、经济性的方法。建模仿真过程不仅为该B级车的选型和匹配提供了依据,对AT车的匹配研究也有借鉴意义。     

基于改进型序号总和理论的企业绩效评价研究及实证分析

序号总和理论是多方案(指标)筛选或优化的一种很好的方法,分析斯皮尔曼等级相关系数,作为该理论的关键步骤,具有先天不足。通过理论演绎,提出了改进型序号总和理论,同时,通过选取的四种绩效评价方法进行实证,对比分析发现,改进型序号总和理论,不仅能扩大原理论的运用范围,还具有原理论同样的优势,都能实现优秀方案筛选或为方案优化提供指导。     

河南理工大学学生体质检测结果比较与分析

目的：研究高校在校生年级学生身体素质发展趋势。方法：对河南理工大学2010年度四个年级学生《国家学生体质健康标准》测试成绩和等级进行统计分析。结果：学生较低体重比例较大,正常体重比例几乎不到半数,同时肥胖者稍多,男生尤其突出;大四男生肺活量不及格率升高,优秀率下降。立定跳远成绩不及格率最高,优秀率最低;大四学生耐力跑成绩不及格率升高,优秀率下降;学生总分不及格率大一到大三呈下降趋势,大四又上升,大四男生良好率和优秀率下降。结论：学生身体形态和身体素质大一到大三呈上升趋势,大四呈下降。     

Relationship between weight status and cognition in children: A mediation analysis of physical fitness components

ABSTRACT

Cross-sectional study aimed to analyse differences in cognitive performance across fitness components categories (cardiorespiratory fitness [CRF], speed-agility and muscular fitness [MF]) and weight status in children, and to determine whether physical fitness mediates the association between body mass index (BMI) and cognitive performance. Fitness components and BMI were measured using standard procedures in 630 children aged 5-to-7 years from the provinces of Cuenca and Ciudad Real, Spain. BADyG was used to assess cognitive performance. We used ANCOVA models to test mean differences in cognition scores by BMI and fitness categories. Hayes’s PROCESS macro was used for mediation analyses. Children with normal weight scored better in spatial factor and general intelligence than their overweight/obese peers (p < 0.05), but differences were attenuated when controlling for CRF (p > 0.05). Children with better results in CRF and speed-agility scored better in all cognitive dimensions even after controlling for BMI (p < 0.05). Similarly, children with high MF obtained better scores in verbal factor (p < 0.05). All fitness components acted as mediators of the relationship between BMI and general intelligence (p < 0.05). These findings highlight the crucial role of fitness in minimising the negative effect of excess weight on children’s cognition.

Abbreviations: BMI: Body mass index; CRF: Cardiorespiratory fitness; MF: Muscular fitness; BADyG E1: Battery of general and differential aptitudes; SES: Socioeconomic status; SD: Standard deviation; IE: Indirect effect     

Better Economy on Indoor Track Compared to Treadmill Running With 1% Inclination

ABSTRACT

Purpose: The purpose of this study was to investigate the differences in metabolic responses between the track and the treadmill (1% inclination) running. The latter is recommended for use in laboratory settings to mimic outdoor running. Method: Seventeen male endurance athletes (mean 25.8, s = 3.8 years) performed 4-min running bouts on an indoor track and the treadmill. Results: At all speeds (11, 13, and 15 km·h^?1) athletes showed better economy on the track running compared to the treadmill expressed as oxygen (7.9%, 5.2%, and 2.8%) and caloric (7.0%, 5.3%, and 2.6%) unit cost. Rating of perceived exertion was evaluated substantially higher at all speeds on the treadmill (F(1,16) = 31.45, p < .001, η²_p = .663) compared to running on the track. Participants presented lower heart rate (F(1,16) = 13.74, p = .002, η²_p = .462) on the track at the speed of 11 and 13 km·h^?1 compared to the treadmill, but not at 15 km·h^?1 (p = .021). Conclusions: We conclude that constant inclination (i.e.. 1%) during the treadmill test might not be suitable to reproduce comparable effort to running on the track; rather, there is an optimal treadmill inclination for different intensities to reproduce similar effort compared to the track running.