基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Scie...基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Science、PubMed和中国知网等数据库的有关研究文献,从应用基础和训练效果方面对VBT的研究证据进行梳理和分析。结果显示:①常用的多关节力量训练动作的平均速度/平均推动速度均与%1RM呈强负相关关系,构建的个体速度与%1RM关系模型能使动作速度精确关联%1RM;②速度损失百分比与重复次数百分比呈强正相关关系,能够准确利用两者的关系模型推算特定速度区间的完成次数;③速度损失百分比与疲劳关系紧密,能量化疲劳和刺激水平,控制力量训练中过度疲劳带来的负面效应;④VBT能有效提升力量水平,相比传统力量训练方法,VBT能在疲劳程度和训练量更小的情况下提升运动表现;⑤VBT是实现力量训练科学化的重要途径,相关科学研究和实践应用领域应对其给予更多关注。展开更多
The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coeffi...The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coefficients, the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations, combined with the κ-ε turbulence model, were solved using finite volume technique. The pressure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by solving a velocity divergence-derived Poisson-like equation. With the computed aerodynamic forces, the formula of the restriction speed at which the train passed curved rail in cross wind was deduced to analyse the influences of aerodynamic forces on the restriction speed. Results of numerical investigations showed that aerodynamic lift and overturn moment increased more and more rapidly with train speed and wind speed. The enhancement trends showed nonlinear phenomena and enhanced risk in the course of train movement. When the train travels at a high speed and encounters a huge cross wind, the influence involved by nonlinear risk increment will extremely impair safety of train. The following conclusion can also be drawn: The effect of aerodynamic lift makes restriction speed reduce, however, the influences of aerodynamic drag to the limit train speed rest on the direction of wind flow. When the wind blows from inner rail to outer rail, aerodynamic forces shall reduce the restriction speed, by contraries, when the wind blows from outer rail to inner rail, aerodynamic forces shall increase the restriction speed.展开更多
文摘基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Science、PubMed和中国知网等数据库的有关研究文献,从应用基础和训练效果方面对VBT的研究证据进行梳理和分析。结果显示:①常用的多关节力量训练动作的平均速度/平均推动速度均与%1RM呈强负相关关系,构建的个体速度与%1RM关系模型能使动作速度精确关联%1RM;②速度损失百分比与重复次数百分比呈强正相关关系,能够准确利用两者的关系模型推算特定速度区间的完成次数;③速度损失百分比与疲劳关系紧密,能量化疲劳和刺激水平,控制力量训练中过度疲劳带来的负面效应;④VBT能有效提升力量水平,相比传统力量训练方法,VBT能在疲劳程度和训练量更小的情况下提升运动表现;⑤VBT是实现力量训练科学化的重要途径,相关科学研究和实践应用领域应对其给予更多关注。
基金Supported by the National Natural Science Foundation of China(Grant Nos.50078006,50678176)the National Basic Research Program of China("973"Project)(Grant No.2007CB714706)
文摘The results of numerical investigations of aerodynamic forces and moment coefficients of flow passing a simplified train geometry under different wind speeds are summarized. To compute numerically the different coefficients, the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations, combined with the κ-ε turbulence model, were solved using finite volume technique. The pressure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by solving a velocity divergence-derived Poisson-like equation. With the computed aerodynamic forces, the formula of the restriction speed at which the train passed curved rail in cross wind was deduced to analyse the influences of aerodynamic forces on the restriction speed. Results of numerical investigations showed that aerodynamic lift and overturn moment increased more and more rapidly with train speed and wind speed. The enhancement trends showed nonlinear phenomena and enhanced risk in the course of train movement. When the train travels at a high speed and encounters a huge cross wind, the influence involved by nonlinear risk increment will extremely impair safety of train. The following conclusion can also be drawn: The effect of aerodynamic lift makes restriction speed reduce, however, the influences of aerodynamic drag to the limit train speed rest on the direction of wind flow. When the wind blows from inner rail to outer rail, aerodynamic forces shall reduce the restriction speed, by contraries, when the wind blows from outer rail to inner rail, aerodynamic forces shall increase the restriction speed.
