动作姿态对北欧两项运动员跳台滑雪助滑和起跳气动阻力的影响

Effects of Movement and Postures on Aerodynamic Drag during Ski Jumping In-Run and Take-off Phases in Nordic Combined Athletes

目的:探讨北欧两项运动员不同助滑和起跳动作姿态产生原因其对气动阻力的影响及机理,并将姿态参数对气动阻力的影响进行量化评估。方法:以5名北欧两项国家队运动员为对象,采用风洞测试和高清摄像系统及视频分析系统对其在风洞水平工作段中进行助滑和起跳训练时身体姿态和关节角度参数、气动阻力参数进行采集和分析,通过运动员身体形态、运动学特征等因素分析不同姿态产生的原因,探究其影响助滑起跳姿态的机理。结果:1)同一运动员在保持头部平视(与铅垂线夹角θ_(1)=90.4°)、躯干水平(与水平面夹角θ_(2)=0°)、手部水平伸展、完全蹲踞式(髋关节角度θ_(3)=37.6°)姿态进行助滑时气动阻力最小,具有最佳减阻效果。2)不同运动员的起跳动作中,“膝动带髋式”姿势为最佳减阻姿势,相对于平均气动阻力最大的“髋膝变速同步式”姿势,减阻率达到18.34%。3)皮尔逊相关分析表明,运动员的右侧髋关节内外旋ROM增加,起跳的气动阻力相应减小;右髋屈ROM增加,气动阻力相应会增大,起跳气动阻力的降低,有利于运动员赛季跳台的平均距离的提高,以上3组变量之间相关性均具有显著水平(P<0.05)。结论:不同助滑和起跳姿态下北欧两项运动员的气动减阻效应存在一定差异,影响助滑和起跳气动减阻的因素有运动员专项技术特点、身体形态和运动功能特征、心理和场地环境因素等。研究不同姿态的气动减阻效应能够为运动员减小空气阻力、优化能量分配、改进训练策略、提升竞技表现提供重要的科学指导。

Objective:To investigate the effects of different in-run and take-off postures on aerodynamic resistance of Nordic Combined athletes and its mechanism,and to quantitatively evaluate the influence of stance parameters on aerodynamic resistance.Methods:Wind tunnel test,high-definition camera system and video analysis system were used to collect and analyze the body posture and angle parameters,aerodynamic resistance parameters of five Nordic Combined athletes during the in-run and take-off training in the horizontal working section of the wind tunnel.Results:1)The same athlete has the least aerodynamic resistance and the best drag reduction effects when keeping the head position at eye level(angleθ_(1)=90.4ºwith the plumb line),torso horizontally straight(angleθ_(2)=0ºwith the horizontal plane),hands horizontally extended,and completely squatting(hip angleθ_(3)=37.6º).2)Among the take-off movements of different athletes,the best body posture of drag reduction is“knee driving hip movement”and the reduction rate reaches 18.34%compared with“hip and knee synchronization nonuniform movement”,which has the highest average aerodynamic resistance.3)Pearson’s correlation analysis shows that the right hip internal and external rotational range of motion(ROM)increased,the aerodynamic resistance of take-off phase decreased accordingly;the right hip flexion ROM increases,the aerodynamic resistance will increase accordingly,and the decrease of aerodynamic resistance is conducive to the average distance of jumping platform of athlete in season.The correlation between the above three sets of variables was at a significant level(P<0.05).Conclusions:Different in-run and take-off postures of Nordic Combined athletes have certain differences in aerodynamic drag reduction effects.The factors affecting in-run and take-off aerodynamic drag reduction of Nordic Combined athletes include special technical characteristics,body shape and functional characteristics,psychological factors and field environmental factors,etc.The study on the aerodynamic drag reduction effects of different postures can provide important scientific guidance for athletes to reduce the aerodynamic resistance,optimize the energy distribution,improve the training strategy,and improve the competitive performance.