Skating mechanics of change-of-direction manoeuvres in ice hockey players     

Antoine Fortier  René A. Turcotte 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(4):341-350

Ice hockey requires rapid transitions between skating trajectories to effectively navigate about the ice surface. Player performance relates in large part to effective change-of-direction manoeuvres, but little is known about how those skills are performed mechanically and the effect of equipment design on them. The purpose of this study was to observe the kinetics involved in those manoeuvres as well as to compare whether kinetic differences may result between two skate models of varying ankle mobility. Eight subjects with competitive ice hockey playing experience performed rapid lateral (90°) left and right change-of-direction manoeuvres. Kinetic data were collected using force strain gauge transducers on the blade holders of the skates. Significantly greater forces were applied by the outside skate (50–70% body weight, %BW) in comparison to the inside skate (12–24%BW, p < 0.05). Skate model and turn direction had no main effect, though significant mixed interactions between leg side (inside/outside) with skate model or turn direction (p < 0.05) were observed, with a trend for left-turn dominance. This study demonstrates the asymmetric dynamic behaviour inherent in skating change-of-direction tasks.  相似文献   

Effects of small-volume soccer and vibration training on body composition,aerobic fitness,and muscular PCr kinetics for inactive women aged 20–45     

《运动与健康科学(英文)》2014,3(4):284-292

PurposeThe present study investigated the effects of 16 weeks of small-volume, small-sided soccer training soccer group (SG, n = 13) and oscillating whole-body vibration training vibration group (VG, n = 17) on body composition, aerobic fitness, and muscle PCr kinetics in healthy inactive premenopausal women in comparison with an inactive control group (CO, n = 14).MethodsTraining for SG and VG consisted of twice-weekly 15-min sessions with average heart rates (HRs) of ∼155 and 90 bpm respectively. Pre- and post-measurements of body composition (DXA), phosphocreatine (PCr) on- and off-kinetics, and HR measurements during standardised submaximal exercise were performed.ResultsAfter 16 weeks of training in SG, fat percentage was lowered (p = 0.03) by 1.7% ± 2.4% from 37.5% ± 6.9% to 35.8% ± 6.2% and the PCr decrease in the quadriceps during knee-extension ramp exercise was attenuated (4% ± 8%, p = 0.04), with no changes in VG or CO (time-group effect: p = 0.03 and p = 0.03). Submaximal exercise HR was also reduced in SG after 16 weeks of training (6% ± 5% of HR_max, p = 0.01).ConclusionShort duration soccer training for 16 weeks appears to be sufficient to induce favourable changes in body composition and indicators of aerobic fitness and muscle oxidative capacity in untrained premenopausal women.  相似文献   

TiN薄膜常压化学气相沉积及动力学研究     

杨小毛 《韩山师范学院学报》2000,21(2):57-62

在玻璃基片温度400℃和650℃之间，讨论了TiCl4-NH3-N2体系TiN常压化学气相沉积（APCVD）及动力学。在500－650℃温度范围内。TiN在高温玻璃表面沉积为反应物扩散控制，低于400℃为表面反应控制，其沉积速度明显受玻璃温度，反应物浓度和气体流速影响。  相似文献   

Shoe drop reduction influences the lower limb biomechanics of children tennis players during an open stance forehand: A longitudinal study     

Alexis Herbaut  Emilie Simoneau-Buessinger  Franck Barbier  Christophe Gillet  Maxime Roux  Nils Guéguen 《European Journal of Sport Science》2017,17(10):1261-1269

Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8?mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (?73%, p?=?.005) but increased peak ankle plantarflexors moment (+47%, p?=?.050) and peak ankle power absorption (+107%, p?=?.005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.  相似文献   

原地连续纵跳的运动生物力学特征研究   总被引：2，自引：1，他引：1  

曹志飞  李世明  朱红红 《天津体育学院学报》2009,24(3):269-273

为研究原地连续纵跳的运动生物力学特征,运用录像拍摄与三维测力同步测试的方法对其研究发现,不同频率作用下的时间参数存在一定差异,随着纵跳频率的增加,时间参数都表现出逐渐减小的趋贽.同一频率作用下随着运动时间的延长,支撑时间逐渐增人.蹬伸力峰值随着连续纵跳运动时间的延长呈现明显逐渐减小的趋势,不同频率原地连续纵跳蹬伸力峰值对起跳效果的影响程度是不同的;缓冲冲量和蹬伸冲量随运动时间的延长,也都呈现出明显的逐渐减小的趋势,并且运动前期的恢复系数人于1.  相似文献   

梁富亮单杠团身后空翻一周半越杠再握动作的运动学分析   总被引：2，自引：2，他引：0  

姚侠文  王向东  李伟 《北京体育大学学报》2006,29(11):1560-1562

通过运动学分析揭示了我国优秀运动员完成的单杠团身后空翻一周半越杠再握动作的运动学规律与技术特点,对于进一步发展此类动作有积极的作用.  相似文献   

脂肪酸合成酶缩合中心的羧负离子结合部位     

田维熙 《中国科学院研究生院学报》1990,(2)

本文对六个修饰巯基的试剂失活脂肪酸合成酶(FAS)的动力学进行了系统研究,发现它们与FAS的作用是否属于亲和标记,修饰巯基时的专一性,以及盐和NADPH有无保护,均只与该试剂分子中有无羧基负离子有关,提出在FAS的缩合中心存在一个对羧负离子有特异亲和力的结合部位.该部位可能是丙二酰基在缩合中心的结合部位,为缩合反应所必需,它使携带了丙二酰基的活臂向缩合中心运动,并结合于此进行缩合反应.  相似文献   

酸枝锯末对Cr(VI)的吸附研究     

余美琼  杨金杯  陈秀宇 《闽江学院学报》2014,(2):114-121

实验研究了酸枝锯末对模拟含铬废水中的Cr（VI）的吸附性能,静态吸附结果表明,酸枝锯末对Cr（VI）具有较好的吸附效果．锯末对Cr（VI）的吸附率随着锯末用量的增加而增大;随着溶液初始pH的增大,吸附效果降低;随着吸附温度的上升,吸附效果升高．酸枝锯末对Cr（VI）的吸附符合拟二级吸附动力学模型（R2〉0．99）,吸附平衡前,颗粒内扩散为吸附速率的主要控制步骤;吸附过程可用Langmuir吸附等温线（砰〉0．99）来描述．吸附热力学研究表明,酸枝锯末对Cr（VI）的吸附为自发的吸热反应过程．  相似文献   

跳深跳远练习和跳远踏跳的动力学比较研究   总被引：3，自引：0，他引：3  

吕季东  龙跃玉 《上海体育学院学报》1996,20(4):68-71

采用文献研究及在实验室条件下的动力学测试,对跳深跳远练习与跳远踏跳在形式、内容上的相似程度和差异点进行对比分析。结果显示,跳深跳远练习可以作为发展跳远起跳力量的专门训练手段。  相似文献   

110m栏运动员摆动动作的运动学特征   总被引：4，自引：0，他引：4  

葛青 《西安体育学院学报》2002,19(4):81-83

运用高速摄影及影片解析法获取了我国优秀男子 110m栏运动员第六栏跨栏步技术摆动动作的相关运动学指标。研究结果表明 :我国优秀男子 110m栏运动员跨栏步摆动动作的时相划分为 :大腿分前摆与下压两个亚时相 ,小腿分折叠、打开与保持三个亚时相。摆动腿下压的时机始于身体重心位于栏上瞬时 ,大约经过 0 .0 31s的时间 ,起跨腿加速向前提拉。整个跨栏步摆动腿前摆时间是下压时间的 1.2 5倍 ,前摆的平均角速度慢于下压的平均角速度 ;小腿打开时间是折叠时间的 4 .5 5倍 ,小腿折叠的平均角速度约为打开的 1.74倍  相似文献