Muscle force characteristics of male and female collegiate cross-country runners during overground running     

C. Nathan Vannatta  Thomas G. Almonroeder  Thomas W. Kernozek  Stacey Meardon 《Journal of sports sciences》2020,38(5):542-551

ABSTRACT

Males and females demonstrate unique running mechanics that may contribute to sex-related differences in common running related injuries. Understanding differences in muscle forces during running may inform intervention approaches, such as gait retraining addressing muscle force distribution. The purpose of this study was to compare muscle force characteristics and inter-trial variability between males and females during running. Twenty female and 14 male collegiate cross-country runners were examined. Three-dimensional kinetic and kinematic data were collected during overground running and used to estimate muscle forces via musculoskeletal modelling. Principle components analysis was used to capture the primary sources of variance from the muscle force waveforms. The magnitude of the forces for the hamstrings, gastrocnemius, and soleus muscles were higher across the majority of stance in male runners regardless of footstrike pattern. Males also demonstrated greater inter-trial variability in the timing of the peak gluteus maximus force and the magnitude of local peaks in the gastrocnemius force waveform. Male and female collegiate cross-country runners appear to employ unique lower extremity muscle force characteristics during overground running.  相似文献   

The effects of mid-flight whole-body and trunk rotation on landing mechanics: implications for anterior cruciate ligament injuries     

Meghan L. Critchley  Daniel J. Davis  Michaela M. Keener  Jacob S. Layer  Margaret A. Wilson  Qin Zhu 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(4):421-437

ABSTRACT

The purpose was to quantify the effects of mid-flight whole-body and trunk rotation on knee mechanics in a double-leg landing. Eighteen male and 20 female participants completed a jump-landing-jump task in five conditions: no rotation, testing leg ipsilateral or contralateral (WBRC) to the whole-body rotation direction, and testing leg ipsilateral (TRI) or contralateral to the trunk rotation direction. The WBRC and TRI conditions demonstrated decreased knee flexion and increased knee abduction angles at initial contact (2.6 > Cohen’s dz > 0.3) and increased peak vertical ground reaction forces and knee adduction moments during the 100 ms after landing (1.7 > Cohen’s dz > 0.3). The TRI condition also showed the greatest knee internal rotation angles at initial contact and peak knee abduction and internal rotation angles and peak knee extension moments during the 100 ms after landing (2.0 > Cohen’s dz > 0.5). Whole-body rotation increased contralateral knee loading because of its primary role in decelerating medial-lateral velocities. Trunk rotation resulted in the greatest knee loading for the ipsilateral knee due to weight shifting and mechanical coupling between the trunk and lower extremities. These findings may help understand altered trunk motion in anterior cruciate ligament injuries.  相似文献   

Could knee joint mechanics during the golf swing be contributing to chronic knee injuries in professional golfers?     

Howie Carson  Jim Richards  Simon G. S. Coleman 《Journal of sports sciences》2020,38(13):1575-1584

ABSTRACT

Full three-dimensional movements and external moments in golfers’ knees and the possible involvement in injuries have not been evaluated using motion capture at high sample frequencies. This study measured joint angles and external moments around the three anatomical axes in both knees of 10 professional golfers performing golf drives whilst standing on two force plates in a motion capture laboratory. Significant differences were found in the knee joint moments between the lead and trail limbs for the peak values and throughout all stages during the swing phase. A significantly higher net abduction moment impulse was seen in the trail limb compared with the lead limb (?0.518 vs. ?0.135 Nms.kg^?1), indicating greater loading over the whole swing, which could contribute to knee lateral compartment or anterior cruciate ligament injuries. A significant correlation (r = ?0.85) between clubhead speed at ball contact and maximum joint moment was found, with the largest correlations being found for joint moments at the top of the backswing event and at the end of the follow-through. Therefore, although knee moments can contribute to high clubhead speeds, the large moments and impulses suggest that they may also contribute to chronic knee injuries or exacerbate existing conditions.  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   

低浓度苯胺在大孔树脂上吸附的动力学研究     

李湘  李忠 《西江大学学报》2006,27(2):32-35,49

测定了水相中苯胺在NKA—Ⅱ和AB-8这2种大孔吸附树脂上的吸附等温线和吸附速率曲线．结果表明：极性的NKA—Ⅱ对苯胺的吸附量要高于弱极性的AB-8对苯胺的吸附量，苯胺在2种吸附树脂上的相平衡关系符合Freundlich方程；苯胺在NKA—Ⅱ和AB-8上的吸附受腱扩散控制．动态吸附实验和模拟结果表明：模拟透过曲线与实验透过曲线比较吻合，所建立的模型能够较好地描述苯胺在2种大孔吸附树脂填充柱上的吸附透过过程．  相似文献   

Modeling the kinetics of methane conversion in steam reforming process of coke-oven gas based on experimental data     

ZHANG Jia-yuan ZHOU Jie-min 《重庆大学学报(英文版)》2007,6(3):155-160

Steam-reforming is an effective approach for upgrading methane and hydrocarbon of coke-oven gas into CO and H2, but the kinetic behavior needs more study. We investigated the conversion of methane in coke-oven gas by steam reforming process in an electric tubular flow at 14 kPa with temperature varying from 500 °C to 950 °C, and developed a kenetic model for , ignoring the effects of adsorption and diffusion. The optimal dynamic conditions for methane conversion 14 kPa are as follows:the ratio of the amount of water to the amount of methane is from 1.1 to 1.3;the reaction temperature is from 1 223 K to 1 273 K. The methane conversion rate is larger than 95% when the ratio of the amount of water to the amount of methane is 1.2 at a temperature above 1 223 K with the residence time up to 0.75 s.  相似文献   

聚合物结晶动力学     

杨海  刘天西 《南阳师范学院学报》2007,6(12):37-40,51

总结了几种常见的用于描述聚合物等温及非等温结晶行为的动力学方法,并结合具体的应用实例对这些动力学模型的优缺点等方面进行了简单的讨论。  相似文献   

水分胁迫对茶树叶绿素a荧光动力学的影响   总被引：9，自引：0，他引：9  

王怀玉  罗英 《绵阳师范学院学报》2003,22(2):61-63

水分胁迫下，茶树叶片及叶绿体的光系统Ⅱ(PSⅡ)原初光能转换效率(Fv／Fm)和PSⅡ潜在活性(Fv／Fo)降低，而且随着水分胁迫的加强，降低越明显。三个茶树品种对水分胁迫的响应，也存在一定的差异。表明它们的抗旱性不同，其中福鼎大白茶和黔湄809抗旱性较强。黔湄303较差。  相似文献   

Fe(Ⅲ)-H2O2-甲基紫体系催化褪色光度法测定痕量铁(Ⅲ)     

鲁绪会  柯敏 《安康学院学报》2003,15(1):66-69

研究了Fe(Ⅲ)在酸性介质中催化双氧水甲基紫体系的氧化褪色反应,提出一种测定痕量Fe(Ⅲ)的新方法,体系的最大吸收波长为566nm,Fe(Ⅲ)含量在4～12μg*ml-1符合朗伯-比耳定律,回归方程为ΔA=0.00775C+0.05,相关系数γ=0.9930,最低检出限为2.75×10-7g*ml-1,相对标准偏差为1.83%,结果令人满意.  相似文献   

Kinetics of aerobically activated sludge on terylene artificial silk printing and dyeing wastewater treatment     

官宝红  吴忠标  徐根良 《Journal of Zhejiang University. Science. B》2004,(4)

INTRODUCTIONInordertogetpliableandelegantterylenefabricjustlikesilk,terylenegreigeclothisalwayspretreatedwithalkali-decompositionprocesswh-ereinterylenegreigeclothishydrolyzedtosomeextentinNaOHsolutionatcertaintemperature(T)andpressure.Duringthisprocess,thesuperficialterylenefibreispeeledofffromtheclothanddis-solvedintosolution,inwhichteryleneacid(TA)andethyleneglycolaredischargedaspollutantsinwastewater.Theobtainedterylenefabricwithsi-lkenwrinkleandsoftfeelingiscalledartificialsilkfabr…  相似文献