Association between knee-to-hip flexion ratio during single-leg vertical landings,and strength and range of motion in professional soccer players

Abstract

The aim of this study was to test the correlation between knee-to-hip flexion ratio during a single leg landing task and hip and knee strength, and ankle range of motion. Twenty-four male participants from a professional soccer team performed a continuous single leg jump-landing test during 10s, while lower limb kinematics data were collected using a motion analysis system. After biomechanical testing, maximal isometric hip (abduction, extension, external rotation), knee extension and flexion strength were measured. Maximum ankle dorsiflexion range of motion was assessed statically using the weight bearing lunge test. Pearson correlation coefficients were calculated to determine the associations between the predictor variables (knee and hip strength, and ankle ROM) and the main outcome measure (knee-to-hip flexion ratio). Correlation between knee-to-hip flexion ratio and hip abductors strength was significant (r = ?0.47; p = 0.019). No other significant correlations were observed among the variables (p > 0.05). These results demonstrated that a lower hip abductors strength in male soccer players was correlated with a high knee-to-hip flexion ratio during landing from a single leg jump, potentially increasing knee overload by decreasing energy absorption at the hip. The results provide a novel proposal for the functioning of hip muscles to control knee overload.     

Optimised force-velocity training during pre-season enhances physical performance in professional rugby league players

ABSTRACT

The effectiveness of 8-week force-velocity optimised training was assessed in highly trained professional rugby league athletes. Players (age 24 ± 3 years; body mass 94.9 ± 21.6 kg; height 181.3 ± 6.0 cm) were strength-matched and assigned to a force-velocity optimised group (OP; n = 15) or a general strength-power group (GP; n = 14). Tests included 10-m, 20-m sprints, 3 repetition-maximum squat and squat jumps over five load conditions to ascertain vertical force-velocity relationship. ANCOVA revealed there was a group effect for force-velocity deficit (P < 0.001), with the OP two-fold greater than the GP group (OP pre: 51.13 ± 31.42%, post: 62.26 ± 31.45%, GP pre: 33.00 ± 19.60%, post: 31.14 ± 31.45%, P < 0.001). There were further group effects for 3RM squat (OP pre: 151.17 ± 22.95 kg, post: 162.17 ± 24.16 kg, GP pre: 156.43 ± 25.07 kg, post: 163.39 ± 25.39 kg, P < 0.001), peak power (OP pre: 3195 ± 949 W, post: 3552 ± 1033 W, GP pre: 3468 ± 911 W, post: 3591 ± 936 W, P < 0.001), and SJ (OP pre: 39.79 ± 7.80 cm, post: 42.69 ± 7.83 cm, GP pre: 40.44 ± 6.23 cm, post: 41.14 ± 5.66 cm, P < 0.001). Prescribing F-V deficit training is superior for improving physical performance within highly trained RL players.     

文化负载词“红语”的解读及英译

“红色”在汉文化中寓意颇丰,与之相关的词语多为褒义,这与西方以贬义为主的“红文化”反差甚大。探索与“红”相关词语的英译策略有助于读者更加透彻地理解中国独特的红文化,有助于促进东西方文化的交流与传播。     

比较优势与江西崛起--走出江西看江西发展

江西在中部地区迅速崛起具备资源比较优势，包括区位和自然，人文等。本文基于省情的客观分析提出发展方向及其具体思路，并指出政府在崛起中大有作为，即制度创新，规范行为和观念转变的引导。     

对影响人体爆发力某些因素的研究

通过对西安体育学院不同专项44名学生进行“纵跳”测验进而对爆发力进行测量。通过测量纵跳高度、肌围度、足弓形态，来分析其各项指标之间的关系及其对爆发力的影响。     

女子水球运动员踩水支撑跳跃的技术和训练

女子水球运动员跳跃技术训练要根据女子运动员自身的特点。在跳跃技术动作运用、训练的安排、强度、方法上应区别于男子运动员。     

偏心受力连接中螺栓数的近似计算

对承受偏心拉力（或同时承受弯矩和轴瓦拉力）的螺栓连接和承受偏心剪力的螺栓宫接,分别命同其所需螺的近似公式和方法,算例表明,工程设计中应用本言语公式和方法,简便实用,可以避免反复计算。     

湘西苗族跳鼓活动发展现状与对策研究

本文采用查阅文献资料、调查访问、专家访谈、逻辑分析等方法,以五代苗族鼓王跳鼓为主线,分析湘西苗族跳鼓活动的内容种类、形式、场地器材以及跳鼓王跳鼓特点等现状。提出发展湘西苗族跳鼓活动应加强湘西苗族跳鼓运动的挖掘和提炼整理、加强湘西民族传统体育专项科研队伍和人才队伍建设、完善和建立健全湘西民族传统体育发展的组织保障、强化跳鼓运动的民族传统特色,发挥跳鼓活动的观赏价值、走学校发展路线,从学校开始普及跳鼓等民族传统体育活动、倡导全民健身理念,普及广大社会群体参与跳鼓活动等对策,为湘西苗族跳鼓民族传统体育的发展和推广提供参考意见。     

《工程力学》平面力系分析

物体的受力分析,是静力学研究中的重要技能。