Fatigue increases ankle sprain risk in badminton players: A biomechanical study

ABSTRACT

Ankle sprains are the most common injury in regular badminton players and usually occur at the end of a match or training. The purpose of the present study was to examine the influence of fatigue produced by badminton practice on the lower limb biomechanics of badminton players. It was hypothesized that fatigue induces ankle kinematic and lower leg muscle activity changes which may increase the risk of ankle sprain. Ankle kinematics, ankle kinetics and muscles activities of 17 regular badminton players were recorded during lateral jumps before and after an intense badminton practice session. Post-fatigue, ankle inversion at foot strike and peak ankle inversion increased (+2.6°, p = 0.003 and +2.5°, p = 0.005, respectively). EMG pre-activation within 100 ms before foot landing significantly decreased after fatigue for soleus (?23.4%, p = 0.031), gastrocnemius lateralis (?12.2%, p = 0.035), gastrocnemius medialis (?23.3%, p = 0.047) and peroneus brevis (?17.4%, p = 0.036). These results demonstrate impaired biomechanics of badminton players when fatigue increases, which may cause a greater risk of experiencing an ankle sprain injury.     

浅析艺术设计专业生产性工作室实习的模式

艺术设计专业生产性工作室实习模式是指在学校建立面向市场的企业型艺术设计工作室,让学生按计划到工作室进行生产性实习,提高学生的实际设计能力和水平,这是适应社会需要的一种面向市场的校内实习模式。该模式能较好地解决目前艺术设计专业学生不能适应市场以及实际操作能力差的问题,并且还能使艺术设计专业培养的学生毕业后直接参与实际设计,从而形成学生较高的实际设计能力和应用水平。     

定向运动核心理念在高校体育教学中的时效性研究

针对定向运动核心理念教学在高校体育教学中的方法及形式的时效性、指导思想的时效性以及内容的时效性进行研究,并提出提高定向运动核心理念教学的优化措施.     

“4-8”轴承套圈锻车加工数字化车间研究与探索

通过对“4-8”轴承套圈锻、车加工数字化车间研发背景介绍，国内外发展现状，提出轴承套圈加工工艺流程、数字化车间组成、DNC系统架构、中央控制系统架构及功能等主要内容研究。     

苏区少年先锋队述略

土地革命时期的少年先锋队是一个革命青年的半武装组织。在中国共产党、共青团和苏维埃政府的关心下,少年先锋队领导苏区青年为争取自身阶级利益,保卫苏维埃政权,努力学习知识,并积极投身于革命运动中。他们参与阶级斗争,帮助政府实现各项政治经济政策;开展拥军优属活动,帮助工农群众进行生产建设;训练和培养了大批红军后备力量,帮助红军、赤卫军、游击队保卫苏区政府和人民的安全,并为前线输送了大量优秀战士。在近代中国青年运动史上,少年先锋队组织有着不可磨灭的伟大贡献。     

Mediating effects of resistance training skill competency on health-related fitness and physical activity: the ATLAS cluster randomised controlled trial

The purpose of this study was to examine the mediating effect of resistance training skill competency on percentage of body fat, muscular fitness and physical activity among a sample of adolescent boys participating in a school-based obesity prevention intervention. Participants were 361 adolescent boys taking part in the Active Teen Leaders Avoiding Screen-time (ATLAS) cluster randomised controlled trial: a school-based program targeting the health behaviours of economically disadvantaged adolescent males considered “at-risk” of obesity. Body fat percentage (bioelectrical impedance), muscular fitness (hand grip dynamometry and push-ups), physical activity (accelerometry) and resistance training skill competency were assessed at baseline and post-intervention (i.e., 8 months). Three separate multi-level mediation models were analysed to investigate the potential mediating effects of resistance training skill competency on each of the study outcomes using a product-of-coefficients test. Analyses followed the intention-to-treat principle. The intervention had a significant impact on the resistance training skill competency of the boys, and improvements in skill competency significantly mediated the effect of the intervention on percentage of body fat and the combined muscular fitness score. No significant mediated effects were found for physical activity. Improving resistance training skill competency may be an effective strategy for achieving improvements in body composition and muscular fitness in adolescent boys.     

功能动作测试在中学生基本运动能力评价中的应用

目的：采用功能性动作测试系统（Functional Movement Screen,FMS）评价青少年在完成不同功能动作模式时身体各部分的稳定性、对称性和灵活性,研究其基本运动能力及影响因素。方法：以上海市某中学中随机挑选的100名初中生为研究对象,对他们进行7个特定动作的测试并评分,并对测试结果进行统计分析。结果：FMS测试总分满分为21,受试对象FMS总分均分为14.89,总体水平偏低;女生肩关节灵活性和直腿抬高测试得分显著高于男生,但总分上男女生无显著差异;青少年在完成动作时普遍存在身体晃动、力量不足和两侧肌力不对称现象,髋、膝、踝关节灵活性受限且稳定性较差,脊柱的屈伸能力不足,两侧盂肱关节和髋关节的活动能力不对称。在旋转稳定性、跨栏架和直线弓箭步３个测试中这些不足尤为明显。结论：青少年基本运动能力水平较低,大多数人需要进行矫正训练;男女生总体上的表现差异不显著,但女生在肩部灵活性和直腿抬高测试的表现要优于男生,故男生需加强肩部和髋部关节的灵活性锻炼。     

中国皮划艇国家二队功能动作筛查的应用研究

运用文献资料法、测试法、问卷调查法、专家访谈法和数理统计法对国家皮划艇青年队进行功能动作筛查测试,根据测试结果为备战2020年奥运会提供数据及理论的支持。通过研究发现:划艇运动员的总分情况整体优于皮艇运动员;大部分运动员髋、膝、踝三关节在单一的运动平面中具有较好的协调和稳定性,但在两个以上的运动平面中完成动作的稳定和控制能力有待提高;运动员的髋关节、肩关节及股四头肌柔韧性存在不平衡现象,左侧链与右侧链在多运动平面中协调稳定性也存在不平衡现象;运动员的损伤率较高,且损伤的主要部位是肩和腰。     

Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

华盛顿会议期间的国民外交运动述评

华盛顿会议前后,民众通过组织国民外交团体、联合派遣国民外交代表等形式,表达自身在外交活动中的意愿和诉求,使国民外交运动在独立自主、联合发展方面有了进一步的发展。华盛顿会议后期,民众外交上的诉求未得到满足,国民外交运动由外转内,斗争目标指向北京政府。这种转变,推动了国内政局的变化,也导致了国民外交运动的分裂。