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.     

<中图法>4版个人著作集归类问题

通过一系列的实例分析，指出《中国图书馆分类法》4版个人著作集归类中存在的一些问题，并提出：“党的领导人”类目范围应扩大到对党的建立和发展起过重大作用的领导人；关于历史人物政治理论方面的个人著作集应归属于当时的政治制度史；对于跨学科、综合性的个人著作集，社会科学内容的入C类，自然科学内容的入N类，只有横跨C、N两大类内容的才入Z类等。     

集体主义对英文写作的影响——关于人称代词的个案研究

文章以语言与文化的关系为理论基础，以人称代词和个人主义以及集体主义文化之间的关系为切入点，深入分析了集体主义文化对英语作文的潜意识影响在人称代词方面的表现以及基本认知模式，认为在英语作文教学中不仅要注意语篇、句法和修辞等方面的训练，更要注意英汉文化的区别以及学生的跨文化写作互动意识，尽量避免汉语文化在英语写作中的文化迁移现象。     

植物生长调节剂在作物生产中的安全使用

植物生长调节剂已广泛应用于农作物生产中，能有效改善作物生长状况，提高产品产量和品质，但使用不当也会造成严重的药害。在实际生产中要注意安全使用植物生长调节剂，根据作物品种和使用目标，来选择植物生长调节剂的类型，严格控制浓度及施用方法、时间和次数，从而充分发挥植物生长调节剂的效果。     

A new pedagogical model for adventure in the curriculum: part one – advocating for the model

Background: In recent years increasing attention has been given to models-based approaches to physical education as a way of promoting standards and particular types of learning through better alignment of teacher planning and delivery with pupil learning and achievement. However, little attention has been given to the specific contribution a pedagogical model for outdoor adventure education (OAE) has to make to pupils learning.

Purpose: This paper is presented in two parts. Part one is an advocacy paper and draws upon the broader discourse around models-based practice to make a case for the development of a pedagogical model for OAE. Drawing upon guidelines for models-based approaches to physical education, this paper considers the theoretical foundation, rationale, review of research findings and major theme that inform the development of a model of OAE.

Conclusions: The selected review of the research suggests that the major impact of OAE is upon the affective domain, particularly in relation to pupils developing a positive self-concept. Learning is also evident in the cognitive and physical domains, but this is secondary to learning in the affective domain. Drawing upon the analysis of the research literature, the major theme for the model is identified as ‘personal growth through adventure’ and ‘OAE’ is suggested as the name of the model. Part two of this paper builds upon these foundations to outline what a pedagogical model for OAE might look like in a secondary school in the UK.     

First-rib stress fracture in two adolescent swimmers: a case report

First-rib stress fractures have been described in adolescent athletes in various sports, with only one prior case report of first-rib stress fractures in an adolescent female swimmer. There is a need for research on the cause, management, and prevention of these injuries as they lead to significant morbidity and critical time away from sport for these aspiring athletes. We aimed to describe first-rib stress fractures as a potential cause for non-specific atraumatic chronic shoulder pain in adolescent swimmers and to discuss the different presentations, unique risk factors, treatment, and potential injury prevention strategies of such fractures. We discussed two such cases which were successfully treated with activity modification with restriction of all overhead activity, gradually progressive physical therapy and a return to swimming protocol. First-rib stress fractures can vary in presentation and should be in the differential diagnosis in adolescent swimmers with chronic shoulder pain. These injuries can be successfully managed with rest from overhead activities and physical therapy. Gradual return to competitive swimming can be achieved even with non-union of a first-rib stress fracture. Emphasis on balanced strength training in different muscle groups and proper swimming technique is essential to prevent these injuries.     

缘起法则缺失--"重写文学史"散论

文章通过对重写文学史的缘起、应遵循的方法原则及在写作中当预防的层面等的阐述，阐明了文学史写作的终极目标虚是产生出具有审美性和个人立场的研究型的学术著作，且这种文学史的重写工作需要不断进行。     

Validation of the Microsoft Kinect® camera system for measurement of lower extremity jump landing and squatting kinematics

Cost effective, quantifiable assessment of lower extremity movement represents potential improvement over standard tools for evaluation of injury risk. Ten healthy participants completed three trials of a drop jump, overhead squat, and single leg squat task. Peak hip and knee kinematics were assessed using an 8 camera BTS Smart 7000DX motion analysis system and the Microsoft Kinect® camera system. The agreement and consistency between both uncorrected and correct Kinect kinematic variables and the BTS camera system were assessed using interclass correlations coefficients. Peak sagittal plane kinematics measured using the Microsoft Kinect® camera system explained a significant amount of variance [Range_hip = 43.5–62.8%; Range_knee = 67.5–89.6%] in peak kinematics measured using the BTS camera system. Across tasks, peak knee flexion angle and peak hip flexion were found to be consistent and in agreement when the Microsoft Kinect® camera system was directly compared to the BTS camera system but these values were improved following application of a corrective factor. The Microsoft Kinect® may not be an appropriate surrogate for traditional motion analysis technology, but it may have potential applications as a real-time feedback tool in pathological or high injury risk populations.     

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6?min?mile^?1) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.     

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.