Biomechanics of judo backward breakfall for different throwing techniques in novice judokas     

Sentaro Koshida  Takanori Ishii  Tadamitsu Matsuda  Toshihiko Hashimoto 《European Journal of Sport Science》2017,17(4):417-424

It is generally accepted that proper learning of the breakfall technique during early judo training is essential for attenuating the risk of judo-related head injury. Therefore, it is critical to understand the kinematics and head injury risks of breakfall motion to design a more safe and effective judo teaching paradigm that results in reduction of injury risk. We aimed to investigate the biomechanics of judo backward breakfalls by comparing osoto-gari and ouchi-gari in novice judokas. Twelve male novice judokas (age: 21.3 years, SD?=?0.6 years; height: 1.74?m, SD?=?0.04?m; body weight: 71.3, SD?=?6.4?kg; body mass index: 23.5, SD?=?2.3) volunteered to participate in this study. The kinematic data of the breakfall motion for both osoto-gari and ouchi-gari were collected using a three-dimensional motion analysis technique (200?Hz). We observed significant differences between the movement patterns for the two techniques, especially in the lower extremity movements. In addition, a significantly greater peak extension momentum (osoto-gari: 1.29, SD?=?0.23?kg?m^2?s^?1; ouchi-gari: 0.84, SD?=?0.29?kg?m^2?s^?1) and lower head position along the vertical axis (osoto-gari: 0.18, SD?=?0.05?m; ouchi-gari: 0.31, SD?=?0.08?m) with a large effect size were found in the breakfall for osoto-gari. Our results suggest that a different paradigm is needed for effectively teaching each breakfall technique that will enable us to substantially lower the risk of judo-related head injuries in novice judokas.  相似文献   

Acute fatigue negatively affects risk factors for injury in trained but not well-trained habitually shod runners when running barefoot     

Nicholas Tam  Devon R. Coetzee  Safwaan Ahmed  Robert P. Lamberts  Yumna Albertus-Kajee  Ross Tucker 《European Journal of Sport Science》2017,17(9):1220-1229

Introduction: Many factors may contribute to running-related injury. These include fatigue and footwear, the combination of which has rarely been studied, in particular with reference to barefoot running, recently advocated as a method to reduce injury risk. Methods: Twenty-two runners (12 well-trained and 10 trained) participated in a 10?km fatiguing trial. Knee and ankle joint kinematics and kinetics and electromyography were assessed during overground running in the barefoot and shod condition. This was performed pre- and post-fatigue using a motion capture system and force platforms. Results: Initial loading rate increased in the trained runners when barefoot but not shod. Shod knee stiffness increased in both groups after fatigue, whereas barefoot knee stiffness decreased only in the trained group. A reduction in barefoot bicep femoris pre-activation was found in both groups. During stance, a reduction in vastus lateralis and biceps femoris and an increase in tibialis anterior activity were found over time in both groups and conditions. Trained runners decreased gluteus medius and increased lateral gastrocnemius median frequency for both conditions after fatigue. Conclusion: When fatigued, gait adjustments in habitually shod runners may increase injury risk when running barefoot. Training status may be a risk factor for injury, as less-trained runners experience muscular fatigue changes that may compromise ground reaction force attenuation. Caution is recommended when transitioning to pure barefoot running.  相似文献   

The Dutch language anterior cruciate ligament return to sport after injury scale (ACL-RSI) – validity and reliability     

Anton J. Slagers  Inge H. F. Reininga  Inge van den Akker-Scheek 《Journal of sports sciences》2017,35(4):393-401

The ACL-Return to Sport after Injury scale (ACL-RSI) measures athletes’ emotions, confidence in performance, and risk appraisal in relation to return to sport after ACL reconstruction. Aim of this study was to study the validity and reliability of the Dutch version of the ACL-RSI (ACL-RSI (NL)).

Total 150 patients, who were 3–16 months postoperative, completed the ACL-RSI(NL) and 5 other questionnaires regarding psychological readiness to return to sports, knee-specific physical functioning, kinesiophobia, and health-specific locus of control. Construct validity of the ACL-RSI(NL) was determined with factor analysis and by exploring 10 hypotheses regarding correlations between ACL-RSI(NL) and the other questionnaires. For test–retest reliability, 107 patients (5–16 months postoperative) completed the ACL-RSI(NL) again 2 weeks after the first administration. Cronbach’s alpha, Intraclass Correlation Coefficient (ICC), SEM, and SDC, were calculated. Bland–Altman analysis was conducted to assess bias between test and retest.

Nine hypotheses (90%) were confirmed, indicating good construct validity. The ACL-RSI(NL) showed good internal consistency (Cronbach’s alpha 0.94) and test–retest reliability (ICC 0.93). SEM was 5.5 and SDC was 15. A significant bias of 3.2 points between test and retest was found.

Therefore, the ACL-RSI(NL) can be used to investigate psychological factors relevant to returning to sport after ACL reconstruction.  相似文献   

Mathematical modelling as a tool to assessment of loads in volleyball player’s shoulder joint during spike     

Jacek Jurkojć  Robert Michnik  Krzysztof Czapla 《Journal of sports sciences》2017,35(12):1179-1186

This article deals with kinematic and kinetic conditions in volleyball attack and identifies loads in the shoulder joint. Joint angles and velocities of individual segments of upper limb were measured with the use of the motion capture system XSENS. Muscle forces and loads in skeletal system were calculated by means of mathematical model elaborated in AnyBody system. Spikes performed by players in the best and worst way were compared with each other. The relationships were found between reactions in shoulder joint and flexion/extension, abduction/adduction and rotation angles in the same joint and flexion/extension in the elbow joint. Reactions in shoulder joint varied from 591 N to 2001 N (in relation to body weight [BW] 83–328%).

The analysis proved that hand velocity at the moment of the ball hit (which varied between 6.8 and 13.3 m s^–1) influences on the value of reaction in joints, but positions of individual segments relative to each other are also crucial. It was also proved in objective way, that position of the upper limb during spike can be more or less harmful assuming that bigger reaction increases possibility of injury, what can be an indication for trainers and physiotherapists how to improve injury prevention.  相似文献   

Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? part I: A critical review of the literature     

Bas Van Hooren  Frans Bosch 《Journal of sports sciences》2017,35(23):2313-2321

It is widely assumed that there is an eccentric hamstring muscle fibre action during the swing phase of high-speed running. However, animal and modelling studies in humans show that the increasing distance between musculotendinous attachment points during forward swing is primarily due to passive lengthening associated with the take-up of muscle slack. Later in the swing phase, the contractile element (CE) maintains a near isometric action while the series elastic (tendinous) element first stretches as the knee extends, and then recoils causing the swing leg to forcefully retract prior to ground contact. Although modelling studies showed some active lengthening of the contractile (muscular) element during the mid-swing phase of high-speed running, we argue that the increasing distance between the attachment points should not be interpreted as an eccentric action of the CE due to the effects of muscle slack. Therefore, there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstrings CE during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this, we propose that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running.  相似文献   

Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training     

Liang-Ching Tsai  Yi-An Ko  Kyle E. Hammond  John W. Xerogeanes  Gordon L. Warren  Christopher M. Powers 《Journal of sports sciences》2017,35(24):2405-2411

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.  相似文献   

Bicycle rider control skills: expertise and assessment     

Borut Fonda  Nejc Sarabon 《Journal of sports sciences》2017,35(14):1383-1391

Abstract

Research on how human balance and control bicycles are inconclusive, largely due to the small number of participants in the previous studies. Therefore, the aim of this study was to test the hypotheses that 1) cycling lateral deviation amplitude will reliably show differences between more and less experienced cyclists and 2) more experienced will exhibit slower and smaller steering motions compared to the less experienced cyclists. Twenty-eight experienced and inexperienced cyclists rode a bicycle in a straight line. Lateral deviation, steering and roll were measured. Intersession reliability of the deviation was high with Cronbach’s alpha values higher than 0.75. The amplitude, variability and rate of steering and roll parameters showed statistically significant differences between the groups. The test used in this study is sensitive to detect differences between more and less experienced cyclists and can be used for further research that aims to test the effect of a specific intervention addressing rider control. We also showed that steering and roll angle, which were described before as two of the main motor control actions in bicycle control, differ in the variability, amplitude and rate between more and less experienced cyclists. The results of the present study have practical implications for improving bicycle rider control and increasing the safety of cyclists.  相似文献   

北京市男子大学生足球运动员运动损伤特征与风险因素筛查     

吴放  陈效科 《北京体育大学学报》2017,40(7):56-62

摘要：目的：掌握北京市男子大学生足球运动员运动损伤的流行情况,对导致运动损伤发生的风险因素进行筛查,为进一步预防男子大学生足球运动损伤的发生提供依据。方法：应用方便分层抽样的方法,对参加北京市男子大学生足球联赛甲、乙、丙组的14所高校249名在校大学生足球运动员的损伤情况进行调查,应用T检验、单因素χ2检验与二元非条件logistic回归模型进行分析。结果与结论：充分了解了北京市男子大学生足球运动员的运动损伤现状和特征;筛查出为运动损伤发生的主要的风险因素;错误的技术动作、对手的粗野动作导致损伤发生的主要诱发事件。  相似文献   

膝关节贴扎技术的临床应用研究进展          下载免费PDF全文

姜敏  陈文华  余波 《体育科研》2017,(5):94-97

膝关节疾病易发多见,贴扎技术作为主要的非侵入性治疗技术也已广泛应用于临床。结合各类膝关节受累疾病总结了近年贴扎相关的临床应用研究进展,为贴扎技术改善膝关节各类主诉尤其是运动功能障碍方面提供一定参考。  相似文献   

功能性动态拉伸训练对男子足球运动员功能动作测试（FMS）和运动损伤患病率的影响          下载免费PDF全文

封旭华  杨涛  孙莉莉  马铁铮  华英汇 《体育科研》2011,32(5):33-36

目的：观察功能性动态拉伸训练对男子足球运动员FMS测试和运动损伤患病率的影响。方法：选择上海U16全运男子足球队队员20名,在男足运动员准备活动中增加为期六周功能性动态拉伸训练计划,前后用FMS测试和评估,并对损伤患病率进行调查。结果：功能性动态拉伸训练计划执行前后FMS测试评分深蹲、跨栏、分蹲、俯卧撑和体旋比较,训练后功能性非常显著改善（P〈0．01）,主动举腿功能性显著改善（P〈0．05）,但肩部柔韧功能未见显著性差异;全队运动损伤患病率由40％降低到24％,未见显著性差异,急性损伤患病率由20％降低到8％,具有显著性差异。结论：用FMS测试对运动员进行功能性测试和评估比较简便科学,由测试结果设计的功能性训练方案在实践应用中可有效降低男子青少年足球运动员的急性运动损伤。  相似文献