Shoe drop reduction influences the lower limb biomechanics of children tennis players during an open stance forehand: A longitudinal study     

Alexis Herbaut  Emilie Simoneau-Buessinger  Franck Barbier  Christophe Gillet  Maxime Roux  Nils Guéguen 《European Journal of Sport Science》2017,17(10):1261-1269

Compared to traditional tennis shoes, using 0-drop shoes was shown to induce an immediate switch from rear- to forefoot strike pattern to perform an open stance tennis forehand for 30% of children tennis players. The purpose of the study was to examine the long-term effects of a gradual reduction in the shoe drop on the biomechanics of children tennis players performing open stance forehands. Thirty children tennis players participated in 2 laboratory biomechanical test sessions (intermediate: +4 months and final: +8 months) after an inclusion visit where they were randomly assigned to control (CON) or experimental (EXP) group. CON received 12-mm-drop shoes twice, whereas EXP received 8?mm then 4-mm-drop shoes. Strike index indicated that all CON were rearfoot strikers in intermediate and final test sessions. All EXP were rearfoot strikers in intermediate test session, but half the group switched towards a forefoot strike pattern in final test session. This switch resulted in a decreased loading rate of the ground reaction force (?73%, p?=?.005) but increased peak ankle plantarflexors moment (+47%, p?=?.050) and peak ankle power absorption (+107%, p?=?.005) for these participants compared with CON. Biomechanical changes associated with the long-term use of partial minimalist shoes suggest a reduction in heel compressive forces but an increase in Achilles tendon tensile forces.  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   

Could Slackline Training Complement the FIFA 11+ Programme Regarding Training of Neuromuscular Control?     

Tobias Jäger  Julian Kiefer  Inge Werner 《European Journal of Sport Science》2017,17(8):1021-1028

The current study compared changes in neuromuscular control between slackline training and the stabilization training elements of the FIFA 11+ programme. Twenty-five students in 2 groups performed a 12-unit training programme. The slackline training group (n?=?13) exclusively trained with a slackline. The stabilization training group (n?=?12) practised exercises as described in the second part of the FIFA 11+ programme. Improvements in balance were assessed using three tests for dynamic, quasi-static, and perturbed postural control: the star excursion balance test (SEBT), the closed-eye single-leg stance, and the MFT S3-Check. Both groups significantly improved the stability and sensorimotor index of the MFT S3-Check (p?<?.001), their range on the SEBT (p?<?.001), and the duration of closed-eye single-leg stance (p?<?.001). The group?×?training interaction was significant for the MFT S3-Check (stability index: p?=?.042; sensorimotor index: p?=?.004) and the SEBT (dominant leg: p?=?.003; averaged both legs: p?=?.016), with the slackline training group showing a larger training effect than the stabilization training group. The results of the present study suggest that slackline training offers similar – or better – improvements in neuromuscular control as the FIFA 11+ warm-up programme. If compliance with the FIFA 11+ programme is declining, then slacklining might offer an alternative approach to reach the training goals of improved sensorimotor control.  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   

Superior short-term learning effect of visual and sensory organisation ability when sensory information is unreliable in adolescent rhythmic gymnasts     

Hui-Ya Chen  Hsiao-Yun Chang  Yan-Ying Ju  Hung-Ting Tsao 《Journal of sports sciences》2017,35(12):1197-1203

Rhythmic gymnasts specialise in dynamic balance under sensory conditions of numerous somatosensory, visual, and vestibular stimulations. This study investigated whether adolescent rhythmic gymnasts are superior to peers in Sensory Organisation test (SOT) performance, which quantifies the ability to maintain standing balance in six sensory conditions, and explored whether they plateaued faster during familiarisation with the SOT. Three and six sessions of SOTs were administered to 15 female rhythmic gymnasts (15.0 ± 1.8 years) and matched peers (15.1 ± 2.1 years), respectively. The gymnasts were superior to their peers in terms of fitness measures, and their performance was better in the SOT equilibrium score when visual information was unreliable. The SOT learning effects were shown in more challenging sensory conditions between Sessions 1 and 2 and were equivalent in both groups; however, over time, the gymnasts gained marginally significant better visual ability and relied less on visual sense when unreliable. In conclusion, adolescent rhythmic gymnasts have generally the same sensory organisation ability and learning rates as their peers. However, when visual information is unreliable, they have superior sensory organisation ability and learn faster to rely less on visual sense.  相似文献   

A knock to the system: A new sociotechnical systems approach to sport-related concussion     

Amanda Clacy  Natassia Goode  Rachael Sharman  Geoff P. Lovell  Paul M. Salmon 《Journal of sports sciences》2017,35(22):2232-2239

Broader contextual factors that influence concussion management have tended to be overlooked. To address this, the present study used a sociotechnical systems approach to identify perceived responsibilities and applied strategies for three domains of concussion management (i.e., prevention, identification and treatment). Participants were 118 members of the community rugby union system in Australia (69.2% male). Participants from throughout the rugby system (e.g., players, parents, coaches, club management) were asked open-ended questions about their perceived responsibilities and the strategies they use for concussion management. It was found that (a) proper training, technique correction and education were recurrent prevention themes; (b) the majority of key stakeholders felt that they could consistently identify concussion; however, medical aids (medics) were the only system actors who stated a responsibility to use standardised concussion assessment measures and (c) less than one third of the respondents indicated their involvement in treating concussion. This study identifies specific junctures in the system that prevents effective concussion management strategies. A sociotechnical systems approach improves the understanding of concussion prevention, and management beliefs and behaviours.  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   

略论学校教育与青少年犯罪预防   总被引：1，自引：0，他引：1  

杨胜 《荆门职业技术学院学报》2007,22(10):71-73

本文简要分析了青少年犯罪特点、犯罪心理以及青少年犯罪在学校教育方面存在的原因。重点阐述了如何完善和改进学校教育,充分发挥学校教育在预防和减少青少年犯罪中的作用。  相似文献   

体力活动与健康:研究及应用   总被引：2，自引：0，他引：2  

王香生  黄雅君 《体育与科学》2008,29(6)

规律性体力活动对健康的益处已经被既往的研究所证实。多种慢性疾病,包括心脏病、2型糖尿病、高血压、中风、肥胖、骨质疏松以及某些癌症的发病都与缺乏规律性的体力活动有关。权威机构已明确提出了关于体力活动的参与指引。大量的研究致力于体力活动干预措施的制定。本文总结了体力活动与健康的研究证据、体力活动在人群中的评价、以及体力活动干预研究的进展,为中国下一步相关研究的开展提供借鉴。  相似文献