Postural balance and rifle stability in a standing shooting position after specific physical effort in biathletes     

Dorota Sadowska  Justyna Krzepota  Andrzej Klusiewicz 《Journal of sports sciences》2019,37(16):1892-1898

The aim of the study was to evaluate the effect of maximal specific physical effort on postural balance and rifle stability in biathletes in a standing shooting position. The study included 10 junior elite biathletes. The measurements were taken with the Vicon system and AMTI force platform. Postural balance and rifle stability characteristics were determined at rest as well as 1 and 5 min post maximal specific physical effort which was performed on a ski ergometer and continued until exhaustion. Maximal physical effort exerted a significant effect on all examined postural sway and rifle sway characteristics. The duration of the post-exercise changes was longer than 5 minutes. Higher post-effort rifle sway was observed in the vertical direction than in the across the shooting line direction. Post-effort postural balance impairment in the shooting line was much greater than in the across the shooting line direction. Moreover, a strong correlation was found between postural balance and rifle stability. Maximal physical effort influenced postural balance and rifle stability during aiming. Rifle sway during aiming in a standing shooting position seems to be coordinated with the postural sway of the biathlete’s body. Thus, an increase in postural sway contributes to greater sway and lesser stability of the rifle.  相似文献   

上肢康复机器人主动康复训练控制策略     

刘鹏  葛小青  李宇  赵佳欣 《中国科学院大学学报》2019,36(4):570-576

近年来，脑卒中和交通事故造成上肢损伤的人数逐年上升，医疗领域对康复器械的需求越来越大。为满足实际需求，开发以气动人工肌肉为驱动器的4自由度（肩关节外收/内展（被动）、前驱/后伸、肘关节屈曲、腕关节屈曲）可穿戴上肢康复机器人。首先设计上肢康复机器人的结构，并采用气动人工肌肉作为肘关节与腕关节的驱动器。然后针对该上肢康复机器人，研究主动康复训练控制策略，设计两种控制策略。通过穿戴实验验证控制策略的有效性和实际应用价值。  相似文献   

Novel mathematical model to estimate ball impact force in soccer     

Takahito Iga  Hiroyuki Nunome  Shinya Sano  Nahoko Sato  Yasuo Ikegami 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(4):477-493

To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of ‘footballer’s ankle’. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.  相似文献   

Accuracy and precision of loadsol® insole force-sensors for the quantification of ground reaction force-based biomechanical running parameters     

Wolfgang Seiberl  Elisabeth Jensen  Josephine Merker  Marco Leitel  Ansgar Schwirtz 《European Journal of Sport Science》2018,18(8):1100-1109

Force plates represent the “gold standard” in measuring running kinetics to predict performance or to identify the sources of running-related injuries. As these measurements are generally limited to laboratory analyses, wireless high-quality sensors for measuring in the field are needed. This work analysed the accuracy and precision of a new wireless insole forcesensor for quantifying running-related kinetic parameters. Vertical ground reaction force (GRF) was simultaneously measured with pit-mounted force plates (1?kHz) and loadsol^® sensors (100?Hz) under unshod forefoot and rearfoot running-step conditions. GRF data collections were repeated four times, each separated by 30 min treadmill running, to test influence of extended use. A repeated-measures ANOVA was used to identify differences between measurement devices. Additionally, mean bias and Bland–Altman limits of agreement (LoA) were calculated. We found a significant difference (p?® devices for these parameters. For these same parameters, the LoA analysis showed that 95% of all measurement differences between insole and force plate measurements were less than 12%, demonstrating high precision of the sensors. However, highly dynamic behaviour of GRF, such as force rate, is not yet sufficiently resolved by the insole devices, which is likely explained by the low sampling rate.  相似文献   

以社区为驱动力实现全民健康的研究     

胡振飞  曾凡鑫 《体育科技文献通报》2020,(6):115-116,127

以社区为驱动力实现全民健康的研究是一条社区推动全面小康之路,最终目的是解决国民健康面临的现实困境,促进健康中国战略的实施。文章通过文献资料法、逻辑分析法等研究方法,从社区对全民健康计划实施的意义着手,较为全面、系统的分析了社区在全民健康目标实现过程中的作用、价值及内在联系,并提出:以卫生服务管理为突破口,构建新型卫生健康管理服务模式;以社区为单位,提升国民健康素养水平;以环境治理为基点,优化社区环境质量;以国家战略为引领,发展社区健康产业等路径,助推全民健康目标的实现进度。  相似文献   

从“文斗”到“武斗”:礼法约束下“斗秧歌”田野调查     

滕希望  郭玉成 《上海体育学院学报》2020,(3):73-83

以海阳大秧歌中的民俗武术活动“斗秧歌”仪式为个案,运用田野调查等方法,从民俗学视角对“斗秧歌”的过程及民俗语境进行分析。认为:海阳大秧歌吸收了军事武术中的兵法谋略与民间武术技术动作,族群生存斗争与比武较技是“斗秧歌”吸收武术元素的重要动因,其逻辑形式表现为礼法约束下由“文斗”到“武斗”的递进,“文斗”体现兵法谋略智慧,武术是“武斗”的主要支撑力量。“斗秧歌”受到礼法约束,以强化乡间社会秩序的稳定,反映了中国传统社会治理中的礼法并施思想。剖析其民俗语境发现,“斗秧歌”是族群生存抗争的仪式手段、护卫生存环境的民间演习、展示个人魅力的艺术舞台,也是地域武术传播的民俗载体。武术与“斗秧歌”之间的融合互动关系,显示武术与民俗活动深厚的历史渊源及武术具有的多元价值属性。  相似文献   

《反兴奋剂运动员权利规则》审思          下载免费PDF全文

裘韵 《体育科研》2020,(2):45-53

《反兴奋剂运动员权利规则》是由世界反兴奋剂机构下属的运动员委员会制定,执行委员会批准通过的首个明确规定运动员在反兴奋剂活动中权利的文件。作为运动员参与反兴奋剂活动的基础,该文件的制定与修订争议不断,多集中于文件名称、法律地位及其内容中不具有强制执行力的部分。在体育组织的干预下,起草者修改了文件的名称并澄清“这不是一份法律文件”,使该文件的意义与价值存疑。建议在日后的修订中慎重考虑文件名称的匹配性,在厘清该文件与《世界反兴奋剂条例》及国际标准关系的基础上,赋予其法律效力或给予象征性法律规则的地位,完善对受侵犯权利救济的指引,加快建立申诉处理机制。  相似文献   

Hip joint kinetics in the table tennis topspin forehand: relationship to racket velocity     

Yoichi Iino 《Journal of sports sciences》2018,36(7):834-842

The purpose of this study was to determine hip joint kinetics during a table tennis topspin forehand, and to investigate the relationship between the relevant kinematic and kinetic variables and the racket horizontal and vertical velocities at ball impact. Eighteen male advanced table tennis players hit cross-court topspin forehands against backspin balls. The hip joint torque and force components around the pelvis coordinate system were determined using inverse dynamics. Furthermore, the work done on the pelvis by these components was also determined. The peak pelvis axial rotation velocity and the work done by the playing side hip pelvis axial rotation torque were positively related to the racket horizontal velocity at impact. The sum of the work done on the pelvis by the backward tilt torques and the upward joint forces was positively related to the racket vertical velocity at impact. The results suggest that the playing side hip pelvis axial rotation torque exertion is important for acquiring a high racket horizontal velocity at impact. The pelvis backward tilt torques and upward joint forces at both hip joints collectively contribute to the generation of the racket vertical velocity, and the mechanism for acquiring the vertical velocity may vary among players.  相似文献   

Effects of a contrast training programme on jumping,sprinting and agility performance of prepubertal basketball players     

Pedro Ángel Latorre Román  Francisco Javier Villar Macias  Felipe García Pinillos 《Journal of sports sciences》2018,36(7):802-808

The purpose of this study was to examine the effects of a 10 week contrast training (CT) programme (isometric + plyometric) on jumping, sprinting abilities and agility performance in prepubertal basketball players. Fifty-eight children from a basketball academy (age: 8.72 ± 0.97 years; body mass index: 17.22 ± 2.48 kg/m²) successfully completed the study. Participants were randomly assigned to experimental groups (EG, n = 30) and control groups (CG, n = 28). The CT programme was included in the experimental group’s training sessions – twice a week – as part of their usual weekly training regime. This programme included 3 exercises: 1 isometric and 2 plyometric. Jumping, sprinting and agility performance were assessed before and after the training programme. Significant differences were found in posttest between EG and CG in sprint and T-test: EG showed better results than CG. Furthermore, there were significant differences in posttest-pretest between EG and CG in squat jump, countermovement jump, drop jump, sprint and T-test with the EG showing better results than CG. The CT programme led to increases in vertical jump, sprint and agility levels, so that the authors suggest that prepubertal children exhibit high muscular strength trainability.  相似文献   

Biomechanical differences of arm swing countermovement jumps on sand and rigid surface performed by elite beach volleyball players     

George Giatsis  Vassilios Panoutsakopoulos  Iraklis A. Kollias 《Journal of sports sciences》2018,36(9):997-1008

The purpose of this study was to investigate the possible arm swing effect on the biomechanical parameters of vertical counter movement jump due to differences of the compliance of the take-off surface. Fifteen elite male beach-volleyball players (26.2 ± 5.9 years; 1.87 ± 0.05 m; 83.4 ± 6.0 kg; mean ± standard deviation, respectively) performed counter movement jumps on sand and on a rigid surface with and without an arm swing. Results showed significant (p < .05) surface effects on the jump height, the ankle joint angle at the lowest height of the body center of mass and the ankle angular velocity. Also, significant arm swing effects were found on jump height, maximum power output, temporal parameters, range of motion and angular velocity of the hip. These findings could be attributed to the instability of the sand, which resulted in reduced peak power output due to the differences of body configuration at the lowest body position and lower limb joints’ range of motion. The combined effect of the backward arm swing and the recoil of the sand that resulted in decreased resistance at ankle plantar flexion should be controlled at the preparation of selected jumping tasks in beach-volleyball.  相似文献