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1.
M.R. Yeadon 《Journal of sports sciences》2013,31(3):209-218
A simulation model and a rigid body model are used to evaluate aerial twisting techniques. It is found that when somersault is not present, a number of cycles of segment counter‐rotation are required to produce one twist. When somersault is present, twist may be introduced by producing tilt using asymmetrical movements of the arms, chest or hips about the sagittal plane. The same asymmetrical movements may be used to remove tilt, although the effectiveness of these techniques is dependent upon body configuration and the direction of somersault. 相似文献
2.
This paper introduces the first stage of a new model-based approach to three-dimensional (3D) human movement tracking. A ‘generate-and-test’
matching procedure was adopted by matching rendered images of a 3D computer graphics model of the human body to target images
of rigid body motion. The set of pixels to be compared were just those corresponding to the model of the body in the rendered
images. The matching criterion to optimize model position and orientation was based on the minimisation of the RGB (red-green-blue)
colour difference between generated model images and associated target images. The method was able to track synthetic image
sequences of a half twisting somersault accurately with root-mean-square (rms) errors of less than 5 mm and 0.3∘ for position
and orientation estimates respectively. The suitability of the proposed approach for rigid body motion tracking was supported
by additional tracking experiments on video image sequences of ‘wooden cross’ trajectories. Comparisons of tracked estimates
against manual digitizing estimates returned relatively small rms difference values on both side somersault and twisting somersault
movements. The proposed approach has the potential to track video images of a human torso using a rigid body model and hence
to track articulated movements by successively adding segments to the model in a hierarchical manner. 相似文献
3.
Pui W. Kong 《Journal of sports sciences》2013,31(5):537-543
Abstract A modelling approach was used in the present study to investigate the role of the hip muscles during the come-out of forward and inward multiple somersaulting dives in a pike position. A planar two-segment model was used to simulate the somersault and come-out of three commonly performed dives from a 3-m springboard: forward two-and-one-half somersault pike dive (105B), forward three-and-one-half somersault pike dive (107B), and inward two-and-one-half somersault pike dive (405B). Three simulations were run for each dive: (1) hip angle was constrained to be constant, (2) hip torque was removed after 0.1 s, and (3) hip angle was constrained to a typical come-out time history used by elite divers. Simulation results indicated that hip flexion torque was required both to maintain a rigid pike position during somersault (range = 205.5–282.3 Nm) and to control the hip extension movement during the come-out (peak torque range = 355.8–548.1 Nm) in forward and inward multiple somersaulting dives. Coaches and divers should be aware that dry-land exercise drills producing hip extension movement by concentric actions of the hip extensor muscles do not replicate the neuromuscular control during the come-out of fast rotating dives. 相似文献
4.
Jemin Kim Margaret A. Wilson Kunal Singhal Sarah Gamblin Cha-Young Suh 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(3):215-229
The purpose of this study was to investigate the vertical angular momentum generation strategies used by skilled ballet dancers in pirouette en dehors. Select kinematic parameters of the pirouette preparation (stance depth, vertical center-of-mass motion range, initial shoulder line position, shoulder line angular displacement, and maximum trunk twist angle) along with vertical angular momentum parameters during the turn (maximum momentums of the whole body and body parts, and duration and rate of generation) were obtained from nine skilled collegiate ballet dancers through a three-dimensional motion analysis and compared among three turn conditions (single, double, and triple). A one-way (‘turn’) multivariate analysis of variance of the kinematic parameters and angular momentum parameters of the whole body and a two-way analysis of variance (‘turn’ × ‘body’) of the maximum angular momentums of the body parts were conducted. Significant ‘turn’ effects were observed in the kinematic/angular momentum parameters (both the preparation and the turn) (p < 0.05). As the number of turns increased, skilled dancers generated larger vertical angular momentums by predominantly increasing the rate of momentum generation using rotation of the upper trunk and arms. The trail (closing) arm showed the largest contribution to whole-body angular momentum followed by the lead arm. 相似文献
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6.
Alison Sheets 《Sports Engineering》2007,10(4):209-219
A gymnast can balance after an uneven parallel bar dismount by contacting the ground with an appropriate body position and
angular velocity. Balanceable gymnastics landings were predicted by dividing landing into two parts: a short duration impact
phase when foot-mat contact forces are high, and a subsequent longer balancing phase during which the gymnast exerts active
control at the joints to attenuate the resulting post-impact velocities and achieve a desired motionless terminal configuration.
This paper identifies controllable sets of pre-impact landing positions and velocities for a typical female collegiate gymnast
that are feasible targets for the end of flight following a single- and double-backward somersault uneven bar dismount with
forward mass centre (CM) velocity. Simple algebraic impulse-momentum models for the impact phase determine impulses necessary
to stop the feet and slow angular velocity. After impact, a dynamic analysis is needed to determine stability because non-negligible
post-impact angular and linear velocities are possible. For almost all successfully balanced landings, ground contact occurs
with the CM positioned above the feet and between the toe and heel, because the linear impact impulses that stop the feet
also contribute to an angular impulse that slows angular momentum. Only at the largest pre-impact angular velocities following
a double-somersault dismount can contact occur with the CM in front of the toe. The gymnast is in balanceable preimpact orientations
longer when rotating more slowly and with a smaller angular momentum; therefore balance may be more likely after performing
a single-somersault dismount with a large moment of inertia. 相似文献
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9.
运动生物力学分析、对比分析、文献资料等方法,对我国优秀男子蹦床运动员陆春龙与董栋813〈空中技术进行研究。研究发现813〈,屈体姿势形成是在第一个180°转体后,当翻转360°时身体迅速打开,展体结束时腾空高度接近最高高度,随后翻转和转体同时进行转体的速度比翻转的速度快,第一个180°转体动量距来自双臂急剧摆动产生,后面540°转体动量距来髋关节的屈伸产生。 相似文献
10.
《European Journal of Sport Science》2013,13(6):563-568
AbstractRecent literature has related differences in pelvis–trunk coordination to low back pain (LBP) status. In addition, repetitive motions involving bending and twisting have been linked to high incidence of LBP. The purpose of this study was to examine trunk sagittal motion – axial rotation (‘bend and twist’) coordination during locomotion in three groups of runners classified by LBP status (LBP: current low back pain; RES: resolved low back pain and CTR: control group with no history of LBP). Trunk kinematic data were collected as running speed was systematically increased on a treadmill. Within-segment coordination between trunk sagittal and transverse planes of motion (trunk lean and axial rotation, respectively) was calculated using continuous relative phase (CRP), and coordination variability was defined as the between stride cycle standard deviation of CRP (CRPvar). Bend–twist coordination was more in-phase for the LBP group than CTR (p = 0.010) regardless of running speed. No differences in CRPvar were found between the groups. The results from our coordination (CRP) analysis were sensitive to LBP status and suggest that multi-plane interactions of the trunk should be considered in the assessment of LBP. This analysis also has potential for athletically oriented tasks that involve multi-plane interactions of the trunk, particularly ones that contain asymmetric action, such as sweep rowing or a shot on goal in field hockey or ice hockey. 相似文献
11.
David Zahradnik Daniel Jandacka Gabriela Beinhauerova Joseph Hamill 《Journal of sports sciences》2020,38(20):2367-2373
ABSTRACT The lateral tilt of the arms accompanied by trunk lateral tilt is a typical blocking manoeuvre in volleyball. However, during this unanticipated blocking movement, an associated risk of ACL injury may result. The aim of the present study was to compare associative ACL risk factors at the initial contact and the first and second peak of VGRF during an unanticipated blocking movement with different arm positions. Synchronized kinematic and kinetic data were collected for each trial of each condition. Student paired t-tests and effect size were used to determine differences between two conditions (S – with arms straight up from the body) and (T – with the arms and trunk laterally tilted). The results showed that the T condition significantly decreases knee flexion, increases VGRF at the foot contact, first peak force and increases the valgus moment at the first peak force. The values of the associated risk factors for a non-contact ACL injury appear to be related to the tilted arm position accompanied by trunk tilt towards to right lower limb during landing. The players should be taught to land with greater knee flexion and, if possible, a double-leg landing to decrease right lower limb loading during the blocking manoeuvre. 相似文献
12.
蹦床前屈三周转体540度动作的跟踪诊断 总被引：4，自引：3，他引：1
应用摄像电脑分析诊断等运动生物力学手段,为提高国家队重点运动员叶帅前屈三周转体540度动作的准确性和稳定性,提供技术诊断科技服务。结果表明:增加腾空高度,准确把握团身和展体时机,加快前半程空翻和转体速度,提高了动作质量和成功率。 相似文献
13.
Bethany Shifflett Carl Timm Leamor Kahanov 《Research quarterly for exercise and sport》2013,84(3):357-362
Abstract The electrogoniometer was used to study locomotion and some athletic movements. Motion patterns for the knee and ankle joint were established for walking and running on the horizontal and for walking up and downhill. Changing the inclination of the walking surface produced alterations of the knee and ankle goniograms which were consistent with body mechanics necessary to adjust to the respective grades. Knee and ankle goniograms are presented for the back handspring, front somersault, and back somersault. An electrogoniometer was waterproofed and used to obtain goniograms during the performance of three swimming strokes. Goniograms are also presented for throwing a baseball and putting the shot. 相似文献
14.
Ian Harris Sujae Michael Koh 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):72-87
The aims of this study were to gain insights on sepaktakraw serves, identify technique differences, and establish factors influencing ball speeds. The best successful kuda and sila serves of nine elite male national sepaktakraw players were captured using seven ProReflex 1000 optical cameras operating at 240 Hz. The kuda and sila serves are non-planar kicking techniques exhibiting a non proximal-to-distal sequence. Differences in kicking kinematics (P < 0.05) signify differences between techniques. Compared with the sila, the kuda kicking limb is a longer rigid segment that moves over a greater range of motion. Together with a greater increase in foot and shank angular accelerations approaching ball contact, this leads to marginally higher kuda foot impact speeds. Since foot speeds were not at their peak during impact, a longer rigid kuda kicking limb was the primary determinant of kuda ball release speeds. Greater range of motion enables the longer rigid kuda lever to generate greater kicking angular momentum, resulting in greater impact impulse. This immediately translated to the significantly higher ball release speeds based on the impulse–momentum relationship. Coaching implications include improving hip joint flexibility and working on a fluid movement of a longer rigid segment kicking technique. 相似文献
15.
Edvard Kolar Katarina Andlovic Kolar Stanko Štuhec 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):69-78
Abstract The aim of our research was to study the relationships between performance variables in a support backward swing (SBS), which was used as a progressive step in the learning procedure for a 1#fr1/4> straddle‐piked front somersault and the swing prior to a 1#fr1/4> straddle‐piked front somersault from support to bent arm support on the parallel bars (5/4S). Mitja Petkov?ek, parallel bars gold medallist at the 2000 EC in Bremen, performed these elements. Kinematic analysis involved CMAS software (Praha, 1993), and the Suskana body segment model that has 17 points and 15 segments. Kinetic variables were estimated using 2D IMGIM software, which has 8 points and 6 segments (Colja and ?uk, 1994). The results indicated that some kinematic aspects of the two types of swings were similar but there were important differences in kinetic aspects of the motion. During the swing for the 5/4S, force and torque were higher than in the SBS. 相似文献
16.
Isabelle Rogowski Thomas Creveaux Laurence Chèze Raphaël Dumas 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):166-175
Scapular dyskinesis is recognized as an abnormality in the kinetic chain; yet, there has been little research quantifying scapular motion during sport tasks. Tennis forehand drives of eight highly skilled tennis players were studied to assess the scapulothoracic kinematics and evaluate repeatability using video-based motion analysis. Scapulothoracic downward/upward rotation, posterior/anterior tilt, and internal/external rotation were computed using an acromial marker cluster. On average, the upward rotation, anterior tilt, and internal rotation varied from 1° to 26°, from 7° to 32°, and from 42° to 100°, respectively, during the tennis forehand drive. During the backswing and forward swing phases of the forehand stroke, small changes were observed for the three scapular angle values, while all angles increased rapidly during the follow-through phase. This suggests that the tennis forehand drive may contribute to scapula dyskinesis, mainly due to the great amplitude in scapulothoracic anterior tilt and internal rotation observed during the follow-through phase. Knowledge of normal scapula motion during sport tasks performed at high velocity could improve the understanding of various sport-specific adaptations and pathologies. 相似文献
17.
Abstract High ground reaction forces during the front foot contact phase of the bowling action are believed to be a major contributor to the high prevalence of lumbar stress fractures in fast bowlers. This study aimed to investigate the influence of front leg technique on peak ground reaction forces during the delivery stride. Three-dimensional kinematic data and ground reaction forces during the front foot contact phase were captured for 20 elite male fast bowlers. Eight kinematic parameters were determined for each performance, describing run-up speed and front leg technique, in addition to peak force and time to peak force in the vertical and horizontal directions. There were substantial variations between bowlers in both peak forces (vertical 6.7 ± 1.4 body weights; horizontal (braking) 4.5 ± 0.8 body weights) and times to peak force (vertical 0.03 ± 0.01 s; horizontal 0.03 ± 0.01 s). These differences were found to be linked to the orientation of the front leg at the instant of front foot contact. In particular, a larger plant angle and a heel strike technique were associated with lower peak forces and longer times to peak force during the front foot contact phase, which may help reduce the likelihood of lower back injuries. 相似文献
18.
Abstract The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles. 相似文献
19.
蹦床网上男子单人两周类空翻基本难度动作连接技术运动学特征的研究 总被引：7，自引：0，他引：7
刘海元 《西安体育学院学报》2002,19(1):76-79
主要采用影片解析法 ,以我国蹦床集训队中 2名优秀运动员为研究对象 ,对网上两周类空翻基本难度动作连接技术运动学特征的分析。得出在入网时 ,采用全脚掌入网 ;压网阶段膝关节先缓冲或保持一定角度然后再蹬伸 ,而踝关节却处于缓冲状态 ;离网阶段膝关节和踝关节的变化与连接空翻的方向不同而不同。在连接过程中 ,身体重心在垂直方向上的位移远远大于水平方向上的位移 ,重心基本呈垂直上下运动。 相似文献
20.
Abstract Theories causing rotation of the body in diving were critically reviewed and a statement relating angular momentum to both the angle of lean and the angle of force was presented. Equations were developed by which the partition of energy between rotation and translation could be computed. 相似文献