共查询到20条相似文献，搜索用时 633 毫秒
1.
Vassilios Gourgoulis Nickos Aggelousis Giorgos Mavromatis Athanasios Garas 《Journal of sports sciences》2013,31(8):643-652
We investigated the linear kinematics and the change in energy of the barbell and the angular kinematics of the trunk and leg during the snatch technique of 12 elite male Greek weightlifters under competitive conditions after the new weight classification. Two S-VHS cameras operating at 60 Hz were used to record the lifts. The spatial coordinates of selected points were calculated using the direct linear transformation procedure; after digital filtering of the raw data, the angular displacements and angular velocities were calculated for the hip, knee and ankle joints. The following variables were also calculated for the barbell: vertical and horizontal displacement, vertical linear velocity and acceleration, external mechanical work and power output. The results revealed that all weightlifters flexed their knees during the transition phase, independently of their weight category. This indicates that the athletes use the elastic energy produced during the stretch–shortening cycle to enhance their performance. In nine athletes, we found that the barbell trajectory did not cross a vertical reference line that passed through the initial position of the barbell. The vertical linear velocity of the barbell was increased continuously from the beginning of the movement until the second maximum extension of the knee joint, with no notable dip being observed. Regarding the change in energy of the barbell, we found that the mechanical work for the vertical displacement of the barbell in the first pull was significantly greater than the mechanical work in the second pull. In contrast, the estimated average mechanical power output of the athletes during the vertical displacement of the barbell was significantly greater in the second pull than in the first pull. We conclude that the major elements of the snatch technique of elite Greek weightlifters have not been aff ected by the new weight classification. 相似文献
2.
3.
Sezgin Korkmaz 《Journal of sports sciences》2016,34(11):1088-1093
The strength and technical competence of junior female lifters play a decisive role not only for their current but also adulthood performance. The objective of this study was to investigate the three-dimensional kinematics of the snatch technique in junior female weightlifters. Ten elite junior female weightlifters participated in the study. Two cameras operating at 50 fields per second were used to record the lifts. The heaviest successful lifts were selected for the kinematic analysis. The kinematical data were obtained using a motion analysis system. The duration of the first pull was significantly longer than that of the other phases (P < 0.05). Maximum extension angle and velocity of the lower limb joints were significantly greater in the second pull (P < 0.05). The greatest extension angle was found in the knee joint during the first pull, while the greatest extension angle was observed in the hip joint during the second pull (P < 0.05). Maximum extension velocity of the knee and hip joints was significantly greater than that of the ankle in both phases (P < 0.05). In addition, the vertical velocity of the barbell and the absolute and relative power outputs was significantly higher in the second pull than in the first pull (P < 0.05). In the snatch lifting of junior female weightlifters, the angular kinematics of lower limb joints, the linear kinematics and trajectory of the barbell and other energy characteristics are similar to and consistent with the values reported in literature for adult female weightlifters. 相似文献
4.
The purpose of this study was to determine the association between weightlifting performance and vertical barbell acceleration patterns. Barbell kinematic time-series data were tracked from 18 snatches from six weightlifters during a regional weightlifting competition. These data were used to calculate vertical barbell accelerations. Time-series data were normalised to 100% of lift phase, defined as the time interval between barbell lift-off and maximum height of the barbell during each snatch lift. The time-series data were then entered into a pattern recognition algorithm that extracted principal patterns and calculated principal pattern scores. Body mass-normalised lift weight, which was used to quantify weightlifting performance, was significantly correlated (r = 0.673; P = 0.033) with a pattern that captured a difference in peak vertical barbell acceleration between the transition and the second pull phase. This correlation indicated that barbell acceleration profiles of higher weight snatch lifts were characterised by smaller decreases in acceleration during the second knee bend and smaller peak acceleration during the second pull phase. Weightlifting coaches and sports scientist should monitor and track vertical acceleration of the barbell, with focus on acceleration profiles that limit (1) deceleration during the transition phase between the first and second pull and (2) peak acceleration during the second pull phase of the snatch. 相似文献
5.
举重抓举和下蹲翻运动学比较与用力特征分析 总被引：4，自引：0，他引：4
运用三维运动学的研究方法对参加2003年全国女子举重锦标赛的10名运动员的抓举和下蹲翻进行运动学分析并对力量的特点进行比较分析;运用逆向动力学方法对两种技术动作的主要关节的净力矩进行比较分析。结果表明,膝关节角度在提铃离地时刻有显著性的差异;对力量参数回归分析表明,运动员抓举杠铃重量的能力很大程度上取决于运动员所能够输出的最大功率,而运动员下蹲翻杠铃重量的能力很大程度上取决于运动员对杠铃的作用力的积累过程;对于抓举和下蹲翻动作髋关节净力矩分析表明,对于抓举,髋关节最大净力矩与对应此时刻的髋关节角度呈负相关,而对于下蹲翻,髋关节最大净力矩则与所试举的杠铃重量呈正相关。 相似文献
6.
Torstein E. Dæhlin Tron Krosshaug Loren Z. F. Chiu 《Journal of sports sciences》2018,36(19):2242-2249
The purpose of this research was to investigate how lower extremity work was distributed during the pull of cleans performed lifting the barbell to the minimum height required to receive it in a full squat (minimal height clean); or with maximum effort to elevate the barbell as high as possible and receiving it in either a full (maximal effort clean) or partial (power clean) squat. Eight weightlifters screened for proficient technique performed these clean variations at 80% of one repetition maximum. Work performed on the barbell and by the lower extremity net joint moments (NJM) was computed from marker trajectories and ground reaction forces. Total barbell work, lower extremity NJM work, knee extensor work, and knee joint excursion during the second pull was lower in the minimal height clean than the maximal effort and power cleans (P < 0.05). This research demonstrates that more knee extensor work is performed in the second pull of maximal effort and power cleans compared to the minimal height clean. The larger knee extensor work performed is due to larger knee joint excursion during the second pull of the maximal effort and power cleans, but not larger knee extensor NJM. 相似文献
7.
ABSTRACTThis study examined the weightlifting load effects on the lower extremity coordination pattern during a snatch pull movement. Twenty male elite weightlifters performed snatch trials in each of the three load conditions [light (30%), medium (65%) and heavy (90%) of their maximum weightlifting capacities]. Kinematic data for the transition, second pull and take-off phases of a snatch were collected at 200 Hz using an eight-camera motion capture system. Angle-angle plots and coupling angles were calculated for further analyses. The results indicate that participants utilised knee flexion control-strategy in light and medium load conditions during the transition phase, but not for in-phase strategy in heavy load condition. In the second pull phase, participants utilised concurrent ankle dorsiflexion and knee extension, followed by hip extension strategy. The heavy load condition exhibited the distinct coordination strategies before knee extension. In the take-off phase, light and medium load conditions appeared to use thigh-phase strategy (right ankle-knee: p = 0.788, left: p = 0.035, right knee-hip: p = 0.012, left: p = 0.017, right ankle-hip: p = 0.029, left: p = 0.011). This suggests that the heavy load condition requires the use of two-joint coordination patterns (in-phase or anti-phase) as compared to the other lighter load conditions. 相似文献
8.
Chiu LZ Schilling BK Fry AC Salem GJ 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(2):260-273
For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, nondeformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90-155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5-30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small (< 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre. 相似文献
9.
全国举重冠军伍超抓举154kg的技术特征分析 总被引：1，自引：0，他引：1
通过SIMI°Motion三维录像分析系统,对2011年全国举重冠军赛冠军伍超的抓举技术动作进行运动学分析,揭示其抓举154 kg的技术特征。结果显示:伍超的身体重心和杠铃重心距离较近,并在整个提铃过程中杠铃重心的垂直速度呈上升趋势;膝关节角、躯干角、髋关节角、杠铃中心点垂直速度随时间变化曲线符合抓举的技术特点;从整体上看,伍超的技术较为合理,且有较大的提升空间。 相似文献
10.
山东省优秀男子举重运动员抓举技术动作生物力学分析 总被引：2，自引：0，他引：2
根据定性与定量相结合的原则,采用摄像解析及三维测力相结合的方法,对山东省男子举重队6名运动员的抓举动作进行诊断和评价,为其改进技术动作,提高运动成绩提供参考依据.研究结果表明,抓举过程中杠铃中心点运动轨迹应尽可能成垂直直线向上,S型弧度要小,发力后杠铃应达到一定最大速度,部分优秀运动员下蹲时加速度大于自由落体加速度,杠铃上抛中心点与身高的比值应控制在70%左右.抓举过程中人体膝关节角度曲线成双峰,而髋关节角度曲线为单峰,髋关节不可过早打开,躯干也不可过早用力.抓举整个过程环环相扣,每个阶段的发挥对下一阶段均有重要影响,对抓举的技术分析应采用系统的思考方法. 相似文献
11.
12.
Loren Z. F. Chiu Brian K. Schilling Andrew C. Fry George J. Salem 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):260-273
For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, non-deformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90–155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5–30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small ( < 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre. 相似文献
13.
运用三维运动学研究方法,对参加2019年亚洲举重锦标赛暨东京奥运会资格赛的我国男子举重67kg公斤级优秀运动员谌利军与冯吕栋抓举技术进行对比分析。研究结果认为:提铃准备阶段,冯吕栋身体姿势更符合抓举中“近”的技术要求;总体上,冯吕栋伸膝提铃和引膝提铃阶段技术动作优于谌利军,谌利军发力和惯性上升及接铃阶段技术动作优于冯吕栋。谌利军抓举过程中主要存在伸膝提铃阶段髋关节打开过早,引膝提铃阶段膝关节回屈角度小以及整个抓举过程中杠铃重心左右偏移量过大的问题;冯吕栋主要存在发力和惯性上升阶段“两心”前后距离过大,杠铃相对于运动员水平运动幅度大,垂直运动幅度小以及接铃过程中杠铃下落距离长,下降速度过快的问题。建议谌利军加强膝关节主要屈伸肌群的力量训练以及进行身体左右侧力量平衡的评估;冯吕栋应掌握在发力和惯性上升阶段正确的用力方向,并改善接铃节奏。 相似文献
14.
Ray G. Burdett 《Research quarterly for exercise and sport》2013,84(3):193-197
Abstract The lifting techniques of 10 world-class weightlifters were compared to those of 26 skilled collegiate weightlifters while performing the first portion of the snatch, from the lift-off of the barbell to the catch of the barbell overhead with the body in a squatting position. Cinematography was used to measure the joint angles, position of the center of gravity of the body, and the position of the barbell. Results indicated that the world-class weightlifters raised the barbell to a relatively lower height, assumed more flexed positions at the hips and knees with a smaller angle between the shank and floor during certain stages of the lift, and lowered their bodies more rapidly during the squatting portion of the lift than the collegiate weightlifters. 相似文献
15.
我国优秀举重运动员体能模型研究 总被引：1，自引：0，他引：1
以我国优秀举重运动员为研究对象,通过文献资料调研和数理统计的等方法,建立我国优秀举重运动员体能模型(包括指标模型、权重模型、均值模型与评价体系)。结果表明,优秀举重运动员体能指标模型包括:肩宽、髂宽指数、克托莱指数、血睾酮、高抓、借力推、体前屈等7个指标;指标权重模型中,以高抓占有最大权重(0.52),髂宽指数所占权重最小(0.03);另外,不同重量级别之间,肩宽、克托莱指数、高抓、借力推4个指标的差异具有显著性,以重量级最大,中量级次之,轻量级最小。在我国优秀举重运动员体能模型评价体系中,虽然不同性别各重量级别各指标的单项评分标准各不相同,但对其综合评价时,各等级标准相差不大。 相似文献
16.
Kristof Kipp Carolyn Meinerz 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(2):272-282
Although the power clean is an almost ubiquitous exercise in the strength and conditioning setting, relatively little is known about the biomechanics of successful and unsuccessful power clean lift attempts. The purpose of this study was to determine biomechanical differences between successful and unsuccessful power clean lift attempts in male collegiate athletes. Fifteen male lacrosse players (Age: 20.1 ± 1.2; Height: 1.78 ± 0.07 m; Body mass: 80.4 ± 8.1 kg; Relative one-repetition maximum power clean: 1.25 ± 0.13 kg/kg) were videotaped during a lifting session that required the completion of maximal effort power cleans to establish a one-repetition maximum. The position of the barbell was digitised and used to calculate the displacement, velocity, acceleration, and acceleration vector of the barbell. The results revealed that unsuccessful attempts were characterised by differences during the second pull phase. Unsuccessful lifts exhibited greater peak forward barbell displacement, lower backward barbell velocities, and lower resultant acceleration angles during the second pull. Strength and conditioning coaches should therefore emphasise limited forward motion of the barbell during the second pull and instruct athletes to generate a more backward-directed force during the second pull in order to lift greater loads during testing and subsequent lifting sessions. 相似文献
17.
An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39-0.0057 × knee angle (degress), with goodness-of-fit value, r2 = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods. 相似文献
18.
Carlos Balsalobre-Fernández Gretchen Geiser John Krzyszkowski Kristof Kipp 《Journal of sports sciences》2020,38(6):710-716
ABSTRACTThe purpose of this study was to investigate the validity of a smartphone app to measure biomechanical barbell parameters during the snatch. Ten collegiate NCAA division I athletes performed two repetitions each at 40, 50, 60, 70, and 80% of their 1-repetition maximum snatch. Barbell motions were simultaneously recorded with a motion capture system and the smartphone app. The motion capture system recorded the 3-D position of a reflective marker attached to the end of the barbell while the smartphone app was used to record sagittal plane video and track the shape of the weight plate from which the barbell center was derived. Peak forward (PFD) and backward (PBD) displacements and peak vertical displacement (PVD) and velocity (PVV) were calculated from both sets of data. Significant, strong to very strong Pearson’s product-moment correlation coefficients between both systems were noted for all parameters (r = 0.729–0.902, all p < 0.001). Small significant biases between systems were observed for PVD (ES = 0.284, p < 0.001) and PFD (ES=0.340, p < 0.01), while trivial to small, non-significant biases were observed for PBD (ES = 0.143) and PVV (ES = –0.100). Collectively, the results suggest that the app can provide biomechanical data of barbell motions similar to a 3-D motion capture system. 相似文献
19.
Abstract An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39–0.0057 × knee angle (degress), with goodness-of-fit value, r 2 = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods. 相似文献
20.
The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1 +/- 0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67 +/- 0.20 to 3.21 +/- 0.29 times body weight and increased significantly as external load increased (P < 0.05). Bar linear velocity ranged from 0.54 +/- 0.11 to 2.50 +/- 0.50 m x s(-1) and decreased significantly with increasing external load (P < 0.05). Hip, knee and ankle angles at maximum ground reaction force were affected by external load (P < 0.05). The force-barbell velocity curves were fitted using linear models with coefficients (r2) ranging from 0.59 to 0.96. The results suggest that maximal force exertion during squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force-velocity relationship was linear and independent from the set of data used for its determination. 相似文献