The continuous measurement of the springboard reaction force in gymnastic vaulting

A new method was established for the continuous measurement of force applied from a springboard to a gymnast in vaulting (board reaction force). Male gymnasts performed a handspring vault using a springboard mounted on force platforms. A high-speed video camera sampled the springboard motion at 500 Hz. The springboard was initially partitioned into 29 segments. The force due to the accelerative motion of the springboard was determined by summing the forces of the individual segments. The board reaction force acting on the gymnast was calculated by subtracting the force due to the accelerative motion of the springboard and weight from the force recorded by the force platform. The new method succeeded in illustrating transient changes of the board reaction force. The horizontal and vertical components of the peak values of the board reaction force were three and two times greater respectively than the average values. A series of tests was conducted to determine whether the number of segments of the springboard model could be reduced without affecting accuracy. A model consisting of only four segments produced almost the same accuracy as the 29-segment model. The simplified model is recommended as a more efficient method to measure board reaction force.     

德拉古莱斯库和陆斌跳马前手翻动作技术的分析与比较

运用三维DLT法，对2004仙桃国际体操精英邀请赛跳马冠军德拉古莱斯库和亚军陆斌的前手翻动作技术的速度指标、时间指标、高度和远度指标进行对比分析，得出陆斌在踏跳和推手环节上与德拉古莱斯库存在差异，并对该环节的技术细节进行了对比分析，找出问题所在，以期为陆斌以及我国跳马前手翻类动作的训练和技术改进提供参考依据。     

撑杆跳高支撑力测试装置的设计及动态特征分析

撑杆跳高运动插斗处动态力的测试受到多种因素的影响，分析测力平台在测试中的受力状态，指出装置的设计中应重点考虑装置的实用性，分析其刚性、质量及阻尼的影响，在最大限度简化结构的基础上提高其测试精度。     

Effects of load on ground reaction force and lower limb kinematics during concentric squats

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?·?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 (r ²) 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.     

德拉古勒斯库跳马前手翻团身前空翻2 周转体180°运动学分析

通过录像观察法和运动生物力学研究方法,分析揭示罗马尼亚优秀运动员德拉古勒斯库完成的跳马“前手翻团身前空翻2 周转体180°”动 作运动学规律和技术特点,为我国运动员发展该类型动作和科学指导运动训练提供了理论依据和技术参考。结果表明：德拉古勒斯库完成的跳 马“前手翻团身前空翻2 周转体180°”技术动作稳定,质量较高,技术成熟,符合运动生物力学原理,能起到示范和借鉴作用。     

Simultaneous measurement of back and front foot ground reaction forces during the same delivery stride of the fast-medium bowler

Six male cricket bowlers (mean - s x ¥ : age 23.5 - 1.3 years; height 1.83 - 0.04 m; body weight 826 - 20 N) performed their typical bowling action at a set of stumps positioned at standard pitch length (20.1 m). A specially designed force platform rig allowed the correct positioning of two force platforms to be achieved beneath an outdoor polyflex runway (0.017 m depth) for each player's delivery stride pattern. For the back foot, the peak vertical ground reaction force was 1.95 - 0.08 kN (2.37 - 0.14 BW) and the braking force was 0.77 - 0.12 kN (0.94 - 0.16 BW). For the front foot, the peak vertical force was 4.80 - 0.92 kN (5.75 - 0.98 BW) and the braking force was 2.93 - 0.56 kN (3.54 - 0.67 BW). The mean peak vertical loading rate for front foot contact was 205 - 52.8 kN·s -1 (249 - 64 BW·s -1 ) with mean values ranging from 81 to 446 kN·s -1 (98 to 540 BW·s-1). The range for back foot contact was much smaller, 25-70 kN·s -1 (30-85 BW·s -1 ), with a mean of 41.7 - 7.10 kN·s -1 (50.6 - 8.6 BW·s -1 ). Mean peak impact occurred 24 ms after touchdown for the back foot and 16 ms after touchdown for the front foot. At impact, mean peak loading rates were greater for the front foot at 246 kN·s -1 (298 BW·s -1 ), with a range of 80-483 kN·s -1 (98-534 BW·s -1 ), than for the back foot at 65 kN·s -1 (79 BW·s -1 ), with a range of 40-84 kN·s -1 (49-110 BW·s -1 ).     

Validation of a wireless shoe insole for ground reaction force measurement

Ground reaction force measurements are a fundamental element of kinetic analyses of locomotion, yet they are traditionally constrained to laboratory settings or stationary frames. This study assessed the validity and reliability of a new wireless in-shoe system (Novel Loadsol/Pedoped) for field-based ground reaction force measurement in hopping, walking, and running. Twenty participants bilaterally hopped on a force plate and walked (5 km/hr) and ran (10 km/hr) on an instrumented treadmill on two separate days while wearing the insoles. GRFs were recorded simultaneously on each respective system. Peak GRF in hopping and peak GRF, contact time (CT), and impulse (IMP) in walking and running were compared on a per-hop and step-by-step basis. In hopping, the insoles demonstrated excellent agreement with the force plate (ICC: 0.96). In walking and running, the insoles demonstrated good-to-excellent agreement with the treadmill across all measures (ICCs: 0.88–0.96) and were reliable across sessions (ICCs within 0.00–0.03). A separate verification study with ten participants was conducted to assess a correction algorithm for further agreement improvement but demonstrated little meaningful change in systemic agreements. These results indicated that the Novel Loadsol system is a valid and reliable tool for wireless ground reaction force measurement in hopping, walking, and running.     

The influence of the vaulting table on the handspring front somersault

The traditional “horse” was replaced by a new vaulting “table” in artistic gymnastics competitions in 2001.The aim of this study was to determine whether the table led to a change in vaulting technique. This was achieved by comparing three-dimensional video-based analyses (50 Hz) of selected biomechanical discrete and continuous variables across four elite male gymnasts performing a series of handspring front somersault vaults on the traditional horse and the new table. Individual joint and inter-segment coupling (continuous relative phase) were used to quantify techniques used on the two apparatuses. Differences were attributed in part to the design and construction of the new table. No differences were observed for the approach and take-off from the board. Significant differences in hip flexion at board take-off and strike angle on the table were observed. One of the effects of the latter was an increase in vertical take-off velocity compared with the horse. Individual strategies were observed in hip and shoulder coordination patterns that were obscured when group data were considered. Close monitoring of the evolution of skill on this new apparatus is paramount for gymnastics coaching, and further studies of current elite competitive vaulting techniques are required.     

浅谈凌洁平衡木分腿后手翻的训练

分腿后手翻是体操世界冠军凌洁平衡木成套动作中的一个重要动作。通过总结该动作的训练经验得出 :平衡木分腿后手翻的技术要点是“蹬”和“撑” ;坚持运用有针对性的保护帮助手法可有效地建立正确动力定型 ;在训练过程中要掌握火候 ,由地面过渡到低木、再上高木循序渐进 ,惟此才会水到渠成。     

The biomechanical design of a training aid for a backward handspring in gymnastics

This study was carried out to design, construct and assess a training aid to assist in the learning of a backward handspring. A backward handspring is often the first backward dynamic skill gymnasts will learn and so its performance can be accompanied by anxiety. International high performance coaches were surveyed to establish the key coaching requirements of a backward handspring training aid. A video analysis of the skill was used to determine characteristic dimensions of the skill, and these were used in the design of the training aid. The aid was designed and manufactured in accordance with European Standards for safety. The device’s safety for use in supporting the backward handspring was confirmed through testing. The assessment of the training aid using 11 gymnasts showed that it permitted a safe dynamic performance; provided support; did not obstruct technically good performances; allowed progressive use by novices without additional coach support; and was adjustable for gymnasts of various size and ability. When assessed against other training aids, it was the only aid that fulfilled all of the key coaching requirements.     

当今世界男子跳马发展趋向的断想

采用录像跟踪与数理统计法 ,对’ 99世界体操锦标赛男子四个种类比赛中的跳马动作起评分与完成情况进行分析。结果表明 :运动员选择 10分起评动作呈集中化趋向。比赛中 ,努力完成高起评分动作并力求使完成情况少失分是运动员提高完成动作效能获取高分的直接思考点。跳马单项决赛中 ,跳“双 10分”起评动作 ,注重“保一争二”的训练策略是当今世界男子跳马夺牌或夺冠的必然选择。     

The relationship between inertial measurement unit-derived ‘force signatures’ and ground reaction forces during cricket pace bowling

Abstract

This study assessed the reliability and validity of segment measured accelerations in comparison to front foot contact (FFC) ground reaction force (GRF) during the delivery stride for cricket pace bowlers. Eleven recreational bowlers completed a 30-delivery bowling spell. Trunk- and tibia-mounted inertial measurement units (IMUs) were used to measure accelerations, converted to force, for comparisons to force plate GRF discrete measures. These measures included peak force, impulse and the continuous force–time curve in the vertical and braking (horizontal) planes. Reliability and validity was determined by intra-class correlation coefficients (ICC), coefficient of variation (CV), Bland–Altman plots, paired sample t-tests, Pearson’s correlation and one-dimensional (1D) statistical parametrical mapping (SPM). All ICC (0.90–0.98) and CV (4.23–7.41%) were acceptable, except for tibia-mounted IMU braking peak force (CV = 12.44%) and impulse (CV = 18.17%) and trunk vertical impulse (CV = 17.93%). Bland–Altman plots revealed wide limits of agreement between discrete IMU force signatures and force plate GRF. The 1D SPM outlined numerous significant (p < 0.01) differences between trunk- and tibia-located IMU-derived measures and force plate GRF traces in vertical and braking (horizontal) planes. The trunk- and tibia-mounted IMUs appeared to not represent the GRF experienced during pace bowling FFC when compared to a gold-standard force plate.     

对2003年全国体操锦标赛男子跳马比赛的情况分析研究

通过对2003年"东渡杯"全国体操锦标赛男子跳马比赛情况的技术统计、分析与研究,揭示了我国运动员在跳马项目上的长处,同时也指出了存在问题,尤其是与第37届世锦赛跳马前8名相比还有一定差距.因此,提出了几点积极建议,为教练员和运动员在训练中提供参考.     

The influence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists

The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev min -1 ) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.     

男生支撑跳跃项目中运动损伤与个性关系的研究

本文通过对学生个性特征的测试和在体操课支撑跳跃项目中损伤情况的调查,发现受伤组与对照组在Ｃ、H、Ｑ３和Ｑ４四个因素上存在显著性差异,表明该项目中的运动损伤与学生的个性特征关系密切,可为预防和减少运动损伤提供一定的参考。     

间歇训练理论在艺术体操训练中的运用

通过对国内外有关文献的分析研究，探讨了极强性间歇训练法、强化性间歇训练法和发展性间歇训练法在艺术体操身体训练和技术训练的运用方案及其训练方法设计的原则，旨在为我国艺术体操的科学训练提供参考。     

从2015年世界体操锦标赛探析中国体操现状

采用文献资料法、数理统计法,对2015年第46届世界体操锦标赛中国队各项成绩进行分析,结果表明:中国男队在团体项目和单项的吊环、双杠项目上有望夺冠,全能和自由体操有一定的实力,跳马、鞍马和单杠项目不具备夺牌的实力;中国女队在团体和高低杠项目上有望夺冠,自由体操和全能项目具备夺牌的实力,平衡木和跳马不具备夺牌的实力.     

技巧前手翻辅助练习器的研制和应用研究

采用献资料、实验研究、数理统计等方法，研究设计技巧前手翻辅助练习器。实验表明：该辅助练习器能有效地进行保护与帮助，有利于学生对技巧前后翻技术的理解和掌握，有利于减轻教师负担和提高教学效果，并符合学生生理、心理和运动技能形式规律，在技巧前手翻教学中具有一定的可行性和推广性。     

Effects of neuromuscular function and split step on reaction speed in simulated tennis response

Abstract

The purpose of this study was to examine whether split step (small hop before step) would be more beneficial than no-split condition in simulated tennis response situation. In addition, it was studied if movement time of the response is related to separately measured force production capabilities and reflex sensitivity of the players. Nine skilled male tennis players participated in this study. Subjects stood on a force plate and reacted to a light signal and moved to appointed direction as fast as possible. With split step the participants were 13.1% faster (P <0.05) than without split step from the start to the distal end of the so called close range movement continuum (2.70 m). This was mainly explained by 43.6% faster time (P <0.05) from the signal to the onset of force production. Greater vertical forces were observed with split step: 15.7% greater F(z) mean force (P <0.05), 60.0% greater F(z) peak force (P<0.01). In split step both mean (r= ? 0.813, P <0.01) and peak (r=?0.765, P <0.05) vertical forces (Fz) correlated negatively with the time from the onset of the force production to the photocell. With split step higher EMGs were observed in muscles responsible for ankle joint movement indicating that different strategies were used. Due to the split step the players were able to start the movement faster which mostly explains the advantages over the no-split step condition. Split step condition may also benefit from stretch shortening type of muscle action.     

程序教学法在技巧踺子小翻连接技术教学中运用效果探讨

采用对照实验法,对技巧踺子小翻连接技术教学进行程序教学法与传统教学法的比较研究。结果证明：程序教学法在该技术教学中,符合体育系学生体操基础水平与学习能力,能从技术上保证该技术的合理分解,教学上符合复杂技术教学中的人体条件反射原理,教学结果优于传统教学法。建议在体操其他复杂技术教学中广泛采用程序教学法。