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1.
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   

2.
Validation of portable 2D force binding systems for cross-country skiing   总被引：2，自引：2，他引：0  
The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anterior–posterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement reference systems that are currently used when skiing on snow. During sport-specific imitation jumps, differences in peak forces and impulses between the classic binding and the reference systems ranged from 8.0 to 19.9 % and were two to three times greater compared to differences between the skate binding and the reference systems (range ?5.9 to 5.5 %). However, high similarity coefficients were observed with both bindings (classic binding 0.990–0.996, skate binding 0.996–0.999) compared to the reference systems. Based on these results, the skate binding was shown to be fully valid for use in field measurements of skate skiing, whereas some improvements have to be performed in the construction and sensor placements for the classic binding (vertical as well as anterior–posterior force component).  相似文献   

3.
Vertical jump height is thought to provide a valuable index of muscular power, which is an important factor in sports performance and for assessing the mobility and functional capacity of injured or aged individuals. The purpose of the present study was to investigate the criterion validity of four popular devices for measuring vertical jump height. A belt mat, contact mat, portable force plate, and Vertec were compared to a criterion device, a laboratory force plate. Forty participants performed three maximal countermovement jumps on each device in a counterbalanced order, using block randomization. The criterion device presented the highest mean value (50.3 cm). The portable force plate and belt mat devices recorded similar jump height values to the criterion device (within 1 cm). The contact mat and Vertec devices recorded significantly lower values than the criterion device (P < 0.001). The mean difference ± limits of agreement were: belt mat -0.1 ± 5.5 cm, contact mat -11.7 ± 6.4 cm, portable force plate -0.8 ± 3.9 cm, and Vertec -2.4 ± 6.6 cm. In conclusion, the portable force plate and belt mat devices provided valid measures of vertical jump height, whereas the Vertec and contact mat devices did not.  相似文献   

4.
Abstract

The aims of this study were to: (1) assess the reliability of various kinetic and temporal variables for unilateral vertical, horizontal, and lateral countermovement jumps; (2) determine whether there are differences in vertical ground reaction force production between the three types of jumps; (3) quantify the magnitude of asymmetry between limbs for variables that were established as reliable in a healthy population and whether asymmetries were consistent across jumps of different direction; and (4) establish the best kinetic predictor(s) of jump performance in the vertical, horizontal, and lateral planes of motion. Thirty team sport athletes performed three trials of the various countermovement jumps on both legs on two separate occasions. Eccentric and concentric peak force and concentric peak power were the only variables with acceptable reliability (coefficient of variation = 3.3–15.1%; intra-class correlation coefficient = 0.70–0.96). Eccentric and concentric peak vertical ground reaction force (14–16%) and concentric peak power (45–51%) were significantly (P < 0.01) greater in the vertical countermovement jump than in the horizontal countermovement jump and lateral countermovement jump, but no significant difference was found between the latter two jumps. No significant leg asymmetries (–2.1% to 9.3%) were found in any of the kinetic variables but significant differences were observed in jump height and distance. The best single predictors of vertical countermovement jump, horizontal countermovement jump, and lateral countermovement jump performance were concentric peak vertical power/body weight (79%), horizontal concentric peak power/body weight (42.6%), and eccentric peak vertical ground reaction force/body weight (14.9%) respectively. These findings are discussed in relation to monitoring and developing direction-specific jump performance.  相似文献   

5.
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.  相似文献   

6.
为揭示下肢运动性疲劳对纵跳的动力学特征的影响,22名男性体育教育专业大学生志愿参加了实验。结果表明,随着下肢负荷时间的增加纵跳的垂直方向分力和冲量下降,而左右、前后方向分力和冲量增加,三个方向的力矩随负荷时间的延长而增加。  相似文献   

7.
Abstract

Researchers and clinicians have suggested that overuse injuries to the lower back and lower extremities of figure skaters may be associated with the repeated high impact forces sustained during jump landings. Our primary aim was to compare the vertical ground reaction forces (GRFs) in freestyle figure skaters (n = 26) and non-skaters (n = 18) for the same barefoot single leg landing on a force plate from a 20 cm platform. Compared with non-skaters, skaters exhibited a significantly greater normalised peak GRF (3.50 ± 0.47 × body weight for skaters vs. 3.13 ± 0.45 × body weight for non-skaters), significantly shorter time to peak GRF (81.21 ± 14.01 ms for skaters vs. 93.81 ± 16.49 ms for non-skaters), and significantly longer time to stabilisation (TTS) of the GRF (2.38 ± 0.07 s for skaters vs. 2.22 ± 0.07 s for non-skaters). Skaters also confined their centre of pressure (CoP) to a significantly smaller mediolateral (M–L) (25%) and anterior–posterior (A–P) (40%) range during the landing phase, with the position of the CoP located in the mid to forefoot region. The narrower and more forward position of the CoP in skaters may at least partially explain the greater peak GRF, shorter time to peak, and longer TTS. Training and/or equipment modification serve as potential targets to decrease peak GRF by distributing it over a longer time period. More comprehensive studies including electromyography and motion capture are needed to fully characterise the unique figure skater landing strategy.  相似文献   

8.
为探索肌内效贴贴扎小腿腓肠肌对纵跳动力学特征及小腿其他肌肉活动的影响,本文对10名国家二级及以上水平运动员进行无、有贴扎纵跳实验,每组5人随机进行纵跳实验,重复3次,选择最佳测试成绩进行对比分析。结果表明,肌内效贴能够提高纵跳高度（P＜0.01）,增加最大蹬伸力和最大缓冲力（P＜0.05）,对蹬伸时间和最大蹬伸力梯度也有影响（P＜0.05）;同时,在蹬伸阶段,肌内效贴贴扎使双腿内侧腓肠肌积分肌电（iEMG）和均方根振幅（RMS）增加（P＜0.05）,使一侧胫骨前肌iEMG和RMS减少（P＜0.05）。但在缓冲阶段,对小腿各肌肉IEMG和RMS均无显著性差异（P＞0.05）。可见,肌内效贴使部分纵跳动力学特征发生改变,对小腿内侧腓肠肌肌肉活动也有促进作用。  相似文献   

9.
Whilst previous research has highlighted significant relationships between golfers’ clubhead velocity (CHV) and their vertical jump height and maximum strength, these field-based protocols were unable to measure the actual vertical ground reaction force (vGRF) variables that may correlate to performance. The aim of this study was to investigate relationships between isometric mid-thigh pull (IMTP), countermovement jump (CMJ), squat jump (SJ) and drop jump (DJ) vGRF variables and CHV in highly skilled golfers. Twenty-seven male category 1 golfers performed IMTP, CMJ, SJ and DJ on a dual force platform. The vertical jumps were used to measure positive impulse during different stretch-shortening cycle velocities, with the IMTP assessing peak force (PF) and rate of force development (RFD). Clubhead velocity was measured using a TrackMan launch monitor at a golf driving range. Pearsons correlation coefficient analyses revealed significant relationships between peak CHV and CMJ positive impulse (r = 0.788, p < 0.001), SJ positive impulse (r = 0.692; p < 0.001), DJ positive impulse (r = 0.561, p < 0.01), PF (r = 0.482, p < 0.01), RFD from 0–150 ms (r = 0.343, p < 0.05) and RFD from 0–200 ms (r = 0.398, p < 0.05). The findings from this investigation indicate strong relationships between vertical ground reaction force variables and clubhead velocity.  相似文献   

10.
Skiing     
The purpose of the investigation was to study the relationship between thrust phase duration, ground reaction force, velocity increase after pole thrust and pole angles versus pole length during double poling in roller skiing. Seven male regional elite cross‐country skiers volunteered as subjects for the study. The subjects performed a maximal double pole thrust on roller skis with each of the three different pole lengths: ‘short’, self‐selected (normal) and ‘long’. The short and long poles were 7.5 cm shorter and 7.5 cm longer than the self‐selected pole length. The subjects made seven maximal pole thrusts with each pole length, which were randomly selected during 21 trials. For each trial the subjects accelerated from a 1.2 m high downhill slope attaining a speed of 3.92 m.s‐1 before making a maximal double pole thrust on a force plate placed at the bottom of the slope. The vertical (Fz), anterior‐posterior (Fy) and medio‐lateral (Fx) reaction forces of the left pole were measured by the force plate. The positions of the pole were recorded in 3‐D by an opto‐electronic system. Thrust phase duration, impulse, mean force, velocity increase after pole thrust and pole angles were calculated from the recorded data. Double poling with long poles produced a significantly larger propulsive anterior‐posterior reaction force impulse and velocity increase than normal (p < .05) and short poles (p < .05). This was in spite of a larger mean anterior‐posterior reaction force being produced with short poles. Thus, thrust phase duration was a primary factor in determining propulsive anterior‐posterior impulse. For the practitioner, the results can be useful in the selection of pole length when the aim is to increase thrust phase duration, anterior‐posterior force impulse and velocity.  相似文献   

11.
Anterior cruciate ligament (ACL) injuries commonly occur during jump-landing tasks when individuals’ attention is simultaneously allocated to other objects and tasks. The purpose of the current study was to investigate the effect of allocation of attention imposed by a secondary cognitive task on landing mechanics and jump performance. Thirty-eight recreational athletes performed a jump-landing task in three conditions: no counting, counting backward by 1 s from a randomly given number, and counting backward by 7 s from a randomly given number. Three-dimensional kinematics and ground reaction forces were collected and analysed. Participants demonstrated decreased knee flexion angles at initial contact (p = 0.001) for the counting by 1 s condition compared with the no counting condition. Participants also showed increased peak posterior and vertical ground reaction forces during the first 100 ms of landing (p ≤ 0.023) and decreased jump height (p < 0.001) for the counting by 1 s and counting by 7 s conditions compared with the no counting condition. Imposition of a simultaneous cognitive challenge resulted in landing mechanics associated with increased ACL loading and decreased jump performance. ACL injury risk screening protocols and injury prevention programmes may incorporate cognitive tasks into jump-landing tasks to better simulate sports environments.  相似文献   

12.
Progress in micro-electromechanical systems has turned inertial sensor units (IUs) into a suitable tool for vertical jumping evaluation. In total, 9 men and 8 women were recruited for this study. Three types of vertical jumping tests were evaluated in order to determine if the data provided by an IU placed at the lumbar spine could reliably assess jumping biomechanics and to examine the validity of the IU compared with force plate platform recordings. Robust correlation levels of the IU-based jumping biomechanical evaluation with respect to the force plate across the entire analysed jumping battery were found. In this sense, significant and extremely large correlations were found when raw data of both IU and force plate-derived normalised force–time curves were compared. Furthermore, significant and mainly moderate correlation levels were also found between both instruments when isolated resultant forces’ peak values of predefined jumping phases of each manoeuvre were analysed. However, Bland and Altman graphical representation demonstrated a systematic error in the distribution of the data points within the mean ±1.96 SD intervals. Using IUs, several biomechanical variables such as the resultant force–time curve patterns of the three different vertical jumps analysed were reliably measured.  相似文献   

13.
This study assessed the validity of a tri-axial accelerometer worn on the upper body to estimate peak forces during running and change-of-direction tasks. Seventeen participants completed four different running and change-of-direction tasks (0°, 45°, 90°, and 180°; five trials per condition). Peak crania-caudal and resultant acceleration was converted to force and compared against peak force plate ground reaction force (GRF) in two formats (raw and smoothed). The resultant smoothed (10 Hz) and crania-caudal raw (except 180°) accelerometer values were not significantly different to resultant and vertical GRF for all running and change-of-direction tasks, respectively. Resultant accelerometer measures showed no to strong significant correlations (r = 0.00–0.76) and moderate to large measurement errors (coefficient of variation [CV] = 11.7–23.9%). Crania-caudal accelerometer measures showed small to moderate correlations (r = ? 0.26 to 0.39) and moderate to large measurement errors (CV = 15.0–20.6%). Accelerometers, within integrated micro-technology tracking devices and worn on the upper body, can provide a relative measure of peak impact force experienced during running and two change-of-direction tasks (45° and 90°) provided that resultant smoothed values are used.  相似文献   

14.
ABSTRACT

The aims of the present study were to provide an in-depth comparison of inter-limb asymmetry and determine how consistently asymmetry favours the same limb during different vertical jump tests. Eighteen elite female under-17 soccer players conducted unilateral squat jumps (SJ), countermovement jumps (CMJ) and drop jumps (DJ) on a portable force platform, with jump height, peak force, concentric impulse and peak power as common metrics across tests. For the magnitude of asymmetry, concentric impulse was significantly greater during the SJ test compared to CMJ (p = 0.019) and DJ (p = 0.003). No other significant differences in magnitude were present. For the direction of asymmetry, Kappa coefficients revealed fair to substantial levels of agreement between the SJ and CMJ (Kappa = 0.35 to 0.61) tests, but only slight to fair levels of agreement between the SJ and DJ (Kappa = ?0.26 to 0.18) and CMJ and DJ (Kappa = ?0.13 to 0.26) tests. These results highlight that the mean asymmetry value may be a poor indicator of true variability of between-limb differences in healthy athletes. The direction of asymmetry may provide a useful monitoring tool for practitioners in healthy athletes, when no obvious between-limb deficit exists.  相似文献   

15.
This study examined the predictive ability of the medicine ball chest throw and vertical jump for muscular strength and power in adolescents. One hundred and ninety adolescents participated in this study. Participants performed trials of the medicine ball chest throw and vertical jump, with vertical jump peak power calculated via an estimation equation. One-repetition maximum and peak power for the chest press and leg press were assessed using pneumatic exercise machines. The medicine ball chest throw strongly correlated with chest press one-repetition maximum and peak power, while the vertical jump peak power strongly correlated with leg press one-repetition maximum and peak power. The predictive ability of medicine ball chest throw was better than vertical jump peak power for muscular strength and power when controlling for sex, age, height, weight, and maturation, and was not affected by involvement in sports. Results show good predictive ability of the medicine ball chest throw for muscular strength and power in adolescents, while predictable ability of vertical jump peak power is weakened when other factors are taken into account.  相似文献   

16.
Chronic elbow injuries from tumbling in female gymnastics present a serious problem for performers. This research examined how the biomechanical characteristics of impact loading and elbow kinematics and kinetics change as a function of technique selection. Seven international-level female gymnasts performed 10 trials of the round-off from a hurdle step to flic-flac with ‘parallel’ and ‘T-shape’ hand positions. Synchronized kinematic (3D-automated motion analysis system; 247 Hz) and kinetic (two force plates; 1,235 Hz) data were collected for each trial. Wilcoxon non-parametric test and effect-size statistics determined differences between the hand positions examined in this study. Significant differences (p < 0.05) and large effect sizes (ES>0.8) were observed for peak vertical ground reaction force (GRF), anterior–posterior GRF, resultant GRF, loading rates of these forces and elbow joint angles, and internal moments of force in sagittal, transverse, and frontal planes. In conclusion, the T-shape hand position reduces vertical, anterior–posterior, and resultant contact forces and has a decreased loading rate indicating a safer technique for the round-off. Significant differences observed in joint elbow moments highlighted that the T-shape position may prevent overloading of the joint complex and consequently reduce the potential for elbow injury.  相似文献   

17.
The aim of this study was to identify the anthropometric and physical prerequisites for high difficulty floor tumbling and vaulting. Twenty 8-14 year old female talent-selected gymnasts performed handstand push-offs, and single and multiple jumps on a portable Kistler force plate. The force curves were analysed using Kistler and Excel software to obtain peak displacement, peak take-off force, and power The gymnasts were also assessed for sprinting, with and without vaulting, and standing broad jump performances. Video footage from the vault take-off was analysed using Video Expert II software to obtain the horizontal and vertical take-off velocities. Each gymnast's best vault starting score, three best floor tumbling skills, and anthropometric characteristics were recorded. Statistical analysis included one-way analysis of variance (ANOVA) to examine the effect of age (8-10 years, 11-12 years, 13-14 years) on the performance measures and linear regression analysis with performance start score for vault or best floor tumbling score as the outcome variable. The best regression model for indicating vaulting talent had, as predictor variables, resultant velocity at take-off from the board, squat jump power, and average power during the last five jumps in the continuous bent-leg jump series. The best regression model for indicating floor tumbling ability had, as predictor variables, age, vault running velocity, and reduced ground contact time in a handstand push-off.  相似文献   

18.
运用摄像及三维力同步测试4种不同坡角的下坡跑,结果表明:下坡跑步长短于平道跑,支撑腿在离地时人体重心比着地时低,从而使单步支撑过程中下坡跑比平道跑要省能;下坡跑导致受试者的着地方式发生很大变化,使得受试者受地面作用力大小、方向与平道跑差异明显,其中垂直作用力冲击峰值随坡角增加而增加,而活动峰值变化不明显,水平制动冲量增加的幅度比驱动冲量下降的幅度要大,制动力占主导地位,这种作用效果显然是由着地腿肌肉收缩形式的改变有关,并最终导致下坡跑单步支撑过程中出现能量节省化。  相似文献   

19.
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.  相似文献   

20.
ABSTRACT

The aim of this investigation was to assess the reliability and validity of the Fitjump system. Fifty-seven participants (age = 22.62 ± 5.24 years, height = 180.69 ± 12.53 cm, body mass = 75.61 ± 9.56 kg) performed three countermovement jump (CMJ) and squat jump (SJ) with a 1-week interval for test and retest reliability. For validity, the participants performed the same jump protocol on the force platform while being simultaneously measured with the Fitjump system. There was excellent test–retest reliability of the Fitjump system for CMJ and SJ with high intraclass correlation coefficient (ICCs) (0.97 and 0.97, respectively), low coefficient variation (CVs) (2.3% and 2.4%, respectively), and low typical error of estimate [(TEE (%)] (4.0% and 4.4%, respectively). For validity, ICCs were extremely high for CMJ and SJ (0.93 and 0.94, respectively), with low TEE (%) (2.9% and 2.0%, respectively). However, Fitjump overestimated jump height for CMJ and SJ (3.54 and 3.37 cm, respectively; p < 0.001) when compared with the force platform. As a conclusion, the Fitjump system demonstrated excellent test–retest reliability and high relationship with a systematic bias for validity. Therefore, the Fitjump system can be used as a portable tool for monitoring vertical jump changes over time, but it should not be used interchangeably with a force platform.  相似文献   

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