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1.
The following research approximated how the central nervous system of Paralympic wheelchair athletes resolve kinematic redundancies during upper-limb movements. A multibody biomechanical model of a tetraplegic Paralympic athlete was developed using subject-specific body segment parameters. The angular joint kinematics throughout a specified Paralympic sport movement (i.e., wheelchair curling) were experimentally measured using inertial measurement units. The motor control system of the Paralympian was mathematically modelled and simulated using forward dynamics optimization. The predicted kinematics from different optimization objective functions (i.e., minimizing resultant joint moments, mechanical joint power, and angular joint velocities and accelerations) were compared with those experimentally measured throughout the wheelchair curling movement. Of the optimization objective functions under consideration, minimizing angular joint accelerations produced the most accurate predictions of the kinematic trajectories (i.e., characterized with the lowest overall root mean square deviations) and the shortest optimization computation time. The implications of these control findings are discussed with regards to optimal wheelchair design through predictive dynamic simulations.  相似文献   

2.
Improved understanding of mobility performance in wheelchair basketball is required to increase game performance. The aim of this study was to quantify the wheelchair-athlete activities of players in different field positions and of different playing standard during wheelchair basketball matches. From video analysis, absolute and relative duration and frequency of wheelchair movements and athlete control options were examined in 27 national standard and 29 international standard players during entire wheelchair basketball matches. Between-group factorial analysis of variances identified that national players drove more forward (42.6 ± 6.8 vs. 35.4 ± 3.7%; effect size Cohen’s d (ES) = 1.48) and started more often driving forward (33.9 ± 2.6 vs. 31.8 ± 2.8; ES = 0.77) during a match while the mean activity duration for a single driving forward activity was longer (4.3 ± 0.9 vs. 3.7 ± 0.6 s; ES = 0.75) than for international players. Furthermore, national players performed fewer rotational movements (21.8 ± 4.0 vs. 28.9 ± 7.8%; ES = –1.30) and started less often with the rotational movements (35.0 ± 3.6 vs. 40.5 ± 5.5; ES = –1.21) while the mean activity duration for a single rotation activity was shorter (2.1 ± 0.3 vs. 2.3 ± 0.3 s; ES = –0.67) than for international players. Differences in mobility performance among guard, forward and centre players were minimal. The results should help wheelchair basketball coaches specify wheelchair-handling training techniques and means to optimise wheelchair-athlete configurations.  相似文献   

3.
Abstract

The purpose of the present study was to identify which game-related statistics discriminate winning and losing teams in men’s and women’s elite wheelchair basketball. The sample comprised all the games played during the Beijing Paralympics 2008 and the World Wheelchair Basketball Championship 2010. The game-related statistics from the official box scores were gathered and data were analysed in 2 groups: balanced games (final score differences ≤12 points) and unbalanced games (final score differences >13 points). Discriminant analysis allowed identifying the successful 2-point field-goals and free-throws, the unsuccessful 3-point field-goals and free-throws, the assists and fouls received as discriminant statistics between winning and losing teams in men’s balanced games. In women’s games, the teams were discriminated only by the successful 2-point field-goals. Linear regression analysis showed that the quality of opposition had great effects in final point differential. The field-goals percentage and free-throws rate were the most important factors in men’s games, and field-goals percentage and offensive rebounding percentage in women’s games. The identified trends allow improving game understanding and helping wheelchair basketball coaches to plan accurate practice sessions and, ultimately, deciding better in competition.  相似文献   

4.
The aim of this study was to determine the relationship between force and velocity parameters during a specific multi-articular upper limb movement – namely, hand rim propulsion on a wheelchair ergometer. Seventeen healthy able-bodied females performed nine maximal sprints of 8?s duration with friction torques varying from 0 to 4?N?·?m. The wheelchair ergometer system allows measurement of forces exerted on the wheels and linear velocity of the wheel at 100 Hz. These data were averaged for the duration of each arm cycle. Peak force and the corresponding maximal velocity were determined during three consecutive arm cycles for each sprint condition. Individual force–velocity relationships were established for peak force and velocity using data for the nine sprints. In line with the results of previous studies on leg cycling or arm cranking, the force–velocity relationship was linear in all participants (r?=??0.798 to ?0.983, P?<0.01). The maximal power output (mean 1.28?W?·?kg?1) and the corresponding optimal velocity (1.49?m?·?s?1) and optimal force (52.3?N) calculated from the individual force–velocity regression were comparable with values reported in the literature during 20 or 30?s wheelchair sprints, but lower than those obtained during maximal arm cranking. A positive linear relationship (r?=?0.678, P?<0.01) was found between maximal power and optimal velocity. Our findings suggest that although absolute values of force, velocity and power depend on the type of movement, the force–velocity relationship obtained in multi-articular limb action is similar to that obtained in wheelchair locomotion, cycling and arm cranking.  相似文献   

5.
Abstract

We examined the reliability and validity of the assistant referee intermittent endurance test (ARIET), a modified Yo-Yo IE2 test including shuttles of sideways running. The ARIET was carried out on 198 Italian (Serie A-B, Lega-Pro and National Level) and 47 Danish elite soccer assistant referees. Reproducibility was tested for 41 assistant referees on four occasions each separated by one week. The ARIET intraclass correlation coefficients and typical error of measurement ranged from 0.96 to 0.99 and 3.1 to 5.7%, respectively. ARIET performance for Serie A and B was 23 and 25% greater than in Lega-Pro (P < 0.001). The lowest cut-off value derived from receiving operator characteristic discriminating Serie A-B from Lega-Pro was 1300 m. The ARIET performance was significantly correlated with [Vdot]O2max (r = 0.78, P < 0.001), %HRmax after 4 min of ARIET (r = ? 0.81, P < 0.001) and Yo-Yo IR1 performance (r = 0.95, P < 0.001), but not sprint performance (r = ?0.15; P = 0.58). The results showed that ARIET is a reproducible and valid test that is able to discriminate between assistant referees of different competitive levels. The lack of correlation with sprinting ability and close correlations with aerobic power, intermittent shuttle running and sub-maximal ARIET heart rate loading provide evidence that ARIET is arelevant test for assessment of intermittent endurance capacity of soccer assistant referees.  相似文献   

6.
The aim of this study was to investigate the reliability and validity of a soccer short passing test using the Footbonaut training system. Forty-eight young skilled soccer players and 31 lesser-skilled soccer players completed a test and a retest, each involving four sessions a day of a Footbonaut short passing test (FSPT). We found significant differences in mean execution times for skilled (mean [M]?=?2487, standard deviation [SD] ?=?155) and lesser-skilled players (M?=?2682, SD?=?176) but no significant difference in accuracy (M?=?74.13, SD?=?7.65; M?=?72.19, SD?=?8.13) between groups. The results from linear mixed-effects models show that there were no significant effects of repeated measurements on execution time. In contrast, we found an estimated increase of 0.86% in accuracy per session for both groups. In conclusion, the FSPT offers a reliable and valid method to differentiate young soccer players at different competitive levels, using execution time.  相似文献   

7.
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8.
Abstract

We assessed the agreement between maximal oxygen consumption ([Vdot]O2max) measured directly when performing the 20-m shuttle run test and estimated [Vdot]O2max from five different equations (i.e. Barnett, equations a and b; Léger; Matsuzaka; and Ruiz) in youths. The 20-m shuttle run test was performed by 26 girls (mean age 14.6 years, s = 1.5; body mass 57.2 kg, s = 8.9; height 1.60 m, s = 0.06) and 22 boys (age 15.0 years, s = 1.6; body mass 63.5 kg, s = 11.5; height 1.70 m, s = 0.01). The participants wore a portable gas analyser (K4b2, Cosmed) to measure [Vdot]O2 during the test. All the equations significantly underestimated directly measured [Vdot]O2max, except Barnett's (b) equation. The mean difference ranged from 1.3 ml · kg?1 · min?1 (Barnett (b)) to 5.5 ml · kg?1 · min?1 (Léger). The standard error of the estimate ranged from 5.3 ml · kg?1 · min?1 (Ruiz) to 6.5 ml · kg?1 · min?1 (Léger), and the percentage error ranged from 21.2% (Ruiz) to 38.3% (Léger). The accuracy of the equations available to estimate [Vdot]O2max from the 20-m shuttle run test is questionable at the individual level. Furthermore, special attention should be paid when comparisons are made between studies (e.g. population-based studies) using different equations. The results of the present study suggest that Barnett's (b) equation provides the closest agreement with directly measured [Vdot]O2max (cardiorespiratory fitness) in youth.  相似文献   

9.
There is limited research studying fluid and electrolyte balance in rugby union players, and a paucity of information regarding the test–retest reliability. This study describes the fluid balance of elite rugby union players across multiple squads and the reliability of fluid balance measures between two equivalent training sessions. Sixty-one elite rugby players completed a single fluid balance testing session during a game simulation training session. A subsample of 21 players completed a second fluid balance testing session during an equivalent training session. Players were weighed in minimal clothing before and after each training session. Each player was provided with their own drinks which were weighed before and after each training session. More players gained body weight (9 (14.8%)) during training than lost greater than 2% of their initial body mass (1 (1.6%)). Pre-training body mass and rate of fluid loss were significantly associated (r?=?0.318, p?=?.013). There was a significant correlation between rate of fluid loss in sessions 1 (1.74?±?0.32?L?h?1) and 2 (1.10?±?0.31?L.?h?1), (r?=?0.470, p?=?.032). This could be useful for nutritionists working with rugby squads to identify players with high sweat losses.  相似文献   

10.
In The Netherlands, the 4-Skills Scan is an instrument for physical education teachers to assess gross motor skills of elementary school children. Little is known about its reliability. Therefore, in this study the test–retest and inter-rater reliability was determined. Respectively, 624 and 557 Dutch 6- to 12-year-old children were analyzed for test re-test and inter-rater reliability. All tests took place within the school setting. The outcome measure was age-expected motor performance (in years). Results showed a small practice effect of .24 years for re-test sessions and assessment of motor skills was possible with acceptable precision (standard error of measurement = .67 years). Overall, intraclass correlation coefficient (ICC) was .93 (95% confidence interval: .92–.95) for test–retest reliability and .97 for inter-rater reliability. For the repeated measures, the smallest detectable change (SDC) was 1.84 and limits of agreement were –1.60 and 2.08 years. It can be concluded that the 4-Skills Scan is a reliable instrument to assess gross motor skills in elementary school children.  相似文献   

11.
Touch/control football boots are reportedly designed for optimal passing and dribbling. Little research exists on the effect of boot design on touch/control performance and no validated protocol has been developed for assessing passing and dribbling from an equipment focus. This study aimed to assess the effect of upper padding on dribbling and passing performance using a test–retest reliable test setup. Eight university players performed a protocol of dribbling, short and long passing in football boots with 0 and 6 mm of upper padding (Poron foam). The protocol was completed twice; the 0-mm padding results were used for test–retest validation, while the 0-mm versus 6-mm padding results were used to investigate the effect of padding. Dribbling performance was assessed though completion time, number of touches applied and lateral deviation from cones and passing performance through ball velocity and offset from target. The protocol demonstrated good test–retest reliability and indicated no significant differences in any of the 12 performance variables between the 0- and 6-mm padded boots. These findings suggest an element of design freedom in the use of padding within football boot uppers without affecting dribbling or passing performance.  相似文献   

12.
Abstract

We investigated cardiovascular fitness and haemodynamic responses to maximal cycle ergometer exercise test in children. The participants were a population sample of 425 children (204 girls, 221 boys) aged 6–8 years. Heart rate (HR) and systolic blood pressure (SBP) were measured from the beginning of pre-exercise rest to the end of recovery period. We provided reference values for peak workload and changes in HR and SBP during and after maximal exercise test in girls and boys. Girls had a lower cardiovascular fitness, indicated by peak workload per body weight [mean (2 s) 2.7 (0.9) vs. 3.1 (1.0) W · kg–1, P < 0.001] and lean mass [mean (2 s) 3.5 (0.9) vs. 3.8 (1.0) W· kg–1, P < 0.001] than boys. Plateau or decline in SBP close to the end of the test was found in about third of children and was considered a normal SBP response. Girls had a slower HR decrease within 2 min after the test than boys [mean (2 s) 53 (18) vs. 59 (22) beats · min–1, P < 0.001]. The results are useful for physicians and exercise physiologists to evaluate cardiovascular fitness and haemodynamic responses to exercise in children and to detect children with low exercise tolerance or abnormal haemodynamic responses to exercise.  相似文献   

13.
The Test of Gross Motor Development – Second Edition (TGMD-2) is a widely used evaluation tool of children’s fundamental motor skills (FMS). This study illustrates how exploratory structural equation modeling (ESEM) addresses current limitations associated with TGMD-2 factor structure. Using the normative dataset from the TGMD-2 manual, we test alternative measurement models using ESEM and confirmatory factor analysis (CFA) and assess measurement invariance between boys and girls and across age. Findings highlight complexity and poor discriminant validity in the two-factor solution that is accentuated when relying on CFA independent clusters assumption. Results also demonstrate differential item functioning (DIF) across age for three of the 12 TGMD-2 indicators. Taken together, this study provides valuable information on the need to reevaluate the TGMD-2 factor structure and can guide revisions for the third edition of the TGMD.  相似文献   

14.
This study aimed to determine whether kinematic data during countermovement jump (CMJ) might explain post-activation potentiation (PAP) phenomenon after an exhausting running test. Thirty-three trained endurance runners performed the Léger Test; an incremental test which consists of continuous running between two lines 20 m apart. CMJ performance was determined before (pre-test) and immediately after the protocol (post-test). Sagittal plane, video of CMJs was recorded and kinematic data were obtained throughout 2-Dimensional analysis. In addition to the duration of eccentric and concentric phases of CMJ, hip, knee and ankle angles were measured at four key points during CMJ: the lowest position of the squat, take-off, landing, and at the lowest position after landing. Additionally, heart rate was monitored, and rate of perceived exertion was recorded at post-test. Analysis of variance revealed a significant improvement in CMJ (p = 0.002) at post-test. Cluster analysis grouped according to whether PAP was experienced (responders group: RG, n = 25) or not (non-responders group: NRG, n = 8) relative to CMJ change from rest to post-test. RG significantly improved (p < 0.001) the performance in CMJ, whereas NRG remained unchanged. Kinematic data did not show significant differences between RG and NRG. Thus, the data suggest that jumping kinematic does not provide the necessary information to explain PAP phenomenon after intensive running exercises in endurance athletes.  相似文献   

15.
Abstract

Recent international normative data for the 20-m shuttle-run test demonstrated a below-average performance index for UK children. The aims of the present study were to create an international comparison of 20-m shuttle-run test performance in a sample of English children and to identify age- and sex-specific differences in test performance. Mass, stature, body mass index, and 20-m shuttle-run test performance were measured in 2041 children aged 11 – 15 years (963 boys, 1078 girls). Performance was expressed as maximum running velocity and a performance index was created by generating z-scores. The shuttle-run test performance index was higher than the existing published value (?0.046, 95% confidence interval [CI] ?0.070 to ?0.022) for all children (0.061, 95% CI = 0.006 to 0.115), for boys (0.075, 95% CI = ?0.022 to 0.171), and for girls (0.048, 95% CI = ?0.010 to 0.106). Boys' relative performance increased significantly (F = 4.43, P = 0.002) throughout the measured age range, whereas girls' relative performance tended to decrease (F = 1.98, P = 0.096). The results were favourable when compared with existing values. Differences in performance index may be due to the different geographical areas from which present and past samples were drawn. Reasons for differences in the performance indices between boys and girls warrant further investigation.  相似文献   

16.
Abstract

The aim of this study was to compare the reliability, internal responsiveness and interchangeability of the Yo-Yo intermittent recovery test level 1 (YY1), level 2 (YY2) and submaximal YY1 (YY1-sub). Twenty-four young soccer players (age 17 ± 1 years; height 177 ± 7 cm; body mass 68 ± 6 kg) completed each test five times within pre- and in-season; distances covered and heart rates (HRs) were measured. Reliability was expressed as typical error of measurement (TEM) and intraclass correlation coefficient (ICC). Internal responsiveness was determined as effect size (ES) and signal-to-noise ratio (ESTEM). Interchangeability was determined with correlation between training-induced changes. The TEM and ICC for distances in the YY1 and YY2 and for HR in YY1-sub were 7.3% and 0.78, 7.1% and 0.93 and 2.2% and 0.78, respectively. The ESs and ESTEMs were 0.9 and 1.9 for YY1, 0.4 and 1.2 for YY2 and ?0.3 and ?0.3 for YY1-sub. Correlations between YY1 vs. YY2 and YY1-sub were 0.56 to 0.84 and ?0.36 to ?0.81, respectively. Correlations between change scores in YY1 vs. YY2 were 0.29 and ?0.21 vs. YY1-sub. Peak HR was higher in YY1 vs. YY2. The YY1 and YY2 showed similar reliability; however, they were not interchangeable. The YY1 was more responsive to training compared to YY2 and YY1-sub.  相似文献   

17.
Abstract

There has been no previous investigation of the concurrent validity and reliability of the current 5 Hz global positioning system (GPS) to assess sprinting speed or the reliability of integrated GPS–accelerometer technology. In the present study, we wished to determine: (1) the concurrent validity and reliability of a GPS and timing gates to measure sprinting speed or distance, and (2) the reliability of proper accelerations recorded via GPS–accelerometer integration. Nineteen elite youth rugby league players performed two over-ground sprints and were simultaneously assessed using GPS and timing gates. The GPS measurements systematically underestimated both distance and timing gate speed. The GPS measurements were reliable for all variables of distance and speed (coefficient of variation [CV] = 1.62% to 2.3%), particularly peak speed (95% limits of agreement [LOA] = 0.00 ± 0.8 km · h?1; CV = 0.78%). Timing gates were more reliable (CV = 1% to 1.54%) than equivalent GPS measurements. Accelerometer measurements were least reliable (CV = 4.69% to 5.16%), particularly for the frequency of proper accelerations (95% LOA = 1.00 ± 5.43; CV = 14.12%). Timing gates and GPS were found to reliably assess speed and distance, although the validity of the GPS remains questionable. The error found in accelerometer measurements indicates the limits of this device for detecting changes in performance.  相似文献   

18.
The study compared the agreement, internal consistency, and measurement stability of the GE iDXA, BOD POD, and InBody 720. Body composition of 43 men and 37 women (31.4 ± 10.7 years; 90% Caucasian and 10% other) was assessed in triplicate using each method over two different days. Mean percent body fat (% BF) of the participants was different for all three machines (27.6 ± 10.0% [GE iDXA)] 25.6 ± 10.4% [BOD POD], and 21.3 ± 10.6% [InBody 720]; p < .05). The coefficient of variation for same day repeated measures was 1.06% (GE iDXA), 3.29% (BOD POD), and 2.97% (InBody 720). The coefficient of variation for 2-day repeated measures was 1.81% (GE iDXA), 4.61% (BOD POD), and 4.24% (InBody 720). The difference between the GE iDXA and BOD POD was within acceptable variability, while the InBody 720 significantly underestimated % BF. The internal consistency was highest for the GE iDXA, followed by the InBody 720, and then the BOD POD.  相似文献   

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