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1
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Associations Between Rate of Force Development Metrics and Throwing Velocity in Elite Team Handball Players: a Short Research Report

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Marques M., Saavedra F., Abrantes C., Aidar F.
Journal of Human Kinetics
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2011
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vol. 29A
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issue Special Issue
53-57
EN
Performance assessment has become an invaluable component of monitoring participant's development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0, 56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads.
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Analysis of Speed Performance In Soccer by a Playing Position and a Sports Level Using a Laser System

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Ferro A., Villacieros J., Floría P., Graupera J. L.
Journal of Human Kinetics
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2014
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vol. 44
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issue 1
143-153
EN
The purpose of this study was to determine the kinematic variables that identify the quality of velocity in soccer players at different competitive levels and playing positions. This study had two independent variables: 1) a competitive level (competitive and non-competitive players); and 2) a playing position, with four levels (central defenders, wide defenders/midfielders, central midfielders and forwards). Forty-two soccer players took part in a 30 m sprint-test, which was measured using a laser sensor-type 1 (LDM301-Jenoptik) at 2000 Hz. Absolute and relative times, average velocities and absolute and relative maximum velocities over 10 m sections were analyzed at 200 Hz with BioLaserSport®. There were no significant differences in average velocity between competitive and non-competitive players; however, the former reached a greater maximum velocity in the 10-20 m section. Average velocity in the 0-10 m section identified specificity among playing positions in competitive players. The forwards were the fastest followed by the central midfielders, the wide defenders/midfielders and the central defenders. No differences were found among the non-competitive players. Average velocity over the 0-10 meter section may be an important indicator when assigning a playing position for competitive players. These results support the use of more accurate systems, such as a laser system, to identify soccer players’ speed qualities (including maximum velocity) during short sprints.
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Kinematic Tactics in the Women's 800 m Freestyle Swimming Final at the Beijing 2008 Olympic Games

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Lipińska P.
Baltic Journal of Health and Physical Activity
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2009
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vol. 1
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issue 1
86-92
EN
Background: The purpose of this study was to obtain knowledge on tactics of long distance swimming at the highest women professional level.Material/Methods: Eight swimmers, finalists of 800 m distance of freestyle of the Beijing 2008 Olympic Games were examined. The distribution of velocity of swimming for the entire distance based on 50 m segments was analyzed. Partial, halves and quarters velocity, speed indexes and linear and nonlinear regression equations were calculated.Results: It was revealed that better swimmers (placed 1-3) had their distribution of swimming as an ascending line and with very small difference between segmental velocity and that of the entire distance, while the rest of swimmers had a descending velocity line and a higher dispersion of partial values.Conclusions: High performance swimmers have to hold uniform velocity of movement with small dispersion along the entire distance of swimming.
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Importance of Muscle Power Variables in Repeated and Single Sprint Performance in Soccer Players

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López-Segovia M., Dellal A., Chamari K., González-Badillo J. J.
Journal of Human Kinetics
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2014
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vol. 40
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issue 1
201-211
EN
This study examined the relationship between lower body power and repeated as well as single sprint performance in soccer players. The performance of nineteen male soccer players was examined. The first testing session included the countermovement jump (CMJL) and the progressive full squat (FSL), both with external loads. Power in the CMJL and FSL was measured with each load that was lifted. The second session included a protocol of 40-m repeated sprints with a long recovery period (2 min). The number of sprints executed until there was a 3% decrease in performance for the best 40-m sprint time was recorded as a repeated sprint index (RSI). The RSI was moderately associated with power output relative to body mass in the CMJL and FSL (r = 0.53/0.54, p ≤ 0.05). The most and least powerful players (determined by FSL) showed significant differences in the RSI (9.1 ± 4.2 vs. 6.5 ± 1.6) and 10 m sprint time (p [...] 0.01). Repeated and single sprints are associated with relatively lower body power in soccer players.
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Effect of Performance Speed on Trunk Movement Control During the Curl-Up Exercise

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Barbado D., Elvira J. L. L., Moreno F. J., Vera-Garcia F. J.
Journal of Human Kinetics
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2015
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vol. 46
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issue 1
29-37
EN
Trunk exercise speed has significant effects on neuro-mechanical demands; however, the influence of a variety of exercise speeds on motor control of the trunk displacement remains unknown. The aim of this study was to assess the effect of performance speed on trunk motion control during the curl-up exercise by analyzing the kinematic variance about the sagittal trajectory. Seventeen subjects volunteered to perform curl-ups at different cadences controlled by a metronome. Standard deviation (SD) and range (RG) of shoulder girdle medial-lateral displacement (SGML) and detrended fluctuation analysis (DFA) of SGML were calculated to examine linear variability and long range autocorrelation of medial-lateral upper trunk displacements, respectively. In addition, SD, RG and DFA of centre of pressure medial-lateral displacement (COPML) were performed to analyze the behavior of the motor system while controlling trunk displacement. Although SD and RG of COPML increased as speed increased, the curl-up cadence did not have significant effects on SD and RG of SGML. These results suggest that although high speed curl-ups challenged participants’ ability to carry out medial-lateral adjustments, an increase of performance speed did not modify the linear variability about the sagittal trajectory. Regarding DFA, the scaling exponent α of SGML and COPML was higher for the fastest movements, mainly in long term fluctuations. Therefore, to maintain the target trajectory, participants used different strategies depending on performance speed. This is to say, there were less trajectory changes when participants performed the fastest exercises.
6
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THE INFLUENCE OF SPRINT BLOCK START ELEMENTS ON INITIAL VELOCITY OF 100 METRE RACE

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Terczyński R.
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2014
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vol. 8
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issue 4
87-96
EN
The aim of this paper was to investigate whether it is possible to evaluate the relationship between different phases of sprint start objectively. The participants of the research were the top level of elite National Sprint Team (8 female, 9 male). The run times were as follows: 10.39 ±0.12 s for men and 11.63 ±0.20 s for women. The data that were taken into account during the research in order to examine typical kinetic parameters of the sprint start were: reaction time, delay between simple reaction time and reaction time (IAAF), time to front peak force, time to rear peak force, delay between end of front force and gun signal and total start time. The analysis of the study identifies the major kinematic parameters of the phases of the sprint start and block acceleration that influence the results of sprint running. The following correlation analyses were conducted, a linear regression for the typical kinetic parameters of the sprint start, initial speed on 100 metre race. Finally, a simple coaching related model for the development of sprinting is presented which is consistent with scientific evidence recommendations for coaches to make changes in training.
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Kinematics of the Hip and Body Center of Mass in Front Crawl

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Fernandes R., Ribeiro J., Figueiredo P., Seifert L., Vilas-Boas J.
Journal of Human Kinetics
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2012
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vol. 33
15-23
EN
The kinematic profiles of the hip and center of mass in front crawl swimming were compared to quantify the error of using a fixed body point to assess intracyclic velocity variations at moderate intensity exercise. The practical goal was to provide a useful tool, easy and fast to assess, and to use as feedback, for assessing swimming efficiency. Sixteen swimmers performed an intermittent incremental protocol that allowed assessing the individual anaerobic threshold velocity. One complete stroke cycle was analysed at the step intensity corresponding to each swimmer's anaerobic threshold. The subjects were videotaped in the sagittal plane using a double camera set-up for two-dimensional kinematical analyses. The hip and the center of mass presented similar mean velocity and displacement values, being highly related to both parameters. However, the hip reflects the center of mass forward velocity and horizontal displacement with 7.54% and 3.24% associated error, respectively. Differences between hip and center of mass were observed for intracyclic velocity variations (0.19±0.05 and 0.25±0.08, respectively, for a p<0.001), and the negative mean error value found (-0.06) evidenced a tendency of the hip to overestimate the center of mass velocity variation. It is possible to conclude that the hips forward movements might provide a good estimate of the swimmer's horizontal velocity and displacement that is relevant for diagnostic purposes, especially to assess swimming efficiency through the intracyclic velocity variations. Nevertheless, the hip point error magnitude should be taken into consideration in data interpretation.
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The Effect of the Number of Sets on Power Output for Different Loads

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Morales-Artacho A. J., Padial P., García-Ramos A., Feriche B.
Journal of Human Kinetics
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2015
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vol. 46
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issue 1
149-156
EN
There is much debate concerning the optimal load (OL) for power training. The purpose of this study was to investigate the effect of the number of sets performed for a given load on mean power output (Pmean). Fourteen physically active men performed 3 sets of 3 bench-press repetitions with 30, 40 and 50 kg. The highest mean power value (Pmax) across all loads and Pmean were compared when data were taken from the first set at each absolute load vs. from the best of three sets performed. Pmean increased from the first to the third set (from 5.99 ± 0.81 to 6.16 ± 0.96 W·kg−1, p = 0.017), resulting in a main effect of the set number (p < 0.05). At the 30 kg load Pmean increased from the first to the third set (from 6.01 ± 0.75 to 6.35 ± 0.85 W·kg−1; p < 0.01). No significant effect was observed at 40 and 50 kg loads (p > 0.05). Pmax and velocity were significantly affected by the method employed to determine Pmean at each load (p < 0.05). These results show a positive effect of the number of sets per load on Pmean, affecting Pmax, OL and potentially power training prescription.
9
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Specific Measurement of Tethered Running Kinetics and its Relationship to Repeated Sprint Ability

86%
Sousa F., Reis I. d., Ribeiro L., Martins L., Gobatto C.
Journal of Human Kinetics
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2015
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vol. 49
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issue 1
245-256
EN
Repeated sprint ability has been widely studied by researchers, however, analysis of the relationship between most kinetic variables and the effect of fatigue is still an ongoing process. To search for the best biomechanical parameter to evaluate repeated sprint ability, several kinetic variables were measured in a tethered field running test and compared regarding their sensitivity to fatigue and correlation with time trials in a free running condition. Nine male sprint runners (best average times: 100 m = 10.45 ± 0.07 s; 200 m = 21.36 ± 0.17 s; 400 m = 47.35 ± 1.09 s) completed two test sessions on a synthetic track. Each session consisted of six 35 m sprints interspersed by 10 s rest under tethered field running or free running conditions. Force, power, work, an impulse and a rate of force development were all directly measured using the sensors of a new tethered running apparatus, and a one-way ANOVA with Scheffé post-hoc test used to verify differences between sprints (p < 0.05). Pearson product-moment correlation measured the relationship between mechanical variables and free running performance. A total impulse, the rate of force development and maximum force did not show significant differences for most sprints. These three variables presented low to moderate correlations with free running performance (r between 0.01 and -0.35). Maximum and mean power presented the strongest correlations with free running performance (r = -0.71 and -0.76, respectively; p < 0.001), followed by mean force (r = -0.61; p < 0.001) and total work (r = -0.50; p < 0.001). It was concluded that under a severe work-to-rest ratio condition, power variables were better suited to evaluating repeated sprint ability than the other studied variables.
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Kinematic Analysis of the Instep Kick in Youth Soccer Players

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Kapidžić A., Huremović T., Biberovic A.
Journal of Human Kinetics
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2014
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vol. 42
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issue 1
81-90
EN
We attempted to establish which applied kinematic variables significantly contributed to the efficiency of the instep kick motion in soccer. The study sample comprised 13 boys (age: 13 ± 0.5 yrs; body mass: 41.50 ± 8.40 kg; body height: 151.46 ± 5.93 cm) from the FC Sloboda school of soccer. Each participant performed three kicks with maximum strength that were video recorded with two synchronized cameras (Casio Ex-F1) positioned 12 m away from the place of the kick. Data were collected by analyzing the video recordings of each kick. Data processing was performed using the APAS motion analysis system (Ariel Dynamics Inc., San Diego, CA). On the basis of the forward selection method of multiple regression analysis, we determined the correlations between the prediction variables and the selected criteria (speed of the ball; p = 0.01). On the basis of the regression coefficients, it was concluded that two variables significantly contributed to the speed of the ball: speed of the foot of the kicking leg at the time of contact with the ball (p = 0.01) and the distance between the angle support leg and center of the ball (“foot posterior displacement”) (p = 0.01). In order to achieve the best possible technical performance and, therefore, a higher speed of the ball, soccer players must pay attention to two important elements during training. First, it is necessary to position the support leg as close to the ball as possible and, second, maximize the force used in the initial phases of the kick to achieve a high speed of the kicking foot
11
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Content available

Flow characteristics after installation of floating bridge in open channel

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Ibrahim M. M., Eltoukhy M. A. R., Ghanim A. D., Ibrahim M. M., Eltoukhy M. A. R., Ghanim A. D.
Journal of Water and Land Development
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2021
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issue 49
12
Content available remote

The Importance of Movement Velocity as a Measure to Control Resistance Training Intensity

86%
González-Badillo J., Marques M., Sánchez-Medina L.
Journal of Human Kinetics
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2011
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vol. 29A
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issue Special Issue
15-19
EN
Configuration of the exercise stimulus in resitance training has been traditionally associated with a combination of the so-called ‘acute resistance exercise variables’ (exercise type and order, loading, number of repetitions and sets, rests duration and movement velocity). During typical resistance exercise in isoinertial conditions, and assuming every repetition is performed with maximal voluntary effort, velocity unintentionally declines as fatigue develops. However, few studies analyzing the response to different resitance training schemes have described changes in repetition velocity or power. It thus seems necessary to conduct more research using models of fatigue that analyze the reduction in mechanical variables such as force, velocity and power output over repeated dynamic contractions in actual training or competition settings. Thus, the aim of this paper was to discuss the importance of movement velocity concerning control training intensity.
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