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    Wyświetlanie 1-8 z 8
    Tytuł:
    Jumping performance and take-off efficiency in two different age categories of female volleyball players
    Autorzy:
    Jandova, Sona
    Janura, Miroslav
    Powiązania:
    https://bibliotekanauki.pl/articles/306340.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    biomechanika
    skoki
    wysokość
    siła
    wiek
    biomechanics
    vertical jump
    height
    power
    age
    Opis:
    Vertical jump height is recognised as a determinant factor in elite volleyball performance. In previous studies there are different opinions on whether vertical jump height performance improves during maturation or not. The aim of this study was to assess the differences in jumping abilities in two different age groups of female volleyball players and to determine the take-off efficiency during repeated jumps. Methods: Seventeen female volleyball players from two different age categories – adults and under 16 years – participated in this study. Quattro Jump 9290BA force platform (Kistler, Winterthur, Switzerland) was used to assess the jumping performance during squat jumps, counter movement jumps, and 45-second continuous jumps. Results: Jumping performance did not differ significantly between the two groups. The main efficiency of the conversion of mechanical work into mechanical energy was only 24% and it decreased during the test. Conclusions: The influence of age on the jumping performance in a group of female volleyball players was not confirmed. Take-off efficiency was in both groups quite low and it did not improve during the test.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 2; 55-61
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of selected biomechanical parameters in female team sports players
    Autorzy:
    Pietraszewski, B.
    Struzik, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307048.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    countermovement jump
    drop jump
    RSI
    torque
    vertical jump
    skoki
    trening
    biomechanika
    Opis:
    The aim of this research was to evaluate the biomechanical parameters of lower limbs and their influence on height of vertical jump. The research was conducted on a group of females practicing basketball and volleyball. The following equipment was used during the experiment: a force plate by Kistler, a Biometrics electrogoniometer and a specially designed chair to measure static torque by OPIW Opole. The results indicated that the jumping abilities of the examined athletes were poor. No statistically significant correlations were observed between knee static torque and heights of vertical jumps: CMJ and DJ. The authors suggest modification of the McClymont index (RSI) to evaluate the selection of platform height during plyometric training. Such modification would enable better choice of loads and better training control of the subject.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2013, 15, 4; 103-108
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Concurrent validity and reliability of proprietary and open-source jump mat systems for the assessment of vertical jumps in sport sciences
    Autorzy:
    Pueo, B.
    Jimeney-Olmedo, J. M.
    Lipińska, P.
    Buśko, K.
    Penichet-Tomas, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307394.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sportowiec
    skoki
    sport
    test
    athlete
    jump
    open-hardware
    sports
    switch
    Opis:
    Vertical jump tests are used to assess lower-limb power of athletes in sport sciences. Flight time measurement with jump-mat systems is the most common procedure for this purpose. The aim of this study was to analyze the concurrent validity and reliability of two proprietary systems (Globus and Axon) and an open-source system (Chronojump). Methods: A conditioning electric circuit governed by a controlled wave generator is designed to substitute athletes jumping on a physical mat. In order to look for possible differences associated to timekeeping by each microcontroller device, all three systems are fed by the circuit simultaneously. Results: Concurrent validity was high for the three systems. Standarized typical error of estimate (TEE) was trivial, according to MBI interpretation, as well as perfect Pearson correlation coefficient. Reliability was assessed using coefficient of variation of flight time measure, resulting in 0.17–0.63% (0.05–0.12 cm) for Globus, 0.01% (0.09 cm) for Chronojump and 5.65–9.38% (2.15–3.53 cm) for Axon. These results show that all jump-mat system produced nearly identical measures of flight time so they can be considered valid and reliable for practical purposes. In comparison, Chronojump showed the best performance whereas Axon showed enough variability and disagreement to pose a problem in testing elite athletes. Conclusions: These experiments show that open-source jump mats are as valid and reliable as their proprietary counterparts at a lower cost. Therefore, practitioners can be confident in using Globus or Chronojump systems to test athletes’ jump height because of their negligible errors and Axon system to monitor general population.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2018, 20, 3; 51-57
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimation of potential elastic energy during the countermovement phase of a vertical jump based on the force-displacement curve
    Autorzy:
    Struzik, Artur
    Zawadzki, Jerzy
    Powiązania:
    https://bibliotekanauki.pl/articles/306373.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    skoki
    elastyczność
    sztywność
    rozciąganie
    countermovement jump
    elasticity
    quasi-stiffness
    stretch-shortening cycle
    Opis:
    Purpose: One inconvenience in finding experimental evidence for the relationship between potential elastic energy and vertical jump height is the difficulty of estimating the value of the stored potential elastic energy. Therefore, the aim of this study is to present a simple method of estimating the potential elastic energy stored by lowering the center of mass during the countermovement phase of a vertical jump. Methods: The research was conducted on 30 able-bodied male university students (age: 20 years, body height: 183.1 ± 7.9 cm, body mass: 80.3 ± 10.4 kg). Each participant performed 10 single countermovement jumps with arms akimbo to maximal height. Measurements employed a Kistler force plate. The value of potential elastic energy was estimated based on the curve of dependence of the ground reaction force on the vertical displacement of the jumper’s center of mass. Results: The mean value (±SD) of potential elastic energy collected due to lowering of the center of mass during the countermovement phase of a vertical jump was 183 ± 69 J. 24.3% of this value can be considered the part of the potential elastic energy (44 ± 21 J) that comes from the transformation of kinetic energy. The total change in gravitational potential energy due to lowering the center of mass was 240 ± 58 J. Conclusions: This estimation of potential elastic energy is only general and rough. However, certain estimations of potential elastic energy may offer some insight into the phenomenon relating vertical quasi-stiffness and the ability to store potential elastic energy with vertical jump height.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 1; 153-160
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fatigue alters the biomechanical contribution of lower extremity joints during a stretch-shortening cycle task
    Autorzy:
    Sun, Xiaole
    Xia, Rui
    Zhang, Ximi
    Zhen, Luo
    Fu, Weijie
    Powiązania:
    https://bibliotekanauki.pl/articles/949743.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    skoki
    zmęczenie
    sztywność
    stretch-shortening cycle
    drop jump
    fatigue
    stiffness
    joint work
    Opis:
    This study aimed to explore the effect of fatigue on the biomechanical contribution of the lower extremity joints during a typical stretch-shortening cycle (SSC) task. Methods: 15 male athletes completed drop jump (DJ) under pre- and post-fatigue. Vicon motion capture system and 3D Kistler force plates were used to collect kinematics and ground reaction force data simultaneously. Results: Under fatigue condition, 1) the DJ height decreased; the touchdown angle of knee and ankle reduced and the range of motion increased; 2) the maximum push-off moment and power of knee was reduced; 3) the stiffness of knee, ankle, and legs was reduced; 4) the energy generation and the net energy of the ankle decreased; 5) the energy contribution of knee decreased during the eccentric phase. Conclusions: Fatigue altered biomechanical contribution of the lower extremity joints by changing the movement pattern during DJ. The control ability of the knee and ankle were decreased. Eventually, the jump performance was reduced. In addition, the decrease of stiffness as well as the energy contribution of these joints can be used as sensitive indices to evaluate the performance of DJ after fatigue.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 2; 11-19
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of reliability and concurrent validity of of two optoelectric systems used for recording maximum vertical jumping performance versus the gold standard
    Autorzy:
    Słomka, K. J.
    Sobota, G.
    Skowronek, T.
    Rzepko, M.
    Czarny, W.
    Juras, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/307083.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    niezawodność
    sport
    skoki
    reliability
    counter movement jump
    motion capture
    sports performance
    optoelectric
    Opis:
    The objective of this study was to evaluate the reliability and validity of two alternative systems used for jumping performance measurement. Methods: Two groups of subjects were tested. The first group consisted of 15 male adults (21.3 ± 1.7 years ) and the second group consisted of 16 female volleyball players (17.2 ± 0.9 years). We used three different systems of data collection in the study. Two of the used systems are based on optoelectric components. The Optojump Next system is referred to as the optoelectric system, and BTS Smart-E is refered to as the video system. Concurrent validity of these systems was verified with the use of “gold standard” which is force platform. All systems were used to estimate the height of vertical jumps. Results: Both optoelectric systems occurred to be highly reliable with the ICCs=0.98 for Optojump and 0.9 for BTS Smart. Their concurrent validity with the force platform data was also very high r=0.99 and r=0.97 respectively. Conclusions: Comparison of these two systems shows distinct differences between them where Optojump system is more suitable for quick and reliable sports testing, when BTS-Smart for research and clinical testing.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2017, 19, 2; 141-147
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Lower extremity power in female soccer athletes : a pre-season and in-season comparison
    Autorzy:
    Pietraszewski, B.
    Siemieński, A.
    Bober, T.
    Struzik, A.
    Rutkowska-Kucharska, A.
    Nosal, J.
    Rokita, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307077.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    skoki
    trening plyometryczny
    energia
    biomechanika
    countermovement jump
    drop jump
    plyometric training
    relative power
    Opis:
    Purpose: Lower extremity power is an important physical capacity of a soccer athlete. Power represents, and can be modified by, the training of strength and speed. Pre-season and in-season training differs in the relative emphasis on these two quantities. It is nevertheless desirable that the mechanical power remain the same or become higher during the in-season period. The purpose of this study was to identify changes in quantities related to “explosive strength” and to check whether, in collegiate female soccer players, pre- and inseason lower extremity power will remain unaltered. Methods: Twenty collegiate female soccer players, representing all field positions, participated. Lower extremity power was assessed by a series of drop jumps executed from four different heights (15, 30, 45, and 60 cm). Mechanical power was calculated using subject’s mass, jump height, and acceleration due to gravity. This value was further normalized by body mass of each athlete to obtain the relative (or normalized) mechanical power. Results: The normalized lower extremity mechanical power was highest when landing from the 30 cm height for both pre- and inseason periods. However, contrary to expectations, it turned out lower during the in-season than during the pre-season test, even though no significant differences were found between the corresponding jump heights. Conclusions: It is concluded that altered, perhaps inadequate, training strategies were employed during the in-season period. Besides, advantages of adding the relative mechanical power as a season readiness indicator are underlined compared with relying on the jump height alone.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2015, 17, 3; 129-135
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Leg stiffness adjustment during hopping at different intensities and frequencies
    Autorzy:
    Mrdakovic, V.
    Ilic, D.
    Vulovic, R.
    Matic, M.
    Jankovic, N.
    Filipovic, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/307107.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    połączenie
    węzeł podatny
    sztywność
    skoki
    joint stiffness
    jumping performance
    preferred hopping frequency
    spring-mass model
    Opis:
    Understanding leg and joint stiffness adjustment during maximum hopping may provide important information for developing more effective training methods. It has been reported that ankle stiffness has major influence on stable spring-mass dynamics during submaximal hopping, and that knee stiffness is a major determinant for hopping performance during maximal hopping task. Furthermore, there are no reports on how the height of the previous hop could affect overall stiffness modulation of the subsequent maximum one. The purpose of the present study was to determine whether and how the jump height of the previous hop affects leg and joint stiffness for subsequent maximum hop. Ten participants completed trials in which they repeatedly hopped as high as possible (MX task) and trials in which they were instructed to perform several maximum hops with 3 preferred (optimal) height hops between each of them (P3MX task). Both hopping tasks were performed at 2.2 Hz hopping frequency and at the participant's preferred (freely chosen) frequency as well. By comparing results of those hopping tasks, we found that ankle stiffness at 2.2 Hz (p=0.041) and knee stiffness at preferred frequency (p=0.045) was significantly greater for MX versus P3MX tasks. Leg stiffness for 2.2 Hz hopping is greater than for the preferred frequency. Ankle stiffness is greater for 2.2 Hz than for preferred frequencies; opposite stands for knee stiffness. The results of this study suggest that preparatory hop height can be considered as an important factor for modulation of maximum hop.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2014, 16, 3; 69-76
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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