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EN
The state of athletes’ muscles is not constant, but it differs depending on the stage of sports training, which is associated with different degrees of muscle fatigue. There is thus a need to find a non-invasive and simple method to assess muscle fatigue. The aim of the study was to determine the relationship between muscle fatigue due to physical effort and changes in skin temperature, measured using a thermographic camera. Methods: The study involved 12 volleyball players. The participants were to maintain 70% of peak torque in the joint for as long as possible. We measured peak torque and the time of maintaining 70% of its value (tlim) as well as continuously recording skin temperature and electromyographic (EMG) signals in the region of the belly of the rectus femoris. The measurements were taken twice: before and after a series of squats. Results: The study found that tlim decreased when isometric contraction was performed after physical effort. Pre- and post-exercise skin temperature did not differ significantly, however, the increase rates of temperature and the root mean square (RMS) of the EMG signals grew significantly. In most of the players, skin temperature also correlated with the RMS, median frequency (MDF), and mean frequency (MF) of the EMG signals. Conclusions: Measuring the time of maintaining submaximal torque during isometric contraction and the slope coefficient for the increase in temperature recorded using a thermographic camera can be a simple, cost-effective, and non-invasive method of assessing fatigue and efficiency decreases in the muscles in volleyball players.
EN
The purpose of this study was to investigate the relationship between somatotype, muscle torque, maximal power output and height of rise of the body mass centre measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), and power output measured in maximal cycle ergometer exercise bouts in female volleyball players. Fourteen players participated in the study. Somatotype was determined using the Heath–Carter method. Maximal muscle torque was measured under static conditions. Power output was measured in 5 maximal cycle ergometer exercise bouts, 10 s each, at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight (BW). All jump trials (ACMJ, SPJ and CMJ) were performed on a force plate. The mean somatotype of volleyball players was: 4.9-3.5-2.5. The value of the sum of muscle torque of the left upper extremities was significantly correlated only with mesomorphic component. Mesomorphic and ectomorphic components correlated significantly with values of maximal power measured during ACMJ and CMJ. Power output measured in maximal cycle ergometer exercise bouts at increasing external loads equal to 2.5, 5.0 and 7.5% of BW was significantly correlated with endomorphy, mesomorphy and ectomorphy.
PL
W prezentowanej pracy dokonano porównania zawodników piłki siatkowej (n = 24) z siatkarzami plażowymi (n = 20), pod kątem osiąganych maksymalnych momentów sił mięśniowych, dla 10 zespołów mięśniowych. Badania przeprowadzono na specjalnych stanowiskach służących do pomiarów momentów sił w warunkach statyki. Badane grupy zawodników różniły się wysokością i masą ciała, jednak uzyskane wyniki pozwalają przypuszczać, iż zawodnicy obu dyscyplin charakteryzują się podobnymi wartościami względnej, maksymalnej siły mięśniowej i topografii momentów sił.
EN
This study presents a comparison of volleyball (n = 24) and beach volleyball (n = 20) players, in terms of maximal muscle torques for 10 muscle groups. The measurements were taken on a specific mechanical stands that were designed and built for measuring muscle torques under isometric conditions. Body mass and body height differed in examined groups significantly; however obtained results suggest, that players of both disciplines rather have similar level of relative muscle strength and a strength distribution.
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