Wyniki wyszukiwania - BazTech

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Analysis of volleyball players’ force generation during jump spike from the perspective of electromyographic characteristics

Wang Zi, Zhao Min

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 2

147--155

EN

The aim of this study was to investigate the force characteristics of novice athletes and professional athletes in completing a cross spike at position four from the perspective of electromyographic characteristics. Methods: Ten novice and ten professional athletes were selected as subjects. The electromyographic characteristics of the athletes were obtained by the Noraxon Ultium electromyography (EMG) and compared. Results: In the first stage, i.e., the takeoff stage, the activation level of the rectus abdominis and external abdominal obliques was significantly higher in the professional group ( p < 0.05). During the second stage, i.e., the stage of flying to hit the ball, the professional group had a higher integrated electromyography (iEMG) value in the trapezius. Moreover, it showed significantly higher muscle contribution from the rectus abdominis (5.59 ± 1.58%), external abdominal obliques (3.67 ± 1.21%), and trapezius (10.12 ± 2.61%) compared to the novice group ( p < 0.05). In the third stage, i.e., the stage of landing and buffering, p < 0.05 in the comparison of the iEMG values of trapezius and gluteus maximus between the two groups. Moreover, the professional group exhibited higher muscle activation levels in all muscles except for the gastrocnemius, compared to the novice group ( p < 0.05). Conclusions: Professional athletes display superior muscle coordination and more effective muscle force generation in the trunk and lower limbs during the execution of the jump spike action.

2

Changes in electromyographic signals and skin temperature during standardised effort in volleyball players

Kuniszyk-Jóźkowiak W., Jaszczuk J., Czaplicki A.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 3

115--122

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.

3

Somatotype : variables related to muscle torque and power output in female volleyball players

Buśko K., Lewandowska J., Lipińska M., Michalski R., Pastuszak A.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 2

119--126

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.

4

Maksymalne momenty sił mięśniowych zawodników uprawiających piłkę siatkową i siatkówkę plażową

Michalski R., Lipińska M.

Aktualne Problemy Biomechaniki

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2011

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z. 5

95--98

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.