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The Examination of Different Tests for the Evaluation of the Efficiency of the Eggbeater Kicks

100%
Stirn I., Strmecki J., Strojnik V.
Journal of Human Kinetics
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2014
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vol. 41
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issue 1
215-226
EN
The eggbeater kick presents an important basic technical skill in water polo. The aim of this study was to examine some different tests in order to recommend the best ones for the evaluation of the eggbeater kick. Twenty eight young male water polo players performed one test (squat jump) on land and ten tests in water: tethered swimming with legs only, using alternating and simultaneous eggbeater kicks, jumps out of water from basic and vertical (arms vertically above the head) position, water start and swimming two meters and swimming horizontally with legs only five meters with a flying start. The differences between tests were checked by executing dependent t-tests, while Pearson"s correlation coefficients were calculated to evaluate the correlation between different parameters. Results showed that when performing alternate eggbeater kicks greater average forces were produced by the water polo players when compared to consecutive simultaneous eggbeater kicks. However, a short time maximal acceleration of the body in the vertical and horizontal plane was greater when the single simultaneous kick was performed. It was determined that horizontal swimming using legs only and a squat jump were less useful for the evaluation of the eggbeater kick. Therefore, the recommendation was to measure the average force of successive alternating eggbeater kicks, the height of the jump out of the water from the basic position and the water start and swim over a distance of 2 meters.
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The Effects of Muscle Strengthening on Neuro-Musculo-Skeletal Dynamics in A Squat Jump: A Simulation Study

88%
Prokopow P.
Human Movement
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2011
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vol. 12
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issue 4
307-314
EN
Purpose. The aim of this study was to quantitatively investigate the effects of muscle strengthening in a vertical squat jump based on a neuro-musculo-skeletal model and a forward dynamics simulation. Methods. During simulation trials, 16 major muscle groups of the lower extremities were gradually strengthened up to 20%. Results. Complex yet systematic deviations in body kinematics, kinetics and the neural control pattern were observed as a result of gradual muscle strengthening. Conclusions. Based on the generated results it was concluded that: (i) the pattern of kinematical changes depends on which muscles are strengthened, while the magnitude of the changes depends on how much the muscles are strengthened. (ii) Adjustment of muscle coordination, in some cases, can be performed without adjustment of neural control. (iii) The adjustment of neural control is done in an adaptive manner. (iv) Inter-segmental coordination is further altered if a smaller number of muscles are strengthened. (v) The main effect of equally strengthening all the muscles is an increase in joint torque, which is proportional to the increase in muscle strength.
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Effects of a Low-Load Gluteal Warm-Up on Explosive Jump Performance

75%
Comyns T., Kenny I., Scales G.
Journal of Human Kinetics
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2015
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vol. 46
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issue 1
177-187
EN
The purpose of this study was to investigate the effects of a low-load gluteal warm-up protocol on countermovement and squat jump performance. Research by Crow et al. (2012) found that a low-load gluteal warm-up could be effective in enhancing peak power output during a countermovement jump. Eleven subjects performed countermovement and squat jumps before and after the gluteal warm-up protocol. Both jumps were examined in separate testing sessions and performed 30 seconds, and 2, 4, 6 & 8 minutes post warm-up. Height jumped and peak ground reaction force were the dependent variables examined in both jumps, with 6 additional variables related to fast force production being examined in the squat jump only. All jumps were performed on a force platform (AMTI OR6-5). Repeated measures analysis of variance found a number of significant differences (p ≤ 0.05) between baseline and post warm-up scores. Height jumped decreased significantly in both jumps at all rest intervals excluding 8 minutes. Improvement was seen in 7 of the 8 recorded SJ variables at the 8 minute interval. Five of these improvements were deemed statistically significant, namely time to peak GRF (43.0%), and time to the maximum rate of force development (65.7%) significantly decreased, while starting strength (63.4%), change of force in first 100 ms of contraction (49.1%) and speed strength (43.6%) significantly increased. The results indicate that a gluteal warm-up can enhance force production in squat jumps performed after 8 minutes recovery. Future research in this area should include additional warm-up intervention groups for comparative reasons.
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