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Showing 3 results for Impulse
omparison of effects of two type resistance exercises on vertical force and impulse caused by diagonal blows on the spike skill of female volleyball players
Dr Mohsen Barghamadi, Miss Roghayeh Parsa, Dr Amir Fatollahi,
Volume 0, Issue 0 (11-2019)
Abstract
Volleyball players are looking to apply their force at a short  time speed  to  transfer more  diagonal  and vertical blows  on the ball  so  that  you land  on the  opposing  team's field more quickly and make it  difficult for the  opposing  team players to  receive. It seems that various types of resistance training can improwe the vertical force of the spike skill.
Therefore the aim of the current study is to compare the effects of two types of resistance training (exercises with cable machines and exercise with barbells and free weights) on vertical force and impulse caused by diagonal hit on spike skill in college girl volleyball players. The present study method was semi-experimental. The statistical samples in this study included 45 girl volleyball players from university of Mohaghegh Ardabili. In three groups of 15 in groups 1 and 2 strength training intervention for two days a week, in 7 strenght movements with a cable bodybulding machine and barbell, dumbbell, and medicine training tools, observing the principle of overload in three movement intensities: 80%, 5 repetition, 90%, 2 repetition, 100%, one maximum repetition and in the third group in the form of a control group were identified. Strength training as an independent variable and vertical force and impulse as a dependent variable. Bertek force plate was used to record ground reaction forces. The table was used to adjust height, the invisible thread and the ball for the dominant hand shot in the volleyball players. In this study, ANOVA test was used with a significance level of 0.05. The effects of the force resulting from the diagonal impact on the ball in line with the vertical force of the ground reaction were significant in intervention group 1 (p< 0.008) and intervention group 2 was not significant (p< 0.133).The effect of the impulse time factor in the strength training group was significant in the vertical component of the ground reaction in intervention group1 (P<0.030) and in intervention group 2 (P<0.023). The difference between the groups in the intervention group shows the effect of the vertical force factor in the intervention group 1 with the impact factor (v = 0.016) compared to the group 2 also, in the impulse factor, impact factor was effective in intervention group1 (v = 0.190) and strength training in intervention group 2 (v = 0.167).  It seems that barbell and medicine ball strength exercises increased force in diagonal strikes and produce the maximum vertical force in the shorter time to the ball in the spike skill of the diagonal strike of the volleyball players.

Immediate effects of femoral external rotational and abductoral taping on ground reaction force characteristics during running
Dr Amir Ali Jafarnezhadgero, Mrs Elham Sorkheh, Mr Goodarz Ghiasvand,
Volume 15, Issue 14 (10-2017)
Abstract
Introduction and aim: Taping is a common method used by athletes to improve muscular function. The aim was to assess the immediate effect of femoral external rotational and abductoral taping on three-dimensional ground reaction force characteristics, their time to peak, impulse, displacement of center of pressure, vertical loading rate, and free moment during stance phase of running. Method: 24 healthy men (age: 24.6±2.5 years; mass: 74.8±6.2 kg; 177.1±7.9 cm) were included in the study. Ground reaction force data was recorded by a Kistler force platform (sampling rate: 1000 Hz). Paired sample t-test was used for statistical analysis. Results: Compared to without taping condition, taping significantly reduced the peak impact and peak active vertical ground reaction forces during stance phase of running (P≤0.05; low to moderate effect size). Taping application increased and decreased the vertical loading rate (19%, P=0.047, moderate effect size) and the peak free moment values (P≤0.001), respectively. The values of the anterior-posterior and vertical impulses during taping condition were greater than that of without taping condition (P≤0.001; low effect size). Conclusion: Femoral external rotational and abductoral taping could improve the values of free moment, but this is not the case in vertical loading rate during the stance phase of running.
The effect of corrective exercise on walking ground reaction force components in children with genu varus
A.a Jafarnezhadgero, F Ghorbanlou, S.m Alavi-Mehr, M Majlesi,
Volume 17, Issue 18 (12-2019)
Abstract
Genu varus is one of the malalignment of the lower limbs, the failure to correct it leads to secondary abnormalities in adulthood. The purpose of this study was to investigate the effects of a corrective exercise program on ground reaction forces, loading rates, impulses and free moment during stance phase of walking. 17 children with genu varus were volunteered to participate in this study (Age:11.71±1.68 years, Height:1.40±0.09 meter, Weight:35.14±11.47 Kg, and BMI:17.49±3.61Kg/M2). Ground reaction forces were recorded with two Kisler force plates during pre and post-test. At the dominant limb, the amount of time to peak in the mediolateral ground reaction force component during heel contact decreased by of 61.90% (P=0.011). Also, the time to peak of the vertical ground reaction force component during mid-stance tend to increase significantly by 11.47% during the post-test compared to the pre-test (P=0.063). The values of peak ground reaction force components, loading rate, impulse and free moment did not show any significant differences between pre and post-test. The findings showed that the corrective exercise trainings used in the present study had the most effect on the time to peak components of the GRF, but there were no significant effects on the loading rate, impulses, and free moment components. The corrective exercises used in the present study have had the most effect on the time to peak of ground reaction forces and improve them. On the other hand, these exercises did not have any significant effect on the vertical loading rate, impact and free moment values.

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