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Showing 4 results for Ground Reaction Force

Leila Najafi, Javid Mostamand, Ali Amiri, Behzad Mahaki,
Volume 3, Issue 4 (1-2014)
Abstract

Introduction: The aim of the current study was to measure ground reaction force and center of pressure (COP) during lower extremity perturbation in single leg standing whit knee flexion and extension in healthy subjects, in addition to revealing reliability of the device used for the related perturbation for using another studies, reliability is one of the characteristic of measuring instrument , this indicates that measuring instrument to what extent in the same conditions gives the same results. Materials and method: perturbation device was built firstly, rotational perturbation (trunk and femur rotation on weigh bearing tibia ) were applied to the dominant leg of 13 healthy subjects during single leg standing . Four models of rotational perturbation (external and internal tibial rotation with knee flexion and extension) were applied to the lower extremities to collect ground reaction force and centre of pressure in these subjects. Subjects attached to lower extremity perturbation device and standing whit single leg on force plate. Subjects were then asked to repeat the tests procedure after a week’s interval. Results: The intra class correlation coefficient and Cronbanch's Alpha values during within and between sessions tests for four models of rotational distributions showed the relatively high reliability of these measurements during single leg standing , the intra class correlation coefficient exceeded 0.7 in all dominants. Conclusion: The relatively high reliability of ground reaction force and centre of pressure measurements during four different perturbations of external and internal tibial rotation with knee flexion and extension in healthy subjects suggests that these measurements can be used during single leg standing in future studies.

Faraj Fatahi, Gholamali Ghasemi, Mohamad Taghi Karimi,
Volume 6, Issue 2 (7-2016)
Abstract

Purpose: Core stability training (CST) has increased among athletes. The study hypothesis is that neuromuscular training and exercises of central area of trunk, pelvis and hip can reduce injury risk, and specifically peak vertical ground reaction forces in drop landing task. Therefore, the objective of this study was to evaluate kinetics during single leg drop landing test following a CST intervention.
Methods: The present research was a quasi-experimental study with pretest/posttest and a control group. After giving their informed written consent, 30 athletes (15 in the experimental group, and 15 in the control group) volunteered to participate in the training program consisting of CST sessions, 3 times per week for 8 weeks. Training group was performed the CST during 8 weeks but control group did not perform these exercises. Kinetics variables in pretest and posttest during single-leg drop landing were measured by motion analysis and force plate device. To compare the obtained data, mixed ANOVA repeated measure at significance level of P<0.05 was used. All analyses were done by SPSS 22.
Results: The results revealed that the peak vertical ground reaction forces, loading rate, and average loading rate significantly reduced following 8 weeks CST intervention (P<0.05).
Conclusion: This study shows evidence that core stability training improves landing kinetics, and may reduce lower extremity injury risk in athletes.


Arefeh Mokhtari Malekabadi, Amirali Jafarnezhadgero, Farshad Gghorbanlou,
Volume 10, Issue 4 (10-2020)
Abstract

Purpose: The current study aimed to evaluate the effects of barefoot and shod running with two different styles on ground reaction force-frequency content in recreational runners with low arched feet.
Methods: The statistical sample of this research was 13 males with Pronated Feet (PF) (Mean±SD age: 26.2±2.8 y; height: 176.1±8.4 cm; weight: 78.3±14.3 kg). A force plate (Bertec, USA) with a sample rate of 1000 Hz was used to record the reaction forces under each foot. Three test conditions in our study included shod running with rearfoot, midfoot, and forefoot patterns. Repeated-measures Analysis of Variance (ANOVA) was used for analyzing the data.
Results: During forefoot running, the research subjects attained 10% higher GRF values in vertical direction, compared with rearfoot running (P˂0.001, d=2.133). Forefoot running decreased the peak vertical GRF, compared to rearfoot running (by 12%, P=0.01, d=0.826). Barefoot running decreased the peak vertical GRF, compared to shod running (by 6%, P=0.027, d=1.143). The collected results revealed a significantly lower FyMed (P<0.02, d=1.11, 14%), Fy99.5% (P<0.02, d=0.11, 8%), and greater FyNe (P<0.02, d=0.72, 10%), Fz99.5% (P<0.01, d=4.30, 124%), and FzNe (P<0.01, d=1.65, 44%) when running with rearfoot strike pattern, compared with forefoot strike pattern.
Conclusion: The study subjects with pronated feet experienced greater GRF values during forefoot running than rearfoot; such data may imply an increased risk of running injuries. Therefore, forefoot running is not recommended for runners with pronated feet.

Dr. Milad Piran Hamlabadi, Dr. Amirali Jafarnezhadgero, Ms Kimia Hoseinpour,
Volume 14, Issue 4 (10-2024)
Abstract

Purpose: Footwear used by military individuals is essential to be scientifically evaluated during daily activities. This research aims to examine muscular activities while running with rubber’s new boots compared to used boots in men with healthy and pronated feet.
Methods: Twenty-four men aged 20-25 years (12 men in the pronated group, and 12 men in the healthy group) participated in this research using the convenience sampling method. The subjects received two used and new boots. The boots were made of rubber. Electromyography (EMG) data of the dominant limb were collected while running at constant speed. 
Results: The main effect of “boot type” for semitendinosus muscle activity (P=0.018, η2=0.248) during the loading phase and tibialis anterior (P=0.041, η2=0.177) during mid-stance. 
Conclusion: Rubber boots mileage effect on selected muscle activities in men with and without pronated feet. The use of used rubber boots can increase running-related risk factors. 


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