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Background and aim: Flexible flat foot is a common deformity in lower extremity, the foot arch collapses and the ground reaction forces does not apply properly to the foot. Backward walking is a common rehabilitive technique and is utilized to improve strength and balance. The purpose of this present study is to compare the salient points vertical ground reaction force measurements in flat foot patients while walking forward and backward with those of healthy subjects using a force plate system.
Materials and methods: 10 flexible falt foot female subjects  and 10 healthy female  subjects were  recruited to participate in this study. Each Subject walked 5 times forward and 5 times backward and the vertical ground reaction force was measured by a force platform.
Results: The results of this present study suggest a significant difference in kinetic pattern of forward walking compared to backward walking in both healthy and flexible flat foot participants. The force related to first peak of vertical ground reaction force was significantly less in forward walking compared to backward walking (p=0.000). Whereas the force related to trough and second peak of vertical ground reaction force were significantly high in forward walking compared to backward walking (p=0.000).
Conclusion: The results of this study show that backward walking changes the ground reaction force compared to forward walking and the main characteristic of this difference is due to decrease of forces applied to the heel of foot which may be important in flat foot patients.

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Background: Flexible flat foot is a congenital common deformity in lower extremity associated with ligamentus laxity. This deformity may cause hammer toe, heel spur, inflammation of achille tendon, early muscle fatigue during sport, foot imbalance and pain in leg, knee and hip. The use of insole with medial arch support considered as one of the common treatments for patients. The purpose of this study was to determine the effect of a composite insole, Ethyl Vinyl Acetate (EVA) with Poron layer on ground reaction force on subjects with flexible flat foot in comparison with common EVA insole.

Materials and Methods: Fifty two subjects (14 Male and 38 female) between 18-40 years of age with flexible flat foot participated in this study. Twenty six subjects received Poron insole (EVA with Poron layer) and 26 subjects received common EVA insole. After assessment each subject asked to walk with normal speed across two force plate in two conditions, walking with insole and shoe and walking without insole. Then each subject asked to use insole for forty hours during two weeks. Vertical ground reaction force in the first session and after two weeks was assessed.

Results: Impact force and first peak of vertical ground reaction force (F₁) with Poron insole in comparison with shoe significantly increased in second session (P<0.05). The second peak (F₃) with common insole in comparison with shoe significantly increased in second session (P<0.05). Significant reduction was noted in first peak (F1) with common insole in second session in comparison with first session (P<0.05). There was no observable significant difference in two groups before and after intervention.

Conclusion: The results of this preliminary study show that both insoles change vertical ground reaction force in comparison with shoe alone. But using a composite Poron Layer on EVA insole has not demonstrated a significant difference with common arch support insoles. Therefore application of Poron Silicon layer on EVA insole by itself can not show a significant reduction of ground reaction force.

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Background and aim: One of the common problems in elderly people is falling. The effort to identify environmental risk factors at home and their modifications may control falls and injury in the elderly. Home FAST as a valid and reliable screening tool is used to identify elderly at risk of falling at home and in society.
Materials and methods : International quality of life assessment (IQOLA) was used for validity and reliability of Home fast. After forward and backward translation , the questionnaire was evaluated for content validity by 5 occupational therapists. Sixty participants aged over 65 were randomly selected through five geographical regions of Tehran. Inter-rater and test-retest with one week interval were conducted by two occupational therapists.
Results: Agreement among experts about the validity of screening tool of Home FAST (χ²= 25.008) were more than 96%.The correlations of test-retest with relative and absolute coefficients were high (ICC = 0.72 and SEM = 0.89). Also, the correlation coefficients between the raters with absolute and relative (ICC = 0.88 and SEM = 0.54) were significant, indicating the high reliability of this test.
Conclusion: This study shows the reliability and validity of the test are high. Since, test items are conformable to fall prevention goals, these results can be expected. The tool can be used by professionals.

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Background and Aim: An immaculate review of the literature reveals some changes on the vertical ground reaction force (VGRF) in ACL deficient knee subjects. However, the details are not clear yet. The current study aimed to study these changes in the ACL-deficient and apparently healthy knees of the coper and non-coper ACL-deficient knee subjects in comparison with the normal knees.

Materials and Methods: Sixteen unilateral ACL-torn subjects included 8 copers and 8 non-copers were recruited in this quasi-experimental study and were compared with 16 normal knee subjects (8 subjects matched to each coper and non-coper groups). All subjects walked barefoot and with their preferred speed in a 6-meter walkway and placed their wanted foot on the platform of a Zebris pedobarograph tool. The patients were asked to place their injured and healthy feet separately on the platform. The control group placed their foot matched to the ACL-deficient legs on the platform. The testes were repeated so much to have five acceptable trials. The outcome measures included the peak F1Z, F2Z, F3Z of the vertical ground reaction force values and the times to reach these peak values as well as total stance time of the tested feet.

Results: The results showed only a significant lower F₁Z value in the non-coper ACL-deficient knee subjects (p=0.008). No significant changes were shown in the F₂Z, F₃Z or the times reach to F₁Z, F₂Z and F₃Z values (p>0.05). The stance time of the coper ACL-deficient knee subjects increased significantly in the non-coper ACL-deficeint knee subjects when compared to the coper and healthy knees (p=0.005).

Conclusion: The reduced F1Z of the vertical ground reaction force at initial contact as well as increased total stance time seen only in non-coper ACL-deficient knee subjects reveals inadequate compensatory mechanism in these patients as a counter force stress at initial contact and weight bearing. However, the coper ACL-deficient knee subjects compensated these forces with good strategies and walked very similar to the control group.

Keywords: Vercial ground reaction force (VGRF), Time to peak vertical ground reaction force components, Coper & non-coper ACL-deficient knee subjects, Pedobarography.

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Background and Aim: Anterior cruciate ligament (ACL) injury is common in sports competition and training. Following ACL rupture, neuromuscular system performance is disrupted. Perturbation training can improve the function of patients with ACL reconstruction. The aim of the present study was to assess the effects of perturbation training on ground reaction force and functional status of these patients .

  

Materials and Methods: Twenty patients with ACL reconstruction were randomly assigned into intervention (mean age: 24/2 ±3/4 years) and control (mean age: 27/1 ± 2/5 years) groups. The intervention group performed ten sessions perturbation training with rocker board, wobble board and Bosu. Peak vertical ground reaction force (GRF) and time to peak vertical GRF were recorded by KISTLER force plate during single leg landing from a 30cm height step. In addition, cross hop test also was evaluated as a functional test.

  

Results: Before perturbation training, both GRF and time to peak vertical GRF in reconstructed knee had not significant difference between two groups (P>0/05). In addition, functional test score had not significant difference between the groups (P=0/62). Following perturbation training, peak vertical GRF in reconstructed knee was greater than that in control groups (P<0/003).Although time to peak vertical GRF in reconstructed knee increased, there was not statistically significant difference between two groups (P=0/50). Furthermore, functional test score was statistically greater in intervention group (P=0/03).

  

Conclusion: This s tudy showed that perturbation training can improve functional status in patients with ACL reconstruction. In addition, force plate findings indicated that the patients tolerated more forces at longer time in single leg landing.

  

Key words: Perturbation training, Ground reaction force, ACL reconstruction, Function