Extended Abstract
1. Introduction
Hearing loss is one of the most common sensory disorders in developed countries [1, 2] and is usually diagnosed in the first years of life. Three sensory systems are involved in controlling balance and posture, including visual, proprioceptive and vestibular systems. Among these, the vestibular system, in addition to control, plays an important role in human interaction with the environment [6]. Although various studies have focused on the analysis of gait in individuals with hearing loss [9, 17], biomechanical variables are not commonly considered in their activities including gait. Walking is a complex task that requires functional coordination of various biomechanical variables. Modification of walking techniques has recently been recommended as a part of rehabilitation programs [20].
Therefore, the biomechanical variables related to walking are of clinical importance and are used to provide feedback that can be used to evaluate the therapeutic effects or to plan rehabilitation programs. Despite assessments of balance, movement disorders, and factors related to health and quality of life, the gait of these individuals has not yet been properly examined [15]. Therefore, it is necessary to evaluate the kinematic pattern and gait variability of deaf children. The aim of this study was to analyze the gait variability of deaf people in comparison with healthy people at medio-lateral and anterior-posterior directions during walking.
2. Methods
The study population consists of all deaf and normal-hearing people living in Hamedan. Among them, 10 deaf people (aged 8-14 years) and 10 normal-hearing peers with similar age and anthropometric characteristics volunteered to participate in the study. The 3D Vicon motion analysis system was used to measure the kinematic gait variables in both groups. After the pre-test assessment, subjects participated in the proprioception training program for 4 weeks, 3 sessions per week each for 45 minutes with an emphasis on the proprioceptive system. After the training period, a post-test assessment was performed. In this study, the spatio-temporal gait parameters were extracted using Polygan version 3.5.2 software, and the formula (coefficient of variation) was used to calculate the variability of these parameters. Paired t-test was used for within-group comparison and independent t-test was used for between-group comparison. All statistical analyses were performed in SPSS software by considering a significance level of (P<0.05).
3. Results
The results of within-group comparison showed that variability in parameters cadence and gait speed, stride length and step length, stride time, step time, double-leg support time, single-leg support time, opposite leg support time and swing time was not significantly different before and after proprioception training. This indicates that gait variability was not affected between groups after exercise and the difference between the two groups was not significant (P>0.05).
4. Discussion
Most children who have vestibular disorder are not diagnosed because they have the ability to walk [23], but these children do not participate in games and outdoor activities, and teachers often complain of poor balance and coordination in these children that may prevent them from performing ideally [24]. In the present study, it was shown that the difference between the deaf and control groups when walking in normal position was high, but not significant. However, when walking, the gait speed decreased significantly in deaf children compared to healthy peers. 
Proprioception training could not have a significant effect on gait speed and cadence, but the difference between the two groups after exercise was reduced; however, deaf children still had a slower gait speed after exercise therapy. Despite assessments of balance, movement disorders, and factors related to health and quality of life, there is still no educational program for these children except in cases where neurological and orthopedic injuries have been identified [15]. The results of several studies consistent with these results have shown that the gait speed in deaf people is slower than in healthy people [9, 25, 26]. Studies have also shown that deaf people have poor cognitive function, especially executive function [27, 28]. The association between impairment in executive function and gait has been confirmed by several studies [29-31] which is clearer during dual-task walking.

Ethical Considerations
Compliance with ethical guidelines
All subjects voluntarily participated in the present study after signing a consent form.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-profit sectors.
Authors' contributions
All authors contributed in preparing this article. 
Conflicts of interest
The authors declared no conflict of interest