Extended Abstract
1. Introduction
Apper Crossed Syndrome (UCS) is a type of musculoskeletal system involvement that results in shortening of the anterior muscles and weakening of the posterior muscles. Certain postural abnormalities are seen in those with UCS which includes the forward head, rounded shoulders, and thoracic kyphosis. This disorder has been developed due to the change of lifestyle from active to inactive. In today’s population, UCS is very common among all age groups. According to evidences, the prevalence of UCS is also high among the student community. 
One of the tools that have forced people to work for hours without mobility is computer. Students are among those who spend many hours per day working in front of a computer, where the upper body posture especially the neck, are misaligned which predisposes a person to upper limb abnormalities. In the spine region, hyperkyphosis means an increase in the kyphosis angle, which also affects the cervical and lordotic curvatures and causes the trunk to move forward more. 
The abnormal tendency of the trunk forward in kyphosis reduces the supportive role and flexibility of the spine, and causes chest, lung, and heart problems. Therefore, it is necessary to pay attention to the inappropriate postural conditions of students as the national assets of the country. Exercise in different conditions and with different tools can have a great impact on correcting posture. One of these exercises is physioball exercise. Using physioball can increase the activity of the muscles that produce movement, and this increase is in the muscles of different parts, including the shoulder girdle [21], lower limbs and trunk muscles. More muscle involvement during exercise is one of the most important goals of each type of exercise. The aim of the present study was to investigate the effect of selected corrective exercises with physioball on the posture of computer users with UCS.
2. Participants and Methods
This is a quasi-experimental study with pretest/posttest design. Twenty-four female computer users with head forward, round shoulder, and thoracic kyphosis were selected using purposive sampling method and randomly divided into two control (n=12) and exercise groups (n=12). photogrammetry method was used to measure the angle of forward head and round shoulder at the same time, and a flexible ruler was used to measure the degree of thoracic kyphosis. To measure chest expansion, the chest circumference was first measured at the end of the exhalation with a tape. The subject was then asked to take a deep breath. The chest circumference was measured again and the difference between the two measurement values was recorded. The change in forward head, round shoulder, thoracic kyphosis, and chest expansion were measured before and after exercise. ANOVA and paired t-test were used to analyze the data.

3. Results
The results of the present study showed a significant difference in thoracic kyphosis (P=0.001), round shoulder (P=0.001), forward head (P=0.002) and chest expansion (P=0.002) between pretest and posttest phases. Shapiro-Wilk test results indicate normal distribution of data for thoracic kyphosis and round shoulder (P>0.05), and abnormal distribution of data in forward head and chest expansion in study groups (P<0.05). Therefore, parametric methods of ANOVA and paired t-test were used to analyze the thoracic kyphosis and round shoulder variables and nonparametric Mann-Whitney U and Wilcoxon tests.

4. Discussion
Improvement in angles of forward head, round shoulders and kyphosis and chest expansion size in female computer users with UCS indicated optimal effectiveness of selected corrective exercises with physioball in improving posture. 

5. Conclusion
The present study focused on the muscles involved in this deformity, which was designed and implemented based on Janda’s chain reaction theory and the Brugger’s gear model. The exercises simultaneously affected all three postural deformities (hyperkyphosis, forward head, round shoulder), and the subjects participated actively and dynamically in the exercises. The use of this training program is recommended for computer users.
Ethical Considerations
Compliance with ethical guidelines
The present study obtained its ethical approval from the Guilan University of Medical Sciences (Code: IR.GUMS.REC.1397.480) and is a clinical trial registered by the Iranian Registry of Clinical Trials.
Funding
This study was extracted from the master thesis of first author approved by the Department of Sport Injuries and corrective Exercises, University of Guilan, Rasht, Iran.
Authors' contributions
Conceptualization, methodology, supervision: All authors; Investigation, writing original draft, resources: Parisa Sedaghati. editing & review: Fariba Javazi and Hasan Daneshmandi.


Conflicts of interest
The authors declared no conflict of interest. 
Acknowledgements
The authors would like to thank the Deputy for Research of the University of Guilan and all the subjects who sincerely participated in the present study.