Introduction
Student life and the university environment are stressful, and students face academic, financial, marital, behavioral, and social problems. Therefore, the prevalence and incidence of psychological and physical injuries in students are higher than in the general population. One of the psychological needs of human beings is the feeling of self-worth or self-esteem. Numerous studies report that high self-esteem is the key to success in people. Self-esteem is an essential and effective psychological factor in health and quality of life. Happiness is one of the main components of quality of life in all age groups, especially students. Happy students have a high concentration level and can solve problems with the least energy when facing problems and adverse situations. There is a wealth of evidence that regular physical activity promotes mental health, reduces the symptoms of depression and anxiety, and increases life satisfaction and quality of life. Given the importance of happiness and self-esteem in individuals, especially students, we decided to investigate the effect of exercise on the self-esteem and happiness of operating room students.
Methods
The present study is a quasi-experimental study with a pre-test-post-test design with a control group. The study population comprised all female students in the operating room of the School of Nursing and Midwifery of Arak University of Medical Sciences. The research sample included 80 female students selected by convenience sampling and then randomly divided into experimental and control groups. After giving the informed consent form, the students completed questionnaires about personal information, self-esteem, and happiness. Then, the samples of the experimental group walked individually for 30 minutes a day (afternoon) for eight weeks, while the students of the control group did not participate in any organized training programs or regular sports activities during this period. After eight weeks of walking, the subjects were again asked to answer the questionnaires carefully. The study data were analyzed in SPSS-16 using descriptive-(mean and standard deviation) and inferential statistics (paired and independent t tests due to the normal distribution of data). The significance level in this study was P<0.05.
Results
The mean age of the experimental group (21.65± 0.24 years) and the control group (21.7±0.35 years) show no significant difference between the two groups (P=0.16). There was no statistically significant difference between the control and experimental groups before the intervention in the mean scores of self-esteem (P=0.63). Nevertheless, after the intervention, a statistically significant difference was observed in the mean scores between the experimental and control groups (P=0.04) (Table 1).


Also, the happiness score in the post-intervention stage in the experimental group increased compared to the control group (P=0.013) (Table 2).


Discussion
Exercise can play an influential role in increasing students’ self-esteem and happiness, thereby promoting their mental health and improving their quality of life. Therefore, it is recommended that sports programs be held at the university to promote happiness and increase students’ self-esteem.

Ethical Considerations
Compliance with ethical guidelines
The present article’s ethical code (IR. Arakmu. REC. 1395.70; IRCT2016090519102N4) was received from Arak University of Medical Sciences. Ethical principles were observed that included obtaining permission to conduct research, taking informed written consent of research participants, having no obligation to participate in research and keeping confidential information obtained from them, and announcing research results without mentioning the names and personal details of students.

Funding
This article results from a research project approved by the Student Research Committee of Arak University of Medical Sciences and funded by the Deputy for Research and Technology of Arak University of Medical Sciences.

Authors' contributions
All authors equally contributed to preparing this article.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank the Deputy for Research and Technology of Arak University of Medical Sciences and all students who participated in this study.



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