Introduction
The COVID-19 pandemic, quarantine and related restrictions have affected many aspects of life, including physical activity and mood. Therefore, compliance with restrictive rules and measures, such as social distancing, requires the highest level of self-control for people (14). In the meantime, regular exercise and physical activity can have psychological benefits such as recovery from disease, psychological well-being and prevention of depressive symptoms, and be effective in maintaining mental health and help reduce other chronic diseases and physical disabilities during the pandemic.
Since general quarantine was effective in preventing and controlling the COVID-19 and responding appropriately to its effects on mental disorders, its implementation for controlling or preventing infectious diseases is important. The question that arise is that when, why and under what circumstances the government can fulfill its duty for imposing quarantine measures during the COVID-19 pandemic? In this regard, the present study aims to investigate the relationship between physical activity and mood disorders of athletes in racket sports while are in general quarantine during the COVID-19 pandemic.
Materials and methods
This is a descriptive-correlational study with cross-sectional design. The study population consists of all badminton and table tennis players in Iran from April to June 2020. In this regard, 196 athletes (123 males and 73 females) were finally selected using a convenience sampling method and after removing incomplete questionnaires. Physical activity  levels were measured by inquiring about the type, frequency and intensity of training (from low to very high) before and during the COVID-19 pandemic, that were extracted from the 5-item physical activity questionnaire developed by Cho and has acceptable reliability and validity. The face validity of its Persian version was confirmed by 10 experts and its reliability was determined through a pilot study on 30 respondents using Cronbach’s alpha which was reported 0.89. To evaluate the mood states of participants, we used the short form of Brunel Mood Scale (BRUMS). Although this instrument has 65 items rated on a five-point scale (from 0 = No to 4= Extremely), we used its 16 items (12 for negative mood and 4 for positive mood). The internal consistency (Cronbach’s alpha) of the subscales and overall scale ranges from 0.82 to 0.96. In the present study, Cronbach’s alpha for the overall scale was obtained 0.90.  Data were analyzed in SPSS v.22 by using descriptive statistics for demographic characteristics (such as age, gender, educational level, etc.) and inferential statistics including Kolmogorov-Smirnov test, chi-square test, ANOVA and Pearson correlation test. The significance level was set at 0.05.
Results
 Findings showed a negative significant relationship between mood states and changes in the intensity of training caused by the pandemic (Table 1).


The intensity of training compared to the duration of training was able to affect the mood states of athletes; as the intensity of training increased, the mood decreased.
Discussion
Based on the results of the present study, it can be concluded that physical activity has a positive effect on the mood states of racket players. Physical activity is associated with mental health such as mood, anxiety and depression, self-concept and mental health and the quality of life. The results of the present study indicated that quarantine of athletes in racket sports can have negative effects on their moods. Although this research is theoretically novel, but it had some limitations. Firstly, it was conducted only on table tennis and badminton players; therefore, it is not possible to generalize the results to other athletes. The second limitation was that the results were based on assessing correlations; it is not logical to explain and interpret the results based on cause-and-effect relationships. Therefore, experimental studies in this field are recommended. It seems that, by observing health protocols, moderate-intensity physical activities can have a positive effect on the mood of athletes in racket sports, which can help them comply with quarantine and social distancing measures.

Ethical Considerations
Compliance with ethical guidelines
This study obtained ethical approval from the Sport Sciences Research Institute of Iran (Code: IR.SSRC.REC.1399.070).

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors.  

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

Conflicts of interest
The authors declare no conflict of interest

Acknowledgements
The authors would like to thank all participants as well as the Sport Sciences Research Institute of Iran for their cooperation and support.

 

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