Changes in physical activity level of adolescents and its relationship with mental health during regular COVID‐19 prevention and control

Abstract Purpose This study aimed to analyze the impact of regular prevention and control of COVID‐19 on the physical activity level (PAL) of adolescents and the relationship between PAL and mental health. Methods Using the convenience sampling method, two stages of the on‐site cross‐sectional investigation were conducted in 11 middle schools in Guiyang City in China. There were 1132 participants who completed the Physical Activity Questionnaire for old children (PAQ‐C) in October 2020, and 1503 participants who completed the PAQ‐C and Mental Health Inventory of Middle‐school students (MMHI‐60) in October 2021. All participants reported their demographic data. Descriptive, quantitative statistics were used for data analysis. One‐way ANOVA was used to explore associations between PAL and mental health. Results The results of statistical analysis showed a gradual yearly increase in the PAL of teenagers, and the PAL of male junior middle school students has a significant increase (p < .05); while that of adolescents in Grade 10 significantly decreased (p < .001). There is a statistically significant correlation between adolescents’ mental health (except for anxiety) and PAL (p < .05). The overall abnormal rate of mental health was 27.9%; The PAL and the total mean score of mental health had a negative correlation (p < .001). There was a significant difference between mental health scores and corresponding PAL (p < .001). Furthermore, there are statistically significant differences in scores of mental health factors corresponding to varying PAL among junior high school students and male students (p < .05). Conclusions The regular epidemic prevention and control measures had significant adverse effects on the PAL of girls and high school adolescents, especially Grade 10 adolescents. Improving adolescents’ PAL can promote their mental health. Interventions based on PAL slightly lower than the level recommended in the physical activity guidelines can bring significant mental health effects.


INTRODUCTION
According to the World Health Organization (WHO), 81% of adolescents aged 11−17 worldwide do not engage in enough physical activity (World Health, Organization), and one in seven (14%) adolescents aged 10−19 have experienced mental health problems (World Health, Organization). The coronavirus disease 2019 (COVID-19) pandemic has had a severe impact on the mental health and well-being of people worldwide (World Health, Organization); "isolation and social distance associated with COVID-19 lead to a higher incidence of anxiety and depression" (Pearson, 2020). In the first year of the COVID-19 pandemic, the physical activity time of children and adolescents showed a decline. Research shows that physical activity is related to positive mental health outcomes (Paterson et al., 2021). David Nieman suggests engaging in moderate-intensity exercise during the  pandemic to enhance the immune system and eliminate the negative effects caused by aging, obesity, and lack of physical activity (Ainsworth & Li, 2020). Declining physical activity trends among adolescents are a key global health problem, affecting their cardiovascular metabolism and mental health (van Sluijs et al., 2021).
In April 2020, "guarding against imported cases and preventing a resurgence of the outbreak at home" and orderly "restart" of economic and social activities became the focus of the epidemic prevention and control work in China ( , 2020), marking the entry of China into the regular prevention and control of COVID-19. Regular epidemic prevention and control measures, such as maintaining social distancing, have led to limited peer communication among adolescents and changes in the structure of daily life, which may have hidden adverse effects on the physical and mental health of adolescents (Oberle et al., 2010). Measures such as home quarantine and social distancing during an epidemic also cause a certain negative impact on physical exercise at all intensity levels (Ammar et al., 2020).
Children and adolescents experienced decreased physical activity and increased sleep in the first year of the COVID-19 pandemic (Ainsworth & Li, 2020). In the United States, the physical activity level (PAL) of people aged 3−18 years decreased significantly (Tulchin-Francis et al., 2021). Therefore, the mental health of children and adolescents in the post-epidemic era cannot be ignored ( , , & , 2021). Furthermore, physical exercise plays a more decisive role in an epidemic caused by a major infectious disease in that it can alleviate psychological stress and stabilize the emotional state, improve the body's immunity, and has a placebo effect ( , & , 2020 COVID-19 on physical and mental health (  ,  ,  & , 2021), further research is required to assess the effects of different levels of physical activity on mental health during the COVID-19 pandemic (Abdelbasset et al., 2021). Therefore, studying the adolescent physical activity change trend and mental health status and their relationship in the post-epidemic era can not only help understand the impact of COVID-19 on adolescent physical activity and enrich the research on the relationship between adolescent PAL and mental health but also acts as a theoretical reference for adolescent physical activity and mental health intervention.

Sample size
The sample size was calculated according to the following predictive equation ( , 2010): When α = 0.05, p = .5, then k = 1.96; The expected effective response rate of the questionnaire is 80%. Due to the fact that adolescents aged 12-18 are actually divided into two qualitatively different groups: middle school students and high school students, the sample size for each group is ≥ 482, and the total sample size is ≥ 964. The sample size for both stages is≥ 964, thus meeting the sampling requirements.

Measuring tools
The self-made questionnaire, Physical Activity Questionnaire for Chil- Medium physical activity level (MPAL) is the level of physical activity slightly below the recommended guidelines. Low physical activity level (LPAL) stands for physical inactivity. Furthermore, based on the MMHI-60 scores reflecting the overall psychological health status, adolescents were divided into two categories: the normal group and the abnormal group. Since the sample size of the more severe and above grades was extremely small, the status of each mental health factor was divided into four grades: normal, mild, moderate, and more severe and above.

Research subjects
The study was approved by the Academic Ethics Committee of the

Statistical tools and methods
Statistical significance was set at p < .05. All statistical analyses were conducted using the statistical package for the social sciences (SPSS-26.0 software, Armonk, NY, USA).

Changes in adolescent PAL
The average PAL of adolescents between 2020 and 2021 ranged from 2.47 to 2.49; the PAL in 2021 was slightly higher, but the difference  Table 2).

Descriptive statistics and correlation analysis
The total average score of adolescent mental health was 1.72 ± 0.63, and the score of each psychological factor ranged from 1.59 to 1.91, which was lower than the overall critical value of 2, indicating that most adolescents had good mental health. The overall level of mental health was at an abnormal rate of 28%. A higher value of the total mean score of adolescent mental health and the mean score of all individual factors indicate higher abnormal rates. The abnormal rate of the health status of each psychological factor was between 24.4% and 42.3%: obsessivecompulsive symptoms and emotional imbalance had an abnormal rate of over 40%; anxiety, learning pressure, and depression had an abnormal rate of over 30%; psychological imbalance was the only factor with an abnormal rate slightly lower than 25%.
The correlation coefficient between adolescent PAL and the total mean score of mental health and scores of each psychological factor ranged from −0.86 to −1.43. Except for anxiety (p = .001), all other nine psychological factors and the overall mean score of mental health and PAL had statistically significant p values (p < .001). Thus, high school teenagers' PAL corresponded to decreased mental health scores and increased mental health levels (see Table 3).

Relationship between adolescent PAL and mental health
The mean score of overall mental health and the scores of all 10 psychological factors decreased with the increase in PAL; that is, the mental health score corresponding to LPAL was the highest, and that corresponding to VPAL was the lowest (except for the obsessivecompulsive symptoms factor). The difference in the correlation scores TA B L E 2 Statistical description and ANOVA of adolescent physical activity level. .000
From the perspective of gender, except for the equal scores for maladjustment, mental health scores for all other factors were higher for female students than for male students; that is, male students were more likely to have maladjustment problems than female students, while female students were more likely to have issues with overall mental health and the other nine mental health factors (see Table 4).
The results of one-way ANOVA showed a statistically significant correlation between adolescents' overall mental health and other health factors (except for anxiety which did not show a significant correlation) with different levels of physical activity (p < .05). Furthermore, there were statistically significant differences in scores of mental health factors corresponding to varying levels of physical activity between junior high school students and male students (p < .05).
From the perspective of gender, male students had significant differences in mental health scores corresponding to different levels of physical activity. For female students, only the total mean score of mental health, paranoia, and psychological imbalance showed significant differences for varying levels of physical activity. There were significant differences in mental health scores corresponding to different levels of physical activity among junior high school students. However, only obsessive-compulsive symptoms showed a significant difference in scores corresponding to varying levels of physical activity among senior high school students. This indicates that mental health scores corresponding to different levels of physical activity differ by gender and age (see Table 5).

Adolescent PAL
Based on the PAQ-C/PAQ-A classification (Benítez-Porres et al., 2016; Chen et al., 2008;Dan et al., 2007), the PAL of adolescents in the postepidemic period was found to be in a medium and low state, which was consistent with the "low high-intensity physical activity level among children and adolescents in China" ( , , & , 2019) in the pre-epidemic period. Furthermore, adolescent PAL in this study conforms to the reports that "adolescent physical activity level gradually decreases with age" (Voss et al., 2013). The PAL of female students was lower than that of male students, which is consistent with the findings of previous studies ( ,  distancing during the epidemic also harmed physical exercise at all levels of intensity (Ammar et al., 2020).
Because the government has adopted the strictest normalized epidemic prevention and control measures, such as "social distancing," " lock-downs," "closure of sports halls and gymnasiums" to mitigate the spread of COVID-19 in China. These approaches restrict the mobility, daily activities (Ammar et al., 2020;Ammar et al., 2020;Trabelsi et al., 2021), and social interactions of the individuals (Ammar et al., 2020;Ammar et al., 2021). So, the reduction in PA time and step counts was accompanied by increased behavioral stress during COVID-19 lockdown (Dergaa et al., 2022).
The findings in this study showed that adolescents in China adapted to the regular prevention and control of COVID-19 and their PAL gradually increased, returning to the level before the epidemic. In particular, junior high school boys significantly improved their level of physical activity.

Adolescent mental health level
Symptoms of psychological distress and disorder have been widely reported in people under quarantine during the COVID-19 pandemic . Two studies indicate that the COVID-19 outbreak engendered anxiety, depression, sleep disturbances, and other psychological issues in China (Qiu et al., 2020;Wang et al., 2020). The abnormal rate of overall mental health among adolescents was 27.9%, higher than the average reported by WHO. The abnormal rate of each mental health factor ranged from 24.4% to 42.3%, slightly lower than the rate reported by studies   There was conclusive evidence to support the potential negative impact of the pandemic on adolescent mental health. Stressful life events, extended home confinement, worry, overuse of the internet, and social media are factors that could influence the mental health of adolescents during this pandemic (Jones et al., 2021). Globally, adolescents of varying backgrounds experience higher rates of anxiety, stress , and depression (Duan et al., 2020;Ellis et al., 2020;Qi et al., 2020;Tee et al., 2020;Zhang et al., 2020) due to the pandemic.
In China, due to the heavy learning tasks of middle school students, parents and children lack sufficient communication in their daily lives. To some extent, this situation has been improved and has also alleviated some of the psychological burden on teenagers during the epidemic. Because studies have shown that the implementation of social support leads to positive mental health outcomes (Qi et al., 2020). The positive benefits were related with coming in closer and having more family discussions between parents and their children during COVID-19 home quarantining (Tang et al., 2021). Therefore, the changes in the mental health status of adolescents are relatively small during COVID-19.

Adolescent physical activity and mental health
There was a positive correlation between adolescents' PAL and mental health, and the differences between LPAL and various mental health factors (except anxiety) corresponding to MPAL or VPAL were statistically significant. In particular, emotional imbalance and obsessivecompulsive symptoms corresponding to LPAL were in an abnormal state, indicating that good mental health effect could be achieved if the PAL was slightly lower than the level recommended by physical activity guidelines, and there was no significant difference between the mental health level and the recommended PAL. Research has shown that "moderate and above physical activity improved the mental health of adolescents, but no such association was found in low-intensity physical activity" (Duan et al., 2020;Ellis et al., 2020). This study showed that mental health benefits brought by different levels of physical activity differed based on gender, age, and other psychological factors, indicating that PAL-based interventions will have different effects in improving adolescents' mental health.
Physical inactivity and reduced PA levels are associated with increased levels of anxiety during COVID-19 pandemic in Canada (Qi et al., 2020;Zhang et al., 2020), Brazil (Doré et al., 2016;Tang et al., 2021), France, and Switzerland (Costigan et al., 2016). It has been shown that physical activity has a substantial positive effect on mental health (Tee et al., 2020). It may be a very effective way to improve the mental health and physical health through promoting the PAL of teenagers.

Conclusion
During the regular prevention and control of COVID-19, the PAL of adolescents in China was generally medium and low. The findings of this study show that adolescents have adapted to the new normal, and their PAL has gradually returned to the level before the epidemic. Regular epidemic prevention and control measures mainly harm female and high school adolescents. The abnormal rate of adolescent mental health is within the normal range but is still high. The mental health level of senior high school students is higher than that of junior high school students, and of male teenagers is higher than that of female teenagers. There was a significant positive correlation between PAL and the mental health of teenagers. The findings suggest that a slightly lower PAL than the recommended level could significantly improve the mental health of teenagers. Improving VPAL can improve the overall mental health of middle school students and male students; however, there is a limited effect on the mental health of high school students and female students.
Therefore, if no distinction is made based on gender or age, mental health interventions for adolescents should consider a slightly lower level of physical activity than the recommended level. For male and junior high school adolescents, the recommended level of physical activity should be considered. For high school and female adolescents, PAL-based mental health interventions have limited effect; nonetheless, if PAL-based interventions are to be adopted, it is suggested to consider physical activities slightly lower than the recommended level.

Study limitations and future prospects
There are several limitations of this study. First, the data used in the research were obtained from self-administered questionnaires.
There might be memory bias in the data. Second, the samples in this study were all from Guizhou Province, with limited representation.
Future research should expand the geographical scope of the study and adopt a longitudinal survey design to further analyze the relationship between PAL and the mental health of teenagers.

AUTHOR CONTRIBUTIONS
Conceptualization, writing-review and editing, funding acquisition, investigation, methodology, software, formal analysis, Dong Ru-bao; data curation, writing-original draft preparation, project administration, supervision, Dou Kai-yun. All authors have read and agreed to the published version of the manuscript.

ACKNOWLEDGMENTS
The authors would like to thank all participants for their participation in this study.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE
Before the start of this study, informed consent was obtained from all participants. This study was approved by the Ethics Committee at the School of Physical Education of the Guizhou Normal University of China. All methods were carried out in accordance with relevant guidelines and regulations.
We declare that none of the authors holds any financial interests or conflict of interest associated with the ChatGPT or NLM technologies discussed in this paper. None of the authors has collaborated or consulted with any individuals or organizations that have a financial or other interest in the ChatGPT or NLM technologies. 1

CONSENT FOR PUBLICATION
No individual or indemnifiable data are being published as part of this manuscript.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.