University students are in a transitional period of growth, and the change of environment and the expectations of family and society for higher education imposes stress on university students, making some of them suffer from mental health problems. Depression is one of the common mental health problems among university students [1
], which may have an adverse impact on their academic performance and their future development [3
]. Various health behaviors have been indicated as risk factors of depression among this population. Due to the nature of the higher education system, sedentary behavior (SB) and lack of physical activity (PA) are some of them.
SB is defined as a person in a sitting or reclining posture requiring an energy expenditure lower than 1.5 metabolic equivalents [4
]. A recent systematic review showed that university students spend 7.29 h per day in sedentary activity based on self-reported data [5
]. Compared to the general young adult population, a considerable proportion of university students engage in higher levels of SB [5
]. The SB levels of some university students even surpass those of desk-based workers [6
]. Excessive SB has been found to be associated with an increased risk of depression according to a meta-analysis [7
]. Among various SB domains, self-reported screen time has been found to be significantly associated with adverse mental health outcomes, while there is no significant association of mental health outcomes with sitting time spent at work and transportation [7
PA has been shown to be associated with depression among university students [7
]. Some evidence suggests that high levels of PA can play a protective role as a counter to the negative effects of SB on all causes of mortality [15
], and on self-reported mental and social health outcomes in some regions [16
]. However, some studies show that SB is a risk factor somewhat independent of PA for depression in university students [17
], and for multiple adverse health outcomes in adults [7
Sport university students are expected to lead an active lifestyle. High levels of PA and low levels of SB have been believed to be associated with a positive self-concept and reductions in mental health problems, such as depression and anxiety [21
]. As a result, SB and PA in this population and their association with depression have received little attention. For studies focusing on this topic, the samples mainly originate from comprehensive university students [7
]. Although some studies have conducted surveys on the psychological problems of university athlete students, analyses of related factors are dominated by sociodemographic factors [22
]. Moreover, some systematic reviews showed that the prevalence of depression and other mental health symptoms during the COVID-19 pandemic was higher than before its outbreak in the pooled global population [26
], and that university students in China suffered from a higher prevalence rate of depression during the pandemic than in normal circumstances [27
]. Therefore, the depression of students of sports universities in China also warrants attention after the outbreak of COVID-19.
To this end, our study investigated depression, SB, and PA of students of a sport university and analyzed the association of depression with total and domain-specific SB and PA so as to provide a profile of depression and SB among this population and a reference for potential interventions in their lifestyle.
A cross-sectional survey was conducted on undergraduates majoring in physical education, a typical discipline in Beijing Sport University in March 2021, which included athlete students of physical education courses and non-athlete students of sport science courses. Undergraduates in grades 1 to 3 were asked to complete an online self-administered questionnaire. Senior students were excluded because they had been in internships and had not led a typical school life.
Measures for SB, PA, depression and demographic information were included in the online questionnaire.
Participants were asked to report their SB (h per day) across several domains: attending class, completing schoolwork, recreational screen time, socializing, performing hobbies, and any other sedentary activities over the last 7 days.
PA was investigated by asking the frequency of participation in vigorous physical activity (VPA refers to activity requiring significant physical effort and making someone breathe much harder than normal). Participants indicated their participation level by checking one of the following categories: every day, a few times a week, a few times a month, a few times a year, and under no circumstances.
Depression was measured using a nine-item Patient Health Questionnaire (PHQ-9). The responses were divided into four levels according to the frequency of symptoms in the past two weeks: never = 0 points, several days = 1 point, more than half of the time = 2 points, and almost every day = 3 points. The total score of the scale was 0 to 27 points. Those scoring 5 and above had depressive symptoms [28
]. This scale showed good validity in a previous study among Chinese university students [29
]. The Cronbach’s alpha value of these nine items was 0.89, which was larger than 0.70 and showed good reliability in this survey [31
Demographic information included gender, grade, profession, place of hometown, whether only child or not, parents’ marital status and monthly family income, body mass index (BMI), smoking and drinking. BMI was calculated based on self-reported weight and height (kg/m2). According to the Chinese Guideline for Overweight and Obesity Prevention, BMI ≥ 24 kg/m2 was defined as overweight.
The counselors were asked to provide the QR code for the online questionnaire in the WeChat group of each class. They provided and sent reminders a total of three times. Undergraduates completed the questionnaire anonymously and of their own free will. Informed consent was provided via the homepage of the online survey and was obtained when participants completed the survey. This study protocol was approved by the Ethics Committee of Sport Science Experiment, Beijing Sport University (2020046H).
2.4. Design and Data Analysis
The data were analyzed using the Statistical Package of the Social Sciences (SPSS Version 20; IBM Inc., Armonk, NY, USA). The median, inter-quartile range (IQR), mean, and standard deviation (SD) of total and domain-specific sedentary time were presented. Then, they were treated as dichotomous variables based on the median. The mean was used when comparing sedentary time with the other research reported in the Discussion section of this paper. The detection of depression, VPA, and demographic information was also treated categorically and was presented as number (%). The between-group differences were tested by the Chi-squared test (Bonferroni method). The association of depression with total and domain-specific SB and VPA was examined by a stepwise backward logistic regression, after adjusting for demographic information. Odds ratios (ORs) with 95% confidence intervals (CIs) were presented. The significance level was p < 0.05.
By investigating depression, SB, and PA of sports university students, it was shown that depression is commonly found among this population, and their sedentary time is close to the level of global university students. Our results provide evidence of the association of depression with total and domain-specific SB by showing that only recreational screen time was associated with an increased risk of depression; educational sedentary time spent completing schoolwork was associated with a decreased risk of depression, and there was no relationship between depression and other modalities of SB. This study also supported that the effect of SB on depression is somewhat independent of the frequency of VPA. Sports university students are not immune to depression and inactive lifestyles. Their mental health and health behaviors require attention. Future research on the causal relationships between various reasons for SB, levels of PA, and depression are necessary for more targeted interventions among this population.