The Coronavirus disease 2019 (COVID-19) pandemic has led to more than 100 countries implementing various forms of restriction measures during 2020 (Dunford et al., 2020). Social distancing, travel restrictions, curfews, and school closures have been combined with hygienic efforts to slow the spread of COVID-19. Modeling studies have reported that these public health measures are important to reduce virus incidence and mortality, and may proceed into 2022 (Kissler et al., 2020; Nussbaumer-Streit et al., 2020). While effective, the social and economic impacts of lockdowns may have negative consequences for psychological health. Excessive quarantining is linked to symptoms of depression, anxiety, irritability, and insomnia (Brooks et al., 2020). Factors such as boredom, misinformation, supply concerns, frustration, and financial loss are stressors that trigger a change in mood state and may also lead to a decline in mental health (Brooks et al., 2020). Survey results among individuals from pre and during the pandemic reported a three-fold increase in depression, and those with lower social and economic resources had higher levels of depression (Ettman et al., 2020). These are all correlated with increased suicidal ideations, particularly amid Covid-19 lockdowns (Chen et al., 2020).

Of particular concern are University and college students, who have been faced with the stress of remote learning and rapid life adjustments due to COVID-19-related restrictions (Husky et al., 2020; Sahu, 2020). A small survey of 195 University students noted increased stress and anxiety among 71% of the participants (Son et al., 2020). Further, the Centers for Disease Control and Prevention (CDC) reported 63% of college-aged young adults (18–24 years of age) in the U.S. had elevated depression or anxiety between May and June 2020 (Czeisler et al., 2020). Elevated mental stress among young people may result from inadequate coping skills in the face of COVID-19-related social isolation and boredom; and, even more exacerbated among University students who may have been displaced from the traditional campus setting, leading to learning challenges and grade insecurities (Son et al., 2020; Torales et al., 2020).

Physical activity is often overlooked as a lifestyle habit to preserve mental health. Individuals who are regularly active are less likely to be diagnosed with depression or anxiety (Goodwin, 2003). Moreover, those who met moderate to vigorous physical activity (MVPA) guidelines (defined as either 150 min/week of moderate intensity exercise or 75 min/week of vigorous intensity exercise; or, an equivalent combination of both, by the United States Health and Human Services and World Health Organization) reported a 39% reduction in monthly days of poor mental health (Piercy et al., 2018; Bull et al., 2020). Individuals who were active but did not meet guidelines demonstrated a 25% reduction in days of poor mental health as well, indicating even a small amount of exercise is beneficial (Piercy et al., 2018; Fluetsch et al., 2019). In light of these findings, the World Health Organization (WHO) recently stated that adults should limit the amount of sedentary time and replace it with physical activity of any intensity or type (Bull et al., 2020; Dempsey et al., 2020). These data suggest that University students who consistently participate in physical activity may be less likely to experience depression and anxiety related to COVID-19 restrictions. Unfortunately, evidence has demonstrated a high prevalence of sedentary behavior among University students (Arias-Palencia et al., 2015). This may inadvertently influence mental health among this group (Lee and Kim, 2019).

Therefore, the aim of this study was to explore physical activity and sedentary behavior associations with depression and anxiety symptoms among young adult University students during COVID-19 restrictions in the Fall 2020 semester.

The survey was distributed via email to 4,000 randomly selected students in late October 2020. A total of 852 started the survey, 75 were removed due to not meeting exclusion criteria designating a sample of 777 participants in the parent study (Coakley et al., 2021). For the current study, another 80 did not complete the physical activity section of the survey and were removed from subsequent analyses. Therefore, 697 undergraduates 18–25 years of age were included. Average age was 21.29 ± 1.62 years. Sixty-two percent (n = 431) were female; 31.6% (n = 220) were White; 29% were Hispanic, Latino, or Spanish (n = 204); and 22.7% (n = 158) reported being multiracial. Of note, in Fall 2020 the undergraduate population was 57% female; 30% white, 50% Hispanic, 3% African American, and 4% were multiracial. The majority of survey responders (47.2%, n = 329) were employed part-time, and 35% were not employed (see Table 1). No missing data were present among main analytic variables including GAD-7 (measure of anxiety) and PHQ-9 (measure of depression).

A physically active lifestyle supports mental health (Goodwin, 2003). This study identified that University students that did not achieve recommended MVPA weekly targets had higher PHQ-9 and GAD-7 scores indicating more severe symptoms of depression and anxiety, respectively. In addition, through multivariate regression analysis, amount of daily sitting time had a significant association with both more severe depression and anxiety symptoms during the COVID-19 restrictions among University students in fall 2020.

In 2018, the U.S Department of Health and Human Services, along with the WHO in 2020 updated physical activity guidelines (Piercy et al., 2018; USDHHS, 2018). The recommendations suggest that adults should aim to achieve at least 150–300 min of moderate intensity aerobic exercise, or 75–150 min of vigorous intensity aerobic exercise per week, or an equivalent of both. For the first time, the new guidelines highlight the benefits of physical activity for several conditions affecting the brain, such as depression, anxiety, and Alzheimer's disease; however, nearly 80% of Americans do not meet guidelines. Data from this study demonstrated that 49% of University student participants did not meet MVPA exercise goals. Those who reported less than MVPA targets, determined by evaluating weekly moderate intensity (150 min/week) and vigorous intensity (75 min/week) exercise behavior, scored higher on the PHQ-9 for depression and GAD-7 for anxiety, compared to those who achieved the MVPA targets. Correlation analysis also revealed that PHQ-9 scores were negatively associated moderate exercise minutes per week, and trended with weekly vigorous intensity exercise. Accordingly, individuals with more severe symptoms of depression and anxiety reported lower moderate and, or, vigorous exercise minutes per week. These data suggest that University students who achieve PA recommendations during COVID-19 restrictions were likely to have a lower depression and anxiety symptoms. However, reverse causality cannot be ruled out based on these data. It is possible that elevated depression related to COVID-19 lockdown measures contributed to lack of physical activity. While less studied, data has suggested a link between depression and development of a sedentary lifestyle (Roshanaei-Moghaddam et al., 2009). Specifically, individuals with elevated baseline depressive symptoms were 1.79 times more likely to be physically inactive (Allan et al., 2007). In addition, young people with mood disorders are at increased risk of developing poor health behaviors such as smoking and excessive weight gain (Katon, 2003; McElroy et al., 2004). Young adults with symptoms such as low energy levels, irritability, anxiousness, and lack of self-esteem, along with co-existing negative health habits would likely lack motivation to exercise, nor see the mental health-related benefits of being physically active.

Several observational studies have demonstrated a positive impact of PA on symptoms of depression among women, minority populations, men, and University students (Wise et al., 2006; McKercher et al., 2009; Currier et al., 2020; Tao et al., 2020). Of note, the majority of survey responders in the current study were female (62%), and of minority ethnic backgrounds (~66%). These findings suggest that physical activity may protect against mental health decline in young adults during COVID-19 lockdowns. Limited comparative data exists regarding the role of PA on symptoms of depression during the COVID-19 pandemic among young people. Pieh et al., reported a higher prevalence of depression (PHQ-9 > 10) among adult Austrians, and particularly young adults (<35 years of age) after 4-weeks of lockdowns, and a nearly five-fold increase compared to pre-pandemic times (Pieh et al., 2020).

To date, there have been no accurate evaluations of PA and depressive symptoms during the COVID-19 pandemic among only young adults. In Spain, it was demonstrated that those who met PA guidelines for moderate or vigorous exercise had lower depression scores during COVID-19 lockdowns, but only older adults 60–92 years of age were included (Carriedo et al., 2020). Similar relationships between PA and depressive symptoms were reported in Norway among 1,281 adults, aged 19–90 years (Ernstsen and Havnen, 2020). Early pandemic data from spring and summer 2020 have suggested an alarming mental health decline, notably among young adults, which may be due to a lack of developed coping and emotional behaviors (Compas et al., 2014; Czeisler et al., 2020). In addition, young people are less likely to recognize their mood/behavior changes, and seek therapeutic assistance (Pedersen and Paves, 2014). The current data support the notion that young University students who exercise more and achieve PA recommendations are less likely to experience symptoms of depression. Therefore, encouraging PA behavior may be a therapeutic option. However, the causal effect cannot be evaluated.

Symptoms of anxiety were higher among those that did not meet MVPA recommendations, and anxiety symptoms severity was inversely associated with weekly minutes of vigorous exercise. A similar relationship between physical activity and perceived anxiety was observed among 2,250 middle-aged adults during the Fall 2020 COVID-19 lockdown in Spain (López-Bueno et al., 2020). Those who met WHO physical activity recommendations were nearly half as likely to report elevated anxiety (López-Bueno et al., 2020). Meta analytical findings have demonstrated a small reductive effect of physical activity on symptoms of anxiety among non-clinical populations (Rebar et al., 2015). Mechanisms include psychological changes such as mood enhancement and self-efficacy, along with neurophysiological adaptations (Portugal et al., 2013). However, conflicting data regarding the benefits of exercise on symptoms of anxiety have been reported (Bartley et al., 2013). The multivariate analyses in the current study revealed a non-association between physical activity (both moderate and vigorous intensity) and symptoms of anxiety. One explanation is that the anxiolytic effect of exercise is transient, termed the “endorphin effect,” and is diminished after a short period of time (Anderson and Shivakumar, 2013). In addition, the impact of exercise training may be more evident among those who have clinically diagnosed anxiety (Herring et al., 2010).

Sitting time (h/week) was positively associated of depression symptom severity and vigorous intensity exercise had a negative association that was trending toward significance (p = 0.054). Female gender identity was also associated with depression severity. Sitting time and female gender identity were also significantly associated with anxiety symptom severity. The average sitting time per day for this cohort of University students was 8.61 h/day, which is similar to the 7.59 h/day reported in a recent survey among 244 students (Lee and Kim, 2019). Activities performed while sitting were not evaluated in the current study, but recent data suggest that passive behaviors such as watching television worsened depressive symptoms, and television watching time has surged since the COVID-19 pandemic (Dixit et al., 2020; Huang et al., 2020). Among University students, an increase in sitting time has been linked to both anxiety and depression (Lee and Kim, 2019). Moreover, due to COVID-19 restrictions, physical activity may have been replaced by sedentary behavior and sleep among young adults (Zheng et al., 2020). The current data reveals that every additional hour of sitting time was associated with an increase in PHQ-9 score by 0.19, and GAD-7 score by 0.17 while holding other predictors constant. Interestingly, in a study published in 2001, low levels of physical activity such as achieving at least 75 min per week of any type of PA was associated with 45% lower prevalence of depression among women (Dunn et al., 2001). This equates to ~10 min per day of activity and could be accomplished by simply walking outside. Therefore, fully achieving PA recommendations may not be required to prevent an increase in symptoms of depression and anxiety; however, avoiding sitting time is very important for mental health (Dempsey et al., 2020).

The results of the study should be interpreted with several limitations in mind. First, the response rate was lower (17%) than desired for an online survey; however, the sample size is comparable to similar survey studies that analyzed PA and mental health during COVID-19 lockdowns (Nulty, 2008; Barkley et al., 2020; Carriedo et al., 2020). Second, the survey was conducted at one University in the Southwest region of the U.S., and may not be generalizable to all undergraduate students. Third, survey completers may not have understood the difference between moderate and vigorous exercise, which may have influence reported data. Fourth, the IPAQ was used to assess moderate and vigorous exercise, and groups were allocated based on their physical activity. The IPAQ is reported to be reliable among young adults, but has also been reported to overestimate PA (Papathanasiou et al., 2009; Lee et al., 2011). Fifth, the PA and sedentary behavior was assessed by self-report, which is potentially subject to misreporting. However, this study used a short-term recall of PA activity (last 2 weeks) which may reduce the magnitude of reporting errors (Matthews et al., 2012). Lastly, no previous or current diagnoses or treatment of depression and anxiety was assessed.

It is clear that COVID-19 restrictions and the prolonged nature of a global pandemic are linked to a decline in mental health among young adult University students (Czeisler et al., 2020; Son et al., 2020). Social isolation, campus displacement, and academic-related stress (assignments and online transitions) may be linked to elevations in symptoms of depression and anxiety. Physical activity is an important stress relieving behavior, and students that achieved recommended MVPA guidelines had lower levels of depression, but the majority of University students do not meet PA recommendations. Moreover, sedentary behavior (evaluated as sitting time per day) was significantly associated with both depression and anxiety symptom severity. Efforts should be made to encourage students to engage in some form of PA each day, and to avoid sitting time. As little as 10 min per day of exercise has been shown to support mental health, and the implementation of home-based exercise training protocols such as bodyweight exercises may be a simple strategy to reducing symptoms of depression and anxiety (Rebar and Taylor, 2017).

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by University of New Mexico IRB. The patients/participants provided their written informed consent to participate in this study.

KC conceived the study and carried out methodology and data collection. DL performed data collection and data analyses. KH and FA assisted with methodology, data collection, and analyses. MZ contributed to methodology and data analyses and also complete the first draft of manuscript. All authors contributed to manuscript revisions, and table/figure development.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.