*4.2. Relationship between PA and Mental Health*

The present study suggests that 43% of university students were physically active during the coronavirus lockdown, according to the WHO recommendation (≥150 min/week of PA) [45]. A previous study found that 56% of Chinese college students were physically active at moderate or vigorous levels during the national quarantine [18]. The results suggest that the sample of Ukrainian students may be less involved in PA than the group of Chinese undergraduates. However, the previous research [18] used different measurement methods (i.e., a seven-item International Physical Activity Questionnaire—IPAQ) to assess weekly PA during the last two weeks according to three categories: light, moderate, and vigorous. Thus, the previous and present studies are not fully comparable.

Furthermore, the number of active students decreased significantly in comparison to the situation before the COVID-19 outbreak in Ukraine, which is consistent with some previous studies [23,34,46,47]. Stanton et al. [23] showed that negative physical activity changes are associated with increased depression, anxiety, and stress symptoms. Research indicates that exercise withdrawal may consistently result in an increase in depressive symptoms and anxiety [71].

Consistent with other research [18,51], this study indicates that there is a significant and inverse relationship between PA and anxiety and depression during the COVID-19 pandemic. A longitudinal survey showed that PA directly alleviated general negative emotions in college students during the peak time of the COVID-19 outbreak in China [18]. The volume of moderate-to-vigorous leisure-time PA (MVPA) was also positively associated with mental health and negatively related to the symptoms of anxiety and depression among post-secondary students aged between 16–24 years [72]. Furthermore, increasing PA during the COVID-19 lockdown was related to lower anxiety and improved well-being among individuals who were inactive before the pandemic [49].

Ukrainian undergraduates with anxiety and depression symptoms are between 1.6 and 1.9 times less likely to be physically active than their counterparts without mental health problems. This result is consistent with the previous population study of DeMello et al. [73], which showed that individuals who do not engage in PA are two times more likely to exhibit symptoms of depression and anxiety compared with those who regularly pursue PA. Furthermore, the highest association with PA was found in this study for participants with a dual anxiety and depression diagnosis. Forte et al. [74] also found that severe depression was most common among adolescents with comorbid anxiety and low PA levels.

The anti-depressive and anxiolytic effects of physical activity on clinical and non-clinical populations were evidenced in a great number of studies e.g., [70,71,75,76]. A systematic review and meta-analysis showed that PA reduces depression by a medium effect and anxiety by a small effect, in non-clinical populations [77,78]. Previous meta-analyses found a moderate-to-strong negative relationship between PA and depression and inconsistent association of PA with anxiety (ranged between not statistically significant effect to a moderate beneficial effect of PA on anxiety) in clinical populations. Previous findings suggest that high PA significantly reduced the prevalence of depressive problems, but not anxiety disorders, among Chinese first-year college students [25]. In contrast, this study found a statistically significant but rather weak association of PA with anxiety and depression. The hierarchical regression model with PA, sex, exposure to COVID-19, and PCI as predictors explained only 14% of anxiety and 15% of depression variability. PA can solely explain 1% of anxiety variability and 3% of depression variability, as shown in the hierarchical regression model in the fourth step of the analysis. Thus, more research is necessary to explain the specific relationship between these variables.
