The association between physical activity and mental health during the first year of the COVID-19 pandemic: a systematic review

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly contagious virus that infects humans and causes coronavirus disease-19 (COVID-19), which is currently having a damaging impact on almost all countries worldwide [1]. To bring this pandemic to an end, a large share of the world needs to be immune to the virus, and the safest way to achieve this is with a vaccine. Fortunately, in December 2020 the vaccination started in the United Kingdom [2] and is currently pursued in different countries [3]. Until November 2021, 53.3% of the world population has received at least one dose of a COVID-19 vaccine [4]. However, the number of infected people and deaths continues to grow [5]. The World Health Organization (WHO) published a weekly report and on 16th of November 2021 it was observed a increasing trend in new global weekly cases [6]. From the beginning of the pandemic, as a community mitigation strategy used to reduce the spread of COVID-19, most countries adopted the stay-at-home order as well as the stimulation of facemask wearing and hygiene habits [7, 8].

As a consequence of the stay-at-home strategies, mainly during the first year of the COVID-19 pandemic, studies had reported multiple behaviour changes. Some common impacts include disturbed eating behaviours [9], changes in alcohol consumption [10], and substance use [11]. A wide range of psychological outcomes has been observed during the virus outbreak, including a reduction in well-being as well as increases in depressive and anxiety symptoms [12, 13]. Considering the need for social distancing measures, the investigation of possible factors that can mitigate the negative effects of social distancing on mental health should help the promotion of intervention strategies.

Physical activity (PA) is well recognised as a key factor for the prevention and management of mental illness, including mental disorders such as depression and anxiety as well as the promotion of mental health such as well-being [14, 15]. Nevertheless, globally, approximately 23% of adults and 81% of adolescents do not meet the WHO recommendations regarding PA for maintaining health [16‐18]. This situation even worsened with the COVID-19 pandemic. Studies have demonstrated that PA declined and sedentary behaviour increased during the COVID-19 pandemic stay at home order in many countries, regardless of the subpopulation [19]. Different studies sought to investigate whether these changes in PA were associated with mental health indicators during the COVID-19 pandemic and a previous systematic review synthetised that PA is an effective strategy to face the psychological effects of the COVID-19 pandemic [20]. However, the previous review included articles published between 1 January 2019, and 15 July 2020, before the second wave of the COVID-19 pandemic. Therefore, our systematic review aimed to update those findings and clarify if PA is associated with mental health during the first full year of the COVID-19 pandemic and to analyse if PA mitigates the effects of the stay-at-home order on mental health. We aimed to explore the first year of the COVID-19 pandemic because it was the period when restrictive orders were strictest when people were strongly encouraged to comply with the stay-at-home order.

This systematic review focuses on the association between PA and mental health during the first year of the COVID-19 pandemic. In particular, we sought to answer if PA mitigates the effects of the stay-at-home order on mental health. The COVID-19 pandemic generated numerous challenges for public health, particularly the significant burden of mental health in the population [58, 59]. In addition, PA has been recognized as an effective mitigation strategy for improving mental health [60]. The COVID-19 pandemic has been affecting all continents in the world, at different scales. This study analysed 31 research articles, 27 about adults and old adults and 4 about children and adolescents. The articles are mainly based on cross-sectional studies and five are longitudinal studies. In nearly all of the studies comprised in the present systematic review, investigators used online surveys as the main procedure to collect data. Overall, the studies suggested that higher PA is associated with less negative mental health symptoms, such as depression, anxiety, well-being, and fear, independently of age.

The studies observed that women showed more depressive symptoms than men [28, 39, 50, 53, 55], and this trend increases with age [24] Furthermore, individuals with a lower level of masculinity traits (not specifically females) increased risk of developing depression [36], and women experienced more generalised anxiety [41]. The reduction of PA levels may mostly influence the mental well-being of females [38, 49]. Those findings are expected since the literature is consistent in signalising sex differences in most mental disorders [61]. On the whole, the prevalence rates of anxiety and depression were both higher than the rates found in previous studies before the COVID-19 pandemic [36, 37, 43, 45, 48, 57], which highlights a worsening in mental health during the first year of the COVID-19 pandemic. Regarding age, younger individuals experienced significantly higher anxiety and depression, also income influenced mental health, lower-income participants present worse mental health [37].

Five articles conducted a longitudinal study. Among those studies, four enrolled adults and old adults [28, 44, 46, 50, 51] and in one the sample comprised children [52]. Among the studies that have collected measures before and after the stay-at-home order, both observed a significant reduction in PA [44, 46]. Two study collected measures after the stay-at-home order and during this period physical activity mean score decreased minimally [51], and depressive symptoms increase as the weeks of isolation go [28]. Other studies also reported a reduction in self-reported PA [26, 33, 34, 37, 38, 42, 43, 45, 56, 57] and increase in sedentary behaviour [25, 26, 34]. Individuals who reported larger decrease in MVPA pre to during COVID-19 reported relatively poorer mental health [33]. Participants whose mental health got “worse” or “much worse” had greater reductions in physical activity [37]. Also, increased levels of physical activity were associated with stronger effects on wellbeing [42]. The reduction was more pronounced in men than women [32, 38, 44], in vigorous PA [38], and between those with lower health-related quality of life scores before the COVID-19 pandemic [46]. The possible explanation for this sex-difference is that men are more engaged in group/community PA and sports in clubs or gyms, and those were more impacted by the COVID-19 restrictions. Also, women are more engaged in low and moderate physical activities, which can be done at home. Besides, women spent more time in housework activities. Women without changes in childcare provision reported more opportunities to be physically active [41]. The same sex-differences were observed in an Italian study [62]. Increases in PA were observed for a minority, but the majority of the respective study samples demonstrating a positive change were individuals who did not meet recommended PA guidelines before the COVID-19 pandemic [32, 38]. Additional reasons could be an increase in awareness for health issues and more time to pursue PA during the stay-at-home order [32]. These behaviour changes can help to maintain a more active lifestyle during the pandemic. Another study found an increase of 40% in PA in a sample that was already active before the COVID-19 pandemic [35]. PA could be used as a coping strategy to deal with the consequences of the pandemic. The place where individuals prefer to practice PA seems to be important, since active participants reported greater connectedness to nature and nature relatedness than the inactive population [35].

There was no consensus across studies for the optimal PA levels for mitigating negative mental symptoms. The more the physical activity is frequent and vigorous, the best people feel themselves [24]. Among Chinese students, 2500 METs minute/week of PA every week was the optimal dose to alleviate negative emotion [50]. On the other hand, a Spanish community sample study showed that 477 METs-minute/week was associated with a 33% decrease in the probabilities of notable depressive symptoms [39]. The difference between the values must be relativised considering the samples’ characteristics. The first one concerns students with a mean age of 20 years [50], and the second one concerns a community sample with a mean age of 43.2 years for women and 40.5 years for men [39]. In addition, it is claimed that at least 3000 METs-minute/week reduce the odds of depressive symptoms by 47% [39]. These studies used the IPAQ to assess PA, and according to IPAQ, to reach a minimally active category at least 600 METs minute/week is needed [63]. The American College of Sports Medicine also recommends for healthy adults aged 18–65 years at least 600 METs minute/week but did not specify the minimum dose to prevent depressive symptoms [14, 64].

Studies also examined the association between PA and mental health according to PA intensity. Moderate-intensity PA (e.g., walking or jogging on a treadmill, using an elliptical trainer, cleaning house) is associated with better mental health outcomes than vigorous-intensity PA [36, 40], and light-intensity PA [40]. On the other hand, vigorous-intensity PA better predicted depressive symptoms than moderate-intensity PA; also the effect size was higher for the association between vigorous-intensity PA and level of resilience compared with moderate-intensity PA [27]. One study found that performing high PA levels has no positive effect on depressive symptoms [39]. Another study explored the type of PA and showed that stretching and resistance training were associated with lower anxiety, and three types of PA (household chores, stretching, and resistance training) were associated with lower depression symptoms [48].

One study explored the association of specific types of physical exercise and mental health, and founded that home-based group entertainment exercise, rope skipping and badminton, Chinese traditional sports, video dancing and sensory-motor games present a greater reduction in mental health than others types [40].

Sedentary behaviour was observed in few studies and contradictory findings were observed. No association between sedentary time and depressive symptoms was observed [26, 36]. However, other studies have shown that sedentary behaviour was associated with poorer mental health [25], well-being [32] and perceived stress [44].

Concerning the association between PA and mental health outcomes among children and adolescents, only four articles were selected. Some issues must be highlighted. This population had to face, beyond the reality that changed from the COVID-19 pandemic, the changes in the education system such as online learning became the main learning method for students and uncertainty of academic development, which probably caused more anxiety level [52, 53]. Both moderate and highly active groups were significantly associated with less depressive symptoms [53] and anxiety [52, 53], and only the most active adolescents reported significantly lower insomnia symptoms [53] and better mood states [55]. Days of physical activity per week was stronger predictor of well-being than minutes of physical activity per week [54].

Regarding old-age samples, the studies mentioned the particular vulnerability to changes in social circumstances, and highlight the importance of health-related quality of life [46] and levels of resilience [27] to deal with the consequences of the COVID-19 pandemic on the PA level. The stay-at-home order can cause greater distress and feelings of sadness, considered specific risk factor for depressive symptoms [34]. Mental health and physical activity decrease pre to during stay-at-home order [47]. In a group that were previously regular participants of a formal exercise program, MVPA was significantly higher within the non-depressed group compared with depressed group [26]. Being active previously of COVID-19 confinement did not prevent 30.4% of Brazilian older adults from having depressive symptoms, but these results is much lower than prevalence of depression in Brazilian general population, which is 68% [34].

The present systematic review had some limitations that must be mentioned. First, the studies present correlative analyses, not causal ones, thus randomised controlled trials must be conducted in the context of the COVID-19 pandemic and the stay-at-home order to clarify the direction of the association. However, beyond the COVID-19 context, randomised controlled trials showed that PA interventions show beneficial effects on mental health outcomes such as depression and anxiety [65]. Thus, a nuanced perspective particularly during the COVID-19 context in future research is needed. Moreover, the included studies with community samples were limited, and the analyses were mostly based on convenience samples with college students, which had specific characteristics and low mean age. Thus, future research needs to focus on representative study samples.

This review helps to clarify the positive association between PA and mental health during the first year of the COVID-19 pandemic, especially considering the effects of the stay-at-home order worldwide. Although there is an association between increased PA and improved mental health, further studies are needed, specifically randomised clinical trials, to identify the direction of this relationship, and what kind of PA, intensity, and frequency are most indicated to maximise the effects. Also, an investigation to examine the association during the second year of the COVID-19 pandemic is needed. The impact of the COVID-19 pandemic on mental health may be continuous and long-term [66, 67]. Thus, public health agencies must provide timely and effective interventions, in which PA and exercise should be a priority.