Currently, the number of new COVID-19 cases are on the rise worldwide. Most of the countries already adopted measures of social distance to contain the spread of the virus and even more strict measures like partial or full lockdown to relief their highly pressured health systems (Han et al., 2020).

This unprecedented scenario drastically changed daily routines and restricted individuals’ freedom. In addition, the uncertainty around the pandemic progression, its economic, social, and public health impact, will undoubtedly contribute to emotional distress and increased risk for psychiatric illness among the general population (Pfefferbaum and North, 2020). In line, a recent systematic review found that the COVID-19 pandemic is associated with highly significant levels of psychological distress among the general population (Xiong et al., 2020). Indeed, these findings on mental health are clear and concerning, and can be explained by the fear of being infected or infecting others, mandatory home confinement, and the impossibility to spend time with loved ones that are dying or even for not being allowed to perform the usual farewell rituals. These factors can lead to negative feelings of anxiety, helplessness, depression, irritability, and anger (Mari and Oquendo, 2020). Shortly after the beginning of this pandemic, Holmes et al. (2020) published a call for action in Lancet Psychiatry highlighting the need to investigate the impact of COVID-19 on mental health, particularly, on vulnerable groups like older adults, in order to design strategies that mitigate its negative health consequences (Holmes et al., 2020).

Older adults are a vulnerable group that was particularly affected because they were asked to self-isolate at home and avoid any unnecessary contact with other people. While isolated at home, they are likely to have restricted access to physical activity and, therefore, prone to become more sedentary and less active (Valenzuela et al., 2020; Woods et al., 2020), which can lead to consequences such as functional decline, frailty, depression, metabolic syndrome, and increased risk of all-cause mortality (Roshanaei-Moghaddam et al., 2009; Rezende et al., 2014). Concomitantly, social isolation and loneliness are major risk factors linked with poor physical and mental health status (Wu, 2020). These aggregated factors can lead to an unprecedented negative cycle with impact on older adult’s health and well-being.

Mental health problems are common in older adults, particularly depressive symptoms. In Portugal, the estimated prevalence of anxiety and depression are 9.6 and 11.8%, respectively (de Sousa et al., 2017). These numbers are expected to rise as a result of this health crisis. Krendl and Perry (2020) found that older adults reported higher depression and greater loneliness succeeding the onset of the pandemic (Krendl and Perry, 2020). Adding to this, Nguyen et al. verified that people aged 60 years or above had increased the likelihood of depression and poor health-related quality of life during the ongoing pandemic (Nguyen et al., 2020).

The relationship between physical activity and depression has been described. Physical exercise, a subcategory of physical activity, can positively impact several biological (from inflammation to the endocrine system) and psychosocial processes like social support and self-esteem that integrate the pathophysiology of depression (Kandola et al., 2019). Robust evidence from a meta-analysis of prospective cohort studies found a protective role of physical activity in the incidence of depression among older adults, since individuals with high levels of physical activity had 21% lower odds of depression compared with those with low levels of physical activity (Schuch et al., 2018). Moreover, low levels of physical activity and sedentary behavior (SB) are associated with a greater risk of depression and mental health problems (Mammen and Faulkner, 2013; Huang et al., 2020). SB has been associated with negative physical and mental health consequences, independent of the physical activity (Smith et al., 2018). The results, so far, indicate an association between SB and perceived stress, risk of insomnia and sleep disturbance, cognitive performance, and dementia (Falck et al., 2017; Yang et al., 2017; Ashdown-Franks et al., 2018), which are critical problems among older adults. However, some results are still unclear and inconsistent, and need further investigation.

Also, there seems to be an important association between physical fitness and depression. Another meta-analysis found that low cardiorespiratory fitness was associated with a 64% higher risk of depression when compared with high cardiorespiratory fitness; however, authors reinforced the substantial heterogeneity seen between studies (Kandola et al., 2019). In this sense, it is expected that physically active older adults might have increased protection against the detrimental impact of home confinement on mental health (Caputo and Reichert, 2020; Moreira et al., 2020).

The impact of home confinement caused by the COVID-19 outbreak on older adults’ activity behaviors and mental health has yet to be investigated in depth, as this information can enlighten policy efforts during the next few months of this pandemic. Therefore, this study aims to analyze physical activity levels, sitting time, and physical fitness status and their relationship with depressive symptoms after home confinement in older adults that used to participate in formal exercise program.

A cross-sectional study was conducted on post-confinement data aiming to analyze physical activity levels, sitting time, physical fitness, and their relationship with depressive symptoms in previously active older adults.

The present study analyzed the physical activity levels, sitting time, and physical fitness status after 11 weeks of home confinement due to the COVID-19 pandemic and explored their relationship with depressive symptoms on older adults that were previously regular participants of a formal exercise program. Overall, participants self-reported drastic changes in physical activity and sitting time, but presented high physical fitness levels after 11 weeks of home confinement, above the average for the Portuguese normative values (Marques et al., 2014). Symptomatology of depression was found in 52.9% of previously physically active older adults after confinement. Our data showed significant differences between groups as the non-depressed group presented higher values of MVPA compared with the depressed group. Furthermore, only MVPA remained negatively associated with GDS-15 scores in the regression analysis.

Depression affects more than 264 million people worldwide, independently of age, gender, and ethnic background. This highly prevalent mental disorder is one of the leading causes of disability and a major contributor to the overall global burden of disease (World Health Organization, 2020a). The long-term mental health impact of COVID-19 may take weeks, months, or even years to become evident (Rajkumar, 2020). According to the World Health Organization, older adults may become more anxious, angry, stressed, agitated, and withdrawn during the outbreak or while in quarantine – particularly those isolated or with impaired cognitive function (World Health Organization, 2020b).

It is well known that PA, and particularly exercise, have a therapeutic effect on individuals’ physical and mental health, especially when performed outdoors or in groups (Burtscher et al., 2020). However, our data showed that being previously active for an average of 5 years did not prevent older adults (52.9%) from reporting suggestive symptoms of depression. Despite not measuring if the participants were already experiencing this symptomatology before the home confinement, this finding was somewhat unexpected for two reasons: First, given the well-known therapeutic effects that PA, and particularly exercise, have on individuals’ physical and mental health, especially when performed outdoors or in groups, as our program did (Burtscher et al., 2020), and second, because some reviews elicit the long-lasting effect of light-to-vigorous exercise on depressive symptoms (Helgadóttir et al., 2017), and only 11 weeks had passed between ceasing the exercise program and the post-confinement assessments. Nevertheless, findings in this matter are still controversial and inconsistent as a systematic review and meta-analysis of randomized controlled trials showed little evidence of a long-term beneficial effect of exercise in patients with clinical depression (Krogh et al., 2011) and suggested a short-term effect instead.

Several authors (Valenzuela et al., 2020; Woods et al., 2020) highlighted the severe consequences of physical–social distancing measures not only in mental health but also on the physical health of older populations. For example, the study results of Ammar et al. (2020) revealed a decline in all levels of PA during the home confinement period and a far more significant increase on sitting time. Our participants reported similar results as almost 90% of the sample decreased their usual PA levels, and 65% increased sitting time, therefore, changing drastically their usual behaviors with possible negative health consequences. The results on PA levels were expected because our sample was previously highly active older adults who performed exercise sessions at least twice a week. However, the results in sitting time may not truly represent their time spent on sedentary activities since it is well known that older adults tend to overestimate their PA levels, particularly MVPA, and underestimate the time spent on SB (Grimm et al., 2012; Harvey et al., 2013). Our non-significant difference on SB between groups of depression can be due to the differences among sedentary activities since a very recent study found that mentally passive SBs, such as watching television, could increase the risk of depression, whereas mentally activity sedentary activities were not associated (Huang et al., 2020). Therefore, more research on sedentary patterns is needed, particularly in these strange times. Nevertheless, and despite recommendations that home confinement should not preclude people from being physically active (Ammar et al., 2020; Centers for Disease Control and Prevention, 2020; Sepúlveda-Loyola et al., 2020), only 57.4% of our sample kept moderate-to-high levels of PA during confinement. In fact, 78.2% of the non-depressed participants were in the moderate and high PA group, while more than half of the participants with depression (61.1%) reported low PA levels.

Moderate-to-vigorous physical activity was negatively associated with GSD-15 score, explaining 16.4% of the variance of GDS-15 score, adjusted for age, gender, and education. Similarly, results of Callow et al. (2020) from a multiple regression model including total physical activity, age, sex, and education accounted for 7.2% of the variance in total depression scores; however, depression symptoms were measured using a 30-item GDS. In agreement, Carriedo et al. (2020), in their cross-sectional study conducted through an online questionnaire, emphasized that older adults who regularly engaged in MVPA during confinement reported lower scores in depressive symptoms. The potential role of physical activity in mitigating depressive symptoms in older adults seems in line with other studies (Kandola et al., 2019) conducted before the COVID-19 pandemic. Emerging research on the efficacy of home-based exercise training programs to maintain and improve PA levels and physical fitness during home confinement is now becoming available (Marcos-Pardo et al., 2020) and could be a way to mitigate the negative mental health impact of confinement. Moreover, many of the adopted strategies for exercise during the COVID-19 pandemic had involved technologies and virtual meetings reducing the possible negative effects of social distancing and isolation, keeping people active and in touch with each other (Armitage and Nellums, 2020; Burtscher et al., 2020; Jiménez-Pavón et al., 2020).

Regarding physical fitness, our participants were above the 50th percentile for the Portuguese population on cardiorespiratory fitness, and above the 75th and 90th percentile on the 8-ft up-and-go test and 30-s chair stand test, respectively (Marques et al., 2014). Therefore, as opposed to the expected, individuals presented higher levels of physical fitness after an 11-week home confinement period. Moreover, none of the physical fitness tests showed significant differences between groups. These results contrast with other investigations conducted either in the older or in younger groups. Rantanen et al. (2000) found that depressed mood was associated with increased risk of steep handgrip strength decline in older men. In another investigation, the results showed that women with depressive or anxiety disorders had significantly lower grip strength compared with healthy controls, but this association was not found in men (van Milligen et al., 2011). Research has also been pointing toward a significant inverse relationship between cardiorespiratory fitness and depressive scores (Galper et al., 2006) independent of physical activity levels and suggesting that exercise interventions aiming at aerobic endurance may play an important role in preventing depression in older adults (Yamagata et al., 2013). In contrast to our investigation, Lee (2015) divided 173 older women (65–80 years) into two groups (GDS-K score ≥ 14 and GDS-K score < 14) and found significant differences between the two groups in the 6-min walk and also in other physical performance tests. The author suggests that improvements in physical fitness through exercise can improve depression by helping the recovery of self-confidence or inducing emotional responses in older adults (Lee, 2015). A possible explanation for this lack of association in our study could be attributed to our sample having above-average levels of physical fitness contrasting to usual research that is conducted in non-exercisers. Nonetheless, the relationship between physical fitness and depressive symptoms remains partially unclear, and there is a need for additional research to clarify if a causal relationship exists.

In short, our study results reinforce the importance to remain active during home confinement due to the potential of MVPA in mitigating the negative impact on depressive symptoms. Further evidence is necessary to acknowledge the role of physical fitness components and SB patterns on preventing or mitigating depressive symptoms.

This cross-sectional study has some strengths that must be addressed. Several authors highlighted the need for research on mental health consequences of these unprecedented times on the general population (Callow et al., 2020; Carriedo et al., 2020; Moreira et al., 2020; Rajkumar, 2020; Torales et al., 2020) and specifically on vulnerable and older populations (Troutman-Jordan and Kazemi, 2020; Vahia et al., 2020), whether through online surveys (3), editorials or opinion papers (2), and review articles (2). Nevertheless, to the best of our knowledge, to date, the current study is the first to present results from in-person physical performance tests and telephone evaluations with previously physically active older adults.

Additionally, it is important to acknowledge some limitations. First, data on PA and depression were gathered via an interview by phone call, which could have a potential influence on our results. Second, self-reported PA assessment has well-known limitations in older adults. Furthermore, the cross-sectional nature of this study does not allow us to determine a cause-and-effect relationship between MVPA and depression score, and our small sample size limits the generalization of our results.

In summary, our findings suggest that MVPA is negatively associated with depressive scores in a home confinement situation. We considered that our findings can be used as a starting point to manage isolation restrictions more effectively and to develop strategies to promote physical activity among older adults during situations of forced lockdowns, as in the present COVID-19 pandemic. Therefore, a multidisciplinary team involving psychologists, social workers, and PA professionals should work together to create strategies to promote at-home physical activity and mental well-being programs during this pandemic as a key to limit depressive symptoms.

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

The studies involving human participants were reviewed and approved by Ethics Committee of the Faculty of Sports, University of Porto (CEFAD 15.2020). The patients/participants provided their written informed consent to participate in this study.

All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.

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.