Discussion
The current systematic review of 66 studies demonstrated that the majority of studies found that PA declined and SB increased during the COVID-19 pandemic lockdown, regardless of the subpopulation or the methodology used. In healthy adults and children, PA during lockdown decreased compared with prelockdown, despite various government organisations and health or exercise practitioners providing guidance on how to stay active during the pandemic and in self-quarantine.87–89 When stratifying between prelockdown PA levels, three studies found that people who were more active prelockdown were more likely to show larger decreases in PA.37 49 67 PA has also been consistently linked with several mental health conditions, suggesting that decreases in PA may lead to increases in undesirable mental health outcomes. Indeed, studies have shown significant increases in anxiety and depression levels during the lockdown.10 Given that decreases in PA have been shown to yield negative affect, increases in anxiety and lower energy levels,39 PA promotion during lockdowns should be aimed not just as people who are currently sedentary, but also for those with high PA levels outside of lockdown. Due to the likelihood of further COVID-19-related restrictions (or another similar pandemic), the promotion of digital based PA (such as PA apps, online video fitness classes or physical training) is recommended. Digital based PA yielded favourable results during the first COVID-19 lockdown, with studies showing positive associations with such digital based initiatives and overall PA during a lockdown.83
Another finding of this review was that participants who had medical conditions also yielded decreases in PA levels, except for patients with an eating disorder. The decreases in PA is particularly concerning as in several of the medical conditions studied because PA can be a form of treatment or symptom alleviation. For example, levels of PA have been shown to be positively associated with quality of life outcomes in both type 1 and type 2 diabetes.90 91 Concurrently, increases in SB have been shown to yield detrimental outcomes in patients with these conditions, except for patients with eating disorder.92 93 Given these added risks of decreasing PA and increasing SB in these special populations, PA promotion and strategies to reduce SB should be implemented should further lockdowns occur. Moreover, practitioners working with these groups should be especially mindful of the detriment that decreasing PA and increasing SB could yield during lockdowns and make the monitoring of PA levels a priority. Patients with eating disorders were found to increase their PA, specifically exercise, during lockdowns. This is equally concerning as there is often pathological relationship between eating disorders and exercise and can lead to increased risks of physical complications such as stress fractures.94 Therefore, practitioners working with patients with eating disorders are advised to keep closely monitoring patients as much as possible during future lockdowns.
There were also large decreases in both the training volume and training intensity of elite athletes while in lockdown, which has led to relative decreases in sport-specific physical performance tests post-lockdown.85 This decrease in athletic readiness for competition should be noted and considered by practitioners who are working with elite athletes, especially regarding training loads and competition scheduling postlockdown.
According to the behavioural change wheel, for a behaviour—for example, PA or SB—to occur, there are three components that are required: capability (psychological and physical), opportunity (physical and social) and motivation (reflective and automatic).95 Despite information on safe exercise during lockdown being available from exercise professionals and some governments (psychological capability), it is not clear from the included studies the reasons why people did or did not engage in PA; however, we can speculate potential reasons for these findings. A reduction in PA is expected as lockdowns required that governments closed sport and leisure facilities, group activities were suspended, and in many countries limits were in place for time spent outdoors.96 This potentially meant people’s regular PA routines were difficult to continue with during lockdown, as indicated by the evidence stating that people considerably changed their modes of PA during lockdown.97 For example, one study found that all types of PA decreased except for ‘moderate intensity leisure-time PA’ (such as housework and gardening) increased,26 another found that ‘yard work’ increased,77 and another found that ‘housework’ increased during lockdown.82 However, despite these mode-specific increases, total PA levels in these respective populations still decreased. This suggests that promoting increases in house-related PA may not be sufficient to increase total PA during lockdowns.
There was also an increase in the number of people working from home during lockdown,98 consequently, PA ordinarily accumulated during commuting will have substantially decreased. A previous study found that adults in the UK (mean age 50.5 years) accumulated 195 min/week (±188.6) of active travel.99 Those who actively commute report significantly greater total PA than those who do not, despite no significant differences in recreational PA shown.99 100 In addition, with schools closed, many parents were balancing home schooling, while working from home themselves; in the UK, this was the case for 85% of employees with school-aged children.101 A decrease in opportunities to be active and additional responsibilities may have led to a decrease in PA.
The majority of the studies in this review showed increases in SB during lockdown. This is unsurprising as many people worked from home, leading to extended sedentary periods and increased screen time.102 103 For instance, de Haas et al104 reported that 44% of Dutch workers had either started to work from home or increased their home working hours, with 30% reporting increases in remote meetings (eg, via videoconferencing). In addition, with most gyms, leisure and sporting facilities closed, time allowed outdoors limited or not allowed, some people may have found it difficult to be active during the lockdown.3 105 With increased ‘free’ time, many may resort to engaging in pastimes such as reading, playing video games and watching television (TV), many of which are sedentary.67
Given that the majority of studies reported a decrease in PA with a concurrent increase in SB during the lockdown, and the impact of these on physical and mental health, it is recommended that interventions or policies are implemented to increase PA (eg, body weight home-workouts, using online exercise classes, walking, running and cycling outdoors) and decrease SB (eg, by using a standing desk and taking regular breaks from sitting) should further lockdowns be enforced in the future. In addition, interventions for PA and/or SB postlockdown should consider that individuals may suffer deconditioning as a result of the lockdowns.
Many of the included studies used surveys to gather information about ‘exercise’, ‘PA, ‘sport’ and ‘training’ but failed to report on how these terms were defined to participants. Future studies should report these definitions for clarity and comparison to be made more easily between studies. This lack of definition may mean that despite ‘exercise’ and ‘training’ decreasing, changes in daily PA may be different in these studies. Monbiot106 reports volunteers providing food packages, collecting medical supplies for the elderly, providing childcare for those in need, meaning they potentially accumulate similar or more ‘activity’ than they realise as it is not prescribed ‘exercise’ or ‘training’.
It is important to note different degrees of lockdown in different countries, even regions within a country, across different dates occurred, making it difficult to quantify the severity of a lockdown and therefore challenging to objectively assess how this impacted behaviours. For instance, those in countries that were able to exercise outdoors following social distancing guidelines may have engaged differently in PA/SB behaviours to those who were not able to leave home, despite both countries being in ‘lockdown’. Although the authors have presented the lockdown descriptions for each included study as reported by the authors, these description vary greatly in detail, making it challenging to categorise them into ‘levels’ of lockdown. The creation of a scale to indicate lockdown severity would be highly beneficial for comparisons to be made between countries when investigating different behaviours, or at the very least it is recommended that this type of information is reported in all future studies. Moreover, within countries some people are given specific guidance (eg, shielding) which requires more intensive lockdown than the general population—none of the included studies recorded this information. It may be beneficial to know participants adherence to lockdown guidelines to provide an indication of potential opportunity to engage in PA. Most studies also report PA without investigating in detail the types, intensities and durations of PA engaged in before and during lockdown, thus, it would be beneficial to investigate these as the magnitude of changes will impact the effects on health.
Limitations
While this systematic review is the first to our knowledge to assess changes in the frequency and modes of PA and SB preockdown versus during the COVID-19 lockdown, the findings should be considered within the limitations of the study. First, the tools used to measure PA and SB were highly heterogeneous, making direct comparison of respective results difficult. Second, demographic information was largely limited, meaning that we were unable to assess any further changes according to demographics further than the discussed topics, which would have given more insight into the review. In addition, the vast majority of studies were based on subjective questionnaires, which carry with them inherent limitations.107 Moreover, many studies asked participants retrospectively about their prelockdown behaviours and their current behaviours during lockdown, thus, the accuracy of participants abilities to accurately recall their behaviours may be questionable. Lastly, most of the studies included were not designed to be nationally representative, making the generalisation of these results difficult.
Future research in this area should focus on yielding directly comparable data using validated PA and SB questionnaires or using objective accelerometer data where possible. In addition, it would be beneficial to have more detailed demographic information, information on the severity of lockdown and participant adherence to lockdown guidelines, and more detailed information on PA behaviours, for instance, the types, intensities and duration of PA before and during lockdown. Future research should also consider investigating the magnitude of the decrease in PA and increases in SB across different populations during the lockdown to aid the identification of populations most in need of targeted interventions. Lastly, future research should consider investigating the reasons why people are showing changes in PA and/or SB. Using behavioural change theory to assess barriers and facilitators to PA/SB during lockdowns would be highly beneficial in the creation of future interventions and policies should lockdowns occur in the future.
