Introduction

COVID-19 has emerged as a public health emergency affecting millions of people’s physical, psychological, and social well-being [1]. State and national governments have enforced lockdowns, home confinements, restrictions on social gatherings and a ban on sports or exercise amenities to contain the spread of the virus [2]. However, the above protective measures have adversely affected the physical and mental health of the global population. Further remote work and virtual classrooms have intensified the physical inactivity and sedentary behavior in the community [3]. Physical inactivity is the inability to meet the global recommendations of 150–300 min of moderate-to-vigorous exercise per week, while sedentary behavior is defined as any waking activity that is characterized by a low energy expenditure (i.e., less than 1.5 METS) [4]. Individuals with high physical inactivity and sedentary behavior are found to have a greater risk of chronic cardiometabolic diseases such as ischemic heart diseases, cancer, obesity, and early mortality [5, 6]. Growing evidence states that physical inactivity and sedentary behavior have substantially increased during the pandemic due to work from home and high screen time [7, 8]. Contemporary evidence suggests that high sedentary time is associated with increased cardiometabolic disease risk independent of weekly physical activity time. Hence, lifestyle interventions focusing on reducing physical inactivity and sedentary behavior are perceived as intriguing measures to prevent the chronic disease risk.

Wearables in promoting physical activity and reducing sedentary behavior

A wearable is defined as “any body-worn computer that provides useful services while the user performs other tasks”, and includes pedometers, smartwatches, smart wears and activity trackers [9]. The growing popularity of the Internet of Things and technologically sound users have raised the market value of wearables by USD 32.63 billion, and compound annual growth is projected as 15% from 2020 to 2027 [10]. By real-time visualizing, measuring and addressing sedentary behavior and physical activity bouts, wearables continue to increase in popularity and accessibility to the extensive data at the population level [11]. Difficulties in the raw data collection and transformation based on ‘phantom’ algorithms make commercial fitness trackers less reliable and valid than research-based accelerometers [12]. Despite its moderate accuracy, consumer-based wearables continue to be widely used to encourage physical activity and reduce sedentary behavior through behavior change techniques such as goal setting, prompts, cues, self-efficacy and social support [13].

Though wearables use became inevitable in contemporary men and women, the advocacy of wearables for promoting PA and reducing sedentary behavior during these unprecedented times is relatively unknown. Our aim was to provide a comprehensive overview of the breadth and results of studies examining the impact and extent of wearable use on the measurement, encouragement and monitoring of physical activity and sedentary behavior in individuals during successive lockdowns. We aimed to describe the wearables used in the promotion of physical activity (sensors to smartphone technology) as an initial contribution to the informative implementation in practice. We conducted a scoping review with the following objectives:

  • To investigate the extent to which the wearables are being used to promote physical activity in the community

  • To collate the evidence regarding the prevalence of physical inactivity and sedentary time in individuals measured and monitored using wearables.

Methods

The present scoping review followed the guidelines of Arksey and O'Malley framework, which consists of five mandatory stages: (1) identifying the research questions; (2) identifying relevant studies; (3) study selection; (4) charting the data; (5) collating, summarizing, and reporting the results [14, 15]. Scoping reviews share similar characteristics of systematic review except for the provision of a broader overview rather than answering a focused question.

Identifying the research question

Our present scoping review was initiated with a question “What is the breadth of wearable use, its physical and social impact on people during an ongoing pandemic?” The present scoping review aimed to collate and summarize the contemporary evidence investigating the use of the wearables in promoting physical activity and the barriers during the COVID pandemic.

Identifying the relevant studies

We searched five electronic databases (Web of Science, Scopus, Cumulative Index to Nursing and Allied Health Literature, Ovid Medline and Embase) for the studies investigating wearables and their use to reduce sedentary behavior and improve PA in healthy and diseased populations during COVID-19 pandemic. We searched with the possible combinations of the MeSH terms “wearable activity trackers”, “wearable activity monitors”, “activity monitors”, “activity trackers”, “fitness trackers”, “wearable fitness devices”, “wearable technology”, “wearable devices”, “Fitbit”, “physical activity”, “physical exercise” “aerobic exercise”, “sedentary behaviour”, “sedentary time”, “sedentary lifestyle”, “physical inactivity” with several combinations of Boolean operators and wildcards. We limited our search to a time frame of December 1st, 2019, to May 10th, 2021. The search was again updated on November 19th, 2021. The sample search strategy is provided as an additional file.

Study selection

We included studies that have: (1) advocated any wearable or digital device; (2) investigated physical activity or sedentary behavior; (3) included only adults; (4) both healthy and diseased; (5) conducted within the timeframe (from December 1st, 2019, till May 10th, 2021. However, the search was again updated on November 19th, 2021); (6) both experimental and observational studies and (7) published only in English. The study selection was based on the PICOT framework, as presented in Table 1.

Table 1 Eligibility criteria by which potential studies included based on the PICOT criteria
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Charting the data

We extracted the following variables to a bespoke extraction sheet: author, year, country, design, the objective of the study, type of the wearable, physical activity and sedentary behavior (step count, step time, sitting time, and moderate-to-vigorous activity time, standing time, calorie expenditure). The measurement errors and the authors attempt for appropriate correction were extracted. Furthermore, the sociodemographic influence on the measurement, if any, was recorded.

Collating, summarizing, and reporting the results

The evidence of the wearables and the associated physical, social and physiological effects were analyzed as qualitative analysis and synthesized narratively to provide the readers and policymakers with the broader knowledge of wearables and their physical, social and mental impact during the pandemic. The data extracted from the search results are provided in Table 2.

Table 2 Characteristics of the included studies that investigated the wearables impact on physical health during the COVID-19 pandemic
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Results

Of 347 screened, seventeen articles were deemed eligible for inclusion and potential scoping was done. Figure 1 shows the flow of the screening and inclusion of the studies for the review. The majority of the studies (n = 14; 82%) included adult participants (n = 7,59,979) ranged from 10 to 742,000. Heterogeneity in the study types was observed as follows: cross-sectional (n = 9; 53%), longitudinal (n = 4; 24%), retrospective (n = 1; 6%), narrative review (n = 1; 6%) and pilot non-randomized studies (n = 2; 12%). Similar heterogeneity was found in participants too in the included studies: pregnant women [27], elderly [24, 26], office workers [21], diabetes [18] and children [25]. All the studies were from high-income countries.

Fig. 1
figure 1

Flowchart of the potential studies screened and included in the review which explored the wearables use for physical activity promotion and sedentary behavior reduction during the pandemic

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Wearables and the measurement of physical and physiological variables

Seven studies administered smartphone-based physical activity measurement through inbuilt accelerometers from which the captured data were transferred to the cloud server and visualized in smartphone applications [16,17,18,19, 21, 24, 31]. Majority of studies (n = 9; 53%) employed wrist bands and wristwatches of multiple technology firms (Apple, Samsung, Xiaomi) and wearable research-based accelerometers [20, 23, 25, 26, 28,29,30, 32]. A few studies (n = 4; 24%) reported the psychometrics of the wearables, and low-to-moderate validity was found [21, 22, 27].

Physical health measurement through wearables

The mean follow-up period of longitudinal studies was 21 weeks [18, 20, 21, 24, 26, 27]. The average reduction in the daily step count after the pandemic compared to before the pandemic was 2812 steps/day. The studies had reported a significant reduction in standing time (− 32.7%), walking time (− 52.2%) and step count (− 29%) during lockdown when the physical activity was monitored with the wearables [22, 26]. Mean energy expenditure was reduced to 70 kcal compared to before pandemic [23]. Only one study by Vile et al. [27] reported a reduction in heart rate variability variable, especially high LF/HF ratio. Further reduction in step count and sleep time was found to be positively associated with body mass [19], depression [26] and workplace stress [32]. Various behavior change techniques such as self-efficacy, goal setting, prompt/cues, information and social networking were associated with the compliance of wearable use [24, 25, 31].

Discussion

From the evidence included, we found a significant increase in the use of wearables to improve physical activity during the confinement or lockdown periods [21, 24]. There is a convincing evidence to show that there is a significant decrease in physical activity and increased sedentary time in people around the world when judged objectively using wearables [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32]. Figure 2 represents the summary of our findings. In the following sections, we discuss about: (1) the increased usage of the wearables in spite of the validity and reliability of the phantom algorithms; (2) role of wearables in regulating physical health during the lockdown.

Fig. 2
figure 2

Summary of the scoping review findings

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Use of wearables during COVID-19

Wearables are intriguing means for measuring and monitoring physical activity at the population level in spite of arguments over their validity and reliability [22]. Cloud computing and artificial intelligence have leveraged healthcare through wearable sensors, increasing health monitoring and medical automation for speedy diagnosis, including COVID-19 [33]. The above facts are reciprocated with double-fold increase in utilization of wearable devices to self-monitor physical behavior during this pandemic [16,17,18,19,20,21,22,23,24,25,26,27,28, 34]. Although found to be less valid and reliable compared to research-based accelerometers, these wearables provide an opportunity for its end users to self-monitor their physical activity levels, energy expenditure, sleep, sitting time and create a framework for personalized prevention [34]. Our review findings also concur with the above findings from the largest British cohort study, the UK Biobank study [34]. Modern trends in mobile technologies have improved activity recognition and estimation of models making smartphones easily accessible and high accuracy in self-monitoring [35]. Recent wearables and their mobile application interface provide more reliable and easily understandable data visualization, thereby gaining popularity, which is seen in the included studies of our review [28]. Smartwatches, smart bands, smart rings, and bracelets are widespread in human activity monitoring and behavior change [36]. Furthermore, wearables embedded with behavior change techniques such as goal setting, information/counseling, prompts, motivation and social support make wearables a potential choice for increased compliance to behavior interventions and long-term behavior change. We found that the behavioral techniques are least addressed in the studies that have employed the wearables for improving physical activity or reducing sedentary behavior in individuals during the pandemic [21, 24]. We recommend that future wearables be developed along with behavioral scientists to understand target behavior (intensity and type of activity) and incorporate maximum behavior change techniques for higher compliance in community settings [37].

Physical health regulation with wearables during COVID-19

Our review results showed active time in all age groups is significantly reduced by at least 30–50% after lockdown compared to pre-pandemic periods [16, 17, 19, 21, 22, 25, 26]. Our findings concur with the recent cross-sectional study that investigated smartphone-based physical activity measurement before and after lockdown and found 37% reduction in weekly minutes of PA [38]. Consumer-based wearables allowed users to monitor their activity levels and may potentially improve their compliance toward long-term behavior change, which are increasingly popular during this pandemic. Brickwood et al. (2019) systematically reviewed 28 randomized controlled trials and found a significant increase in step count (standardized mean difference [SMD] 0.24; 95% CI 0.16–0.33), moderate-to-vigorous physical activity (SMD 0.27; 95% CI 0.15–0.39) and energy expenditure (SMD 0.28; 95% CI 0.03–0.54) with wearables use [39]. Our review findings concur with the results of the above review, which concluded that physical activity and active time could be improved significantly with wearable devices. In our review, most of the included studies involved healthy adults and four studies investigated physical activity changes in pregnant women [27], asthmatic children [25] and diabetes population [18, 24]. We could also find a trend of studies exploring the use of wearable technology in the elderly for improving self-efficacy and behavioral change for physical activity promotion [24, 26].

Restriction on sports amenities, public gathering, home confinement and remote work are some of the potential barriers to adequate physical activity practises during this pandemic [40]. We propose wearables to be an intriguing intervention for measuring, advocating and monitoring physical activity for reaping health benefits for being active during this pandemic [41]. Furthermore, the reduction of active time was adversely associated with physical and mental health [42]. The physiological changes such as improved cortisol, a brain-derived neurotrophic factor associated with increased activity time, are postulated to have favorable effects on mental health [43, 44]. Nevertheless, a longitudinal study by Vile et al. [27] found a reduction in the heart rate variability with lower physical activity during lockdown might have unfavorable effects on cardiovascular disease risk. Thus, wearable technology serves as an intriguing means to promote physical activity and reduce sedentary behavior among healthy population and individuals at risk for chronic diseases during these unprecedented times.

Limitations

Few limitations are worth mentioning: (1) majority of the articles included were conducted between early lockdown (March 2020–June 2020). Hence, the review findings may not represent the intensity of wearables use and their impact on physical activity at present; (2) we observed heterogeneity in terms of age, wearable make and working mechanisms of the Internet of Things and algorithms associated with the cloud transfer and interpretation; (3) furthermore, confounding factors such as financial incentives, personalized coaching, wear time, and multifaceted intervention might be the barriers to establishing the effectiveness of wearables in physical activity advocacy. Hence, our review findings should be interpreted with caution for generalisability; (4) as a scoping review, we aimed to provide an overview or map the existing evidence rather than critically appraising answer to a particular question. Therefore, policy makers should consider the breadth of the existing knowledge rather than depth and provide framework for public health practises when interpreting our review findings. We recommend that future systematic reviews summarize evidence of the impact of wearables on public health that can be translated from research into practice.

Conclusion

Wearables appear to be impending means of improving physical activity and reducing sedentary behavior remotely during this pandemic. National and organizational policies should adopt wearable technologies to promote physical activity, thereby reducing chronic diseases in the general population.