Lower daily steps among U.S. adolescents during the COVID-19 pandemic: Objective findings from the Adolescent Brain Cognitive Development Study

1. Introduction

While the psychological and physical benefits of physical activity are well established, less than one quarter of US adolescents meet the physical activity guidelines recommended by the US Department of Health and Human Services (60 min per day, seven days per week) (U.S. Department of Health and Human Services, 2018). Furthermore, recent studies suggest that with the onset of the COVID-19 pandemic, the proportion of adolescents meeting these guidelines fell to 9 % based on self-report (Nagata et al., 2022a). However, report-based physical activity measures are prone to measurement error (e.g., incomplete quantification) and information biases (e.g., recall). Objective measures such as step counts provide a continuous indicator of activity over multiple days. One worldwide study suggested a decrease in daily step count in adults early in the pandemic (Tison et al., 2020), but there is a paucity of objective data in US adolescents. The aim of this study was to quantify differences in step count before and during the COVID-19 pandemic among a demographically diverse national sample of adolescents.

2. Methods

Cross-sectional data from Year 2 (2018–2020) of the Adolescent Brain Cognitive Development (ABCD) Study were analyzed in 2022. The sample consisted of 4,955 adolescents (total of 71,833 observations) ages 11–14 with 50.0 % female and 41.3 % racial/ethnic minorities. Centralized institutional review board (IRB) approval was obtained from the University of California, San Diego. Written informed consent and assent were obtained from a parent/guardian and the child, respectively, to participate in the ABCD study. Steps per day (steps d^-1) were collected via Fitbit Charge (Fitbit Inc., San Francisco, CA) over a single continuous three-week (21-day) period at the time of their Year 2 annual assessment. Others have shown that Fitbit provides accurate and consistent measurements of daily step count, an estimate of accumulated physical activity, in adolescents over long periods of time (Bagot et al., 2018, Godino et al., 2020). We followed best practices to extract, filter, and process data established by the ABCD Study (Bagot et al., 2018, Godino et al., 2020). We included all days with > 599 min of waking wear within each participant’s three-week study protocol, collected between November 2018 to November 2020. Generalized estimating equations were used to compare repeated measures of daily steps d^-1 for pre- (3/13/2019–11/27/2019) and peri- (3/13/2020–11/27/2020) pandemic, adjusting for sex, age, race/ethnicity, household income, month, and study site. Analyses were conducted in 2022 using Stata 16.1.

3. Results

Total steps d^-1 by month are shown in Fig. 1a. The largest pre- to peri-pandemic differences in daily steps appeared during the typical school months (e.g., non-summer months). Total steps d^-1by day of the week are shown in Fig. 1b. The largest pre- to peri-pandemic differences in steps per day appeared during weekdays. Using generalized estimating equations controlling for potential confounders, the peri-pandemic period was associated with 2,188 (95 % confidence interval 1,960–2,415) fewer steps per day (20.8 % lower) than the pre-pandemic period (9,625 average daily steps pre-pandemic).

Fig. 1.

Comparison of average daily total steps (a) by month and (b) day of the week (box plots with median and interquartile range) recorded from participants in the U.S. Adolescent Brain and Cognitive Development (ABCD) Study either before (3/13/2019–11/27/2019) or during the first year of the COVID-19 pandemic (3/13/2020–11/27/2020). Note: Due to pandemic restrictions, there was a temporary hiatus of ABCD Study Fitbit data collection from May to June 2020.

4. Discussion

In this large, national sample of early adolescents, participants assessed in the first year of the COVID-19 pandemic had 20.8 % fewer average total daily steps than participants in the pre-pandemic period. This difference in daily steps for adolescents is even greater than the mean difference of −1432 steps d^-1 previously reported in adults early in the pandemic (Tison et al., 2020). The largest difference in steps was apparent during weekdays and non-summer months, typically periods of schooling. This finding likely reflects the impact of school closures, cancellation of sports seasons and in-person physical education classes on adolescent physical activity (Nagata et al., 2022a, Nagata et al., 2022b). Limitations of this study include its cross-sectional nature and potential unmeasured confounders, although we controlled for site, month, and sociodemographic factors. Future studies should explore ongoing trends in daily steps among adolescents after resumption of in-person schooling. Given the beneficial effects of physical activity on physical, mental, and social health, promoting physical activity after initial reductions during the pandemic is critical for the current generation of adolescents.

Declaration of Competing Interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ms. Yu has received funding from Cytel Canada Health, Inc. The other authors have no conflict to declare

Data availability

Data used in the preparation of this article were obtained from the ABCD Study (https://abcdstudy.org), held in the NIMH Data Archive (NDA). Investigators can apply for data access through the NDA (https://nda.nih.gov/).