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All content in this area was uploaded by Robert Avram on Aug 17, 2020
Content may be subject to copyright.
OBSERVATION:BRIEF RESEARCH REPORT
Worldwide Effect of COVID-19 on Physical Activity:
A Descriptive Study
Background: On 11 March 2020, the World Health Orga-
nization declared coronavirus disease 2019 (COVID-19) to be
a global pandemic (1). To curb the spread of the disease,
various regional and national governments advocated for so-
cial distancing measures with varying degrees of enforce-
ment, ranging from unenforced recommendations to quaran-
tine and business closures. Physical activity is an important
determinant of health (2) and is likely affected by social dis-
tancing measures. Daily step count, a proxy for physical activ-
ity, has been associated with all-cause mortality (3). Beyond
physical activity, regional step count trends may also provide
a proxy for adherence to social distancing, providing real-time
insights to inform public policy decisions. Because prolonged
social distancing is considered to contain infection, it will be
important to gauge adherence to these measures and their
effect on other aspects of health, such as physical activity.
Objective: To examine worldwide changes in step count
before and after the announcement of COVID-19 as a global
pandemic.
Methods and Findings: In this descriptive study, we used
deidentified, individual-level data from 19 January to 1 June
2020 that were collected from a convenience sample of users
of the free, popular health and wellness smartphone app Ar-
gus (Azumio). Daily step counts were determined using smart-
phone accelerometers and Apple or Android algorithms for
step counting (4). User location was determined by smart-
phone IP address. The COVID-19 pandemic declaration date
used was 11 March 2020. Regional mean steps were calcu-
lated daily, and percentage of change in steps was calculated
daily as a percentage of the regional mean from 19 January to
11 March 2020. Displayed figure regions were selected to
achieve half less-affected and half more-affected regions with
regard to both COVID-19 and social distancing and greater
than 1000 and 700 users at the country and city levels, respec-
tively. This study was exempted by the University of California,
San Francisco Institutional Review Board.
A total of 19 144 639 daily step count measurements
were provided by 455 404 unique users from 187 unique
countries during the study period; 92% of smartphones were
Apple, and 8% were Android. Worldwide, within 10 days of
the pandemic declaration, there was a 5.5% decrease in mean
steps (287 steps), and within 30 days, there was a 27.3% de-
crease in mean steps (1432 steps). There was wide regional
variation in average step count change and in the timing and
rate of that change (Figures 1 and 2). For example, Italy de-
clared a nationwide lockdown on 9 March 2020 and exhibited
a 48.7% maximal decrease, whereas Sweden, to date, has pri-
marily advocated for social distancing and limitations on gath-
erings and showed a 6.9% maximal decrease. Samples from
countries such as Italy and Iran, which had earlier regional
COVID-19 outbreaks, exhibited earlier step count decreases
from their relative baselines. Samples from different countries
varied widely in the number of days after pandemic declara-
tion that a 15% step count decrease was seen: Italy (5 days),
Spain (9 days), France (12 days), India (14 days), the United
States (15 days), the United Kingdom (17 days), Australia (19
days), and Japan (24 days). Step count trends in samples from
U.S. cities exhibited similarities, although there was wide in-
ternational variability (Figure 2).
Discussion: Step counts decreased worldwide in the pe-
riod after COVID-19 was declared a global pandemic. Differ-
This article was published at Annals.org on 29 June 2020.
Figure 1.
Mean daily steps and percentage of change
from step count at baseline, by country.
7000
6000
5000
4000
Mean Daily Steps, n
3000
2000
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
Country
Brazil (n= 3067)
France (n= 4114)
Iran (n= 1302)
Italy (n= 6403)
Japan (n= 4074)
South Korea (n= 1212)
Sweden (n= 2417)
Taiwan (n=2199)
United Kingdom (n= 36 284)
United States (n= 239 543)
Initiation of regional orders
Liftin
g
of re
g
ional orders
10
0
–10
–20
–30
Change From Baseline Steps, %*
–40
–50
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
Top. Mean daily steps, by country. Bottom. Percentage of change in
steps from the prepandemic baseline, by country.
* Prepandemic baseline steps by country were calculated as the mean
daily steps from 19 January to 11 March 2020 for that country. All
values are plotted by region over a rolling 10-d average window for
smoothness. Region sample sizes show total number of users who
contributed data during the study period. Diamonds denote initiation
dates and squares denote lifting dates of regional social distancing
orders, if available. Specific regional orders were assembled from
publicly available sources as accurately as possible. Brazil, South Ko-
rea, Sweden, Taiwan, and the United States: no national orders.
France: stay-at-home orders, only essential businesses open (17
March to 10 May 2020). Iran: lockdown orders, only essential busi-
nesses open (14 March to 20 April 2020). Italy: lockdown orders, only
essential businesses open (9 March to 18 May 2020). Japan: state of
emergency for all prefectures and nonmandatory business closure re-
quest (16 April to 25 May 2020). United Kingdom: ongoing stay-at-
home orders, only essential businesses open (23 March 2020 to
present).
Annals of Internal Medicine LETTERS
© 2020 American College of Physicians 1
ences were seen between regions, likely reflecting regional
variation in COVID-19 timing, regional enforcement, and be-
havior change. Countries that, to date, have had relatively low
COVID-19 infection rates and have therefore not instituted
lockdowns, such as South Korea, Taiwan, and Japan, have still
exhibited decreases in overall step count. Within-region step
count trends likely reflect a combination of changes to physi-
cal activity (for example, walking and exercising) and activities
of daily living (for example, commuting and shopping) due to
social distancing efforts. Assuming no regulatory changes that
affect engaging in physical activity within a region, we suspect
that sustained population-level trends over time may reflect
changes to social distancing adherence (for example, many
regions showed increases from their regional step count nadir
before orders were lifted). Observed variation in step counts
is also likely influenced by socioeconomic inequalities among
regions and disparities in the ability to engage in or access to
recreational physical activity within a region (4).
Figure 2.
Mean daily steps and percentage of change from step count at baseline, by city.
City
Chicago (n= 5470)
Dallas (n= 7617)
Houston (n= 4626)
Los Angeles (n= 6198)
New York (n=10 288)
Philadelphia (n= 1523)
Phoenix (n= 1264)
San Antonio (n= 1250)
San Diego (n= 1468)
San Jose (n= 826)
Initiation of regional orders
Lifting of regional orders
6000
5500
5000
4000
4500
Mean Daily Steps, n
3500
3000
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
A
10
0
–10
–20
Change From Baseline Steps, %*
–30
–40
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
B
8000
7000
6000
4000
5000
Mean Daily Steps, n
3000
2000
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
C
City
Ho Chi Minh City (n= 2312)
London (n= 9510)
New York (n=10 288)
Paris (n= 1708)
Rome (n= 873)
São Paulo (n= 790)
Seoul (n= 814)
Singapore (n= 2137)
Stockholm (n= 1128)
Tokyo (n=2051)
Initiation of regional orders
Lifting of regional orders
10
0
–10
–30
–20
Change From Baseline Steps, %*
–40
–50
11 Feb 2020
25 Feb 2020
10 Mar 2020
24 Mar 2020
7 Apr 2020
21 Apr 2020
5 May 2020
19 May 2020
1 Jun 2020
D
U.S. Cities Worldwide
A. Mean daily steps, by U.S. city. B. Percentage of change in steps from the prepandemic baseline, by U.S. city. C. Mean daily steps in a sample of
cities worldwide. D. Percentage of change in steps from the prepandemic baseline in a sample of cities worldwide.
* Prepandemic baseline steps by city were calculated as the mean daily steps from 19 January to 11 March 2020 for that city. All values are plotted
by region over a rolling 10-d average window for smoothness. Region sample sizes show the total number of users who contributed data during the
study period. Diamonds denote initiation dates and squares denote lifting dates of regional social distancing orders, if available. Specific regional
orders were assembled from publicly available sources as accurately as possible. Chicago: stay-at-home order, only essential businesses open (21
March to 3 June 2020). Dallas: shelter-in-place order, only essential businesses open (24 March to 30 April 2020). Houston: stay-at-home order, only
essential businesses open (24 March to 30 April 2020). Los Angeles: ongoing stay-at-home order, only essential businesses open (19 March 2020
to present). New York City: ongoing shelter-in-place order, only essential businesses open (22 March 2020 to present). Philadelphia: stay-at-home
order, only essential businesses open (23 March to 5 June 2020). Phoenix: stay-at-home order, phased reopening (31 March to 15 May 2020). San
Antonio: stay-at-home order, only essential businesses open (24 March to 30 April 2020). San Diego: ongoing stay-at-home order, only essential
businesses open (19 March 2020 to present). San Jose: ongoing stay-at-home order, only essential businesses open (17 March 2020 to present). Ho
Chi Minh City: nationwide isolation, only essential activities allowed (1 April to 22 April 2020). London: ongoing stay-at-home orders, only essential
businesses open (23 March 2020 to present). New York City: ongoing shelter-in-place order, only essential businesses open (22 March 2020 to
present). Paris: stay-at-home order, only essential businesses open (17 March to 10 May 2020). Rome: lockdown orders, only essential businesses
open (9 March to 17 May 2020). Sao Paulo: ongoing statewide quarantine, only essential businesses open (24 March 2020 to present). Seoul: no
regional orders, citizens asked to remain indoors for 2 weeks starting 29 February 2020. Singapore: stay-at-home order, limits on social gatherings
(7 April to 1 June 2020). Stockholm: no regional orders. Tokyo: state of emergency for Tokyo, nonmandatory business closure request (7 April to
25 May 2020).
LETTERS
2 Annals of Internal Medicine Annals.org
Limitations of this study include sampling bias due to the
reliance on smartphone and app ownership, measurement
error from smartphone-measured step counts, variability in
smartphone carry and use habits, no assessment of activity
intensity, and inability to capture nonstepping exercise (5).
Our data set is a nonrepresentative convenience sample with
a variable number of contributing daily users. It also lacks par-
ticipant characteristics beyond IP address, limiting compari-
sons among regions.
Rapid worldwide step count decreases have been seen
during the COVID-19 pandemic, with regional variability.
Within-region step count trends may reflect social distancing
measures and changes to social distancing adherence; how-
ever, more formal analytic studies are required. The effect of
social distancing measures on overall physical activity, an im-
portant determinant of health, should be considered, particu-
larly if prolonged social distancing is required.
Geoffrey H. Tison, MD, MPH
University of California, San Francisco, and Bakar Computa-
tional Health Sciences Institute
San Francisco, California
Robert Avram, MD, MSc
University of California, San Francisco
San Francisco, California
Peter Kuhar, BS
Azumio
Redwood City, California
Sean Abreau, MSc
Greg M. Marcus, MD, MAS
Mark J. Pletcher, MD, MPH
Jeffrey E. Olgin, MD
University of California, San Francisco
San Francisco, California
Financial Support: Dr. Tison received support from the National In-
stitutes of Health (NHLBI K23HL135274). Azumio provided no financial
support for this study and only provided access to the step count data.
They had no role in the decision to publish the manuscript. Data
analysis and interpretation were done independently from Azumio.
The funders had no role in study design, data collection, and anal-
ysis; preparation of the manuscript; or the decision to publish the
manuscript.
Disclosures: Disclosures can be viewed at www.acponline.org
/authors/icmje/ConflictOfInterestForms.do?msNum=M20-2665.
Reproducible Research Statement: Study protocol and statistical
code: Correspondence about methodological issues or statistical
code should be directed to Dr. Tison (e-mail, geoff.tison@ucsf.edu).
Data set: Data are used under a research license from Azumio. Inqui-
ries for collaboration can be addressed to Dr. Tison (e-mail, geoff.tison
@ucsf.edu).
Corresponding Author: Geoffrey H. Tison, MD, MPH, University of
California, San Francisco, 555 Mission Bay Boulevard, South Box 3120,
San Francisco, CA 94158; e-mail, geoff.tison@ucsf.edu.
doi:10.7326/M20-2665
References
1. World Health Organization. WHO Director-General's opening remarks at
the media briefing on COVID-19—11 March 2020. Accessed at www.who.int
/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media
-briefing-on-covid-19—11-march-2020 on 1 June 2020.
2. Lee IM, Shiroma EJ, Lobelo F, et al; Lancet Physical Activity Series Working
Group. Effect of physical inactivity on major non-communicable diseases
worldwide: an analysis of burden of disease and life expectancy. Lancet. 2012;
380:219-29. [PMID: 22818936]
3. Saint-Maurice PF, Troiano RP, Bassett DR Jr, et al. Association of daily step
count and step intensity with mortality among US adults. JAMA. 2020;323:
1151-1160. [PMID: 32207799]
4. Althoff T, Sosic R, Hicks JL, et al. Large-scale physical activity data reveal
worldwide activity inequality. Nature. 2017;547:336-339. [PMID: 28693034]
5. Case MA, Burwick HA, Volpp KG, et al. Accuracy of smartphone applications
and wearable devices for tracking physical activity data. JAMA. 2015;313:
625-6. [PMID: 25668268]
LETTERS
Annals.org Annals of Internal Medicine 3