Nearly a century ago, the 1918 influenza pandemic was regarded as the most severe
pandemic in recent history.
The virus, known as H1N1, infected 500 million persons worldwide and claimed an estimated
50 million lives. The pandemic lasted nearly 2 years with sporadic activity characterized
by 3 waves of occurrence. Nearly 100 years later, in January 2020, we found ourselves
in the midst of another global pandemic, the novel coronavirus (coronavirus disease
Within 5 months of outbreak, COVID-19 has infected over 6 million persons worldwide
with over 380,000 confirmed deaths.
While nearly every region of the world has experienced the virus, Europe and North-
and South American countries are among the most impacted countries with the greatest
burden of COVID-19 in terms of the incidence and mortality.
Among the most vulnerable populations, older adults and persons with serious underlying
medical conditions or compromised immune systems are at greatest risk of contracting
In addition, people living in densely populated areas or rural areas with poor access
to health care, living in congregate housing and multi-generational households, and
those who work in the service industry also have a high risk for contracting COVID-19.
This includes many racial and ethnic minorities, immigrants, and refugees.
Requiring people to practice social distancing and undergoing self-quarantine and/or
self-isolation are public health mitigation strategies and actions many countries
have used to control and prevent the widespread of COVID-19.
In some countries, such as the United States and Canada, residents have been asked
to practice social distancing. That is, to keep at least 2 m distance from other people,
not to gather in groups, and to stay out of crowded places and avoid mass gatherings.
In other countries, such as Italy, Spain, and China, residents have been required
to self-quarantine in their homes or elsewhere and to limit movement outside for extended
periods of time or at all. Persons ill with COVID-19 are told to self-isolate in places
separate from others to avoid spreading the illness. In addition, schools and many
jobs have transitioned to online to mitigate the effects of the pandemic. Restaurants,
gyms, parks, community centers, and other public places used for social activities
and recreation have closed in response to COVID-19 resulting in significant disruptions
and changes in everyday schedules for work, school, recreation, and social engagement
routines. Given COVID-19 closures and changes with reductions in daily movement, what
is the impact on physical activity (PA) or exercise routines?
PA has been shown to be vitally important in improving the human immune system and
reducing risk for diseases and health conditions during normal circumstances and in
the current precarious conditions. In this special topic of the Journal of Sport and
Health Science, we address this important public health issue by inviting researchers
from around the world to present unique and pertinent topics about PA during these
challenging times. Within this context, the specific topic covered in this Issue range
from the impact of COVID-19 on PA, physical and mental health benefits of PA, practice
and promotion of PA, to setting a global public health research agenda on PA.
In a review article David Nieman provides an overview of exercise immunology with
an important public health message of engaging in moderate-intensity exercise training
for enhancing the immune system and negating the negative impact attributable to aging,
obesity, and physical inactivity during this COVID-19 pandemic. Two original research
study articles model the impact of COVID-19 on childhood obesity and on children's
adherence to movement guidelines. Using the national kindergarteners’ body mass index
data from a U.S. cohort study, Ruopeng An projects the trajectory of standardized
BMI and childhood obesity prevalence from April 2020 to March 2021 under various scenarios
of school closures and restricted PA. Findings from An's study show an increasing
trend over the projected time horizons in both BMI values and obesity prevalence with
differences noted among gender and race/ethnicity groups. Similarly, applying a classification
decision tree analysis to a national sample of Canadian parents of young children,
Guerrero and colleagues examine profiles of children aged 5–17 years who are more
or less likely to meet the 24-h movement behavior guidelines during the COVID-19 lockdown
period. Findings from their study show associations between several key demographic
and parental factors and children's PA, screen time, and sleep, with parental perceived
capability to support their children's movement behaviors and restrict screen time
being an important influence in strategizing and promoting PA among children during
the challenging times of the COVID-19 pandemic. Two opinion articles share information
relevant to PA practice. In an effort to address the impact of COVID-19 on PA practices
on children and youth in China, Chen et al. provide guidelines for administrators,
physical education teachers, and parents when reintroducing children and youth to
PA following a prolonged COVID-19 quarantine period. Similarly, Jurak et al. present
best practices from a Slovenian viewpoint for ways children, adolescents, and adults
can engage in PA during the quarantine period. In a final article, in addressing the
importance of establishing a public health research agenda that can reveal the effects
of COVID-19 on PA, Sallis and colleagues outline several important research areas
aimed at understanding the impact of the pandemic on PA. Within a behavioral epidemiology
framework, the authors propose emergent topics that focus on (a) PA as a mitigation
strategy to moderate the impact of the coronavirus; (b) the development of PA measurements
that are relevant in a pandemic context; (c) changes in PA behaviors; (d) reducing
disparities in PA; (e) developing and evaluating interventions that take into account
social, cultural, and built environmental factors to increase PA for COVID-19 prevention
and treatment; and (f) translating the research into practice and policy for the current
and future pandemics.
Collectively, these papers provide a snapshot of the importance of initiating and/or
maintaining PA during and after the COVID-19 global pandemic. They also address the
importance of establishing a public health research agenda and social systems to advance
knowledge about PA during and after COVID-19 and to assure all persons have an equal
opportunity to engage in PA behaviors, respectively. In viewing multiple health benefits
of PA, we are reminded that PA is a behavior that lends itself to a coordinated, multi-disciplinary
team approach to address adequately its multiple dimensions. This approach is especially
relevant in the presence of the COVID-19 global pandemic. From this perspective, we
hope the articles in this special topic will serve as both scientific and public health
impetus for stimulating research ideas that will lead to a better understanding of
the impact of PA in helping boost the immune system, ameliorate symptoms, lower the
risk of infection from the exposure to the coronavirus, and identify strategies to
help children and adults remain physically active during the global pandemic.
Declaration of competing interests
The authors declare that they have no competing interests.