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Emerging epidemiological reports on the coronavirus (COVID-19) in children show that they are less likely than adults to be infected and have severe illness. Why do young children seem to be less affected by COVID-19?
While there is currently no scientific-based data to answer this crucial question, researchers have focused their hypotheses on the young immune system, age-related differences in receptors (ACE2) in the renin-angiotensin system (RAS), and children’s altered inflammatory responses to pathogens. Specifically, children appear to be less likely to develop a dangerous immune response – often referred to as a cytokine storm.
Due to substantial advances in exercise immunology over the past few decades, it is becoming evident that many of the health benefits of regular physical activity may be directly related to activation of the immune system. Studies show age-related changes in the immune system across the life span. In general, healthy children experience smaller overall perturbations to the immune system in response to an acute stress, such as a bout of exercise, and demonstrate a faster recovery from such perturbations compared with adults. Some evidence exists to also suggest that moderate-to-high levels of physical activity are associated with lower incidence of infection and illness in children.
Human growth is a dynamic process regulated by the hormonal milieu and can be affected by immune mediators. What is particularly intriguing is that many of the hormones and mediators involved in natural growth in children also appear to play substantial roles in the adaptive responses to physical activity and exercise. Our group at UC Irvine has been instrumental in demonstrating age-related stress/inflammatory responses to exercise in children. We’ve showed that many of the genomic and epigenetic pathways identified in the immune cells of children following exercise are related to growth and repair, as well as to disease prevention. While inflammatory mediators are often associated with obesity and other medical conditions, research has demonstrated that even among sedentary, otherwise-healthy children, inflammatory mediator levels are higher than among those regularly active in organized sports.
Altogether there is mounting evidence of the beneficial effects of acute and chronic (training) exercise on the immune system of the growing child. Although we still have no research-based data on the direct effect of exercise or training on COVID-19 infection and management, making sure our children maintain regular physical activity and exercise in a safe environment is an important strategy to keep them healthy and sustain their immune system function during the current stay-at-home situation.
ACSM’s Exercise is Medicine® Pediatric Committee developed an Rx for Health series public handout encouraging parents to keep their children moving during this crisis. The handout specifies that physical activity can provide immediate benefits like relieving stress, decreasing behavioral problems, sharpening concentration and boosting the immune system. It also shares creative ways children can stay active indoors and outdoors (if allowed).
Always remember that doing some activity is better than none and every bit of activity benefits health. So, let’s help our children stay active!
Shlomit Radom-Aizik, Ph.D., serves as the executive director at the UC Irvine Health Pediatric Exercise and Genomics Research Center and as an associate professor in the Department of Pediatrics in the School of Medicine at the UC Irvine. Dr. Radom-Aizik is an ACSM member.