Physical activity (PA) has strong relevance for limiting the harms to human health and well-being due to the coronavirus disease-2019 (COVID-19) pandemic. 1 Active muscles produce chemicals that improve immune functioning, which in turn reduces the extent of infections, and decreases inflammation, and these are the main causes of the lung damage from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. PA is a powerful preventive and therapeutic intervention for the most common pre-existing chronic conditions that increase risk of severe COVID-19 infections and mortality. 2, 3 PA's effectiveness in preventing and treating anxiety and depression could have worldwide benefits during this stressful global crisis. 2 PA enhances the efficacy of vaccines, 4 so active lifestyles will continue to be relevant through every phase of the pandemic. Worldwide, about 23% of men and 32% of women are at risk for the underlying conditions of COVID-19, severe COVID-19 infections, and stress-related psychological symptoms, because they do not meet PA guidelines, based on self-report measures. 5, 6

It is likely that prolonged shelter-at-home measures will lead to reduced PA and increased sedentary behaviors that adversely affect immune function and enhance risk for chronic health conditions. 7, 8 Many people, especially with low incomes, do not have equipment, Internet access, or indoor space to make at-home PA realistic. Thus, the current pandemic is almost certain to exacerbate socioeconomic inequities in PA. 9, 10, 11