Sarcopenia: An underlying treatment target during the COVID-19 pandemic.

The role of skeletal muscle mass in modulating immune response and supporting metabolic stress has been increasingly confirmed. Patients with sarcopenia, characterized by reduced muscle mass and muscle strength, were reported to have poor immune response and metabolic stress when facing acute infection, major surgeries, and other attacks. Based on empirical data, patients with sarcopenia are speculated to have increased infection rates and dismal prognoses amid the current 2019 novel coronavirus disease (COVID-19) epidemic. COVID-19 infection also aggravates sarcopenia because of the increased muscle wasting caused by systematic inflammation and the reduced physical activity and inadequate nutrient intake caused by social isolation. Notably, the interventions targeting skeletal muscle are anticipated to break the vicious circle and benefit the treatment of both conditions. We recommend sarcopenia assessment for populations with advanced age, inactivity, chronic disease, cancers, and nutritional deficiency. Patients with sarcopenia and COVID-19 infection need intensive care and aggressive treatments. The provision of at-home physical activities together with protein supplementation is anticipated to reverse sarcopenia and promote the prevention and treatment of COVID-19. The recommended protocols on nutritional support and physical activities are provided in detail.