Association of circulating muscle-derived myokines irisin and myostatin with COVID-19 severity

These findings suggest that, through the release of bioactive myokines, skeletal muscles contribute to the regulation of systemic inflammation and oxygenation, thereby influencing the clinical course of SARSCoV-2 infection. Elevated irisin reflects heightened inflammation, severe hypoxemia, and extensive lung involvement, whereas increased myostatin is associated with severe inflammation and critical illness.