Fig. 1

The early and late phases of muscle wasting in acute respiratory distress syndrome. The early phase of muscle wasting begins with the onset of lung injury and is caused by lung and systemic inflammation and to a lesser degree disuse, both leading to muscle atrophy. The late phase of muscle wasting begins as lung function recovers and acute systemic inflammation resolves. Disuse continues in many patients during the late phase. Muscle function deteriorates in the early phase, and dysfunction persists in many patients during the late phase, which may last for years despite resolution of lung injury and cessation of ongoing muscle atrophy. Factors mediating recovery trajectories in the late phase are poorly understood