Early mobilization, which has been recognized as a primary component of acute-phase rehabilitation interventions, is associated with better outcomes. One randomized trial of mechanically ventilated patients reported an association between early mobilization and better outcomes, including higher rates of discharge to home, fewer days in the intensive care unit, and less hospital-acquired comorbidity, such as ventilator-associated pneumonia and intensive care unit delirium. Moreover, small randomized trials also have observed better physical functional status when patients who experienced a stroke are mobilized 24-48 h after hospitalization. Another large-scale clinical registry reported the association of early mobilization with clinical outcomes in patients following heart failure. Early ambulation within 2 days of hospitalization is also associated with decreased length of hospital stay and post-discharge 30-days readmission rates. Elderly patient populations such as those in Japan often have multiple comorbidities and physical frailty, which may contribute to longer hospital stay and lower rates of discharge to home. Iatrogenic sarcopenia caused by excessive bed rest is one of the major hospitalacquired comorbidities in the clinical setting, and it is considered preventable by early mobilization.