During critical illness, patients experience significant and rapid onsets of muscle wasting and dysfunction with loss of strength, mass, and power. These deficits often persist long after the ICU, leading to impairments in physical function including reduced exercise capacity and increased frailty and disability. While there are numerous studies describing the epidemiology of impaired muscle and physical function in the ICU, there are significantly fewer data investigating mechanisms of prolonged and persistent impairments in ICU survivors. Additionally, while several potential clinical risk factors associated with poor physical recovery have been identified, there remains a dearth of interventions that have effectively improved outcomes long-term among survivors. In this article, we aim to provide a thorough, evidence-based review of the current state of knowledge regarding muscle dysfunction and physical function after critical illness with a focus on post-ICU and post-hospitalization phase of recovery.