To describe the physical therapy protocols used in critically ill patients to attenuate skeletal muscle atrophy. We conducted a search in PubMed and Embase from inception to November 2020. Observational or experimental studies published in English or Spanish that evaluated the effect of physical therapy protocols on the attenuation of skeletal muscle atrophy in critically ill patients through muscle strength or mass measurement were considered eligible. Studies were only included if they reported a detailed description of the dosing of the interventions. Seventeen studies met the eligibility criteria. We included randomised clinical trials (n = 16) and observational studies (n = 1). The total population of the included studies was 872 critically ill patients. The studies aimed to evaluate the reliability, safety or effectiveness of neuromuscular electrical stimulation (n = 10) protocols, early mobilisation (n = 3), ergometer training (n = 2), transfers in tilt table (n = 1), and blood flow restriction (n = 1). Physical therapy protocols are part of the critically ill patient's integral management. Strategies such as passive mobilisation, in-bed and out-of-bed transfers, gait training, ergometer training, and neuromuscular electrical stimulation substantially impact critically ill patients' prognoses and quality of life after hospital discharge.