Elderly patients who experience a prolonged ICU stay are at high risk for developing post intensive care unit syndrome (PICS), a serious medical condition manifested by loss of muscle mass, weakness, malnutrition and neurocognitive decline. PICS often leads to chronic disability, prolonged mechanical ventilation and the need for costly extended stays in long term care facilities (LTCs). The investigators' preliminary study shows attempts at rehabilitating patients who have already developed PICS are minimally effective, resulting in only modest improvements in functionality. This project will determine the effects of mobility-based physical rehabilitation (MPR) combined with neuromuscular electric stimulation (NMES) and high protein supplementation (HPRO) early in a patients ICU stay on preventing PICS related musculoskeletal and functional deficits, and improving clinical outcomes.