Muscle preservation during hospitalization: energy balance, protein intake, and habitual physical activity

Muscle loss during hospitalization is a major clinical concern, as it has been associated with reduced physical function, quality of life, and increased mortality. This review outlines the key causes of muscle wasting and highlights practical strategies to support muscle mass preservation during hospitalization. Physical inactivity, along with reduced energy and protein intake, are the primary drivers of muscle atrophy during hospitalization by suppressing muscle protein synthesis (MPS). Maintaining energy balance is critical to prevent declines in MPS rates and attenuate muscle loss. Preserving habitual protein intake is essential and, when total energy intake is reduced, should be achieved through a more protein-dense diet. Preventing disuse atrophy requires at least some level of daily physical activity. Physical activity sensitizes skeletal muscle to the anabolic properties of protein ingestion, enabling greater use of protein-derived amino acids for MPS. Therefore, frequent in-hospital movements, such as bed-to-chair transfers and walking, should be encouraged. When voluntary activity or muscle contractions are impossible, exercise mimetics, like neuromuscular electrical stimulation, may be applied to stimulate muscle activity and limit muscle mass loss. Preserving muscle mass during hospitalization requires a multimodal approach: achieving energy balance, maintaining protein intake, minimizing muscle disuse, and, whenever necessary, apply exercise mimetics.