Exercise, particularly resistance training, attenuates muscle strength loss and preserves muscle mass during hospitalization and bed rest, whereas no consistent benefits are observed during spaceflight. Exercise initiated after disuse shows modest potential for restoring muscle function. Current evidence is insufficient to determine whether preventive or therapeutic initiation provides superior outcomes. Further high-quality randomized controlled trials are required to define the optimal timing, modality and dose of exercise for clinical rehabilitation and aerospace applications.
Padilha et al. (2026) studied this question.