Impact of Physical Exercise on Hospitalized Older Adults Malnourished or at Risk, With Oral Nutritional Support

Inclusion Criteria: * Aged 75 years or above * Hospitalized in the Acute Unit of the Geriatrics Service at the University Hospital of Navarra * 4 days or more of expected hospitalization * Malnourished according to the GLIM criteria or at risk of malnourishment (MUST scale) * Barthel Index ≥ 60 points * Capable of tolerating oral intake * Able to walk (with or without assistance) * Able to understand instructions and communicate * Consent to participate in the study after being informed of its objectives and who sign the informed consent (the participant or their legal guardian in case of disability). Exclusion Criteria: * Advanced major neurocognitive disorder (GDS 6 and 7) * Uncontrolled cardiac arrhythmia, acute pulmonary thromboembolism, acute myocardial infarction, or bone fractures within the last 3 months * Chronic kidney disease stage 4 or 5 * Safe and effective swallowing only with pudding texture * Inability to participate in the physical exercise program due to physical limitations * Participate in another study that may interfere with data interpretation or have participated in another study in six months prior to their entry into the study.