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

The main objective of the present study is to evaluate the differences in the impact of an intervention based solely on physical exercise on the functionality of hospitalized older patients, in an Acute Geriatric Unit, who are malnourished or at risk of malnutrition.

As secondary objectives:

1. To assess and compare changes in body composition following the intervention during hospitalization.
2. To evaluate and compare dietary intake, appetite progression, and food consumption throughout the intervention period.
3. To compare in-hospital infectious complications between the two groups.
4. To describe and compare changes in nutritional biochemical parameters between groups after the intervention and 30 days post-discharge.
5. To study changes in other physical function measures throughout the study period and compare them.
6. To describe the presence of molecular markers related to senescence and sarcopenia in patients and compare them between groups at discharge.
7. To study and compare changes in participants' cognitive status.
8. To evaluate and compare changes in perceived quality of life.
9. To assess and compare changes in maximal dynamic strength before and after the intervention.
10. To describe and compare hospital stays and 30-day readmission rates of study participants.
11. To describe participants' personal satisfaction with the intervention.
12. To describe the presence of potential side effects attributed to the intervention during the study period.

• Physical exercise (Other): Progressive, supervised multicomponent physical exercise program, including aerobic resistance, strength, and balance training. Strength training for lower limbs (leg press and knee extension) and upper limbs (seated chest press) will be adapted to each individual's functional capacity.
• Usual Care (Other): * Hospital physiotherapy for preventing nosocomial disability when necessary. * Hospital diet modifications appropriate to each participant's clinical situation. * Oral nutritional supplementation aimed at meeting daily nutritional requirements: 30 kcal/kg body weight, 1.5-2 g protein/kg body weight, 25 g daily fiber. * Approximate free water intake: women 1.5 L/day, men 2 L/day (unless clinically restricted).

Primary outcomes

• Function [Through study completion, an average of 4 days]: SPPB - Short Physical Performance Battery

Secondary outcomes

• Anthropometrical Measurements [Through study completion, an average of 4 days]: Bioimpedance: PHASE ANGLE (PhA), Fat-Free Mass (FFM) and Muscle Mass (MM). Conventional and vectorial bioelectrical impedance analysis with a single-frequency bioelectrical impedance analyzer at 50 kHz (BIA 101 RJL, Akern Bioresearch, Florence, Italy)
• Dietary intake [Through study completion, an average of 4 days]: Semi-quantitative questionnaire and a daily appetite assessment
• Number and type of infectious complications [Through study completion, an average of 4 days]
• Nutritional status biomarkers [Through study completion, an average of 4 days, and 30 days post-discharge]: In blood: proteins, prealbumin, albumin, transferrin, lymphocytes, 25-hydroxyvitamin D, C-reactive protein.
• Functional status [Through study completion, an average of 4 days, and 30 days post-discharge]: Barthel Index, Lawton Index
• Frailty status [Baseline]: Linda Fried's Frailty Scale, from 0 to 5 (0 robust; 1,2 pre-frail; 3 to 5 frail).
• Strength of upper and lower limbs [Through study completion, an average of 4 days]: Leg press, chest press, knee extension, and handgrip strength
• Cognitive status [Through study completion, an average of 4 days]: Mini-Mental State Examination, 4AT
• Affective status [Through study completion, an average of 4 days]: Yesavage's 15-item Geriatric Depression Scale (GDS-15)
• Quality of life of participants [Through study completion, an average of 4 days]: EuroQoL-5D-3L
• Adverse effects possibly attributed to the intervention [Through study completion, an average of 4 days]

Sex: All, ages: 75 Years to any

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.