Delirium is an important cause of morbimortality in older adults admitted to hospital. Multicomponent interventions targeting delirium risk factors, including physical exercise and mobilization, have been shown to reduce delirium incidence in 30-40% in acute care setting but little is known about its role in the evolution of delirium, once established.

This study is a randomized clinical trial conducted in the Acute Geriatric Unit of a tertiary public hospital in Navarra, Spain. Hospitalized delirious patients who meet the inclusion criteria will be randomly assigned to the intervention or control group. The intervention will consist of a multicomponent exercise training programme, which will be composed of supervised progressive resistance and strength exercise training during 4 consecutive days. The objective is to assess the effectiveness of this intervention in reducing the following primary outcomes: duration and severity of delirium, functional status, and length of stay.

This study will contribute to determine the usefulness of physical exercise in the management of delirium. It will be the first study to evaluate the impact of a multicomponent intervention based on physical exercise in the evolution of delirium.

This study is a randomized clinical trial conducted in the Acute Geriatric Unit of Navarra University Hospital (Pamplona, Spain) with 40 beds allocated. Hospitalized patients who meet the inclusion criteria will be randomly assigned to the intervention or control group. After signing an informed consent form, the participants will be randomly assigned to either the intervention or control group. The data for both the intervention and the control group will be obtained at five different times: the initial visit during the acute hospitalization, at discharge and at one, three and twelve months after discharge through phone call and clinical history. Adverse events, including muscle pain, fatigue, falls and general aches will be recorded by the training staff.

Delirium will be assessed using the European Spanish version of the 4AT daily during hospitalization until discharge. This tool has been validated for the Spanish population and is a reliable instrument for delirium detection in older patients. Delirium severity will be evaluated with the Memorial Delirium Assessment Scale (MDAS) which is also validated in Spain.

Therefore, brain function will be examinated during delirium and the effects of an intra-hospital exercise program on the prefrontal cortex region and also on muscle function with the use of functional near-infrared spectroscopy imaging (NIRS). Regional cerebral oxygen saturation (Scto2) will be recorded using NIRS through the NIRO-200NX C10448 monitor (Hamamatsu, Japan) by placing one optode on the patient's forehead above the eyebrow (contralateral to the dominant hand) and the other optode on the vastus lateralis muscle. The measurements will be made with the patients resting in the sitting position after 60 seconds, doing trail making test part A and physical exercise at the beginning of the study and at the 4th day of the study, in both intervention and control group.

Inclusion Criteria:

• Patients > 75 years admitted to the Geriatric Service of the Navarra University Hospital for at least 4 days

Exclusion Criteria:

• Refusal to sign the informed consent by the patient/primary caregiver/legal representative or inability to obtain it
• Advanced dementia GDS 6-7
• Moderate functional impairment (Barthel Index less than 45)
• Life expectancy less than 3 months
• Facial dermal pathology
• Acute intracranial pathology (hemorrhages, cerebral infarcts)
• Recent acute myocardial infarction
• Unstable angina
• Severe heart valve insufficiency
• Arrhythmia or uncontrolled arterial hypertension
• Recent pulmonary thromboembolism
• Hemodynamic instability

Data obtained through this study may be provided to qualified researchers with academic interest in delirium and frailty. Data or samples shared will be coded.

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

Access to trial IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA).