Clinical Research Directory

Inclusion Criteria: * Inclusion Criteria Participants must meet all of the following criteria: 1. Age ≥60 years. 2. Habitual total water intake (WI) ≤35 mL·kg-¹·day-¹, including water from drinking water, beverages, and food moisture, as determined by dietary assessment. 3. Community-dwelling. 4. Able to ambulate independently without the use of assistive devices. 5. Able to attend all study visits at the SPRINT laboratories. 6. Clinically stable during the three months preceding study inclusion. 7. No cognitive impairment that would compromise the ability to provide informed consent or comply with study procedures. 8. Willing and able to maintain habitual dietary patterns and physical activity levels throughout the study period, except for the prescribed modification in WI in the experimental group (EG). 9. Able to comply with all study procedures, as determined by the investigators. Exclusion Criteria: 1. Clinically unstable cardiovascular disease. 2. Clinically unstable renal disease. 3. Clinically unstable metabolic or endocrine disease. 4. Clinically unstable type 2 diabetes. 5. Any medical condition requiring fluid restriction. 6. Known history of recurrent hyponatremia. 7. Chronic use of medications known to substantially affect fluid and electrolyte balance, including:- Loop diuretics; * Thiazide diuretics; * Desmopressin; * Sodium-glucose cotransporter-2 (SGLT2) inhibitors. 8. Cognitive impairment preventing the provision of informed consent. 9. Musculoskeletal or neurological conditions that preclude participation in physical performance assessments. 10. Major surgery within the previous six months. 11. Current alcohol or substance abuse. 12. Participation in another clinical trial within the previous three months. 13. Any other condition considered by the investigators to compromise participant safety, study compliance, or interpretation of the study results.