Effects of Transcutaneous Vagus Nerve Stimulation in Older Adults

Inclusion Criteria: * Non-smokers aged 65 to 80, with BMI from 18.5 to less than 30, who consider themselves healthy and are able to maintain their balance for at least 1 minute without assistance, living in A Coruña (Spain), with a 50% allocation to each sex Exclusion Criteria: * systolic blood pressure above 160 mm Hg and diastolic blood pressure above 100 mm Hg, * previous vagotomy, history of syncope in the last two years, or lack of reliable reading in heart rate variability * presence of chronic pain (migraine, back, neck, shoulder, etc.) or being diagnosed with or receiving treatment for malignant, cardiovascular disease (excluding hyperlipidaemia and hypercholesterolaemia), respiratory, neurological or autonomic, metabolic (e.g. diabetes), osteoarticular of autoimmune origin (e.g. arthritis), psychiatric or history of treatment with antidepressants or anxiolytics * impaired cognitive level * presence of any contraindication or difficulty in applying TENS: pacemaker, defibrillator or any implanted electronic device, apprehension of electric current, burns or irritated skin or allergic reaction or any alteration in the area that prevents the electrode from being placed on the left ear; * previous application of electrical stimulation to the ear