The Mito-Frail Trial: Effects of MitoQ on Vasodilation, Mobility and Cognitive Performance in Frail Older Adults

Inclusion Criteria: * men and women aged 65-80 with a slow gait speed (0.4m/s based on a 4m walk) and/or mild cognitive impairment. * good cardiovascular health (not taking any blood pressure/flow/metabolism altering medications) Exclusion Criteria: * A vaccination in past two weeks * Recent acute infection three weeks prior to enrollment * Known immunodeficiency (including HIV infection, primary immunodeficiency, any history of chemotherapy or radiotherapy * Use of medicines during past 6 months known to alter immune response such as high- dose corticosteroids * Severe autoimmune disease requiring biological therapy * Major severe illness and/or Hospitalization in past 3 months * On warfarin or other medications that are considered a blood thinner * Recent fall or other conditions that will impair ability to complete and/or interpret mobility performance test * Known bleeding disorder * Any conditions that would impair the function to perform grip strength test * include advanced neurological disease, severe co-morbid disease, terminal illness with reduced life expectancy, severe disability, unintentional weight loss in last 12 months and participation in another study. * Diabetes patients requiring insulin (For reducing the risk that participants will have hypoglycemic episodes when fasting for study visits) * Baseline ECG QTc \>450 ms in men and QTc \>460 ms in women * Prior diagnosis of ventricular arrhythmia (e.g., ventricular tachycardia, ventricular fibrillation, torsades de pointes)