In this pilot study, the investigators will determine whether supplementation with a mitochondrial-targeted antioxidant (Mitoquinone (MitoQ)) improves mitochondrial function, left ventricular diastolic and vascular function.

Heart failure affects over 5 million American adults and the risk of heart failure increases with age. Diastolic function typically declines with age. Targeting age-related causal factors leading to the decline in diastolic function in both women and men is a major public health initiative. In this pilot study, the investigators will determine whether supplementation with a mitochondrial-targeted antioxidant (Mitoquinone (MitoQ)) improves mitochondrial function, left ventricular diastolic and vascular function in older adults. As an exploratory aim, the investigators will determine whether there are differences between men and women in response to this supplementation.

Inclusion Criteria:

1. 50 - 75 years of age
2. sedentary-to-recreationally active (<3 days of vigorous exercise);
3. nonsmokers;
4. healthy, as determined by medical history, physical examination, standard blood chemistries.

Exclusion Criteria:

1. history of cancer
2. history of cardiovascular disease
3. unwilling or unable to take MitoQ supplement;
4. taking antioxidant vitamins, corticosteroids, or anti-inflammatory medications (e.g., aspirin);
5. taking sex hormone therapy
6. presence of menses within last 1 year;
7. taking any other medications (e.g., antihypertensives, lipid lowering medications) that would interact with MitoQ or impact CV function

Pending