Inclusion Criteria:

• * Age between 65-85 yrs
• * Ability to sign informed consent
• * Montreal cognitive assessment (MOCA) exam score greater-than or equal to 26 4. Free-living, prior to admission

Exclusion Criteria:

• * Cardiac abnormalities considered exclusionary by the study physician (e.g., congestive heart failure (CHF), coronary artery disease (CAD), right-to-left shunt)
• * Uncontrolled endocrine or metabolic disease (e.g., hypo/hyperthyroidism, diabetes)
• * Glomerular filtration rate (GFR) less-than 30 mL/min/1.73m2 or evidence of kidney disease or failure
• * Vascular disease or risk factors of peripheral atherosclerosis. (e.g., uncontrolled hypertension, obesity, diabetes, hypercholesterolemia greater-than 250 mg/dl, claudication or evidence of venous or arterial insufficiency upon palpitation of femoral, popliteal and pedal arteries)
• * Risk of deep vein thrombosis (DVT) including family history of thrombophilia, DVT, pulmonary emboli, myeloproliferative diseases including polycythemia (Hb greater-than 18 g/dL) or thrombocytosis (platelets greater-than 400x103/mL), and connective tissue diseases (positive lupus anticoagulant), hyperhomocysteinemia, deficiencies of factor V Leiden, proteins S and C, and antithrombin III
• * Use of anticoagulant therapy (e.g., Coumadin, heparin)
• * Elevated systolic pressure greater-than 150 or a diastolic blood pressure greater-than 100 (treated or untreated)
• * Implanted electronic devices (e.g., pacemakers, electronic infusion pumps, stimulators)
• * Cancer or history of successfully treated cancer (less than 1 year) other than basal cell carcinoma
• * Currently on a weight-loss diet or body mass index greater-than 35 kg/m2 (a BMI of 35 kg/m2, which includes individuals that fall into to the Class I obesity category, has been selected to improve inclusion and generalizability to a greater percentage of the general population).
• * Inability to abstain from smoking for duration of study
• * A history of greater-than 20 pack per year smoking
• * HIV or hepatitis B or C\*
• * Recent anabolic or corticosteroids use (within 3 months)
• * Subjects with hemoglobin or hematocrit lower than accepted lab values
• * Agitation/aggression disorder (by psychiatric history and exam)
• * History of stroke with motor disability
• * A recent history (less-than 12 months) of GI bleed
• * Depression \[greater-than 5 on the 15 items Geriatric Depression Scale (GDS)\]
• * Alcohol abuse (greater-than 2 drinks per day) or drug abuse (inappropriate use of prescription medications or use of any illicit/illegal drugs for recreational use)
• * Exercise training (greater-than 1 session of moderate to high intensity aerobic or resistance exercise/week)
• * Liver disease (aspartate aminotransferase/alanine aminotransferase 2 times above the normal limit, hyperbilirubinemia)
• * Respiratory disease (acute upper respiratory infection, history of chronic lung disease with resting oxygen saturation less-than 97% on room air)
• * Currently taking a mitochondrial targeted antioxidant or similarly acting nutraceutical
• * Unwilling to cease dietary supplements 4 weeks prior to initiation of bed rest
• * Participated in similar bed rest study during last 12 months
• * Any other condition or event considered exclusionary by the PI and faculty physician