Study of Healthy Aging and Physical Function With Elamipretide

Inclusion Criteria: 1. Male or female aged ≥65 and ≤80 years 2. VO2peak ≤ 37.3ml/kg/min for men and ≤ 25.7ml/kg/min for women as evidence of lower mitochondrial function 3. Are ambulatory and able to perform activities of daily living without assistance 4. Have sufficient venous access for clinical blood draw 5. Willing and able to self-administer injections or have a willing caregiver who is able to administer injections. 6. Speak and read English 7. Have no established daily exercise routine and are not participating in any exercise training program or physical hobby (i.e. dance, martial arts, yoga) and agree to not start any such activities during the course of study participation 8. Willing to avoid the following medications during the course of the study: Anti-seizure medications * Coenzyme Q10, creatine, L-carnitine, and other supplements intended to increase muscle mass, energy or function * Muscle relaxants * Systemic steroid or immunosuppressive use * Opioids (regular use of \> 10 mg/day morphine equivalents) 9. No known allergies/adverse effects from Fexofenadine 10. Provide documentation of informed consent Exclusion Criteria: 1. Have significant disease(s) or condition(s) which, in the opinion of the investigator, may put the subject at risk because of their participation in the study or may influence either the results of the study or the subject's ability to participate in the study 2. Presence of severe renal disease (eGFR \<30 mL/min) or hepatic disease (aspartate aminotransferase \[AST\] or alanine aminotransferase \[ALT\] \>2x the upper limit of normal) as evidenced by laboratory results at Screening. 3. Have a history of rhabdomyolysis 4. Have been hospitalized within 3 months prior to screening for major atherosclerotic events (e.g., myocardial infarction, target-vessel revascularization, coronary bypass surgery or stroke) or other major medical condition (as deemed by the primary investigator) 5. Are currently enrolled in a clinical study involving an investigational product or non- approved use of a drug or device or concurrently enrolled in any other type of medical research judged to be scientifically or medically incompatible with this study 6. Have participated within the last 30 days of screening visit in a clinical study involving an investigational product. \-