Fatigue is a strong predictor of negative health outcomes in older adults. The research in this study will compared the effects of 8-weeks of branched chain amino acids (BCAAs: dietary supplements commonly taken to improve muscle growth and exercise performance) added to exercise on fatigue compared to exercise with a placebo (an inactive, harmless substance). BCAAs could have an impact on improving fatigue common in older adults, especially when exercising.

Thirty participants will be asked to participate in this research study. They will be randomized (like a flip of a coin) to exercise + a placebo or exercise + BCAAs for 8 weeks. We would like to examine the effects of the 8-week exercise + dietary supplement program on body composition (fat and muscle), physical activity habits, fatigue, and physical performance (such as walking and strength). We would also like to assess whether these outcomes are controlled by changes in markers (kynurenine metabolites) in the skeletal muscle and blood.

Inclusion Criteria:

• Fatigue (participants reporting ≥3 on a 1-10 scale)
• Lack of menses for at least one year for women
• BMI 20-50 kg/m2
• Untrained with regard to structured exercise training (is not currently training more than 2x/week)

Exclusion Criteria:

• Taking an anticoagulant medication that is unable to be discontinued before biopsies
• Allergic to lidocaine
• Neurologic, musculoskeletal, or other condition that limits subject's ability to complete study physical assessments or training
• Hepatic (LFTs >2.5xWNL), renal (eGFR<45), , and uncontrolled psychiatric disease
• Cognitive impairment
• Uncontrolled depression
• Any disease or condition considered to be exclusionary based on the clinical opinion and discretion of the principal investigator

Up to 8 weeks