This trial tests whether combining moderate aerobic exercise with the antioxidant MitoQ can improve blood vessel function in postmenopausal women who lack estrogen. MitoQ aims to reduce oxidative stress and enhance blood flow by improving mitochondrial function. The study will compare the effects of exercise with MitoQ, exercise alone, and MitoQ alone. MitoQ is a mitochondria-targeted antioxidant that has been studied for its potential to enhance exercise-induced muscle adaptations and improve peak power in untrained middle-aged men.