Exercise Therapy to Improve Cardiovascular Health in Post-Menopausal Women After Treatment for Early Stage Breast Cancer

Inclusion Criteria: * Aged 21-80 years * Female * Surgically resected early stage (I-III) primary breast cancer * Post-menopausal, defined as one of the following: * Age ≥ 45 with no menses for at least 2 years * Chemically and/or surgically induced menopause through ovarian suppression, as determined by the primary oncologist * Estradiol level of ≤30 pg/mL * An interval of at least one year, but no more than five years, following the full completion of definitive therapy for malignant disease. Definitive therapy is defined as: * Surgery plus radiation * Surgery plus chemotherapy * Surgery plus trastuzumab * Exercise intolerance (i.e., patients must have a VO2peak below the predicted for active age and sex-matched individuals. (+/- the technical error of 1.32 mL/kg/min)\]. Note: Normative values are available up to 80 years of age) * Able to complete an acceptable baseline CPET, in the absence of high-risk ECG findings or other inappropriate response to exercise as determined by the PI, as defined by any of the following criteria: * Achieving a plateau in oxygen consumption, concurrent with an increase in power output; * A respiratory exchange ratio ≥ 1.10; * Attainment of maximal predicted heart rate (HRmax) (i.e., within 10 bpm of age-predicted HRmax \[HRmax = 220-Age\[years\]); * Volitional exhaustion, as measured by a rating of perceived exertion (RPE) ≥ 18 on the BORG scale * Willingness to comply with all study-related procedures. Exclusion Criteria: * Any of the following absolute contraindications to cardiopulmonary exercise testing: * Acute myocardial infarction within 3-5 days of any planned study procedures * Unstable angina * Uncontrolled arrhythmia causing symptoms or hemodynamic compromise * Recurrent syncope * Active endocarditis * Acute myocarditis or pericarditis * Symptomatic severe aortic stenosis * Uncontrolled heart failure * Acute pulmonary embolus or pulmonary infarction within 3 months of any planned study procedures * Thrombosis of lower extremities * Suspected dissecting aneurysm * Uncontrolled asthma * Pulmonary edema * Respiratory failure * Acute non-cardiopulmonary disorders that may affect exercise performance or be aggravated by exercise (e.g., infection, renal failure, thyrotoxicosis) * Presence of any other concurrent, actively treated malignancy * History of any other malignancy treated within the past 3 years (other than non-melanoma skin cancer) * Presence of distant metastatic disease (i.e., stage IV) * Room air desaturation at rest ≤ 85% * Mental impairment leading to inability to cooperate. * Any other condition or intercurrent illness that, in the opinion of the investigator, makes the participant a poor candidate for the trial.