This study is being done to see if patients receiving chemotherapy for breast cancer affects the heart, the ability to exercise and fatigue when compared to patients who do not have cancer.
Inclusion Criteria for Women with Stage I - III Breast Cancer: * Stage I-III female breast cancer (including inflammatory and newly diagnosed or locally recurrent breast cancer) but not metastatic breast cancer being treated with curative intent * \> 18 years old * Scheduled to receive chemotherapy and/or estrogen antagonist aromatase inhibitors (anastrozole \[Arimidex\], letrozole \[Femara\], exemestane \[Aromasin\]). * Able to hold breath for 10 seconds * ECOG performance status 0 -2 * Able to walk at least 2 blocks without chest pain, dyspnea, shortness of breath or fainting * Able to exercise on a treadmill or stationary cycle * Participants in other ongoing clinical trials are eligible for this study Exclusion Criteria for Women with Stage I-III Breast Cancer: * Those with ferromagnetic cerebral aneurysm clips or other intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices or other implanted non-compatible MRI devices (patients with tissue expanders will not be excluded) * If previously measured, known LVEF \<50% * Symptomatic claustrophobia * Unable to provide informed consent * At the beginning of the study, pregnant women and women who are breast-feeding will not be enrolled. * Severe pulmonary hypertension * Within the past 6 months: * Acute pulmonary embolus * Deep vein thrombosis * Within the past month: * Heart attack * Unstable or stable angina (cardiac chest pain) * Left main coronary artery disease * Symptomatic heart failure * Uncontrolled hypertension (SBP \> 180 mm Hg or DBP \> 120 mm Hg) * Severe valvular heart disease * Uncontrolled metabolic disease (diabetes with fasting BS \>300 mg/dl, thyrotoxicosis, myxedema) * Aortic aneurism (\>45 mm diameter) or aortic dissection * Uncontrolled slow or fast heart rhythm causing symptoms or hemodynamic compromise * Hypertrophic obstructive cardiomyopathy * Patient does not understand English Inclusion Criteria for Women Free of Cancer for Comparison: * Healthy female without known coronary artery disease \> 18 years old * Able to hold breath 10 seconds * ECOG performance status = 0 or 1 * Able to walk at least 2 blocks without chest pain, dyspnea, shortness of breath or fainting * Able to exercise on a treadmill or stationary cycle * No personal history of cancer other than superficial skin cancers * Has never received chemotherapy, radiation therapy, immunotherapy, or had breast cancer related surgery * If previously measured, LVEF ≥ 50% Exclusion Criteria for Women Free of Cancer for Comparison: * Inflammatory conditions such as lupus or inflammatory bowel disease * Overt coronary artery disease or heart failure * Those with ferromagnetic cerebral aneurysm clips or other intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices or other implanted non-compatible MRI devices * Symptomatic claustrophobia * Unable to provide informed consent * At the beginning of the study, pregnant women or women who are breast feeding will not be enrolled. * Severe pulmonary hypertension * Within the past 6 months: * Acute pulmonary embolus * Deep vein thrombosis * Within the past month: * Heart attack * Unstable or stable angina (cardiac chest pain) * Left main coronary artery disease * Symptomatic heart failure * Uncontrolled hypertension (SBP \> 180 mm Hg or DBP \> 120 mm Hg) * Severe valvular heart disease * Uncontrolled metabolic disease (diabetes with fasting BS \>300 mg/dl, thyrotoxicosis, myxedema) * Aortic aneurism (\>45 mm diameter) or aortic dissection * Uncontrolled slow or fast heart rhythm causing symptoms or hemodynamic compromise * Hypertrophic obstructive cardiomyopathy * Patient does not understand English