Breastmilk in Response to a Bout of Exercise

Exclusion Criteria: * Active coronary artery disease or heart failure. * Participation in a structured exercise program ≥ 1 day/week in the "inactive" subcohort or \< 3 days per week in the "active" subcohort. * A known medical condition that in the judgment of the investigator might interfere with the completion of the protocol such as the following examples: * Abnormal liver function test results (Transaminase \>2 times the upper limit of normal * Abnormal renal function test results (calculated GFR \<60 mL/min/1.73m2); * If on antihypertensive, thyroid, anti-depressant or lipid lowering medication, lack of stability on the medication for the past 2 months prior to enrollment in the study * Uncontrolled thyroid disease (TSH undetectable or \>10 mlU/L); testing required within three months prior to admission for subjects with a goiter, positive antibodies, or who are on thyroid hormone replacement, and within one year otherwise * Abuse of alcohol or recreational drugs * Active tobacco smoking within the past 3 months * Infectious process not anticipated to resolve prior to study procedures (e.g. meningitis, pneumonia, osteomyelitis). * Uncontrolled arterial hypertension (Resting diastolic blood pressure \>90 mmHg and/or systolic blood pressure \>160 mmHg) at the time of screening. * A recent injury to body or limb, muscular disorder, use of any medication, any carcinogenic disease, or other significant medical disorder if that injury, medication or disease in the judgment of the investigator will affect the completion of the protocol * Active pregnancy * Restrictions on Use of Other Drugs or Treatments: * Any other medication believed to be a contraindication to the subject's participation.