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 diseas…