Supervised Aerobic Training During or After Chemotherapy for Operable Breast Cancer

Inclusion Criteria:

* Aged 21-80 years
* Female
* MSK histologically confirmed early-stage operable breast cancer
* Scheduled to receive chemotherapy in the neoadjuvant or adjuvant setting
* ECOG status of 0 or 1
* Performing less than 150 minutes of structured moderate-intensity or strenuous intensity exercise per week
* If a female of child-bearing potential, must not be pregnant or planning to become pregnant during the study.

  a. Women \< 50 years old must have a negative pregnancy test (urine HCG or serum βHCG) within 2 weeks of beginning chemotherapy.
* Able to complete an acceptable baseline cardiopulmonary exercise test (CPET), in the absence of high risk ECG findings or other inappropriate response to exercise as determined by the investigator.
* Able to achieve an acceptable peak baseline CPET, 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 be randomized to one of the study arms

Exclusion Criteria:

* 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 metastatic disease
* Any of the following 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 (i.e., infection, renal failure, thyrotoxicosis) or
* 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