The investigators propose a randomized controlled trial to determine the effectiveness of inspiratory muscle training in improving exercise tolerance among stage 0-III obese breast cancer survivors.

Randomized controlled trial (RCT) where obese participants (N=133) are randomized to 2 arms: [i] IMT 4 wks + Exercise 12 wks, [ii] SHAM 4 wks + Exercise 12 wks).

Inclusion Criteria:

• completed active treatment for a Stage 0-III breast cancer diagnosis within 6 months to 5 years of enrollment.
• obese as defined by a body mass index (BMI) of 30 to 50 kg/m2
• patients who are on adjuvant endocrine therapy will be allowed to participate.
• sedentary (participating in less than 90 min of moderate intensity activity per week) and have at least one limitation in activity on the 10-question RAND-36 Physical Function Subscale to ensure some exercise intolerance

Exclusion Criteria:

• functional limitations that make independent exercise unsafe
• metastatic breast cancer
• ongoing or active infection with recent antibiotics or steroids
• Bilateral Axillary lymph node dissection (ALND) of >5 lymph nodes on each side, which could increase risk of lymphadenopathy with repeated blood pressure measurements during exercise or if patient has been advised by their clinician to avoid repeated BP measures on both arms. Bilateral Sentinel Lymph Node Biopsy (SLNB) will be allowed.
• heart disease precluding exercise (congestive heart failure, unstable angina pectoris, cardiac arrhythmia)
• psychiatric illness/social situations that would limit compliance with study requirements
• orthopedic or neuromuscular disorders or arthritis that preclude participation in exercise
• unwilling or unable to follow protocol requirements
• pregnant or nursing
• any condition which in the investigator's opinion deems the subject an unsuitable candidate to participate in this study
• presence of provokable ECG changes suggestive of heart disease, or dangerous arrhythmias or exercise induced hypertension, etc. during the cardiopulmonary exercise test
• non-English speaking

We will make deidentified data freely available if requested. The privacy and rights of the participants will be protected.

Data will become available after data collection is complete for up to 3 years.

Deidentified data will be made available on request following approved data use agreements between institutions.

Staff completing outcomes testing and study participants will be blinded to treatment assignment (IMT/SHAM). The IMT/SHAM devices are the same with ability to alter resistance; however, upon use at the lower intensity, the participant may be able to tell whether the device has resistance.