Overview

This study aims to produce new evidence on the efficacy of exercise and diet for cardiometabolic risk reduction in BC survivors. Using a 3-arm RCT with to 6 months of 1) exercise following Health Canada guidelines; 2) the same exercise plus counselling to follow Canada's Dietary Guidelines to improve diet quality; or 3) stretching group, this study will answer the following questions:

• What is the impact of exercise on cardiometabolic health and body composition in BC survivors?
• What is the effect modification of adding a diet quality intervention to exercise on cardiometabolic health and body composition?
• Is there a link between the capacity of skeletal muscle adaptation to exercise (and diet) and insulin resistance in BC survivors?

The investigators hypothesize that: 1) exercise will improve cardiometabolic and body composition outcomes 2) improvements in cardiometabolic outcomes will be enhanced by the addition of diet quality, which will be essential or additive for Matsuda index, metabolic syndrome, Framingham CVD risk, thigh myosteatosis, muscle mass, VO2peak, 3) skeletal muscle insulin signalling transduction will be impaired in BC survivors via dampened expression of insulin-responsive proteins (e.g. GLUT4) and co-occur with impaired muscle quality (e.g., higher rates of fat depots, presence of fibrous tissue) negatively impacting insulin signalling.

Eligibility

Inclusion Criteria:

• Biologically female
• Diagnosis of stage I, II, or III breast cancer, post-menopausal at the time of diagnosis (haven't had a menstrual cycle within 12 months or greater)
• Receipt of aromatase inhibitors for 12 months or more in the past, but do not have to be currently on aromatase inhibitors.
• Willing and able to complete all study assessments
• BMI ≥ 25 kg/m2
• Able to commit to come to the University once per week for 24 weeks.

Exclusion Criteria:

• Received chemotherapy within the past 11 months
• Diagnosed with metastatic cancer
• Currently taking tamoxifen
• Currently receiving chemotherapy, targeted therapy or radiation treatment
• Distant recurrence or diagnosis of metastatic cancer since early-stage breast cancer diagnosis
• Diagnosed cardiovascular diseases, type 2 diabetes, non-alcoholic fatty liver disease, uncontrolled thyroid condition, or respiratory disease (e.g., COPD or severe or uncontrolled asthma).
• Major signs or symptoms of cardiovascular diseases, diabetes, or renal disease (taken from the American College of Sports Medicine's Guidelines for Exercise Testing and Prescription 11th edition Table 2.1: pain or discomfort in the chest, neck, jaw, arms with rest or exercise, shortness of breath at rest or with mild exertion, dizziness or syncope, loss of balance or passing out, ankle edema, palpitations or tachycardia, intermittent claudication, known heart murmur, unusual fatigue with usual activities.)
• American Heart Association's absolute or relative contraindications for symptom-limited maximal exercise testing (myocardial infarction, aortic or coronary artery stenosis, heart failure, pulmonary embolism or deep vein thrombosis, inflammation of the heart (myocarditis, pericarditis, and/or endocarditis), uncontrolled cardiac arrhythmia, advanced or complete electrical heart block, stroke or transient ischemia attack, blood pressure >200mmHg/100mmHg, a cancer diagnosis other than skin cancer)
• Unable to provide informed consent or communicate in English
• Pregnant or breast-feeding currently or in the past 3 months
• Mobility limitations to aerobic exercise (i.e., wheelchair, walker use, limp impeding walking)
• Smoking cigarettes or marijuana within the past 3 months
• Taking exogenous hormones in any format currently or in the past 3 months
• Contraindications to research MRI (e.g., pacemaker, magnetic implants)
• BMI exceeding 40 kg/m2
• Extreme claustrophobia
• Self-report >30 min/week of moderate-to-vigorous intensity aerobic physical activity
• Following a diet that largely restricts entire food groups or time of eating (e.g., vegan, ketogenic, carnivore, one meal a day) in last 3 months
• Experienced significant weight loss (i.e., >5 kg) in past 3 months
• Currently taking weight loss medications
• Diagnosed history of an eating disorder or self-report of potential undiagnosed eating disorder
• Plans to be away/unavailable for a substantial period of the intervention overall (i.e., >4 weeks throughout the 6 months or >2 weeks within the first 12 weeks of the intervention).
• Allergies to local anesthetics