Exercise may ease side effects of breast cancer treatment

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Written informed consent document (ICD) prior to any specific study procedures, showing patience, willingness and ability to comply with the physical activity program in the experimental group, and scheduled visits and study procedures in both groups. 2. Patients ≥18 years of age at signing of ICD. 3. Documented histologically confirmed HR+/HER2- invasive EBC, adequately treated according to standard clinical practice and with absence of any evidence of disease (loco-regional or metastatic at distance). HR and HER2 assessments are performed under institutional guidelines. * HR testing should utilize an assay consistent with the most recent American Society of Clinical Oncology (ASCO)/ College of American Pathologists (CAP) Guidelines. * HER2 negativity is determined as immunohistochemistry (IHC) score 0/1+ or negative by in situ hybridization (ISH) according to the recommendations of the most recent ASCO/CAP Guidelines. 4. Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-2. 5. Pre-, peri-, and post-menopausal women (as determined by the investigator and according to the institutional guidelines) that have already received between 10 and 18 weeks of an AI (with or without a LHRHa) before the randomization in the study and administered according to local guidelines. Note: Patients that are candidate to receive an adjuvant CDK4/6i will only be eligible if the CDK4/6i was initiated at least 6 weeks before the randomization in the study and administered according to local guidelines. 6. Patients must have undergone adequate (definitive) loco-regional therapy (surgery with or without radiation therapy), with or without neo-/adjuvant systemic CT. 7. Patients must have an adequate organ and bone marrow function according to the standard clinical practice and institutional guidelines. 8. Patients must be able and willing to fill out repeated questionnaires on QoL, pain and fatigue, as well as to adhere to the physical activity program. 9. Fluent Spanish language skills for the complete comprehension of the questionnaires. 10. With the consent of the investigator for participation in physical training and considering the medical history of the patient. Exclusion Criteria: 1. Patients have received less than 10 weeks or more than 18 weeks of an AI (with or without a LHRHa) before the randomization in the study. 2. Patients that are candidate to receive an adjuvant CDK4/6i initiated the treatment less than 6 weeks before the randomization in the study. 3. Patients have musculoskeletal injuries. 4. Patients have known significant heart disease (myocardial infarction, unstable angina, congestive heart failure, cardiomyopathy, etc.). 5. Patients with weight over 150kg. 6. Patients have any type of illness or mental condition that prevents or compromises the well-being of the patient or compliance with the procedures. 7. Patients have any cardiovascular contraindication to physical training by the investigator. 8. Patients have been performing supervised training, either aerobic and/or resistance training (at a gym \[group or individual classes\] or in a specific sport), at least 2 days per week in the past 6 months. 9. No access and/or unable to manage the website and other digital tools (i.e. applications) for training sessions.