REstoring Metabolic FLEXibility Through Combined Exercise in Breast Cancer Survivors: A Randomized Controlled Trial.
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Control, Exercise.
- Who it may be relevant to
- Registry conditions: Cancer, Breast Cancer, Neoplasm, Metabolic Flexibility. Basic parameters: 18 years — 70 years · Female.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Spain
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Overview
The REFLEX study is a randomized, controlled clinical trial designed to evaluate the impact of a 16-week supervised, combined exercise program on metabolic flexibility and cardiorespiratory fitness in breast cancer survivors. While cancer treatments have significantly improved survival rates, the disease and its therapies often cause systemic mitochondrial dysfunction and muscle loss. This leads to persistent "metabolic inflexibility"-a reduced ability to efficiently switch between burning carbohydrates and fats for energy. This inflexibility, exacerbated by sedentary behavior and cancer-related fatigue, can severely diminish a patient's functional autonomy and overall quality of life. The trial focuses on assessing whether exercise can restore this metabolic adaptability in women aged 18 to 70 with stage I-III breast cancer who are currently on hormonal treatment and completed neo/adjuvant chemotherapy within the past 6 months. The study operates on the primary hypothesis that an individualized exercise intervention will significantly improve the participants' metabolic flexibility-measured via the metabolic crossover point-and overall aerobic capacity (VO2max) when compared to a control group. Additionally, the trial will analyze secondary outcomes, including changes in cardiovascular and metabolic risk factors, muscle strength, body composition (such as bone mineral density), and patient-reported outcomes assessing quality of life, fatigue, joint pain, anxiety, and depression. A total of 44 participants will be randomly assigned to either the intervention or control group. Participants in the intervention group will complete a 16-week program consisting of two weekly supervised sessions. Each session lasts between 55 and 85 minutes and includes a tailored combination of aerobic and strength training based on the individual's baseline fitness and metabolic thresholds. Participants in the control group. will receive standard educational materials via email, featuring healthy lifestyle and exercise guidelines from the World Health Organization (WHO) and the American College of Sports Medicine (ACSM). To evaluate the program's effectiveness, comprehensive medical and functional assessments will be conducted at baseline, immediately after the 16-week intervention, and at a 3-month follow-up. These evaluations include submaximal and maximal exercise tests on a cycle ergometer to analyze respiratory gases, detailed blood tests, body composition imaging (DXA scans), and maximum dynamic strength testing. Ultimately, the research aims to generate high-quality evidence to optimize standard exercise recommendations for breast cancer survivors and improve their long-term health and resilience.
Interventions
- Behavioral Control
Participants assigned to the control group receive standard care typically provided to patients in this phase of recovery. Instead of a supervised exercise program, these individuals are sent educational materials via email. This material consists of a video and official documents containing basic guidelines and recommendations for a healthy lifestyle, based on standards from the World Health Organization (WHO) and the American College of Sports Medicine (ACSM) for cancer survivors. The document - Behavioral Exercise
The intervention consists of a supervised, in-person, combined exercise program lasting 16 consecutive weeks, conducted at a specialized exercise unit. Participants attend two sessions per week, with at least 48 hours of recovery between sessions, and each session lasts between 55 and 85 minutes. The program follows a "combined" methodology, meaning every session integrates both resistance (strength) and aerobic training. To ensure safety and precision, sessions are led by a graduate in Physical
Primary outcome measures
- Change in Crossover point [Time frame: 7 months]
- Changes in Cardiorespiratory Fitness [Time frame: 7 months]
Secondary outcome measures (12)
- Change in maximal fat oxidation [Time frame: 7 months]
- Change in maximal carbohydrate oxidation [Time frame: 7 months]
- Change in Lower Body Muscular Strength [Time frame: 7 months]
- Change in Upper-Body Muscular Strength [Time frame: 7 months]
- Change in 6-Minute Walk Test [Time frame: 7 months]
- Change in Lower-Body Muscular Endurance (30-sec CST) [Time frame: 7 months]
- Change in Grip Strength [Time frame: 7 months]
- Change in Body Mass Index (BMI) [Time frame: 7 months]
- Change in Body Fat Percentage [Time frame: 7 months]
- Change in Lean Mass Percentage [Time frame: 7 months]
- Change in Bone Mineral Density [Time frame: 7 months]
- Change in EQ-5D-5L Visual Analogue Scale (VAS) [Time frame: 7 months]
Eligibility criteria
Inclusion criteria
- Women aged between 18 and 70 years.
- Confirmed diagnosis of breast cancer in stages I to III.
- Received neo-adjuvant or adjuvant chemotherapy and completed the chemotherapy treatment within the 6 months prior to study enrolment.
- Residency within a distance of less than 40 km from the Hospital Universitario de Toledo.
Exclusion criteria
- Diagnosis of stage IV breast cancer.
- Undergone major surgery within the 4 months prior to enrolment or scheduled for breast reconstruction surgery during the study period.
- Diagnosis of diabetes mellitus with poor glycaemic control, defined as an HbA1c value greater than or equal to 8.5%.
- Presence of an acute infectious disease.
- Absolute or relative medical contraindications for physical exercise or maximal exercise stress testing, according to the American College of Sports Medicine (ACSM) guidelines.
- Serious cardiac or cardiovascular disease, including a history of myocardial infarction, heart failure, or known cardiomyopathy.
- Regular consumption of beta-blockers or any medication that alters the functioning of the nervous system.
- Currently active, defined as engaging in more than 150 minutes per week of structured physical exercise during the 6 months prior to enrolment.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- Randomized
- Model
- Parallel assignment
- Masking
- Single blind
- Primary purpose
- Prevention
Study locations
Spain · 1 center
- University of Castilla-La Mancha (PAFS Research Group) — Toledo
Identifiers
NCT: NCT07405385 · 2024-UNIVERS-12844