Exercise Prescription Guided by Heart Rate Variability in Breast Cancer Patients

Effects of Physical Exercise, and Its Prescription Guided by Heart Rate Variability, on the Cardiotoxicity, Physical and Psychological Health of Breast Cancer Patients

Breast cancer is a chronic disease that has seen a boom in research into its treatments, improvements and effects in recent decades. These advances have also highlighted the need to use physical exercise as a countermeasure to reduce the cardiotoxicity of pharmacological treatments. Patients need a correct daily individualisation of the exercise dose necessary to produce the physiological, physical and psychological benefits. To this end, the present study will use, in a novel way in this population, heart rate variability (HRV) as a measure of training prescription. The primary objective of this randomised clinical trial is to analyse the effects of a physical exercise programme planned according to daily HRV in breast cancer patients after chemotherapy treatment. For this purpose, a 16-week intervention will be carried out with 90 breast cancer patients distributed in 3 groups (control group, conventional preprogrammed physical exercise training group and physical exercise group with HRV daily programming). Cardiorespiratory capacity, strength, flexibility, agility, balance, body composition, quality of life, fatigue, functionality, self-esteem, anxiety and depression of patients before and after the intervention will be evaluated in order to compare the effects of exercise and its programming.

The intervention of 16 weeks will include exercise programmes of 48 sessions conducted three times per week for two of the three study groups. These groups will be: a group participating in a conventional training programme, based on a preplanned intensity progression; and, a group of participants involved in an exercise programme which will vary the exercise intensity regarding patients' daily Heart Rate Variability. Each session will include a warm-up, the main part of cardiovascular and strength training and a cool-down including stretching exercises.

All the participants will be evaluated before and after the intervention measuring clinical, physical and psychosocial assessments. The clinical variables will be evaluated in patients' reference hospital and will involve medical history registers, cardiotoxicity variables, blood analysis and inflammatory factors measures. Physical and psychosocial variables measurement will be carried out in a sports centre and will include the assessment of: body composition, heart rate variability, cardiorespiratory capacity, upper and lower extremities' strength and flexibility, agility and balance, quality of life, fatigue, functionality, life satisfaction, self-esteem, anxiety and depression, shoulder mobility perception, kinesiophobia, physical activity level and exercise motivation.

Inclusion Criteria:

• Being between 18 and 65 years
• Being a breast cancer patient with luminal or triple-negative
• Having completed the radiotherapy treatment, after chemotherapy, approximately one month ago.
• Be able to perform the proposed tests safely

Exclusion Criteria:

• Being undergoing radiotherapy treatment or scheduled for surgery
• Having metastasic cancer
• Not having any serious psychiatric illness