Effect of Physical Training Program on the Exercise Adherence for Breast Cancer Survivor

Breast cancer (BC) is one of the major causes of death worldwide, being the carcinoma with the most diagnoses and their incidence has been steadily increasing in the last two decades. During the course of BC, the patient diagnosed with the disease undergoes a large number of changes at the musculoskeletal level, such as osteosarcopenia (loss of muscle mass and low bone density). In this case, the loss of skeletal muscle mass is directly correlated with lower survival and a higher recurrence of cancer, and sarcopenia can be used as a prognostic factor for mortality in patients with both non-metastatic and metastatic BC. Similarly low muscle mass is also associated with increased frailty and dependency, reduced autonomy, and lower bone mineral density.

In this context, concurrent training, when properly and safely planned, becomes a fundamental tool that can help counteract this osteosarcopenia and help breast cancer survivors (BCS) regain their functional independence, physical and emotional well-being and consequently increase disease survival through a gain in muscle mass, a reduction in fat mass and an increase in bone mineral density.

In the case of BC, the practice of physical activity including strength training can reduce the risk of mortality by 40% through different biological mechanisms. Despite these great indications, only 8% of the cancer population performs 150 min/week of moderate to vigorous intensity exercise, where the vast majority of patients are sedentary and are unaware of the benefits that exercise can have on their disease. Therefore, one of the great challenges we face today in the field of PA and oncology populations is adherence. This is a concept developed by different theories and models from different fields such as motivation or the need for psychological support in addition to the PA program. However, there is no unification regarding the definition of adherence. Adherence can be understood as attendance on a certain program, as the duration of performing PA, as the intensity at which it is performed, or the lack of attendance (lack of uptake). In our case, we understand adherence to PA as the increase in the amount of time that the subject practices PA at a moderate or vigorous intensity.

Creating adherence to concurrent training for BCS is a great challenge today due to the multiple barriers that hinder the adoption and execution of these training commonly called oncological rehabilitation. The long-term benefits of PA in SCM are more than proven so introduction to PA should be the main goal after cancer diagnosis. The most performed exercise modality by BCS is walking, being insufficient to counteract the side effects of treatments, whereas concurrent training is the one that brings the most benefits. On the other hand, one of the tools to improve adherence to PA and increase the benefits it brings is to carry out a supervised training program.

The aim of this study is to determine adherence to moderate/vigorous intensity PA in BCS after a supervised concurrent exercise intervention of 12 sessions.

PARTICIPATION:

This is a prospective, multicenter, randomized, parallel-controlled, prospective pilot study evaluating the effects of a physical activity (PA) program in Breast Cancer Survivor (BCS) using a case-control design. The study population was BCS attending consultation at their referral hospital. The study was conducted in 2018.

The study included women between 18 and 65 years of age diagnosed with stage I-IIIA BC, free of disease and without active chemotherapeutic treatment. Patients were excluded if a) they suffered from a chronic disease that prevented them from following the PA program, b) patients with sequelae of surgery, edema of \>2 degrees in extremities with lymphadenectomy, and c) those women who performed PA according to the recommendations established by the WHO (\>150min of moderate or vigorous physical activity per week).

Seventy-eight eligible women were recruited. 16 women declined to participate in the study leaving a total of 62 women who were randomly divided into 32 for the intervention group and 30 for the control group (Figure 1). All participants completed the intervention and completed the first session of questionnaires. At the 3-month review, 25 women did not complete the questionnaire. Finally, 37 women who completed the questionnaires at the end of the intervention and at 3 months were assessed. The intervention group consisted of 15 women (53.14+- 7.41) and the control group of 22 women (53.07+- 7.43).

INTERVENTION:

The program was carried out in different stages , In the assessment stage, the medical and nursing staff conducted the first data collection. It consisted of a review of patient reports, verification of inclusion and exclusion criteria, anamnesis, clinical examination, anthropometric measurements (weight and height), calculation of BMI, and measurement of previous physical activity (GPAQ questionnaire). Height was measured with a stadiometer and weight was determined with a SECA® floor scale. BMI was then calculated using the formula \[weight (kg)/height (m)2\]. Before the performance and assessment, the study was explained and informed consent was given. Once the patients had been assessed, they were randomly assigned to the control group and the intervention group.

In the execution stage, both groups attended a formative session on healthy habits and nutrition. After this session, the intervention group moved on to the physical activity phase led by physical activity and sports science professionals.

The program had a duration of 12 training sessions, divided into 2 sessions of 1 hour for 6 weeks. Concurrent training was used combining strength, endurance, and coordination exercises. The different types of sessions were interspersed.

Resistance training sessions were performed in a circuit format with \>30" rest periods between exercises. The volume of work ranged from 8 to 12 repetitions at 60% of the estimated 1 maximum repetition (RM). The exercise prescription was based on a dynamic strength test at the beginning of the study where the maximum weight with which the patients could perform 7 repetitions was measured. Throughout the intervention, when the participant could comfortably perform 12 repetitions the working weight was increased to 70% and then to 80% of her estimated RM but never exceeding this limit. For cardiovascular sessions treadmills, bicycles, and elliptical trainers were used. Participants wore a heart rate monitor during all sessions to control the intensity of the training. The cardiovascular work time per session ranged from 25-50 min depending on the intensity of the exercise and the intensity was regulated according to the maximum heart rate (FHR) estimated for each subject between 60-75% calculated by the formula FHR=208.75-(0.73 x age). For neuromotor training sessions, we worked on choreographies with musical support and stretching. The intensity of the sessions was low. The participants wore a heart rate monitor and were instructed not to exceed 60% of their HRF. The different types of training were interspersed, generating variety in the sessions and seeking to offer a diversity of activities adapted to the characteristics and needs of the BCS.

The last phase of follow-up of the participants in both groups was carried out one month, 3 months, and 6 months after the end of the program. During 3 and 6 months of follow-up, the questionnaire was sent by mail and the possibility was offered of sending the questionnaires to each center, making the follow-up by telephone appointment, or attending in person.

DATA COLECTION:

For data collection, the GPAQ questionnaire was used, which was completed by the patients both before starting the program and at the follow-up meetings. This is a 16-item questionnaire validated for the oncologic population to determine the level of PA and sedentary lifestyle the latter being understood as the time a subject in a population spends sitting. The GPAQ differentiates PA performed in the work environment under the qualification of "work" and PA outside the work environment as "Physical Activity". In addition, to know the total PA, the amount of work plus the physical activity performed by the BCSs was added. The GPAQ differentiates the intensity of work into moderate or vigorous and that of the physical activity performed if it is light, moderate or vigorous. To determine the amount of work, PA and total moderate/vigorous PA, both intensities were added together.

STATISTICAL ANALYSIS:

The results of the continuous variables are shown as mean ± standard deviation of the mean (SD), while the number of cases in percentage (%). Statistical analysis was performed with SPSS version 28 (IBM-Inc., Chicago, IL, USA). Statistical significance was determined with a p value \< 0.05.

For the continuous variables, firstly, Kolmogorov-Smirnov tests were performed with the values of the parameters studied (n \< 50) and the homoscedasticity of the variables analyzed was checked using the Levene test. Thus, the differences between IG and CG in the continuous variables were tested by means of a univariate test with the group to which each patient belonged as a fixed factor. In addition, a repeated-measures ANOVA with group factor (IG and CG) was performed to examine the existence of an interaction effect of the intervention with concurrent exercise (time × group) on exercise adherence at 3 months post-intervention. Between-participant effect sizes were calculated using partial eta squared (η 2p). Because this measure is likely to overestimate effect sizes, values were interpreted according to Ferguson \[24\], which indicates no effect if 0 ≤ η2 p \< 0.05; a minimal effect if 0.05 ≤ η2 p \< 0.26; a moderate effect if 0.26 ≤ η2 p \< 0.64; and a strong effect if η2 p ≥ 0.64.

Finally, differences in sociodemographic characteristics as well as baseline breast cancer-related characteristics between both groups (IG vs. CG) of the SCM per study group per study group were assessed using the chi-square test (χ )2.

Eligibility Criteria:
Inclusion Criteria:

* Stage I-IIIA
* Free of disease
* Without active chemotherapeutic treatment

Exclusion Criteria:

* Patients suffered from a chronic disease that prevented them from physical activity program
* Patients with sequelae of surgery, edema of \>2 degrees in extremities with lymphadenectomy
* Those women who performed PA according to the recommendations established by the WHO.