Development of an Educational and Motivational Program to Promote Adherence to Physical Activity and Its Positive Effects in Colorectal Cancer Patients

Objectives and justification of the project In Spain, cancer is the second cause of death after cardiovascular diseases. However, if it is divided by sex, cancer is the leading cause of death for men and the second cause for women. In recent years there has been an increase in new cases of cancer due to population growth and aging, since 2/3 of cancer patients are older than 65 years. In addition to the impact of this disease on people's quality of life, a high economic cost has been estimated for the health system. For example, the total cost of cancer in 2015 in Spain was 7,168 million euros. This situation represents an important public health problem and therefore implies that research on the factors that can prevent or alleviate this disease should be considered as a priority.

In this regard, there is increasing scientific evidence of the physical and psychosocial benefits of exercise both during and after the treatment of this disease. Nevertheless, only 30-40% of cancer survivors perform the necessary physical activity (PA) recommended by the main medical institutions. In fact, a significant number of patients are obese (33%) and have a low cardiorespiratory condition (45%). Despite this, PA continues to decrease after diagnosis and only 5-10% of patients are physically active during treatment and 20-30% after treatment. Therefore, the development of intervention programs aimed at promoting PA should be a fundamental objective in the fight against cancer and its physical and psychosocial consequences. In this line, our general objective will be to develop a motivation PA program for colorectal cancer patients. Specifically, and considering the gaps existing in the current literature, our general objective is subdivided into the following specific objectives:

• To evaluate the physical, psychosocial and behavioural effects, in the short and medium term, of a physical exercise program in which motivational strategies based on self-determination theory are applied.
• To explore qualitatively the benefits of the physical exercise program, as well as the troubles encountered in its implementation.
• To develop an educational guide and an intervention protocol to encourage motivation and adherence to PA of colorectal cancer patients.

Methodology This study will require a sample size of 34 patients. This calculation was made through the G*power software, by means of an analysis of variance (ANOVA), adjusting the values to p <.05, with a statistical power of 80% and an effect size of 0.5. The patients will be recently diagnosed with colorectal cancer in phases II-III by the oncology service of the Hospital Universitario Puerta de Hierro de Majadahonda. Inclusion criteria include to be between 18 and 75 years old, to be undergoing chemotherapy treatment, and to not have any type of associated pathology that prevents them from performing PA. A intervention with an experimental group and a control group will be conducted, where 17 patients will be assigned to a control group, and 17 patients will perform a supervised motivational exercise program.

Measures Cardiorespiratory fitness. Stress tests adapted to the characteristics of the patients will be performed, both in the type of ergometer and in the protocol. We will use electrocardiographic recording and gas exchange analysis. Aerobic and anaerobic exercise thresholds will be established.