The patients included in the experimental group attended an 8-week Pain Informed Movement program in addition to standard medical care. The program was led by a physical therapist with experience in treating patients with chronic pain. This program consisted of 2 face-to-face sessions per week, and they were asked to complete two sessions at home weekly. The first face-to-face session was a group session with 3-6 participants, and the second face-to-face session was individual. Both sessions lasted approximately 1 h. In the group sessions, pain neuroscience education was conducted. In the individual sessions, an individualized functional exercise program was performed by each patient, as well as relaxation techniques. Patients were asked to perform the functional exercises and relaxation techniques at home. Participants were asked to record their compliance with the program and their progress.

Pain intensity and interference were quantified using the Brief Pain Inventory (BPI). The section intended to measure pain intensity on the BPI comprises four items, while the section related to pain interference includes seven items. In the intensity section, responses range on a scale from 0 (no pain) to 10 (maximum pain), while in the interference section, responses range from 0 (no interference) to 10 (total interference). To calculate the severity and interference index, the values of the corresponding items are averaged, obtaining values ranging from 0 to 10, with a higher score indicating greater pain intensity and interference. The BPI has been validated as a reliable and valid tool to evaluate these aspects of pain.

To evaluate the phenomenon of catastrophizing, the Pain Catastrophizing Scale (PCS) was applied. This instrument consists of 13 statements structured on a 5-point Likert scale ranging from 0 (at no time) to 4 (at all times). The PCS breaks down catastrophizing into three components: feelings of helplessness, magnification of difficulties, and rumination about pain. Each of the items describes different thoughts and emotions that people may experience when in pain. The final score is obtained by summing the scores of all the items, resulting in a score ranging from 0 to 52, with higher scores indicating a higher level of catastrophizing.

The Tampa Kinesiophobia Scale (TSK) was used to quantify apprehension related to physical activity and the fear of injury (or re-injury). This scale is composed of 11 statements, which are assigned a score on a 4-point scale (1-4). Total scores vary between 11 and 44 points, with higher values being indicative of greater fear of movement and the possibility of (re)injury.