The Added Value of Transcranial Direct Current Stimulation (tDCS) During Exercise for People With Chronic Widespread Pain

Inclusion Criteria: Patients Participants in the patient group must meet all of the following criteria: 1. Diagnosis of chronic widespread pain (CWP) or fibromyalgia; 2. Age between 18 and 70 years old; 3. Body mass index (BMI) ≤ 35; 4. Widespread Pain Index (WPI) assessment: the WPI questionnaire (0-19 points) will be used to record the number and distribution of painful body sites. Participants will be classified as having CWP if pain is reported on both sides of the body, above and below the waist, and in the axial skeleton, with pain symptoms lasting ≥ 3 months; 5. Stable medication use for at least 1 month prior to study entry. Healthy control group Participants in the healthy control group must meet all of the following criteria: 1. Age between 18 and 70 years old; 2. Body mass index (BMI) ≤ 35; 3. No chronic conditions, such as chronic pain and diabetes. Exclusion Criteria: For both patients and healthy controls, participants will be excluded if they meet any of the following: 1. Current pregnancy or pregnancy within the past 12 months; 2. Contraindications for non-invasive brain stimulation (NIBS), in line with published safety guidelines; 3. History of neurological disorders, including epilepsy (personal or family history), traumatic brain injury, stroke, dementia, or Parkinson's disease; 4. Major medical conditions, including cancer, endocrine or metabolic disorders, urine, genital and cardiovascu-lar diseases (e.g., myocardial infarction, heart failure, arrhythmia, uncontrolled hypertension). 5. Substance abuse. 6. Presence of psychiatric disorders other than depression or anxiety.