## 2 Materials and Methods
### Experimental Procedure  
Participants who met the inclusion criteria attended a physical examination in a laboratory setting. All participants were under prescribed pharmacologic migraine prophylaxis. They were instructed to avoid any analgesic drugs 24 h before the appointment, and in the case of a migraine attack, to reschedule the appointment. All participants were evaluated on a headache-free day. On the day of assessment, the examiner applied a structured screening to collect demographic and clinical data, including migraine frequency (days per month), migraine onset (years), and presence of self-reported neck pain. Participants who reported neck pain answered questions about neck pain frequency (days per month) and intensity (numerical pain rating scale). Subsequently, the following cross-culturally adopted questionnaires were used: Neck Disability Index (NDI), Migraine Disability Assessment (MIDAS), Patient Health Questionnaire (PHQ-9), and Tampa Scale for Kinesiophobia (TSK), to determine the migraine-related disability, depressive symptoms, and fear of movement, respectively. The NDI is a questionnaire designed to assess how the neck pain affects the patient's ability to perform daily activities [30; 31]. The NDI includes 10 items, and each item is scored from 0 to 5. According to the total score, the patient was classified as follows: no disability (0-4), mild disability (5-14), moderate disability (15-24), severe disability (25-34), and complete disability (35 or more) [30; 31]. The NDI is a valid and reliable tool to measure neck-pain-related disability and is used as a guide for clinical decision-making [31; 32]. The MIDAS evaluates migraine-related disability with five questions related to the number of days in the past 3 months during which the patients had partial or complete difficulty in managing everyday life owning to migraine. The patient was classified as follows based on the final score: no disability (0-5), mild disability (6-10), moderate disability (11-20), and severe disability (21 or higher) [33]. The MIDAS has a good reliability [34] and high correlation with physicians' judgments regarding patients' pain, migraine-related disability, and need for medical care [35]. Depressive symptoms were measured using the PHQ-9, a tool containing nine questions to assess the occurrence of depressive symptoms in the past two weeks [36]. Each question is scored on a scale from 0 to 3, with a maximum of 27 points. The severity of depression is classified as follows: minimal (0-4), mild (5-9), moderate (10-14), moderately severe (15-20), and severe (21-27) [34]. The PHQ-9 presents excellent test-retest reliability, and a strong association between its score and functional status, disability days, and symptom-related difficulty [37]. The TSK is a 17-item tool used to assess fear of movement, with items 4, 8, 12, and 16 being reversely scored. Scoring options range from strongly disagree (1) to strongly agree (4), with a total score between 17 and 68 [38]. The questionnaire has a good reliability and correlation with depressive and catastrophic symptoms [39]. After completing the questionnaires, active cervical ROM was assessed by a second examiner, blinded to the participants' clinical condition, using the Multi-Cervical Rehabilitation Unit(r) (BTE Technologies, Inc.(tm), Hanover, NH, USA). The equipment has excellent reliability for measuring ROM in flexion, extension, lateral flexion, and rotation [40]. The examiner positioned the participant in a seated position, with the knee and hip at 90\({}^{\circ}\) flexion and with the trunk restrained by bands to avoid movement compensation during the cervical movements, and the equipment elm was positioned on the head. The participants were instructed to perform the movements of flexion, extension, lateral flexion, and rotation to the maximum possible range (Figure 1) three times in each direction. The presence of self-reported neck pain during movements was also recorded.