Weakness and Imbalance of Neck Muscle Groups as Sources of Chronic Neck Pain: A Cross-Sectional Study

Purpose: This study aimed to investigate weakness and strength ‎imbalances of the four principal neck muscle groups and their ‎association with pain intensity in adults with chronic neck pain.‎ Materials and Methods: This cross-sectional study enrolled 29 ‎patients (22 men, 7 women; aged 20–70 years) with chronic neck ‎pain attending private physiotherapy clinics in Zawia, Libya. The ‎strength of the cervical and capital flexor and extensor groups was ‎graded using manual muscle testing (0–5 scale), and pain intensity ‎was recorded on a 10-point visual analogue scale (VAS). One-sample ‎t-tests compared each muscle group against the normal grade of 5, ‎paired t-tests examined imbalances between and within muscle ‎chains, and Pearson correlations related muscle strength to pain. The ‎significance level was set at p < 0.05.‎ Results: All four muscle groups were significantly weaker than grade ‎‎5 (p < 0.001). The capital flexors were the weakest group (mean 2.62 ‎‎± 0.49). Significant imbalances were found between cervical flexors ‎and capital flexors (p < 0.001), between capital flexors and capital ‎extensors (p < 0.001), and between the anterior and posterior muscle ‎chains (p < 0.001), whereas cervical flexors and extensors were ‎equally affected. Pain intensity correlated significantly with cervical ‎flexor strength (r = −0.455, p = 0.013), capital extensor strength (r = ‎‎−0.406, p = 0.029), and the anterior (r = −0.400, p = 0.031) and ‎posterior (r = −0.422, p = 0.022) chain strength.‎ Conclusion: Chronic neck pain is characterized by pronounced ‎weakness of all neck muscle groups, a selective deficit of the capital ‎flexors, and specific flexor–extensor imbalances. Weaker muscle ‎groups track with higher pain intensity, supporting targeted ‎strengthening of the deep flexors in rehabilitation. ‎