Respiratory muscle strength is one parameter that is currently proposed to be affected in patients with chronic neck pain. This study was aimed at examining whether patients with chronic neck pain have reduced respiratory strength and with which neck pain problems their respiratory strength is associated. In this controlled cross-sectional study, 45 patients with chronic neck pain and 45 healthy well-matched controls were recruited. Respiratory muscle strength was assessed through maximal mouth pressures. The subjects were additionally assessed for their pain intensity and disability, neck muscle strength, endurance of deep neck flexors, neck range of movement, forward head posture and psychological states. Paired t-tests showed that patients with chronic neck pain have reduced Maximal Inspiratory (MIP) (r = 0.35) and Maximal Expiratory Pressures (MEP) (r = 0.39) (P < 0.05). Neck muscle strength (r > 0.5), kinesiophobia (r < -0.3) and catastrophizing (r < -0.3) were significantly associated with maximal mouth pressures (P < 0.05), whereas MEP was additionally negatively correlated with neck pain and disability (r < -0.3, P < 0.05). Neck muscle strength was the only predictor that remained as significant into the prediction models of MIP and MEP. It can be concluded that patients with chronic neck pain present weakness of their respiratory muscles. This weakness seems to be a result of the impaired global and local muscle system of neck pain patients, and psychological states also appear to have an additional contribution. Clinicians are advised to consider the respiratory system of patients with chronic neck pain during their usual assessment and appropriately address their treatment.
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