Respiratory muscle endurance training in patients with chronic neck pain

Introduction: Several studies have reported decreased respiratory muscle strength in chronic neck pain patients1,2. In healthy subjects, respiratory muscle endurance training (RMET) was shown to improve exercise performance3 and to reduce thoracic kyphosis and stiffness of the rib cage4. The aim of this pilot study was to investigate whether RMET might be a feasible and effective treatment for chronic neck pain patients. Methods: This single case study included 2 male subjects (54 and 62 years) with 2 weeks of baseline testing and 4 weeks of RMET. Weekly testing sessions included two self-assessments [Neck Disability Index (NDI), Patient Global Impression of Change (PGIC)] and the measurement of cervical and thoracic spine mobility, chest wall expansion at axilla and xiphoid level, forward head posture and neck flexor muscle endurance. At the beginning and the end of the study, a spirometry (including maximal inspiratory and expiratory pressures) and a respiratory endurance test were performed. Mean, standard deviation and 95% confidence interval of the baseline data were calculated. Data of the intervention phase were analyzed by linear regression analysis. Results: RMET was feasible and effective by increasing performance in the respiratory endurance test from 3 min (subject 1) and 11 min (subject 2) to 40 min. Both subjects indicated in the PGIC a clear improvement of their neck problems. Objectively, progress was only seen in 1 subject who presented with increased chest wall expansion at both levels (p=0.03 and 0.04, respectively) and cervical flexion mobility (p=0.04) and with a tendency to a decrease in forward posture of the head (p=0.113) after RMET. Conclusion: From this pilot study, RMET emerged as a feasible and effective training method for patients with chronic neck pain, although objective progress was only found in 1 subject. Future studies should include more subjects and patients with worse neck function.