Abstract
[Purpose] This study examined the effect of neck restriction by cervical orthosis on pulmonary function and respiratory muscle activity during spirometry. [Subjects] Twelve healthy young males participated. [Methods] They performed spirometry with and without a Philadelphia collar. We also measured respiratory muscle activity with surface electromyography during spirometry. [Results] Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1.0) and peak expiratory flow ratio (PEFR) with the collar were significantly lower compared to without the collar. The muscle activities of the sternocleidomastoid and scalenus with the collar were significantly lower during maximum inspiration. However, the activities of rectus abdominis (RA) and obliquus externus abdominis (OEA) did not change between with and without collar. [Conclusion] Neck restriction by cervical orthosis decreases neck inspiratory muscle activity and VC. In exhalation, FVC, FEV1.0 and PEFR decrease due to the decrease in VC or restriction due to airway narrowing.
