Spinal behavior during tidal and deep breathing in healthy male subjects

Spine has joint connections with all ribs and has muscle attachments with a part of diaphragm, suggesting a key role in respiratory mechanics. In this study, we aimed to investigate movement of the spine during tidal and deep breathing at a seated posture in which the spine was free from artificial restriction. Three-dimensional motion analysis using an eight-camera system (60Hz) was performed in fifteen male healthy volunteers (mean age; 27.1±5.7 years). During tidal breathing, the spine moved very little (< 1 mm) while ventral parts of the ribs and the sternum well moved (1.9-5.2mm) as “pump-handle”. Lumber spine moved toward ventral direction with deep inspiration to TLC while upper thoracic spine did with deep expiration to RV. These results suggested that spine was almost fixed during tidal breathing as the pivot of the ribcage. Breathing to RV or TLC recruited varieties of supplemental respiratory muscles, and transformed spine.