[Purpose] To understand the effect of increased functional residual capacity (FRC) on the
active range of thoracic axial rotation (AROTAR) in healthy young men. [Subjects and
Methods] Thirty-nine right-handed healthy male volunteers (age=20.1 ± 1.6 years)
participated in this study. A standard plastic goniometer was used to measure the AROTAR
in the supine position with both glenohumeral joints fully flexed. AROTAR was recorded at
the resting expiration level (REL) and for 4 different FRC levels: 500, 1,000, 1,500, and
2,000 ml air inhaled at REL. FRC volumes and laterality were analyzed using a two-way
repeated measure of ANOVA and post-hoc analysis. Relationships between the relative value
(AROTAR for each increased FRC level / REL AROTAR × 100) and AROTAR for each increased FRC
level were analyzed using Pearson’s correlation coefficient. [Results] A significant main
effect was found for only FRC factor. AROTAR had a positive moderate correlation with
relative value. The correlation coefficient was higher than 0.5 for in 1,500 and 2,000 ml.
[Conclusion] An increase in FRC might decrease AROTAR and if the REL AROTAR is high, the
decrease in AROTAR due to increased FRC is lesser. It is suggested that maintaining the
thoracic mobility could minimize a COPD patient’s AROTAR limitation and maintain physical
ability.