Purpose: The purpose of this study was to investigate the influence of postural kyphosis on voluntary cough strength.
Methods: Sixteen healthy males participated in this study. Cough peak flow, respiratory function, respiratory muscle strength, chest expansion, maximum phonation time, and respiratory impedance indices (respiratory system resistance at 5 Hz, R5; resonant frequency, Fres) were evaluated under four conditions: non-kyphosis, mild kyphosis, moderate kyphosis, and severe kyphosis. One-way analysis of variance and multiple comparison tests (using the Bonferroni method) were performed to compare the four conditions. Correlations between the change rate of each measured variable by the degree of kyphosis were analyzed using Spearman's correlation coefficients.
Results: Cough peak flow, vital capacity, chest expansion, and maximum phonation time were significantly decreased in moderate kyphosis and severe kyphosis compared with those in non-kyphosis. Respiratory muscle strength and Fres were significantly decreased in severe kyphosis compared with those in non-kyphosis. Moreover, there were significant positive correlations between cough peak flow and vital capacity, expiratory muscle strength, and chest expansion at the xiphoid process (r = 0.27, 0.33, 0.37, respectively, p <0.05).
Conclusions: Our data suggest that cough peak flow is reduced due to decreased lower chest expansion, respiratory muscle strength, and vital capacity at moderate or higher kyphosis.
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