Relationship between kyphosis and cough strength and respiratory function of community-dwelling elderly

Kyphosis may reduce the force of coughing by affecting the factors related to cough peak flow (CPF). This study sought to compare cough strength and respiratory function between non-kyphotic and kyphotic elderly individuals and clarify the relationship between these factors.

The non-kyphotic group comprised 17 elderly individuals with a kyphosis index of less than 15.1, while the kyphotic group comprised 21 elderly individuals with a kyphosis index of 15.1 or higher. Cough strength, respiratory function, respiratory muscle strength, and maximum phonation time were measured, and comparison between two groups and correlation analysis between variables were performed.

CPF, vital capacity, maximum expiratory pressure (PEmax), maximum inspiratory pressure (PImax), and chest expansion at the xiphoid process were significantly lower in the kyphotic group than in the non-kyphotic group. There were significant negative correlations between kyphosis index and CPF (r = -0.37, p < 0.05), PEmax (r = -0.45, p < 0.01), PImax (r = -0.44, p < 0.01) and chest expansion at the xiphoid process (r = -0.38, p < 0.05).

Our results demonstrated that cough strength was significantly lower in the kyphotic compared to non-kyphotic individuals. Furthermore, cough strength decreased with increased severity of kyphosis.