The Correlation Between Peak Expiratory Flow and Abdominal Muscle Thickness in Elderly Females

Abstract

Background: Death from pneumonia is more common in elderly individuals. Expiratory flow plays an important role in minimizing the risk of infection by expelling foreign substances and excessive mucus from the lungs. Expiratory flow results primarily from the activities of abdominal muscles. As part of the normative aging process, there is a decline in muscle thickness. However, little is known about the association of abdominal muscle thickness and expiratory flow rate. Objectives: The purpose of this study was to compare the relationships between peak expiratory flow and individual and combined abdominal muscle thickness in elderly subjects. Methods: Thirty-one elderly females (81.7 ± 5.8 years), who could walk independently, participated in this study. The thickness of the abdominal muscles including, right rectus abdominis, external oblique, internal oblique, and transverse abdominis muscles, was measured using B-mode ultrasound, at the end of a relaxed expiration, with the subject in the supine position. Peak expiratory flow was obtained using a peak flow meter with the subject in the sitting position. Correlations between normalized peak expiratory flow and the thickness of normalized individual and combined muscle were determined using Pearson’s correlation coefficient. Results: Among individual muscles, the thickness of the internal oblique muscle had the highest correlation with peak expiratory flow (r = 0.513, P = 0.003). The combined thickness of the external and internal oblique muscles had the highest correlation with peak expiratory flow (r = 0.563, P = 0.001) among all individual and combined muscles. Conclusions: The current results indicate that thinner external and internal oblique muscles may decrease the peak expiratory flow in elderly females, when compared to elderly females with thicker external and internal oblique muscles.