Correlation between peak expiratory flow and abdominal muscle activity while holding maximum expiration and side bridge exercise in elderly women

Abstract

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 the abdominal muscles. However, data regarding the association of the abdominal muscle activity during expiratory effort and abdominal exercise with expiratory flow rate are limited. This study aimed to assess the correlation between expiratory flow and abdominal muscle activity while holding maximum expiration and side bridge exercise in elderly women. Rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscle activities were measured using electromyography in 14 elderly women (82.8 ± 6.7 years), who could independently walk, performing two tasks: holding breath after maximum expiration in the crook-lying position (maximum expiration) and holding side bridge on knees without breathing indication (side bridge). Peak expiratory flow (PEF) was obtained using a peak flow meter with the subject in the sitting position. Correlations between PEF and the abdominal muscle activity were determined using Spearman rank correlation coefficient. The Ethics Committee of the Kawasaki University of Medical Welfare approved the protocol for this study. Written informed consent was obtained from each subject before participation in the study. The correlation coefficients between PEF and the RA, EO, and IO activities while holding maximum expiration were 0.407 ( P = 0.149), −0.345 ( P = 0.227), and 0.732 ( P = 0.003), respectively. The correlation coefficients between PEF and the RA, EO, and IO activity while holding side bridge exercise were −0.297 ( P = 0.303), −0.552 ( P = 0.041), and 0.147 ( P = 0.615), respectively. Our results showed that higher IO activity while holding maximum expiration or lower EO activity while holding side bridge exercise was related to higher PEF. Thus, maximum expiration and abdominal exercise might be effective in the improvement or prevention of the decrease of expiratory flow.