Relationship between peripheral and respiratory muscle strength and quality of life in patients with chronic obstructive pulmonary disease

Abstract

Design: Cross-sectional study. Objective: Investigate whether there is an association between healthrelated quality of life and peripheral and respiratory muscle strength in patients with COPD. Secondly, it was aimed to investigate if there are differences quality of life in patients with and without muscle weakness. Methods: Twenty patients underwent anthropometric, lung function, quality of life (Saint George’s Respiratory Questionnaire), respiratory, handgrip and quadriceps muscle strength assessments. The normality of the data was verified using the Shapiro-Wilk test. Pearson correlation coefficient test was performed to evaluate the correlation between the total score and domains of the SGRQ (SGRQtotal) and peripheral and respiratory muscle strength and their percentage of predicted (%pred). To compare the domain “impact” between the subgroups of quadriceps strength, it was used the Mann-Whitney test. The t test for independent samples was used to compare the other scores of quality of life among subgroups. Results: There was a moderate correlation of the SGRQtotal and the domains “activities” and “impact” with the quadriceps strength %pred (r=-0.51, r=-0.52 and r=-0.46, respectively). The domain “activities” also correlated with the absolute value of quadriceps strength (r=-0.44) while the maximal expiratory pressure %pred correlated with SGRQtotal (r=-0.45) and with the domain “impact” (r=-0.49). Conclusions: Quadriceps and expiratory muscles strengthare able to reflect the impact that the impairment of activities of daily living have on the quality of life of patients with COPD