Effect of Passive Stretching of Respiratory Muscles on Chest Expansion and 6-Minute Walk Distance in COPD Patients

Background: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Hyperinflation of the lungs leads to a remodeling of the inspiratory muscles that causes postural deformities and more labored breathing. Postural changes include elevated, protracted, or abducted scapulae with medially rotated humerus, and kyphosis that leads to further tightening of respiratory muscles. As the severity of the disease progresses, use of the upper limbs for functional tasks becomes difficult due to muscle stiffness. There are various studies that suggest different rehabilitation programs for COPD patients; however, to the best of our knowledge none recommends passive stretching techniques. The aim of this study was to assess the effect of respiratory muscle passive stretching on chest expansion and 6-min walk distance (6MWD) in patients with moderate to severe COPD. Methods: Thirty patients were divided into two groups, experimental ( n = 15) and control ( n = 15). The experimental group received a hot pack followed by stretching of the respiratory muscles and relaxed passive movements of the shoulder joints. The control group received a hot pack followed by relaxed passive movements of the shoulder joints. Results: In the control group, there was no difference in chest expansion at the levels of both the axilla and the xiphisternum or in 6MWD between baseline and post treatment ( p > 0.05). In the experimental group, chest expansion at the level of the axilla ( p < 0.05) and 6MWD ( p < 0.001) were significantly higher post treatment, while there was no difference in chest expansion at the level of the xiphisternum ( p > 0.05). A comparison between control and experimental groups showed that chest expansion at the level of the axilla ( p < 0.05) and 6MWD ( p < 0.01) were significantly higher in the experimental group, while there was no difference in chest expansion at the level of the xiphisternum ( p > 0.05). Conclusions: Although COPD is an irreversible disease, results of this study indicate that passive stretching of respiratory muscles can clinically improve the condition of such patients, especially in terms of chest expansion and 6MWD. Given the good effects of muscle stretching and the fact that such an exercise is harmless, clinicians and physiotherapists should consider including passive stretching of respiratory muscles in the rehabilitation plan of COPD patients.