Effectiveness of Cough Exercise and Expiratory Muscle Training: A Meta-analysis

Abstract

Coughing is a defensive reflex action of the airway that removes foreign objects and mucus. Here, meta-analysis was performed to review the results of previous studies regarding the effects of coughing exercise and expiratory muscle training (EMT), and to examine the effectiveness of EMT in enhancing cough functions. A systematic literature search was performed using the EBMR, CINAHL, PEDro, MEDLINE, and Ichushi Web (NPO Japan Medical Abstracts Society) databases. Based on a methodological framework, a critical review was performed and summary effect sizes were calculated by applying the random effects model. Both the forced expiration technique (FET) and coughing alone significantly increased mucus clearance. EMT significantly increased expiratory muscle strength, suggesting that it is possible to improve cough effectiveness by EMT. Further studies with larger and more diverse sample groups are necessary to determine the effects of enhancing expiratory muscle strength on cough effectiveness.

Functional outcomes associated with expiratory muscle strength training: Narrative review

“…A total of 24 articles were selected based on the predetermined criteria. Among the reviewed studies, the majority were published in American scientific journals, with the exception of two international publications, one from the Journal of Physical Therapy Science [9] and one from Respiratory Medicine [10].…”

“…Our classification included one meta-analysis of the effects of coughing exercises and EMST in enhancing cough function by Kojima et al [9]. Coughing exercises in the evaluated studies were completed by either coughing alone, a forced expiration technique, or an assisted coughing method.…”

“…According to Kojima et al [9], the reviewed studies reported significant increases in PEmax following EMST. From this meta-analysis, however, it could not be directly determined whether EMST enhanced cough effectiveness because none of the selected studies used PCF to assess cough strength.…”

The Effect of Expiratory Muscle Training on Pulmonary Function in Normal Subjects

“…Studies have shown that expiratory muscle training (EMT) increases maximal expiratory muscle pressure (PE max ), improves pulmonary function, ventilation function and exercise capability and alleviates respiratory distress caused by inspiratory load, activities of daily living or exercise in patients with COPD 12,13) , healthy individuals 10,[14][15][16][17][18][19] , multiple sclerosis (MS) patients [20][21][22] , myasthenia gravis (MG) patients 23) , neuromuscular disease (NMD) patients 24,25) , patients with tetraplegia caused by spinal cord injury 26,27) and Parkinson's disease patients 28,29) . However, some studies have found that: EMT does not increase PE max 30) ; EMT only i m p r o v e s P E m a x , w i t h n o e f f e c t o n o t h e r parameters 31,32) ; and EMT increases PE max , but has no marked impact on other parameters or sufficient evidence is lacking [33][34][35][36] .…”

“…Although some studies have described that EMT may be expected to increase the ability to cough 18,21,29,46) , no general consensus has been reached, as some studies have documented significant improvements in the cough efficacy of MS patients 30) , while others have found no changes in maximal voluntary cough of MS patients 22) . In recent reviews 35,36) , the effects of EMT on cough effectiveness have been described as minimal, and further investigations are warranted. The effects of EMT on pulmonary function, including PCF, have not been sufficiently investigated, but the insufficient effects of EMT on pulmonary function may be due to the contraction velocity of expiratory muscles during EMT.…”