Effects of oral breathing and cervical postural alteration in respiratory mechanics and exercise capacity

Abstract

Introduction: Although chronic and persistent mouth breathing has been associated with postural alterations, causing decreased muscle strength, reduction of thoracic expansion and pulmonary ventilation with consequences in exercise capacity, the relationship between these alterations have been little studied.

Objective: To evaluate exercise tolerance and respiratory muscle strength in relation to cervical posture and respiratory mode (oral breathing (OB) and nasal breathing (NB) children).

Method: An analytical cross-sectional study included 8-11 years old children with clinical otorhilaryngology diagnosis for OB. We excluded obese children, with asthma, chronic respiratory diseases, neurological and orthopedic disorders and cardiac patients. All participants underwent postural assessment, maximal respiratory pressures (maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP)) and six minute walk test (6MWT).

Results: There were 92 children (30 OB and 62 NB). In the OB group, there was no difference between the means of MIP, MEP and 6MWT between the group with posture alteration (severe and moderate) and normal cervical posture. In the RN group, the mean MIP (70.8±19.1 × 54.7±21.7 cmH₂O, p=0.003) and MEP (67.7±22.1 × 50.5±19.5 cmH₂O, p=0.004) were higher in the group with cervical postural alteration. The presence of OB determined the decrease of MIP, MEP and 6MWT. The presence of moderate cervical posture had positive relationship in MIP and MEP values.

Conclusion: Oral breathing affects negatively the respiratory biomechanics and exercise capacity. The head posture, altered moderately, acts as a compensation mechanism to improved respiratory muscle function.