Diaphragmatic amplitude and accessory inspiratory muscle activity in nasal and mouth-breathing adults: a cross-sectional study

J Electromyogr Kinesiol. 2015 Jun;25(3):463-8. doi: 10.1016/j.jelekin.2015.03.006. Epub 2015 Apr 6.


The purpose of this study was to evaluate the electromyographic activity of the accessory inspiratory muscles and the diaphragmatic amplitude (DA) in nasal and mouth-breathing adults. The study evaluated 38 mouth-breathing (MB group) and 38 nasal-breathing (NB group) adults, from 18 to 30years old and both sexes. Surface electromyography (sEMG) was used to evaluate the amplitude and symmetry (POC%) of the sternocleidomastoid (SCM) and upper trapezius (UT) muscles at rest, during nasal slow inspiration at Lung Total Capacity (LTC) and, during rapid and abrupt inspiration: Sniff, Peak Nasal Inspiratory Flow (PNIF) and Maximum Inspiratory Pressure (MIP). M-mode ultrasonography assessed the right diaphragm muscle amplitude in three different nasal inspirations: at tidal volume (TV), Sniff and inspiration at LTC. The SCM activity was significantly lower in the MB group during Sniff, PNIF (p<0.01, Mann-Whitney test) and MIP (p<0.01, t-test). The groups did not differ during rest and inspiration at LTC, regarding sEMG amplitude and POC%. DA was significantly lower in the MB group at TV (p<0.01, Mann-Whitney) and TLC (p=0.03, t-test). Mouth breathing reflected on lower recruitment of the accessory inspiratory muscles during fast inspiration and lower diaphragmatic amplitude, compared to nasal breathing.

Keywords: Diaphragm; Electromyography; Mouth breathing; Nasal obstruction; Respiratory muscles; Ultrasonography.

MeSH terms

  • Adolescent
  • Adult
  • Cross-Sectional Studies
  • Diaphragm / physiology*
  • Electromyography / methods*
  • Female
  • Humans
  • Inhalation / physiology*
  • Male
  • Mouth Breathing*
  • Muscle, Skeletal / physiology
  • Nasal Cavity / physiology*
  • Neck Muscles / physiology*
  • Tidal Volume / physiology
  • Young Adult