Effect of Body Position on Electrical Activity of Respiratory Muscles During Mouth and Nasal Maximal Respiratory Pressure in Healthy Adults: A Pilot Study

Background: This study aimed to analyze the impact of seated, 45° inclined, and supine positions on respiratory muscle strength (Maximal Inspiratory Pressure—MIP, Maximal Expiratory Pressure—MEP, Sniff Nasal Inspiratory Pressure—SNIP and Sniff Nasal Expiratory Pressure—SNEP) and the electrical activity of respiratory muscles in healthy adults. Ten healthy subjects were evaluated. Methods: Personal, anthropometric data (weight, height, BMI) and lung function (spirometry) were collected, followed by random assessments of inspiratory (MIP, SNIP) and expiratory (MEP, SNEP) muscle strength. Respiratory muscle strength maneuvers and surface electromyographic (sEMG) activity were assessed in sitting, 45° inclined, and supine positions. Results: present that MIP was statistically higher in the sitting position compared to the supine position (p < 0.05) and the 45° supine position (p < 0.05), with SNIP: p < 0.05 and SNEP: p < 0.05 as well. Intercostal muscle activity was higher during MIP, MEP, and SNEP maneuvers in the sitting position (p < 0.05). Additionally, rectus abdominis muscle activity was higher in this position during MIP and SNEP maneuvers. Conclusions: The results suggest there are significant differences in inspiratory pressures between positions, with the difference in activity muscle pattern. In conclusion, body position affected maximal respiratory pressures and influences EMG activation of specific respiratory muscles during MIP.