The Effect of Posture on Respiratory Activity of the Abdominal Muscles

Abstract

The purpose of this study was to determine the influence of posture on the expiratory activity of the abdominal muscles. Fifteen young adult men participated in the study. Activities of the external oblique abdominis, internal oblique abdominis, and rectus abdominis muscles were measured electromyographically in various postures. We used a pressure threshold in order to activate the abdominal muscles as these muscles are silent at rest. A spirometer was used to measure the lung volume in various postures. Subjects were placed in the supine, standing, sitting, and sitting-with-elbow-on-theknee (SEK) positions. Electromyographic activity and mouth pressure were measured during spontaneous breathing and maximal voluntary ventilation under the respiratory load. We observed that the lung volume changed with posture; however, the breathing pattern under respiratory load did not change. During maximal voluntary ventilation, internal oblique abdominis muscle expiratory activity was lower in the SEK position than in any other position, external oblique abdominis muscle inspiratory activity was lower in the supine position than in any other position, and internal oblique abdominis muscle activity was higher in the standing position than in any other position. During spontaneous breathing, external oblique abdominis muscle activity was higher during expiration and inspiration in the SEK position than in any other position. The internal oblique abdominis muscle activity was higher during both inspiration and expiration in the standing position than in any other position. The rectus abdominis muscle activity did not change with changes in posture during both inspiration and expiration. Increase in the external oblique abdominis activity in the SEK position was due to anatomical muscle arrangement that was consistent with the direction of lower rib movement. On the other hand, increase in the internal oblique abdominis activity in the standing position was due to stretching of the abdominal wall by the viscera. We concluded that differences in activity were due to differences in the anatomy of the abdominal muscles and the influence of gravity.

Avaliação das pressões respiratórias máximas em pacientes renais crônicos nos momentos pré e pós-hemodiálise

“…18 A PI max value is considered to be low when below 60% of the predicted value, the latter being established based on variables, such as sex and age 16 , body weight 19 , and height. 20 Values greater than 60 cmH 2 O clinically exclude respiratory muscle weakness 18 and there is consensus that patients with PI max £ @[sinal de menor?? ]@ 60 cmH 2 O need specific training of the respiratory muscles.…”

Heliox and Forward-Leaning Posture Improve the Efficacy of Nebulized Bronchodilator in Acute Asthma: A Randomized Trial

“…8,9 Studies of postures and their relationship to that mechanical disadvantage 10,11 suggest that the influence of posture is mainly on the position of the diaphragm, increasing the tension in muscles such as the abdominals and the effect gravity has on them. 10 We studied the effect of forward-leaning posture and heliox as adjuncts to bronchodilator administration in patients with acute asthma crisis in our emergency department.…”

Posture Perfect: The Role of Positioning During Bronchodilator Administration With Oxygen or Heliox

“…15,16 Therefore, the inspiratory muscles contract above FRC, as opposed to at the end of expiration to FRC, 16 and gravitational force due to the weight of the rib cage and shoulders acts as an expiratory force that optimizes expiration. 17 Since FRC and air-flow resistance are inversely related, an increase in FRC leads to a decrease in air-flow resistance, because airway caliber is a function of the cube root of lung volume.…”