Abdominal muscle activity during breathing in different postural sets in healthy subjects.

Objective: This study aims to evaluate the effect of different postural sets on abdominal muscle activity during breathing in healthy subjects.

Methods: Twenty-nine higher education students (20.86 ± 1.48 years; 9 males) breathed at the same rhythm (inspiration: 2 s; expiration: 4 s) in supine, standing, tripod and 4-point-kneeling positions. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique muscles during inspiration and expiration.

Results: During both breathing phases, the activation intensity of external oblique and transversus abdominis/internal oblique was significantly higher in standing when compared to supine (p ≤ 0.001). No significant differences were found between tripod position and 4-point-kneeling positions. Transversus abdominis/internal oblique activation intensity in these positions was higher than in supine and lower than in standing.

Conclusions: Postural load and gravitational stretch are factors that should be considered in relation to the specific recruitment of abdominal muscles for breathing mechanics.