Pattern of respiratory muscle activity during exercise tests in children born prematurely.

Introduction: Preterm children display only slightly lower exercise capacity than term children do during their development, despite their previous cardiopulmonary impairments. This raises doubts about the role of the respiratory muscles' influence on exercise capacity. This study aimed to compare respiratory muscle activity in preterm and term children using an exercise test.

Methods: This cross-sectional study involved comparison of 35 term children and 39 matched preterm children aged 6-9 years, who were born prematurely with a birth weight <1500 g. An adapted treadmill incremental test was utilized and surface electromyography of the sternocleidomastoid (SCM), upper trapezius (UT), and rectus abdominis (RA) muscles was performed. The root mean square was calculated every minute and compared between and within groups. A Monte Carlo simulation was also applied, and the area under the curve was calculated to evaluate the differences between groups.

Results: During the entire exercise, the SCM muscle activity was higher in preterm children with a larger area under the curve than in the term children. There was no difference in the RA and UT muscle activity between groups throughout the test.

Conclusion: The results suggest a greater contribution of the SCM muscle sin preterm children's performance than in term children's performance during high-intensity exercises.

Trial Registration: Brazilian Clinical Trial Registry (ReBec) - RBR-89hr2h.