Recruitment of the Diaphragm and Sternocleidomastoid Muscle During Loaded Inspiration on Varying Sitting Support in Healthy Adults

This is a cross-sectional obsessional study. This study explores how different sitting conditions affect two important muscles-the diaphragm and the sternocleidomastoid (SCM)-work during breathing exercises. The diaphragm is the main muscle for breathing, while the SCM helps when taking deeper breaths. Understanding how these muscles interact while sitting under various conditions can help improve breathing training techniques. The study's objectives are (1) to investigate the relationship between diaphragm thickness fraction with 4 different sitting conditions during loaded inspiration among healthy adults and (2) To investigate the relationship between SCM activity with 4 different sitting conditions during loaded inspiration among healthy adults. This research will conduct healthy adults, who will be instructed to breathe against resistance provided by the IMT while sitting on four different conditions: a regular chair, a soft pad with feet on the ground, a soft pad with feet on two additional soft pads, and a single soft pad with both feet on one pad. By using ultrasound to measure how thick the diaphragm gets and surface electromyography (sEMG) to track SCM activity, the data will be gathered on how these muscles function under different conditions. The goal is to find out if sitting on unstable surfaces, like soft pads, can enhance diaphragm use compared to a stable chair. These surfaces may change how effectively the diaphragm and SCM work together. This research could lead to better recommendations for inspiratory muscle training (IMT), which helps strengthen these muscles, especially for people with breathing difficulties. By identifying how posture influences muscle recruitment during breathing exercises, hoping to contribute valuable insights that can improve rehabilitation programs for individuals with respiratory conditions.

NCT Number	NCT07007923
Lead Sponsor	Hong Kong Metropolitan University
Conditions	Diaphragm
Enrollment	45 participants
Start Date	2025-06-19
Primary Completion	2025-07-31 (estimated)
Study Completion	2026-04-20 (estimated)
Updated on ClinicalTrials.gov	2025-06-06