Which body part is part of the respiratory system and helps breathing when running?

The diaphragm is a crucial part of the respiratory system that aids in breathing, especially during activities like running. When you inhale, the diaphragm contracts and moves downward, creating a vacuum that allows air to flow into the lungs. During exhalation, it relaxes and moves upward, helping to expel air. This muscle's efficient functioning is essential for maintaining adequate oxygen supply during physical exertion.