YMCA Level 2 Fitness Instructor Practice Test 2025 - Free Fitness Instructor Practice Questions and Study Guide

During exhalation, the diaphragm plays a crucial role in the respiratory process. As the diaphragm relaxes, it moves upward toward the thoracic cavity, reducing the volume of the chest cavity. This upward movement is facilitated by the relaxation of the muscle fibers, which leads to a passive process of air expulsion from the lungs. The decrease in volume within the thoracic cavity creates a higher pressure in the lungs compared to the outside atmosphere, causing air to flow out of the lungs.

This natural action of the diaphragm is vital for effective breathing and highlights its function as a primary respiratory muscle. Understanding the mechanics of this process is essential for anyone studying respiratory physiology or working in fitness and health.