Explain the two thorax patterns typically observed in extension patterns (PECs). What happens to the center of mass in each pattern and what is the typical airflow pattern?

• A. Pattern 1: Thorax elevates and turns upward into a hyperinflated posture with lordosis; center of mass shifts back and up; airflow: superior apical breathing with diaphragms in a tonic flat position. Pattern 2: Thorax displaces backwards with apical chambers closed; center of mass shifts back; airflow: excessive belly breathing with poor diaphragm use.
• B. Pattern 1 and Pattern 2 both involve forward-leaning thorax; no changes in center of mass; airflow normal.
• C. Pattern 1: Thorax elevates; center of mass shifts forward; airflow: diaphragms active. Pattern 2: Thorax flattens; center of mass shifts forward; airflow: mixed.
• D. Pattern 1: Thorax rotates; center of mass shifts up; Pattern 2: Thorax rotates opposite; center of mass shifts down; airflow: diaphragms spontaneously adjust.

Answer: (A)