Question

What breathing change occurs at the second ventilatory threshold (VT2)?

a) Expiration becomes more forceful.
b) Breathing settles into a more consistent rhythm.
c) Inspiration is prolonged.
d) Breathing becomes more shallow.

Answer 1

At the second ventilatory threshold (VT2), expiration becomes more forceful due to the higher respiratory rate and increased volume of air per breath required to manage the elevated carbon dioxide levels during intense exercise.

Step-by-step explanation:

The second ventilatory threshold (VT2) is a point of high-intensity exercise where there is a second distinct exacerbation of the rate of ventilation. At this point, expiration becomes more forceful to expel the increased levels of carbon dioxide produced during high levels of aerobic metabolism. This is a result of both a higher respiratory rate and increased volume of air per breath. Pulmonary ventilation during this state is heightened, and the body has to work harder to meet the increased oxygen demand and remove carbon dioxide efficiently.

This change in breathing pattern allows the body to handle the heightened levels of carbon dioxide and maintain oxygen delivery to the muscles. During forceful expiration, accessory muscles, like abdominal muscles and internal intercostals, are actively engaged to push the air out quickly and effectively.