ACE Personal Trainer Practice Exam

What nerves are inhibited during vagal withdrawal when exercise occurs?

1. Sympathetic nerve fibers

2. Parasympathetic nerve fibers

3. Motor nerve fibers

4. Sensory nerve fibers

The correct answer is: Parasympathetic nerve fibers

During exercise, the body undergoes various autonomic adjustments to meet the increased demands for oxygen and nutrients by the working muscles. Vagal withdrawal refers to the decrease in activity of the vagus nerve, which is a key component of the parasympathetic nervous system. This withdrawal reduces parasympathetic influence on the heart, leading to an increase in heart rate and cardiac output. Inhibition of parasympathetic nerve fibers during exercise allows the sympathetic nervous system to dominate, promoting responses that enhance physical performance such as increased heart rate, enhanced blood flow to muscles, and elevated energy availability. This shift is essential for achieving the heightened physiological state required for exercise. Therefore, understanding that vagal withdrawal entails a reduction in the activity of the parasympathetic nervous system confirms that the answer pertains to the inhibition of parasympathetic nerve fibers. This physiological adaptation is critical for supporting the body's movement and efficiency during physical activity.