National Physical Therapy Examination (NPTE) Practice Exam

Which physiological response is primarily influenced by the sympathetic nervous system during acute exercise?

1. Increased peristalsis

2. Increased heart rate

3. Increased rate of breathing

4. Increased blood flow to the skin

The correct answer is: Increased rate of breathing

During acute exercise, the sympathetic nervous system plays a crucial role in preparing the body for increased physical activity. One of the primary physiological responses it influences is the increase in heart rate. This response occurs to ensure that more oxygen-rich blood is delivered to the muscles, facilitating their performance. As exercise intensifies, beta-adrenergic receptors in the heart are stimulated, leading to an increase in heart rate and cardiac output. The increased rate of breathing is also an important response during exercise, as it helps to meet the heightened oxygen demands and remove carbon dioxide more effectively. However, the heart rate response is more directly influenced and prominently increases in the immediate phase of exercise. While increases in peristalsis and blood flow to the skin do occur, they are generally not the primary influences from the sympathetic nervous system during exercise. In fact, the sympathetic activation tends to decrease peristalsis as blood is redirected away from the digestive system to support muscle activity and major organ functions needed during physical exertion. Additionally, blood flow to the skin is often reduced during intense physical activity to prioritize blood supply to the working muscles. Thus, the increase in heart rate stands out as the principal response driven by the sympathetic nervous system in acute exercise scenarios.