What physiological changes occur in the cardiovascular system in response to acute exercise?

During acute exercise, the body undergoes significant physiological changes to meet the heightened demands for oxygen and nutrients by the working muscles. One of the primary responses observed in the cardiovascular system includes an increased heart rate. This elevation in heart rate allows the heart to pump blood more frequently, delivering oxygenated blood to the muscles at a faster rate. Additionally, stroke volume— the amount of blood ejected with each heartbeat—also increases. This happens due to the enhanced venous return to the heart, facilitated by mechanisms such as muscle pump action and respiratory pump, which contribute to increased preload and, consequently, increased stroke volume.

As both heart rate and stroke volume rise, cardiac output, which is the product of heart rate and stroke volume, experiences a marked increase as well. This enhanced cardiac output is crucial during exercise, as it ensures that the working muscles receive sufficient blood supply to sustain their activity levels. Therefore, the correct response highlights this synchronized increase in heart rate, stroke volume, and cardiac output, which are essential adaptations that optimize oxygen delivery and overall exercise performance during acute physical activity.