Final answer:
Stroke volume remains constant during steady state exercise but initially increases and then plateaus during incremental exercise. Cardiac output and blood pressure rise during both types of exercises, and trained athletes demonstrate higher maximal outputs due to a stronger heart.
Step-by-step explanation:
The stroke volume during steady state exercise remains relatively constant once the exercise has reached a steady intensity. As a person continues to exercise at this fixed rate, the heart adapts by maintaining a stroke volume sufficient to supply the muscles with oxygen-rich blood. However, during incremental exercise, where the intensity gradually increases, the stroke volume also increases initially but eventually plateaus or may even decrease at very high intensity levels. This initial increase is attributed to enhanced heart contractility and the Frank-Starling mechanism, where increased venous return leads to increased stroke volume. As the exercise intensity reaches maximal levels, stroke volume plateaus due to the limited filling time of the heart and a maximum cardiac output is approached.
Cardiac output and blood pressure also rise during both forms of exercise, with significant differences observed between trained athletes and nonathletes. Trained athletes have a remarkable ability to increase cardiac output and stroke volume due to a more efficient and stronger heart, as evidenced by their lower resting heart rates and higher maximal outputs.