In an untrained healthy adult performing incremental exercise to exhaustion, the stroke volume characteristically:

• A Rises linearly until maximal effort
• B Remains constant throughout exercise while heart rate carries the entire rise in output
• C Falls progressively after the anaerobic threshold
• D Plateaus at approximately 40 to 50 percent of maximal workload ✓

Explanation

In sedentary individuals, stroke volume increases early in graded exercise and plateaus at roughly 40 to 50 percent of VO2max; beyond this point further rises in cardiac output depend entirely on heart rate. In highly trained endurance athletes, stroke volume continues to climb until near-maximal workloads, which is a key reason for their superior cardiac output. Options A and B describe patterns seen only in specific populations, not the untrained adult.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.