Why do children have higher heart rates than adults at rest and during exercise?

The reason children typically have a higher heart rate than adults, both at rest and during exercise, is primarily due to their lower stroke volume. Stroke volume refers to the amount of blood pumped by the heart with each beat. In children, the heart's ability to fill completely and pump effectively is not as developed as in adults, so their bodies compensate for this by increasing the heart rate.

To maintain adequate blood circulation and meet the metabolic demands during activity, children's hearts beat faster. This physiological adjustment helps ensure that sufficient oxygen and nutrients reach their developing muscles and organs despite the lower volume of blood pumped per contraction. Thus, while their stroke volume is lower, their elevated heart rate compensates, resulting in a significant difference in resting and exercising heart rates compared to adults.

Understanding this relationship highlights the importance of cardiovascular development in children compared to adults and reflects the complexity of the cardiovascular system's adaptations to fulfill the body's requirements during growth and physical activity.