Question

Researchers have observed that athletes and non-athletes have the same mean resting cardiac output, even though athletes have a far lower resting heart rate. How is this possible?

Answer 1

As we know carduac output is equal to multiplication of stroke volume and heart rate i.e. CO=SV×HR

So we have same CO in both at rest while heart rate is low in athletes.

This is due to the fact that stroke volume is higher in the athletes. It is due to hypertrophy of the ventricle's walls. So there is increased contractility and hence the ventricles will eject out more blood on each stroke. Further there is increased venous tone in atheletes which add to increased venous return to heart. So these factors increase the stroke volume of the individual. This increased stroke volume compensated for the decreased heart rate in the athletes to carry the cardiac output normal at reast.