What relationship does the Frank Starling Law describe?

The Frank-Starling Law describes the relationship between end-diastolic volume (EDV) and stroke volume (SV) of the heart. This principle states that the more the heart is filled with blood during diastole (the phase when the heart relaxes and fills), the more forcefully it contracts during systole (the phase of contraction), up to a certain limit. Essentially, an increased EDV stretches the ventricular walls, which enhances the contractility of the heart muscle, leading to a higher stroke volume. This mechanism helps the heart efficiently respond to varying volumes of incoming blood, thus maintaining optimal cardiac output and ensuring that blood delivery meets the body's needs during different states of activity and rest.

Understanding this law is crucial for exercise physiologists as it highlights how heart function can adapt to different physical conditions, especially in relation to cardiovascular fitness and responses during exercise.