How does increased cardiorespiratory fitness typically affect resting heart rate?

Increased cardiorespiratory fitness is associated with a decrease in resting heart rate (RHR) due to several physiological adaptations that occur with regular aerobic exercise. As individuals engage in consistent cardiovascular training, their heart becomes more efficient. This efficiency means that the heart can pump a greater volume of blood with each beat, which allows it to work less strenuously during periods of rest.

Specifically, as the heart's stroke volume increases—meaning the amount of blood ejected with each heartbeat—the body does not require as many beats per minute to maintain adequate circulation and oxygen delivery at rest. Consequently, individuals with higher levels of cardiorespiratory fitness often exhibit a lower resting heart rate compared to those with lower fitness levels.

This physiological adaptation is a key marker of cardiovascular health and fitness, indicating that the heart and lungs are functioning optimally to supply oxygenated blood to the body. Over time, as a person continues to improve their cardiorespiratory fitness through regular exercise, they can expect to see further reductions in their resting heart rate.