What does a lower resting heart rate in well-trained athletes suggest?

A lower resting heart rate in well-trained athletes is indicative of improved cardiovascular efficiency. This efficiency derives from the heart's ability to pump a larger volume of blood with each contraction, allowing the heart to work fewer times per minute while still maintaining adequate circulation and oxygen delivery throughout the body.

This adaptation often results from consistent endurance training, which strengthens the heart muscle, increases stroke volume, and enhances blood flow. As a result, athletes can sustain higher workloads with less strain on their cardiovascular system, reflected in a lower resting heart rate.

While increased metabolic rate, higher oxygen consumption, and greater muscle mass are all potential benefits of being a trained athlete, they do not directly explain the relationship between a lower resting heart rate and cardiovascular efficiency in the same way that improved heart function and stroke volume do.