What is the heart rate of an adult at 40 years old?

A normal human heart rate is between 60 to 100 beats per minute. It is normal is aerobically fit people and very common in athletes. For example, Lance Armstrong (famed professional cyclist) has a resting heart rate of 37. It is not considered normal if you experience symptoms such as weakness, dizziness or difficulty breathing, so see your doctor if you experience these.