Why does your heart beat faster when you exercise?
Your heart beats faster during exercise to pump more blood to your working muscles, delivering the extra oxygen and fuel they need and removing carbon dioxide and heat.
When you exercise, your muscles use energy much faster, which requires more oxygen. Your nervous system and hormones like adrenaline signal the heart to beat faster and more strongly. At rest, an adult's heart pumps about 5 liters of blood per minute. During intense exercise, this can rise to 20 liters or more in a fit person.
Breathing also speeds up to take in more oxygen and remove carbon dioxide. Blood vessels in the muscles widen, while blood flow to areas like the digestive system decreases, directing more blood where it is needed most.
Fitness and heart rate
A normal resting heart rate for adults is about 60 to 100 beats per minute. Regular exercise strengthens the heart, so it pumps more blood with each beat. As a result, fit people often have lower resting heart rates. Some endurance athletes have resting rates below 50.
Did You Know?
A rough estimate of maximum heart rate is 220 minus your age, though actual values vary widely between people.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.