Answer
An increased heart rate.
Work Step by Step
An increased heart rate brings more oxygenated blood through the body, providing more oxygen to muscles to facilitate increased use. This is necessary during times of exercise.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.