If you can't take your heart rate, a good way to recognize that you're exercising efficiently is whether or not
A. you're experiencing a little bit of huffing and puffing.
B. you're gasping for breath.
C. it's difficult to have a conversation.
D. your muscles are burning.
The correct answer is D. Your muscles are burning. If you are experiencing any of the other 3 choices, either you probably have asthma, or you just held your breath during sprints.
