This experiment is very simple. The only equipment you need is a watch with a second hand.
1) Find the pulse in your wrist and count how many times it beats in one minute. This measures your heart rate. It should be between 60-80 beats per minute.
2) Now do sit ups for a minute and count your pulse again. Is there any difference between this and the first reading?
3) Rest for 5 minutes and take your pulse again.
Fit people have a low resting pulse rate. Their pulse rate goes down very quickly after exercise. What happened to yours?