I didn't know where else to post this question, so I did here.

Basicaly I was running today on the treadmill and monitoring my heart rate.
I noticed that for the first couple mins as I was warming up my heart rate got faster. Approx 135 beats per min.. It slowly increased until I started running at my max potential for a while and than dropped to 84 beats per min. But with a hard beat.

Does this happen because when your doing something at your max potential your heart beats harder instead of faster to move the same amount of blood through your system without using as much oxygen?