I have question on HR(heart Rate). when ever I am on the treadmill I always wonder why my heart rate is so low despite me doing the treadmill quite fast. With coffee and eca I can barely hit 125. and without I be around 105. as I train with my partner, he be hitting 190 200. I look at other people they are hitting 170-180, 160. I was wondering why is my heart so low despite peddling like 6(which is pretty fast). The workout partner does 5 speed and he is sweating liek crazy and heart rate is like 190. Why is that?