Heart rate issue
My HR also gets crazy high during exercising. I've check it on various machines as well as "manually" from my pulse in my neck. They all seem to b pretty accurate. I can easily get mine well over 200bpm and have recorded it as high as 236bpm when I was 38. My resting HR is good. I went to a cardiologist and had a battery of tests, stress test, echocardiogram and something else. It was confirmed that my HR skyrockets at a rapid pace. The Dr had to shut down the stress test prematurely. He said my heart was fine but something was triggering it to run fast. He said it was something to do with my endocrine system.
Blood work was ordered and my cardiologist thought that my iron level was low and my thyroid levels were high. He sent me to an endocrinologist who read my results from my blood work. He said that my thyroid levels were on the higher end of normal and that my iron wasn't an issue. He said that none of that would effect my HR. More blood work was done and the results were even better that time.
I take ZERO stimulants (other than Adderall). My primary doctor said to get off the Adderall for 72 hrs and it would be out my system. I got off of it for months and still had the same results.
So now I have one doctor that sent me to the other, that sent me back to the original. A couple thousand dollars in bills and I now realize why they say that doctors "practice" medicine.