I am fairly deconditioned and sedentary, a retired person in his mid 50s who works at a computer a lot. A few years ago, I was able to exercise on a elliptical trainer for 15 or 20 minutes a day. Sometimes with a few rests, because I am trying to keep my heart rate around 140 or 145 during exercise (a rate that is recommended for my age).
Now I am trying to get back into some exercising, but I am worried that my heart rate accelerates very rapidly. When I get on the elliptical, my heart rate goes up to 140 bpm within 60 or 90 seconds. Even with pausing, it's difficult for me to do more than 3 or 4 minutes if I want to keep my rate below 150. This seems strange. I am not feeling any kind of chest pains or odd feelings in my chest or arms, but in such a short time I am not even getting out of breath. I don't feel exhausted, my heart just seems to go too fast.
One morning, when I got on the elliptical, my heart rate showed up as 150 after just 30 seconds, so I visited my doctor. He put me on 25 mg of beta blocker, a low dose. I had a stress echo cardiogram test which came out normal (up to 160 bpm on their treadmill). So they can't find anything major wrong. But I still feel like I cannot start exercising when my heart rate zooms up to such high rates just doing brief mild exercise.