Problem with running

Hi - I have always been a rather athletic person, when I got into college my activity decreased but my weight stayed the same.  I am 5'6" 110 lbs I know that is rather low but I eat a ton, and healthy.  I have been trying to get back in shape and been working out consistently.  This is my 4th attempt in college and I always stop for the same reason.  I can't run for more than 5 minutes without getting extreme chest pains and getting dizzy.  I went to a doctor and I was not given an answer about anything.  My heart rate went up to 200 bpm walking uphill on the treadmill and I was fine.  All of my other tests came back perfect, no problems with my heart that can be seen. There is something about running though that when I begin to run right away my heart rate goes up to 190 and  builds from there.  By the time it gets to 200 I am dizzy and cannot breathe.  What is wrong? I just want to know so that I can exercise and feel comfortable.  It also doesn't matter which pace I go on the treadmill within 5 minutes of running I have to stop.  My boyfriend is a marathon runner and is completely puzzled by my situation.

I guess my question is what could possibly be wrong with me, and could it just be something I need to get used to...I want to push through the pain but I don't know if that is a wise decision.  I am 22 I don't want to leave the world anytime soon.  Please help.

[Michael J. McWilliams, M.D.]

If I saw you in clinic, I would do an exercise stress test and maybe an echocardiogram.  I would be curious what exercise level you could achieve and how quickly your heart rate increases.  I have seen a few patients that just can't run -- they don't have the stamina for it, but they are otherwise normal.  It will be easy to determine your exercise thresholds, but more difficult to tell you why it is what it is.  You may need to start very slowly and gradually work you way back into it.

I hope this helps.