I am not clear on your post if you have a rapid beat during exercise or for no reason at all. If your heart starts to race at 190 on a single beat and stops just as suddenly then you likely have something called svt. What that means is you may have an extra muscle fiber in your heart that causes the signal in your heart to get caught in a loop. The fix is fairly easy but you do need to get diagnosed. If you get the episodes at least once a month a 30 day monitor should catch it. If it is less frequent then it may be more difficult to catch but isn't much of a concern unless your heart is unhealthy or it sustains for an extended amount of time. You should have your heart fully evaluated to make sure it is healthy. Exercising is fine so long as you are not having an episode. I would not exercise during an episode but sit and wait for it to pass or try vagal maneuvers to get it to stop. Look that up on the web as there are a few different things you can try. However if your post is simply that your heart rate rises to 190 during exercise then I would concur with the previous posters thoughts. Take care.
First get advice/approval from your doctor to engage in exercise.. I mean program exercise, not getting up and waling around.
If okay to exercise, start slow don't push it.