The short answer is, it depends (I'll explain below). Only your doctor
will be able to determine if your high heart rate is dangerous. First, bring the issue up with your primary care doctor
. He or she may then refer you to a cardiologist
. If someone has a high heart rate (also known as tachycardia) above 90-100 beats per minute for many months to years, that person may develop heart failure. However, it would be extremely unusual for exercise to cause this problem. Exercise raises the heart rate only for the time you are working out and the pulse returns to normal afterwards. Having tachycardia only during exercise is not dangerous. With that said, if your pulses stays fast after you've rested, then you may have a heart arrhythmia, also known as an abnormal heart rhythm. Arrhythmia's are not uncommon, and can result in abnormally high heart rates which, as stated above, would be dangerous if they were allowed to occur for a long time. Your doctor would need to obtain an electrocardiogram or ECG to determine if you had an arrhythmia. Arrhythmia can be dangerous, so I would advise you to bring the issue up with your doctor. If he or she says you don't have a problem, then please keep exercising!