I have been noticing arrhythmia and i am wondering if exercise can be dangerous?

Get a check up: Sensing an arrhythmia is often not very specific or accurate. If you are concerned, have an evaluation before stressful exercise.

Usually no: Does the exercise make it feel better or worse? Regardless, you should see your doctor to figure out what you are feeling. A 24 hour monitor can be worn to record your heart rhythm. If the symptoms are less frequent, a 30 day event monitor might give your doctor the information needed to give you solid advice. In the meantime it would be best to avoid strenuous exercise.