For the past few months, I have been noticing that when I work out intensely, I begin feeling light headed and
nauseous. I went to a cardiologist and
wore a Holter monitor for 24 hours and the results showed my heart rate going up to 200 while exercising (no arrhythmias, just really fast "normal" beats). The doctor suggested I either try regulating my heart rate myself, or go on 25 mg of beta-blockers (metoprolol).