Ask the doctors: Fainting while doing chin-ups?

Q. I am a healthy 52 year old who likes to stay fit. Recently, I have occasionally fainted after doing eight or 10 chin-ups. My physician did an EKG and stress test the first time this happened and found my heart is normal. He had me wear a monitor for 24 hours, and it indicated nothing was wrong. Your thoughts?

A. Someone who faints during exercise can have a serious life-threatening issue, such as narrowing of a heart valve, thickening of heart muscle (cardiomyopathy), or life-threatening arrhythmias. In your case, the chances of having a serious condition are pretty low, given the negative results of your tests.