You have a slower than normal heart rate. Doctors call this bradycardia. A slow resting heart rate can be normal for athletes because they have a high level of physical fitness.
Certain medications, especially some heart and high blood pressure medicines, will frequently slow the heart rate. Examples include beta blockers (such as atenolol, metoprolol, propranolol) , diltiazem, verapamil, and digoxin.
Do you take any heart or blood pressure medications that can slow your heart rate?