A low pulse rate may be caused by a number of health conditions. Sometimes, a form of heart disease is the reason for slower blood flow throughout the body. Cardiac abnormalities are common, but other conditions that do not involve the heart, such as a metabolic imbalance or certain lung diseases, can create the symptom. A slower heartbeat does not always indicate a health problem, however. Sometimes, just the opposite is true. Athletic individuals who exercise frequently and enjoy optimum cardiovascular health often have a lower than normal pulse rate because the heart does not have to work as hard while at rest, and the body functions more efficiently.