"Other factors known to affect the development of the disease and its symptoms include blood pressure and activity levels. When diagnosed in people over 60 years of age, HCM is often associated with high blood pressure or hypertension. High blood pressure is like weight lifting for the heart; a long history of high blood pressure can itself lead to the overgrowth of the heart muscle. Extensive physical training can also result in an overdeveloped heart. The difference between a professional athlete's heart and the heart of an individual with HCM can be subtle. Other environmental factors that increase one's risk of developing HCM will most likely become apparent as research continues. "