January 20 (HealthDay News) -- Abnormal heart function greatly reduces a person's ability to exercise, say U.S. researchers.

Dr. Jasmine Grewal, of the Mayo Clinic, and colleagues found that people with abnormal diastolic function (when the heart is relaxed and expanded) in the left ventricle have a substantially lower maximum capacity for exercise. The left ventricle is one of the four chambers of the heart.

The study included nearly 2,900 patients who underwent exercise echocardiography, which uses ultrasound to provide information about the structure and motions of the heart. The researchers also assessed left ventricular systolic (contraction) and diastolic function.

Patients with left ventricular diastolic dysfunction while resting had a much lower capacity for exercise than those with normal function. This reduction in exercise ability increased with age.

"In identifying diastolic function parameters as strong correlates of exercise capacity, we have identified potentially modifiable and preventable factors in the development of exercise intolerance. It is well known that exercise training improves diastolic function in healthy individuals ...," the researchers wrote.

The study was published the Jan. 21 issue of the Journal of the American Medical Association.

SOURCE: Journal of the American Medical Association, news release, Jan. 20, 2009