Mass. General study shows how exercise changes structure and functio...(ally about the use of steroids and any w...)

At the end of the 90-day study period, both groups had significant overall increases in the size of their hearts. For endurance athletes, the left and right ventricles the chambers that send blood into the aorta and to the lungs, respectively expanded. In contrast, the heart muscle of the strength athletes tended to thicken, a phenomenon that appeared to be confined to the left ventricle. The most significant functional differences related to the relaxation of the heart muscle between beats which increased in the endurance athletes but decreased in strength athletes, while still remaining within normal ranges.

We were quite surprised by both the magnitude of changes over a relatively short period and by how great the differences were between the two groups of athletes, Baggish says. The functional differences raise questions about the potential impact of long-term training, which should be followed up in future studies.

While this study looks at young athletes with healthy hearts, the information it provides may someday benefit heart disease patients. The take-home message is that, just as not all heart disease is equal, not all exercise prescriptions are equal, Baggish explains. This should start us thinking about whether we should tailor the type of exercise patients should do to their specific type of heart disease. The concept will need to be studied in heart disease patients before we can make any definitive recommendations.

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