Dr. John Mandrola, a cardiologist (specializing in electrophysiology) in Louisville, KY, who blogs at http://www.drjohnm.blogspot.com, brought an interesting report to my attention the other day.
Included among the abstracts presented at the recent annual meeting of the American College of Cardiology was a report from Dr. Jonathan Schwartz (from the University of Colorado) and his father, Dr. Robert Schwartz (from the Minneapolis Heart Institute). It turns out that father and son investigators are both runners.
These investigators examined a group of 25 runners who had completed the Twin Cities marathon for 25 consecutive years and compared these runners to a control group of non-athletes that were similar in terms of age, restinig blood pressure, renal function, smoking history, height, total and LDL cholesterol, and triglycerides. The runners did have a lower heart rate, weight, and body-mass index and higher HDL cholesterol levels.
All of the subjects underwent coronary CT angiography (CTA). This is a relatively simple x-ray test designed to find build-up of calcium in the coronary arteries (the arteries that supply the heart itself). And recall that when these arteries become blocked with calcium-laden plaque, problems such as angina or heart attack (myocardial infarction) may occur.
The investigators found that there was a significantly higher calcium plaque volume in the runners than in the control group. Sixty percent higher, in fact.
Why could this be? Again, the healthy benefits of exercise have been well-established. But the authors here suggest that these healthy benefits might be “counterbalanced by metabolic and mechanical considerations” and that the calcium plaque build-up may be “a response to high exercise levels across a lifetime.”
There have been precious few studies of the long-term effects of (potentially excessive) exercise on the cardiovascular system, so we really don’t know the cause of these findings. But it could well be the case that, beyond some point, the chronic effects of participation in endurance sports may actually be harmful.
Reports like this make you think.