ESSEN, GERMANY. It is well established that regular physical exercise reduces the risk of cardiovascular disease, but it is equally well established that vigorous exercise increases the short-term risk of coronary events (heart attack and stroke), especially among elderly people not accustomed to exercise. A group of German researchers have now taken a look at the cardiovascular risk profile of 108 apparently healthy male marathon (42 km) runners aged 50 years or older and with at least 5 marathons under their belt. Not surprisingly, they found that the marathon runners� Framingham risk score (7%) was significantly lower than the score in a group of healthy age-matched controls (11%). Marathon runners experienced a 52% higher HDL cholesterol level, an 18% lower LDL cholesterol level, a 15% lower body mass index, and a 12% lower systolic blood pressure as well as a significantly lower resting heart rate (65 bpm vs 76 bpm). Coronary artery calcification (CAC) score was similar in marathon runners and age-matched men; however, when CAC scores were compared for marathon runners and age-matched men with a similar low Framingham risk score, then 36% of marathon runners were found to have a CAC score of 100 or higher as compared to only 22% in the control group.

MRI studies of the marathon runners indicated that 12% had late gadolinium enhancement (LGE), a marker of cardiovascular damage. Overall, LGE was associated with high CAC scores and an increased number of completed marathons. During a mean follow-up of 21 months, 4 coronary events occurred among the runners, 2 of which required resuscitation.

The researchers conclude that marathon running does not seem to protect against atherosclerosis as indicated by a high CAC score and may, in fact, exacerbate the problem due to excessive vascular oxidative stress, and frequent bursts of inflammatory cytokines experienced during long-distance running. The authors conclude that, �Regular marathon running has a beneficial effect on the cardiovascular risk factor profile but the extent of calcified coronary plaque is underestimated from that risk factor profile, with 36% of marathon runners aged 50 years or greater having a CAC score of 100 or greater and 9% of these requiring coronary revascularization during two years of follow-up. Advanced CAC scores seem to contribute to increased myocardial damage and appear to impair outcome. Frequent marathon running may not protect these athletes from the risk of coronary events.�

Mohlenkamp, S, et al. Running: the risk of coronary events. European Heart Journal, Vol. 29, 2008, pp. 1903-10
Schmermund, A, et al. The risk of marathon runners � live it up, run fast, die young? European Heart Journal, Vol. 29, 2008, pp. 1800-02 (editorial)

Editor�s comment: This study adds to the evidence that exercise in moderation is good, while vigorous exercise taken to extremes may produce unhealthy stress on the cardiovascular system.