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Too Much Exercise is Just as Bad as Not Enough

After a number of years in which almost no deaths were caused by heart attacks during marathons, at least six runners have died in 2006. Some physicians, including Dr. Arthur Siegel, author of numerous studies of Boston Marathon racers, believe the extended races put the heart at risk.

A study by Dr. Siegel and colleagues examined sixty Boston Marathon entrants. The runners showed normal cardiac function before the marathon.

Twenty minutes after finishing, sixty percent of the group had elevated levels of troponin (a protein that shows up in the blood when the heart is traumatized), and forty percent had levels high enough to indicate the destruction of heart muscle cells. Many also showed noticeable changes in heart rhythms.

Another study, from Germany, showed as many as one-third of middle-aged male marathoners may have higher than expected calcium plaque deposits in their arteries, putting them at a greater risk for heart attack. Over twenty percent of a control group of non-runners had comparable calcium plaque buildup.

Circulation November 28, 2006; 114(22): 2325-2333

New York Times December 7, 2006

The (Lakeland, FL) Ledger December 7, 2006