CARDIAC CHANGES IN MARATHONS AND ENDURANCE RACES

As more and more endurance races and marathons are organised every year across the world, cardiologist are getting more and more interested in the physiological changes in the heart during marathon and endurance races. We know for certain that there are fatalities amongst marathon runners. It has variously been quoted as 1:2 million miles run, or 1: 100,000 participants in 26 Km marathons. We also know that marathon running does induce rise in cardiac enzymes, including CPK and troponins.
Dr Andre La Gerche and colleagues of the University of Leuven, Belgium, studied the effects of maranthon and other endurance races ( including triathlons ) in 40 athletes. They had their baseline cardiac enzymes and echocardiogram done to study both their LV and RV volumes and function. These were repeated immediately after the race and also at 1 week later.
They found that the LV volumes and functions were essentially within normal limits. However, in the RV, the volumes were increased immediately post race, compared to baseline and returned to normal at 1 week. The RV functions however were reduced, in proportion to cardiac enzyme rises, and these all return to normal at 1 week.
If this study is correct ( and we need to await more studies to confirm ), then it would appear that in normal athletes, the RV bears the blunt of the insult during endurance races and marathons. This allows the LV to be protected. Obviously, it has much to do with pulmonary function, pulmonary circulation and pressures and gaseous exchange in endurance races.
This paper in published in the Dec 7th European Heart Journal.
If you take a broader view of this paper, it could also teach us that in acute respiratory distress ( in this case, coping with rapid and efficient gaseous exchange and maintaining a good pulmonary circulation ), the RV has alot to do, and to cope. Those of us with chronic lung diseases must know this as people with COAD copes badly with acute respiratory stress, and should avoid such activities.
Anyway, we should keep an open mind as we await more studies on this important topic of coping with marathon and endurance races. I do not think that we have heard the last word on this topic yet.