I have written before about the troubling reports of certain test results following endurance events.
There is evidence that in the early hours after a marathon or an Ironman type triathlon there sometimes are elevations of troponin in the range seen in myocardial infarctions.There are also reports of echocardiographic changes that could be described as cardiac "fatigue". The changes are those of altered relaxation characteristics and a decreased contractility all of which, along with the elevated troponins returned to normal in 48 hours.There is the hope that all of this is just analogous to the sore leg muscles and raised total CK values that remit in a few days and is of as little consequence but there may be more to it that that.There is at least one report of some of the more subtle echo changes persist at least for one month after a race.
One post marathon study suggested that the above mentioned abnormalities were less marked in the better conditioned runners and another paper found the alterations more likely in first time runners versus more seasoned veteran marathoners. See here for my earlier blog entry discussing some of the issues involved in assessing the harm or absence thereof in marathoners.It should be noted that not all runners show the echo changes and there is a suggestion that the type of ACE gene pattern may play a role in that.
Well,all of the above really address the issue of over use damage that certainly is at least acute and some worry may lead to long lasting permanent cardiac damage, i.e. myocardial fibrosis or an endurance exercise induced cardiomyopathy.
Now for something completely different. There is a report suggesting that many years of marathon running may increase (not a typo) the risk of coronary artery disease at least as possibly indicated by increased coronary artery calcification.This seems counter intuitive as conventional wisdom tells us that exercise may decrease the risk of coronary disease but could this be an instance of " too much of a good thing".See here for that study.
Drs Robert and Jonathan Schwartz reported on a CTA (Coronary Computed Angiogram) study that involved 25 runners who had been running in the 26.2 mile races for 25 years or more and had completed 25 or more marathons.They found a statistically significant increase in calcified coronary plaques and an increase in non-calcified plaques that did not reach the level of statistical significance as compared with 25 controls.