Is marathon running bad for you? According to wider media reports based on an on-line article in the European Heart Journal, then yes, it probably is. But dig a little deeper through the UK national media's sensationalist headlines and then no, it probably isn't.
'Marathon Running Can Damage Your Heart' screamed one particular tabloid. So, in the words of Lloyd Grossman, 'let's take a look at the evidence.' The study was carried out by scientists in Australia and Belgium, who tested 40 elite athletes taking part in high endurance activities such as marathons, triathlons or alpine cycling. The results showed that the group - none of whom had any recorded heart problems - all had slightly altered hearts immediately after competing. The organ had increased in volume, whilst the right ventricle - one of the heart's four chambers - had decreased in function.
However, by the next week of the group 35 of the athletes' hearts had fully recovered and had actually improved in performance due to the repairal process. However, for the remaining five there was evidence of potentially permanent scarring in the heart. These five had also been training and competing for much longer than the rest of the group.
Study leader Dr Andre La Gerche, from the University of Melbourne, Australia, said: "Virtually all of the changes in the athletes' hearts had resolved one week after having taken part in a competitive event.
"In most athletes, a combination of sensible training and adequate recovery should cause an improvement in heart muscle function; that is, the heart rebuilds in a manner such that it is more capable of sustaining a similar exercise stimulus in the future. This positive training response can be over months rather than weeks. The question from our research is whether there are some athletes in whom extreme exercise may cause injury from which the heart does not recover completely. If this occurs, affected athletes may be at risk of reduced performance - a cardiac 'over-training' syndrome - or it may cause arrhythmias (erratic heart beats). If this occurs, it is likely to affect only a minority of athletes, particularly those in whom more intense training fails to result in further improvements in their performance."
Reading between the lines, the study tells us what most sensible endurance runners already know; don't over-train and make sure you get adequate recovery.
Speaking to the Daily Telegraph, medical director of London marathon Professor Sanjay Sharma said: "My personal feeling is that extreme endurance exercise probably does cause damage to the heart in some athletes. I don't believe that the human body is designed to exercise for as long as 11 hours a day, so damage to the heart is not implausible."
Speaking to the BBC, Doireann Maddock of the British Heart Foundation chipped in with: "It is important to remember that the health benefits of physical activity are well established. The highly trained athletes involved in this study were competing in long distance events and trained for more than 10 hours a week."
The unscientific conclusion? Keep enjoying your running - but don't leave your common sense behind.