A report in the European Heart Journal this week put forward a study that endurance runners may be susceptible to heart damage.
This is pertinent news given the tragic death last Sunday of 22-year-old avid runner Malcolm Sng after the Standard Chartered Marathon Singapore.
The study, led by Dr Andre La Gerche, research fellow at University of Melbourne's St Vincent Hospital, studied 40 athletes planning to compete in one of four events - marathon, endurance triathlon, an alpine cycling race and an ultra triathlon.
The athletes who trained for 10 hours a week went through magnetic resonance imaging and had blood tests two weeks before the events and the week after.
They also had an echocardiography, a painless test that uses sound waves to create pictures of the heart.
The study found that the right ventricle, one of four chambers in the heart, was temporarily damaged.
The heart's volume had increased while the function of the ventricle decreased.
After a week, most of the athlete's hearts returned to pre-race condition but five were found to have potentially permanent scarring, or fibrosis.
Dr La Gerche told The Daily Mail that the heart damage found could lead to an irregular heartbeat, also known as arrhythmia.
So do marathon runners have something to fear?
Dr Benedict Tan, medical director of the Singapore Sports Medicine Centre urges against overreacting, saying: "It is way too early to jump to conclusions."
He likened the damage to the hearts of those in the study to that of any muscle under training.
Says Dr Tan: "For your skeletal muscles, the only way to build them and make them stronger is to stress them.
"The idea of training is to elicit an adaptation response, that is the body will repair damaged muscle to make them even stronger."
You may feel sore for a period of time after gym training. With repeated training, the soreness passes as your muscles adapt.
This is also true for the heart.
Says Dr Tan: "Yes, training will stress the heart, but this will make it stronger."
He notes that an athlete's heart becomes bigger and proves to be a "very powerful pumping machine, able to pump more blood than a normal heart".
The heart is a hardy muscle.
He adds: "You can't push a healthy heart to significant damage. Much like how modern cars have a speed limitation device, the heart rate can only go so high but some people don't have that protective mechanism."
What about the fibrosis?
Dr Tan believes closer study is needed, particularly on the ages of the athletes.
An older runner will have more scar tissue than a younger athlete.
On a cautionary note, Dr La Gerche also says his study should not "infer that endurance exercise is unhealthy".
Dr Tan, who won gold medals for sailing at the Asian Games and SEA games and is a member of the Sports Hall Of Fame, agrees that nobody should be put off from exercise.
"There is a lot more evidence of the dangers of inactivity on the body - obesity, diabetes and gout, among many others. The benefits of exercise far outweigh the harm that can occur."
Dr Tan also cites the 2007 report by the Sports Safety Committee, which shows that of all deaths in Singapore during 2005/2006, only 0.046 per cent were sports-related.
He adds: "The incidents of sports-related deaths are extremely rare."
People planning to join endurance events must also consider the humidity, which impacts training.
"Training here requires acclimatisation to avoid heat stoke and exhaustion. Humidity can make you feel tired quicker, making you train less."
This article was first published in The New Paper.