Why you should keep running

I don't look like a runner.

My hips and legs are round and fleshy; my stomach has a permanent paunch. Runners tend to evoke images of long, lean limbs and toned musculature.

I have neither.

But hanging in my bedroom - in the same way a child might proudly wear a sticker on their collar 'For Trying' - are a bundle of 'medals' I have 'earned' over the last few years from taking part in fun-runs.

Over bridges, across cities and to beaches, I have run half-marathons sometimes slowly, even pitifully.

But despite my lack of speed or how pudgy I become, I seem to be able to keep going for as long as I need to. In the words of writer and marathon runner Haruki Murakami; ''At least I never walked''.

Lately, I've been devouring books written by runners about running and am particularly fascinated by those who have run ultramarathons - that is, any distance greater than the 42.19km marathon.

These are races can go for days across unforgiving terrain covering thousands of kilometres.

It just seems so unfathomable a distance to think about, though there is a part of me that likes to believe one day, maybe I could.

It seems I am not alone because increasingly, women are taking up ultramarathons and some suggest that women may even be better equipped to run such distances - and win - than men.

Last month, CBC news reported that 44-year-old Lucy Ryan completed the invitation-only, 217km Death Valley ultramarathon in California in 38 hours, 35 minutes.

''[It was] absolutely fine," she said.

"I only changed shoes once through the whole thing and I only have two blisters and that's it. ''I'm not fast, I'm a slow runner, but I can just keep going forever."

There is no doubt Ryan is mentally and physically tough, more-so than most. But what if women are designed to run these kind of distances, or at least, to be capable of doing so?

In 1997, the Medical Research Council in South Africa decided to see if women could outrun men in ultramarathon races. They compared the performances of men and women in a 90 km race, and found men ran faster than the women up to the marathon distance of 42.2 km. Beyond that distance though, they found women ultramarathon runners had greater fatigue resistance than equally trained men.

One theory is that because women generally tend to carry more fat than men, they also have a metabolic advantage because fat metabolism increases as distance increases.

But this theory is not certain. The point is certainly not to compare women to men, but to try and understand the capabilities of the human body and how both men and women respond to and deal with pain.

One of the best ultramarathon runners in the world is Diane Van Deren, who can run for days on end without sleep. She was the first woman to complete the almost 700 km Yukon Arctic Ultra, a race across frozen terrain battling sub-zero temperatures, one of the toughest races in the world.

''The shoes literally froze on my feet, it was so cold,'' she said.

But it wasn't her metabolism or training that led her resilience to torture. Van Deren puts her success in distance running down to epileptic brain seizures, which became so severe that she underwent a lobectomy - removal of a chunk of her brain - about 15 years ago.

The surgery went well but it had one side effect - she was no longer able to judge the passing of time. Her spatial reasoning had been obliterated.

It meant post-surgery, she could run for days on end without registering the scope of the time passed.

But she has told reporters; ''I think for me, the one advantage over other athletes would be time. I forget how many days I have been out there.'' Until she reaches the finish line, she has no idea how far she has already run, or how far she has left to go.

But as incredible as her story is, there are plenty of others running ultramarathons who have to get through days of running with training and willpower alone.

In the latest journal BMC Medicine, Andrew Murray, an ultra-marathon runner and a doctor of sports and exercise medicine at the SportScotland Institute of Sport, wrote;

''Data is likely to show that competing in such an event can lead to significant musculoskeletal and other injuries, but also that the human body is capable of adapting to incredible endurance loads and can run in excess of a marathon per day despite seemingly significant medical issues.

''[But] ultra-endurance running is increasing dramatically in popularity.''

What no-one seems to be able to answer is why more men and women are taking up the challenge.

''Despite increased 161-km ultramarathon participation in recent years, little is known about those who pursue such an activity,'' wrote Martin Hoffman from the University of California, following his study last year of the factors that lead people to successfully run the distance. (The main factor that led to runners pulling out, FYI, was throwing up).

Completing an ultramarathon is indeed a major achievement, seen by many as the ultimate feat of endurance. And the closest I am ever likely to come to an ultramarathon is reading books about them.

But the more I read the likes of authors like Christopher McDougall and others, it seems there is a high chance both our bodies and minds are built for the challenge.

What's the longest distance you've ever run? How did you train for it/ get through it?

Sydney Morning Herald