The Great North Run 2008

Kebede and Wami claim double win for Ethiopia, and The Sports Scientists return to the field

Apologies for our long absence of late. We are both under quite tight deadlines right now, and until The Science of Sport starts paying our bills then from time to time we have to bow down to our "real jobs" and spend time away from this site. So apologies for "disappearing" all of last week!

Today we are back, though, coming to you from Newcastle, England, where I was part of a field study looking at fluid ingestion, changes in weight, and plasma osmolality in 40 half-marathon runners. More on that later, but for the record it was a stunning day in Newcastle and perfect for a half-marathon---clear blue skies and lots of sunshine, a slight tailwind for most of the course, and a max temp of about 12 C (53.6 F), and the conditions produced two very different but exciting races.

On the women's side it was a local thriller as British runner Jo Pavey went head to head with Gete Wame (ETH) and Magdelane Mukunzi (KEN). Wami and Pavey had let Mukunzi get a gap, and with about one mile to go found themselves trying to claw back the Kenyan. At first it looked like Mukunzi would hold them off, but the two eventually caught her with less than a mile to go. Mukunzi surged repeatedly, but could not shake either of her shadows. Then Pavey had a go at the two Africans and looked strong in doing so. However it was all she had to mount that surge, and in the last 200 m Wame made the move and beat Mukunzi by one second, winning in 1:08:51. The local crowd was cheerling loudly for Pavey and it would have a brilliant upset for the Brit, and in any case it was a great showing for her and a fantastic race to watch down the stretch.

On the men's side it was exciting, but for an entirely different reason. In that race it was 2008 Paris Marathon champ Tsegay Kebede who ran away from the field before the 10 km mark and continued to pull away all the way to the finish, eventually trouncing them in 59:45 and winning by 1:45. The two big favorites, Luke Kibet and Felix Limo, were no where and left 2nd and 3rd for Gebre Gebremariam (1:01:29) and Abdi Abdirahman (1:01:33). If you saw Kebede's Paris win back in April, it was also an occasion where he put his head down and ran way to a win, that time in 2:06:40 in what was his second marathon.

The return of the field study

It is good timing for this as just last year around this time it was the Chicago Marathon and the unusually hot conditions there that spawned our popular series on dehydration and fluid ingestion. In that series we tried to explain how the body mass is not the regulated variable during exercise, and therefore your body does not care about how much weight you lose during a run or cycle. Instead it is most concerned with the concentration of the plasma, or its osmolality, and by drinking to thirst you regulate this variable quite tightly.

So the small study this year at The Great North Run, performed by Dr. Paula Robson-Ansley from the Division of Sport Sciences at Northumbria University, measured the pre and post- body mass and plasma osmolality in 40 male runners (Full disclosure: this study was funded by GlaxcoSmithKline, makers of Lucozade sports drink and one of the sponsors of the race). It was a simple and relatively small study, but the aim was to examine if the runners lose weight while maintaining their plasma osmolality. The preliminary data is in, i.e. the changes in body mass, and it was no surprise to us what the results were. The runners lost an average of 2.2% of their starting mass, and the interesting thing about this is that when you look at any of the field studies published in the scientific literature, the mean change in body mass, independent of the race distance or the weather conditions, is about 2%. In fact scientists knew this in the mid 1960s when John Greenleaf first coined the term "voluntary dehydration" to describe the concept that when people exercise they do not replace 100% of their weight losses.

Science repeats itself

Even more interesting is that as recently as 2007 a sports drink-funded study concluded essentially the same thing that Greenleaf did thirty years ago---that even when given full access to fluids, humans do not replace 100% of their weight losses, which are taken to be a surrogate of fluid losses since one Liter of water = one kg of mass. Therefore if you lose one kg of body mass, then that must eequate to one Liter of fluid. But even in that study the average change in mass during a 75 min run was 1.9%, which is again about 2%. And to go in the entirely different direction, one study from my doctoral thesis measured runners before and after a 56 km ultra-marathon. It was a cool and rainy day, but can you guess what the average weight loss was? (For the record it was 2.1%.) So the question is, "Are we the only ones who think it is a bit uncanny that no matter what the distance and no matter what the conditions, when people drink to thirst they lose the same amount of weight?"

Perhaps there is something going on here, some kind of "regulation," shall we say, of something else other than weight losses, and if you go back to our series last year you will see that this "something" is the plasma osmolality, and that is why we lose some weight: the body does not care about this and is not trying to maintain a 0% change in body mass. If it were then we can assure you that it would accomplish this, because the body is much more clever than a bunch of people in white coats who call themselves scientists, and because it does so in every other instance in which it is critical to maintain some variable within a narrow range: blood glucose, core temperature, blood pressure, or even plasma osmolality.

Looking ahead

It will be worthwhile to revisit the concepts we described in our dehydration series, but for now we must look forward to the fall marathons, and Chicago looms in just one week!

A sub-2 hour marathon?

Before that, however, we received quite a few questions about whether a sub-2 hour marathon would ever be run. This has also been the topic of some discussion in the chat rooms of the running community since Geb went through the 2:04 barrier. So later this week, we'll have a look at this question and whether in fact it might be possible.

Chicago is next...repeat of last year?

Chicago takes place on Sunday 12th, and it is a race we will watch closely, first because of the drama of the event last year as the city experienced higher-than normal temps and had to shorten the race course for many runners.

But more importantly this year I will be at the finish monitoring the environmental conditions all over the course as the event expands its net of safety on the race. Information is power, and if we can know what is happening at different points on the course then as organizers and scientists we will all be in a better position to make difficult decisions if necessary. I hope to do a live post from my vantage point at the finish, providing I have Wifi access, so watch for updates followed by our popular race analysis.

Later this week we will preview the races, which last year were remarkable for their amazing finishes on both the men's and women's sides. Unfortunately neither Patrick Ivuti or Joahaid Gharib will be returning to battle again, but both Adriana Pirtea and Berhane Adere will be racing again, and the question there is whether or not Pirtea will learn from her novice mistake last year and actually keep her eyes on the prize all the way to the finish! And also joining in will be Constantina Tomescu-Dita, the Beijing Olympic champion who has been a regular in Chicago over the years. Will she be able to reproduce the amazing form she showed in Beijing and run away from the field again?

Join us for these exciting races and posts this week, and then we look ahead to NYC where Radcliffe is lining up to defend her title and is again racing against Gete Wame!

Jonathan