le Tour de France 2008: Feed them well

Why eating is important

The 2008 edition of le grande boucle, as it is affectionately known, is now fully underway, and so far each stage has been quite exciting. The tour started without the traditional prologue, and instead was a full on stage. It's slightly uphill finish effectively neutralized the sprinters, and so it was not surprising to see all the main GC contenders at the front. In fact Alejandro Valverde won the stage and took yellow, although we spoke about how much of a challenge it would be to go "wire to wire" in yellow.

Sunday's Stage 2 had its fair share of bumps with four categorized climbs and also a slightly uphill finish. It seemed that again the sprinters would be neutralized, and it was Fabian Cancellara that attacked with one km to go. He could not hold it, though, and even Valverde had a go, but also faded. In the end a big man took victory---Thor Hushovd from Norway powered across the line for his fifth stage win in le Tour. Valverde remained in yellow, however.

During the first two stages there were crashes as the riders passed through the feedzones. These are designated areas where support crew hold out bags full of food and drink. The riders slow down a bit and grab them as they whiz by. Fortunately Stage 3 saw no crashes in the feed zones, but let's looks at why it is so important to eat on the bike.

Energy balance

We can all agree that the energy demands placed on tour riders are pretty astronomical, but it makes more sense to break it down into a specific context. Therefore let's take your "average" 75 kg cyclist and his daily energy demands. His resting metabolic rate, or RMR, is the amount of energy he requires to sit there do nothing all day long. In other words, it is the energy required by his body to maintain all of its life-sustaining functions. For him it is around 1500 calories.

But our cyclist is not just sitting there all day. . .in fact, he is covering upwards of 180 km per stage, often with significant uphill sections which require more energy. Cycling is a pretty efficient activity, however, and it costs our cyclist in the range of 0.3-0.4 calories per km cycled per kg of body mass---or about 25-30 calories per km. The bottom line here is that a 180 km stage will cost our athlete around 4000 calories, depending on the amount of drafting.

It's a lot of cheeseburgers!

Any way you calculate it, our cyclist's total energy expenditure for one day of the tour is very high. His RMR (1500 cal) plus his exercising energy expenditure (4000 cal) adds up to a whopping 5500 calories, which is probably the equivalent of 15+ cheeseburgers! So just to remain in energy balance our rider must consume 5000+ calories a day. Believe us when we say it: that is a lot of food. Add to this the fact that he is on the bike for four or more hours during the day, plus the "anorexic effect" of exercise, plus 8-10 hours of sleep. Suddenly he has only a relatively small window of time to consume large amounts or calories.

If we assume he is otherwise occupied for up to 16 hours a day with riding, sleeping, and other activities, he has only about 7-8 h to ingest 5500 calories, which works out to about 700+ calories an hour during the time he is available to eat and drink. So remaining in energy balance is actually a huge challenge for our tour rider.

Fortunately the race organizers allow the cyclists to grab the feed bags and eat while riding. This is crucial for two reasons. First, it provides more opportunity to choke down a portion of the 5500 calories he needs in a day. Second, the ingestion of carbohydrates during exercise prevents the dreaded "bonk," or hypoglycemia. Many of you probably have bonked before, and therefore you know that when it happens you are finished---no more racing for the day as you limp home and consume gross quantities of food along the way to fill the hole in your tummy!

How much to eat then?

Klaas Westerterp and his colleagues in Maastricht (Netherlands) actually measured the energy intake and estimated the energy expenditure in five cyclists in the 1988 Tour de France. Their average intake was almost 6000 calories per day, while their average expenditure was nearly 6100 calories per day---indicating that these cyclists did a remarkable job of (nearly) maintaining energy balance. They accomplished this by ingesting 49% of their energy while riding, which amounted to whopping 94 g of CHO per hour during each stage! Furthermore, a full 30% of their carbohydrate intake was in fluid form, which makes it substantially easier to meet energy requirements during the 7-8 h when they are not racing or otherwise occupied.

Given this information now, it should now make total sense when you watch the riders rolling through the French countryside, shoving energy bars and other products down their gullets. Hungry or not, they must get the calories into their bodies. Failure to do so will almost certainly result in fatigue and an early exit from the race, because when cycling four or more hours each day it does not take long to accrue a serious energy deficit. When your body does not get enough energy, cycling four hours or more a day becomes an unnecessary activity, and our bodies have an uncanny way of keeping us healthy---suddenly getting on the bike and pedaling requires substantial effort, more so than a few days ago, and eventually you will not be able to keep up with the bunch.

Stay tuned to le Tour---plenty of action ahead

Looking ahead to Tuesday's stage, we see the first individual time trial. It is a pancake flat 29 km ride and will do two things. First, it will create a pecking order for those who will contend for the GC. Second, it will limit any one rider's gains or losses as the distance is so short, and therefore the race should remain close and within reach for the contenders. It also will set the stage for Stage 6 on Thursday, which is the tour's first mountain top finish, and is sure to produce some fireworks!

Fatigue: A mechanistic breakthrough

Columbia researchers shed light on mechanism of muscle fatigue

First, thanks to many of you who sent us the article by Gina Kolata from the New York Times. It is a hot news week, first with this story breaking on Tuesday and also with Roger Clemens and Brian McNamee testifying before a congressional panel on Wednesday. This kind of story on fatigue is right up our alley here at The Science of Sport, and so let's take a look at this and see what it is all about before we get to the Clemens/McNamee hearings.

Why study fatigue?

Since its inception the profession of Exercise Physiology has focused on "fatigue." This is a broad term, and fatigue has many manifestations. We can fatigue during dynamic maximal exercise such as a peak power output test, and we can fatigue during sub-maximal (endurance) exercise. We can also produce muscle fatigue in the lab while contracting a single limb and muscle group, either repeatedly or continuously. So it has many faces, and exercise scientists have been interested in all of these areas for decades. In fact one of the first exercise labs in North America was the Havard Fatigue Lab, and one of their most famous investigations of fatigue involved two dogs, Joe and Sally, who were fed glucose or nothing while running on a treadmill. The scientists were the first to demonstrate in the lab that carbohydrate ingestion during this type of exercise enhances performance.

Great discoveries occur by accident

While a large number of scientists today are interested in what causes fatigue during endurance exercise, the more mechanistic studies focus on actual muscle fatigue---that is, what is actually happening inside the muscle and how that may or may not cause the muscle to stop working as well.

The clinicians at Columbia University were actually interested in congestive heart failure patients. The problem in these patients is that the heart begins to fail as a pump, and the consequence is that things get a bit backed up. The heart becomes more and more filled with blood, thus losing its ability to actually contract and to pump blood, and it was this weakening of the heart that interested Dr. Andrew Marks at Columbia University.

In their quest to understand their heart failure data, they came to realize that certain events at the molecular level contributed to the cardiac fatigue. The problem is that for muscle, either cardiac or skeletal, to contract, we must produce a successful chain of events. In short, a nerve signal reaches the muscle and stimulates the release of calcium (Ca2+). The calcium is what is actually causing the process of muscle contraction. A special part of the muscle called the sarcoplasmic reticulum, or SR for short, releases calcium, flooding the muscle cells with it. The calcium causes muscle contraction to happen, and when we want to relax the muscle the calcium is then pumped back into the SR, thus causing relaxation of the muscle.

The key to Marks' findings is that his group showed the calcium channels were "leaky," and so the calcium was not reaching its target of the muscle cells. The result was that the muscle could not produce the required amount of force, and in the case of the congestive heart failure patients the consequence of this is that the heart begins to fail in its job as a pump.

Translation - from the lab to the "field"

Calcium blocking drugs were originally developed to lower blood pressure, but Marks' lab altered a calcium-blocking drug so that it was a bit less effective. The result appeared to be a drug that shores up the "leaky" channels. Then they exercised mice for 21 days, with one group receiving the drug and one group a placebo. Both groups showed fatigue over the 21 days, which was measured with a continual treadmill run. However the mice that received the drug ran 13 min longer on the 21st day---77 vs. 64 min for the placebo mice.

To help support this finding, Marks' then collaborated with Dr. David Nieman at Appalachian State University in Boone, NC. The drug cannot be administered to human subjects as it has not yet been approved by the FDA, and so Nieman and Marks instead demonstrated that after cycling three days in row for three hours at 70% VO2max, the cyclists had leaky calcium channels. This suggests that, just like the mice during their 21 day training program, the cyclists were becoming fatigued.

The full pdf file is available to everyone and can be downloaded here. Be warned, however. . .even for scientists it is highly specific, and with all of the special abbreviations and acronyms it might take a while to sift thru!

What on earth does this mean???

So will athletes be taking an "anti-fatigue" drug in the near future? Not likely. . .it will take time before Marks' new drug will become available for use in humans. Clinical trails take years to complete, but more telling is the quote by Dr. W. Robb McClellan from UCLA: "In heart failure, there are three medications that improve mortality, but there have probably been 10 times that many tested." So the odds are against a new drug for this condition, and even if it is approved, WADA and other anti-doping organizations would likely include it on their list of banned substances.

For now what we all must do is follow the development of this drug and see how the clinical trials play out. The problem is that fatigue is such a complex event. . .even if the drug prevents the calcium channels from leaking, that is no guarantee that it will enhance performance during self-paced exercise such as road racing and cycling.

Come back tomorrow for our analysis of Clemens' and McNamee's testimony!

Interesting news from the marathon

The sub 2-hour marathon, London 2008, and Paula gets hot

We're bang in the middle of our series on Running Economy, but thought that for today, we'd take a break from that series and turn our attention to a few interesting news stories that are coming out of the world of marathon running.

The Sub-2 hour marathon: Debate re-opened

The first is a discussion about whether a sub-2:00 marathon will ever be run? This is a topic that hit headlines in September this year, when Haile Gebrselassie broke Paul Tergat's world record in the marathon. The margin? 29 seconds, taking the time down from 2:04:55 (run by Tergat four years before) to 2:04:26. We covered the race, and Geb's splits and pacing in a couple of articles at the time.

As tends to happen whenever a barrier is broken, everyone started talking about the prospects of the sub 2-hour marathon. Even Gebrselassie made his predictions, though he was a little more circumspect, suggesting instead that he would run 2:03 some day. But a lot of people were looking even further into the distance, at the 2-hour barrier. And a recent report from the Herald paper quotes Dave Bedford, London Marathon organizer, as predicting that the 2:02 will be run by 2015, and a sub-2 hour time will come in 20 years!

The problem is that even a basic analysis of the world record in the last twenty to thirty years suggests that this talk is likely a touch premature! For example, in the last 22 years, the marathon record has come down by just under 3 minutes, from 2:07:12 in 1985 (Carlos Lopes) to the current 2:04:26. So for Bedford to be correct, we need the next 22 years to yield 50% more than this - 4:30! But even more than this, since Ronaldo da Costa broke Dinsamo's 10-year old record in 1998, we've moved into an era where the record is coming down by seconds, not minutes, making this highly unlikely!

In otherwords, it's difficult to see how anyone is going to knock more than 30 seconds off this time. When Gebrselassie ran his 2:04:26, we all marvelled at how massively he 'shattered' the record, people calling it a once in a lifetime run! And that was for just 29 seconds - in other words, we "only" need another nine performances just like that, and we'll have our sub-2 hour marathon! Now, how often do we expect a runner to line up and smash 30 seconds off a world record? And then of course, the ceiling effect comes into play as well, and says that once we get to the 2:02 range, it will become even more difficult.

I hear some of you saying "What about a Paula-esque performance? She took it down by 2 minutes!". And of course, this may yet happen. But just looking at Gebrselassie's pacing from this world record, you'll see that he is incredibly consistent. That suggests to me that he's right on the limit, because if he had any reserve, you'd see that through fluctuations in pace especially at the end (this is one possible interpretation, I acknowledge that). But given the fact that he took 29 seconds off the time running this kind of race, it's difficult to see how he's going to get 3 seconds/kilometer to get the time down to 2:02. As it was, he was already right on the limit.

So my feeling is that the 2:02 will eventually come, but it won't be by 2015, and a sub-2 hour time will certainly not happen with anyone from the current crop.

As for who is likely to break the world record next, my money would be on Zersenay Tadese, ahead of Bekele. A lot of people are getting hyped up over Bekele and his chances of running 2:02, but I suspect Tadese will be the dominant marathon runner from the current generation of track stars. Time will tell...

The London 2008 Marathon and some implications for the Olympics

Speaking of Dave Bedford and the London Marathon, his marathon predictions might be a little debatable, but one certainly would not want to argue the quality of the field he puts together for the London Marathon!

You can read some of the names here, but the big one is Martin Lel, defending champion and New York champ. Regular readers will know that I'm a huge fan of Lel's, I think he's the complete package, so it was with mixed feelings that I read that he's signed up for London, and that he's currently leading the lucrative World Marathon Majors series.

Why mixed feelings? Because his presence in London, combined with what must be a growing incentive to win a share of the $1 million prize purse means he is thus less likely to compete in Beijing in peak shape, if at all. No word on that yet, but I had really hoped for a race between him and Gebrselassie for the Olympic title - the best Racer in the world against the fastest marathon runner in history, would have been a great clash!

As for Gebrselassie, he is not on London's books yet, but there was talk that he might yet be signed. I seriously doubt it, because he's already running the Dubai Marathon in mid-January. If he then runs London in April, and is aiming for the Marathon in Beijing, that equals one tough year. I know I'd be advising against it, but stranger things have happened...I certainly would lengthen the odds on Gebrselassie if he runs in all three those races.

But it's a bumper field for London, Olympic and World Champions, racers, fast men, strong men, the works. And so the Marathon year will certainly get off to a great start, first with Geb in Dubai and then this field. Let's hope it is as good as the year that has just gone (we'll do a look back at the science and physiology of the year's marathons next week in our "Year in Review" series).

Paula gets hot - in South Africa

Finally, it was with interest that I read this article on Paula Radcliffe and the UK athletics team coming out to my home country, South Africa, for a training camp in January next year. The purpose of the camp is to help the athletes prepare for the Beijing heat and to help them figure out what to drink in Beijing. There are a couple of reasons why this is interesting.

One, it shows that the UK are serious about preparing for the heat, because the plan is to bring out three physiologists to help the athletes figure out their best hydration strategies. They are talking about measuring the salt and sugar content of the sweat in order to help the athletes figure out the optimal hydration strategies.

Regular readers of The Science of Sport will know that we think the best hydration strategy is to drink when you're thirsty! You can read our rationale for this in our series on fluid intake (link on the right of the page) and our series on Muscle Cramps. And it's a lot cheaper than flying athletes out for a training camp! But dodgy science practices aside, I think that this type of camp has as much a psychological benefit as it does physiological. In my experience, athletes benefit when they believe that they have done everything possible to prepare for their event, regardless of whether what they are doing actually works! And so the camp idea will certainly help, because from the article, the athletes are buying in.

One thing it will not do is help the athletes prepare for the heat - it's too far out, and they are only coming in for 10 days. So having achieved some degree of adaptation to the heat, they'll then fly back to cold and wet England and undo it all by mid-February. So the purpose is a planning, rather than a physiological one.

From a scientific point of view, there some pretty large potential potholes. For one thing, each athlete is coming out to South African for only 10 days. We know that with the body's adaptation to the heat, the sodium content of the sweat changes quite dramatically (sweat becomes more dilute). This adaptation takes about 6 days to be achieved, so let's hope the UK physiologists are at least aware of this, and don't make their "proven" recommendations based on the sweat content in the first few days! The values they get in the last few days will be very different from those in the first few! And so if they do this, the UK athletes will just about be drinking sea-water in Beijing!

Secondly, the venue they have chosen (Potchefstroom - a town close to where I grew up), is hardly comparable to Beijing. It has a typical temperature of 25 degrees, and humidity is next to nothing - think dry, and relatively mild heat. Compare Beijing, which will be like a greenhouse meets a steam bath! So I'm not convinced that they are replicating conditions as well as they might. There are two follow-up camps planned, however, and so they probably have this covered.

The other big issue, of course, is that state of training is a critical determinant of both sweat rate and sodium loss in sweat. And so therefore, one would expect the requirements in August (at the Olympics) to be very different from what they are in January, even without the additional factor of the heat! So I see great complications coming!

Again, it just re-inforces the point that because the body is so well designed, so balanced and "intelligent", it can change the amount of salt lost in the sweat depending on heat adaptation and training. So why introduce a third person (or even a second person physiologist), who simply cannot hope to understand the integration of the physiology during exercise as well as the human body can? It is a case of losing sight of the wood for the trees, and over-complicating matters.

From a practical perspective, what constitutes a successful drinking pattern? Is it the fluid intake routine that keeps the body weight the same? Is it keeping the body's salt content the same? Are you trying to keep the core temperature down? Fluid intake doesn't help this to begin with, and we know that most athletes lose weight during the course of the marathon. One thing that I will predict is that if Paula Radcliffe tries to drink so much that she doesn't lose any weight during the race, she'll never win the Olympic Gold medal - she'll be too busy worrying about stomach cramps and nausea to race properly!

Bottom line - drink to thirst. Of course, the idea to practice drinking before Beijing is a good one, and I think it would be a good exercise to allow athletes to exercise with a range of options - high sodium, low sodium, high glucose, low glucose etc., and then see which they find easiest to drink. Because if it tastes too salty to the athelte, then it probably is! The wonders of the intelligent body...

Join us again tomorrow for Part III in the series on Running Economy!

Ross