2009 Fortis Rotterdam Marathon

Kibet and Kwambai have now arrived

Rotterdam has always been a fast course, and since its inception in 1981 it has produced two WRs and the winning time is always around 2:07-2:08. However due to its place on the racing calendar---very close to London---and also due to London's seemingly bottomless budget and insistence on attracting the most incredible fields, Rotterdam has always been that "other" marathon, and instead of being a premier event where the big guns of road running come out to play, it has instead served more as a proving ground for those wanting to show they can challenge the already established stars of the road. That was definitely the case this year as two up-and-coming marathon stars hammered each other after the pacers dropped out to produce an amazing race and the third fastest time ever.

Last year the organizers splurged and forked out to bring in the best of the rest (the "rest" were all running London on the same weekend!). The result was nothing too earth-shattering, but nevertheless William Kipsang ran 2:05:49 (a new course record) and Daniel Rono jogged in about one minute later (2:06:58) as both men ran sub-2:07. The organizers, ever hopeful, were holding out for a new WR because both of those men had good credentials and might just have had a miracle race in them. In the end all they got was a new course record, but that did not stop them from bringing in fresh (and fast) new talent for this year.

The life of Kwambai: Part I

Some of you may (or may not) recall Kwambai from last year in Berlin. He tried heroically to challenge Gebreselassie. . .until Geb made the final move with five km to go on his way to a 2:03:59 and kind of overshadowed what was a significant run by Kwambai. Kwambai tanked the last five km and although he finished over 90 s back from Geb, he still crossed the line in a very fast 2:05:36---nearly seven minutes faster than his previous best time! So this year in Rotterdam he proved that he is not a one-hit wonder as he clearly has moved from being a 2:10 runner down to a serious contendor when he nearly won yesterday in 2:04:27.

The life of Kibet: Part I

Kibet debuted in Milano at the end of last year without much fanfare, winning that race in 2:07:53. That is fast, to be sure, especially given the condition which were apparently pretty cold, but plenty of runners on the circuit are running 2:08. Even more, Kibet has run five half-marathons with a best time of "only" 60:22, so he is fast to be sure, but several runners out there have sub-59s to their credit. So for Kibet to eke out a 2:04:27 in Rotterdam yesterday means he really ran out of his skin. Needless to say he also shattered his PB, taking nearly 3.5 min off his debut time in Milano.

Part II: The duel of Kibet vs. Kwambai

On paper it was half-marathon speedster Patrick Makau who was meant to steal the show as he has a 58:56 half to his credit. However it was his debut, and although impressive at 2:06:14 he was off the back when the racing started after 30 km. Before that there was a field of at least eight runners. The last pacer dropped out at 32 km, and that is when you started to see significant surges by Kwambai who really looked like he had the legs to systematically drop the others one by one. Makau was already seven seconds back at 35 km, but eventual third placer Abel Kirui was hanging in there and stayed with Kwambai's attacks until he was 20 s off the pace at 40 km.

Kwambai put in what he must have hoped would be his final attack after 40 km, and dropped Kibet with less than two km to go. He had a gap of maybe 20 m or so and Kibet was not looking like he could reel Kwambai back in. In fact down the finishing stretch Kwambai looked confident about the move he just made and was zeroing in on the tape when Kibet came storming back:



It was not quite as close as Ramaala and Tergat in NYC 2005, or Ivuti and Gharib in Chicago 2007, but it was fantastic racing by these two runners who now have clearly arrived on the scene. Having produced the third fastest time ever---and only by one second as Gebreselassie's 2nd fastest time stands at 2:04:26---they have let everyone know they have the legs to contend on a flat course.

Their time was the result of a quick pace right from the start, and their split at halfway was 62:35---compared to 62:03 for Geb when he set his record last year in Berlin---although it was not a pure time trial as Kwambai really dropped the hammer and attacked the remaining bunch and the Kibet when he was the only one left running with him. In fact their pacing and splits deserves a further analysis to see exactly what the difference was between their 2:04:27 and Geb's 2:03:59. But in any case both Kibet and Kwambai have increased their worth in a major way. If they can maintain their training without injury we should expect to see them in a big city race at the end of this year or next spring. Is London calling yet guys?

Jonathan

Running Economy Part III

Training techniques to improve economy (or should that be performance?)

Today sees the third and concluding part of our series on Running Economy. It's been a whistle stop tour of a complex subject. We have no doubt that we'll be returning to the topic in time, because it has major implications for how we understand fatigue and performance, but for now, we stuck to the boundaries - there is a lot to be written in the coming week! But hopefully today we'll provide some 'meat' that might help explain economy a little more, as well as provide some practical insights into how it can be improved.

On that note, there's a very valid question about whether you should worry about training specifically to improve your running economy, or whether good, common sense training just happens to improve economy as you do it.

I was out on a training run just yesterday, and have a 10 km loop that I do once in a while. Compared to about a month ago, when I just started running again after a layoff due to illness/injury, I covered the 10km a minute or so faster, running at the same effort level as before. And it occurred to me as I was jogging along that if I were to put on my scientist's hat (or lab coat, if you wish), I would probably find about four or five reasons to explain how I can run faster with the same level of effort - running economy would be one of them, for sure.

So in other words, scientists are sometimes very good at looking at the runner (or sportsman) after the fact and working out that X, Y and Z have changed, and that must explain the faster running, when all along, it's the simple fact that you've been running that explains it! Had I consciously spent the last month trying to improve my economy to help me get faster, chances are I'd only improve by the same amount anyway, or maybe even less!

The point is, sometimes the simplest solution is the best one, and that is the case with running economy. Over-complicating things by trying to target what we've emphasized is only one of many factors contributing to performance is likely to be a bit of a self-defeating task - rather just train, and let it happen!

The best way to improve running economy - just run!

Don't worry, that's not all we have to offer as practical advice for today! But it's the most obvious and truest statement we could make! When it comes to training, practice makes perfect. A great illustration was provided a few months ago when we were discussing Pose Running Technique, and we came across a study that looked at the oxygen cost of running in a group of athletes who had been taught Pose for 12 weeks.

What one would predict is that when learning a new running technique, the oxygen cost would go UP, because you'd be less economical as a result of doing a task that is relatively unfamiliar. And sure enough, that's what they found - running economy was worse when running Pose. A number of people wrote in and said this was expected, and that given more time (than the 12 weeks of training in the study), the Pose Runners would improve their economy. Maybe that's true (the debate about Pose was covered back then, you can link to the posts and read it), but the point is, within 12 weeks, economy was still worse.

Turning that around, it implies that regular running will improve economy. We don't often think of running as a task that requires co-ordination, timing, balance and motor control, but it most certainly is. If you ever want to see that in action, then you need to watch an elite runner training. They move differently from you and me (OK, from me - you may be one of them!). I remember standing track side as SA's Olympic Silver Medallist Mbulaeni Mulaudzi did some 300m repeats once, and being struck by the fact that he just moved differently - the flick of the heel during the swing, the arm carriage, knee drive etc. are all subtly different and I have little doubt that this neuromuscular control, while not exclusively responsible for performance, plays a big part, especially in distance runners. There are some other factors, which we'll touch on in a moment, that also contribute to this, though.

Endurance running - what do the studies show?

A couple of problems exist with the scientific literature on running economy. First, there are surprisingly few studies - remember, running economy was called the "forgotten" variable by one author (Carl Foster). Secondly, the initial level of fitness and ability of the runner plays a huge role, as I'm sure you can appreciate - a good runner needs very different training compared to a novice. So it's a little tricky to tease out the valuable information.

In general,however, research studies support that running economy improves with higher volume, slower running. So longer and slower distance training is more effective as a means to improve economy. The reasons for this include the increase in mitochondria, which means more effective use of oxygen by muscle. Also, it's been found that the longer and slower running eventually leads to a 'learned' neuromuscular response where the vertical oscillation of the runner is reduced. In otherwords, less time going up and down, more energy saved, and this is simply a function of repetition!

Now here's where things get tricky! Many of you are probably thinking "what about speed work?" Surely that will see massive improvements in running economy? There's always confusion about whether faster runners are more or less economical. And here, the general rule is that it follows what one might call The Law of Specificity, which basically says that you'll be good at what you train for! In otherwords, if you are a middle distance runner (800/1500m), then you'll be more economical at higher speeds than a marathon runner at those higher speeds. The interesting thing is that it's been found that this same middle distance runner then becomes less economical at the slower speeds than the marathon runner. So again, economy is good where you train it, which to me really re-inforces the value of training specifically, and how important co-ordination and motor control are!

So the take home message - if you're talking novice runners, with little running behind them, then any running will make a difference (as it did for me in the last month, I'm sure!). This is the point I made earlier - economy improves with fitness, and so any running is beneficial. But if it's performance you're after, and the very small improvements that make a big difference to performance (not just economy), then other forms of training become more critical. This also illustrates the complexity of training, and this is where we get into plyometrics and strength training.

Strength and plyometrics

Let's deal with strength training first. There is evidence that strength training improves running economy, probably because it improves the function of the neuromuscular system. In order to understand this, we first have to run through an admittedly basic introduction to an important concept known as the Stretch Shortening Cycle.

Basically, when you are running, a great deal of muscle activity occurs in the milliseconds BEFORE your foot lands on the ground. Why? Well, the muscle is 'pre-activating' in order to increase stiffness of the leg and joints ahead of landing. The stiffer muscle not only absorbs more shock, but it also helps the muscle-tendon unit to store more energy.

Think of the muscle-tendon as a spring. When you land, the muscle lengthens, in what is called an eccentric muscle contraction. As soon as you then push off, for what is called the concentric part of the running stride, you can 'harness' the energy that was stored when you landed. The concentric contraction is more powerful and more efficient, if it follows the eccentric contraction. It therefore uses less oxygen and energy to do the same job, or can do a better job. This is why if you want to jump up as high as possible (for example, to slam dunk a basketball), you bend down and then 'bounce' back up - you are taking advantage of what is known as the "Stretch-shortening cycle" to improve the performance of your jump.

The same goes for running, where this Stretch shortening cycle is critical to performance. The result of all this pre-activation and concentric-eccentric contraction is that the CONTACT TIME is reduced, and performance is improved. Fatigue during the course of a 5km time-trial has been shown to impair the ability of the muscle to "pre-activate", and the result is that your contact time with the ground goes up. Imagine a ball bouncing off a wall - if it gets softer and softer, it bounces off much more slowly, whereas a very stiff ball returns quickly (golf ball vs squash ball, for example).

How does this relate to running economy and strength?

Well, apart from the obvious theory which is that the muscle is stronger, the theory and evidence is that strength training improves running economy specifically because the contact time and reflexes that control the neuromuscular system are improved.

In particular, there is a type of training, known as PLYOMETRIC training that has been theorized to be very effective as a means for improvement of performance and running economy.

Plyometric training

Plyometric training is an explosive form of strength training, which uses drills like hopping, bounding, jumping, skipping and sprinting. During plyometrics, you are exaggerating the stretch shortening cycle, causing major eccentric and concentric training, and this helps to improve the efficiency of the whole system. The result is that the athlete is better able to store and use energy, and therefore the muscle can produce the same force (and hence running speed) with less energy demand, so VO2 goes down. Also, there is evidence that plyometrics increases the stiffness of joints, and stiffer joints are better able to store and release the energy, again saving the cost of running without sacrificing speed.

There is a very intriguing theory that African runners have a more developed, better functioning stretch shortening cycle that Europeans. Also, a Finnish scientist (Paavoleinen) found that plyometric training improved 5km time-trial performance by 3% (this was in quite good and highly-trained runners, so 3% is no laughing matter), which was associated with reduced contact times and running economy (8% lower).

Having said all this, beware of overdoing plyometrics as the "Secret weapon" for your training! The risk of injury is high, and so this should neither be tried out by novice runners, or done too often. It's a very effective method of training if done properly though. I certainly don't coach athletes without also using this kind of training, though it takes different forms, depending on the athlete - sometimes hill running is sufficient, whereas other times, you can get creative and come up with all sorts of drills, using hurdles, ropes, and your imagination! But again, not something that should be overdone...

Flexibility - you CAN be too flexible

The final component of training we look at is flexibility. There was a time when athletes were being drilled to do as much stretching as possible - failing to do so, we were told, would predispose you to injury. Well, injuries aside, there is evidence the being TOO flexible also negatively affects running economy, and thus possibly performance.

There is confusion about it though (as usual, I guess!). One study, for example, found that improving flexibility of the hip flexors and extensors(to lift the knee) resulted in better running economy. The argument here was that if you are flexible enough, and provided you have balance between left and right, front and back, then you need to do less work to balance and stabilize the body during running.

But then other research has found that being less flexible is better. In fact, more studies show that less flexible runners are more economical than the other way around. For example, from novice runners all the way to elite runners, it's been found that as the flexibility in the trunk (hips, and core muscles) and the legs improves, running economy is lower. Therefore, if you want to be economical, you'd err on the side of being inflexible!

The theory behind this option is far more believable to me. We've discussed how the stiffness and ability of the muscle to store and then release energy helps with running and reduces oxygen cost above. Now, the same goes for flexibility. If you are very flexible in the legs (especially the calf and ankle), then you need to do far more to stablize and store energy, and so it pays to be stiffer, less flexible.

As far as the core muscles and trunk go, the less flexible you are, the more stable the pelvis is, and the less muscle work is required to limit the motion as you run - you're a more 'compact unit' so to speak. To sum it up then - less flexibility means less work required for stability and also more elastic energy return from stiffer muscles and joints. I therefore tend to believe the theory that being less flexible is better for running.

Having said that, it doesn't mean that flexbility is not important. I hope it's quite clear that it's all about BALANCE. In other words, right vs. left, front vs. back balance (in both strength and flexibility) is what determines stability and thus possibly economy. The take home message is therefore to avoid random, indiscriminate stretching, because for all you know, you're messing up your natural balance, increasing injury risk and becoming less economical. But also, don't avoid stretching altogether, because then you might go the other way and get too tight in one important area! Everything in moderation!

Conclusion

So that's it for Part III, and the series. It's been a very interesting one, confirming the words of Carl Foster that running economy is a forgotten aspect of performance! It certainly seems that we have much to learn. The future of running research may be along the lines of the Tadese study that kicked off this series, and perhaps in a year or two, we'll understand much more what causes such remarkable running economy.

My personal feeling is that biomechanics, small calves and long legs aside, there is something critical that we can't quite measure. I am a big believer in the neuromuscular factors affecting performance. I believe that running economy is in fact a symptom of some underlying neuromuscular process or system that confers an advantage of certain runners. When you train, your neuromuscular system improves, you become more co-ordinated and your running economy improves, along with performance. But quite what this neuromuscular adaptation is (apart from the ones we've discussed) is not clear just yet. I feel it will go a long way to explaining the East African dominance in running and will also explain fatigue more comprehensively than any other theory.

So it's quite clear that we're not done with Running Economy! It will be back! We hope that this particular series has been interesting - we certainly haven't had the same debate, but it's a far less controversial topic than the muscle cramps and fluid ones!

Join us over the next few days as we scratch the surface of Baseball's Mitchell report and the report on Pistorius (which we hope is out soon)!

Ross

Running Economy Part II

The Biomechanics of Running Economy

Today sees Part II of our series on Running Economy. After spending the first two posts introducing the concepts and discussing the results from the Zersenay Tadese study, today we move onto some fundamental concepts of running economy - the physiology and biomechanics of running economy explained (partly, we hope!)

I say "fundamental" with some caution, because the more one digs into this particular topic, the more you realise that the science, and our knowledge of how to put running economy into practice, is still a long way off where it should be. I know that our good friend Amby Burfoot is fond of reminding us that science is actually a long way from understanding running physiology, and he's quite right. In the words of Sir Roger Banister, the first man to crack the 4-minute mile and who then went on to become a respected neurologist:

"The human body is centuries in advance of the physiologist, and can perform an integration of heart, lungs and muscles which is too complex for the scientist to analyse"

Running economy is one such 'integration". And with that in mind, let's get to it!

A fundamental paradigm - running economy: one of many explanations?

The first point that I have to make is that we should be careful not to over-emphasize the importance of running economy to performance. Yes, it is important. And yes, any coach, scientist or runner who is dedicated to training and improving performance needs to be aware of running economy and possible means to improve it. And yes, it has been relatively "forgotten" by science in recent times, hence our relatively limited understanding of it. But regular readers of The Science of Sport will also know that we're not particular fond of "magic potion", "silver bullet" training methods or science principles! So we must approach running economy for what it is - one of many explanations for performance.

So when we look at the East Africans, we note that they have a better running economy than the European runners. We also note that the best runners tend to be the most economical, that certain physiological characteristics predispose runners to be more economical, and that certain types of training improve running economy more than others (more on that in our next post, by the way). This is only partly relevant to you as you read this, because ultimately, you must not "lose sight of the wood for the trees", and become so stuck in the running economy analysis that you forget to worry about performance! And let running economy take care of itself...

Factors influencing running economy

Running economy, to repeat, is an integration of numerous systems and characteristics, biomechanical, and physiological factors. It would take a month of articles to cover all of them in detail, so we'll skim the list quite substantially, and discuss these three categories very broadly.

Biomechanical factors influencing running economy

The Zersenay Tadese article attributed his incredible running economy to the small size (and thus lighter weight) of his calves, compared to the European athletes. That is, he is carrying less weight at the extremities than they were, since his calf circumference was a good deal smaller than the Spanish runners he was compared to.

I suspect that this is only part of the answer, and possibly a very small part. As mentioned in Part I, Tadese's economy is much lower than the Kenyan runners tested before him, who probably do not have quite as much of a disadvantage as far as the calf muscle goes. So while the difference between Tadese and the Spanish might be calf-size related, there is more to it than just this.

According to an excellent review article from 2004 (by Saunders, published in Sports Medicine, 2004), the following biomechnical factors are important for running economy:

• Height: Slightly smaller than average is better for men, while slightly taller is better for women - I must confess that I don't have an explanation for the difference!
• Somatotype: Ectomorphic physique demonstrates best running economy. An ectomorph is generally long-limbed, thin, has shoulders that are about the same width as the hips! Think Paul Tergat, or just about any Kenyan long distance runner!
• Body fat: Low percentage, because body fat represents additional weight that must be carried, increasing the oxygen cost of running
• Leg morphology: Most of the weight distributed closer to the hips. In other words, if you have mass, carry it in the quads and not the calves! This agrees with the suggested reasons for Tadese's economy
• Pelvis: Narrow
• Feet: Smaller than average
• Shoes: Lightweight but well cushioned. There is evidence that cushioning improves running economy, possibly because it reduces the work required by the muscle to absorb and cushion the landing (that's the theory, anyway)
• Stride length: Freely chosen. This is interesting, because there is evidence from research that if you chop your stride to try to increase the cadence, your running economy worsens. We touched on this in our series on Pose running recently, and a lot of people find that they chop their stride when trying to use the method. According to the economy research, this would be undesirable. Having said that, if you are overstriding, then it's just as bad, if not worse, because a great deal of energy is lost in braking. This factor, perhaps more than any other, emphasizes that "Practice makes Perfect" and that running is a skill which must be practiced and learned. It happens naturally, yes, but it must be learned.
• Kinematics: A few things here - first of all, low vertical oscillation of the centre of mass. What does this mean? Well, it means don't waste time going up and down if you don't need to. The less you waste on vertical braking forces, the better. It was always rumoured that the most economical runners were effectively "rolling" their legs along beneath their hips - this is in fact a premise of Pose Running, as we discussed once before. There is nothing new to this at all (despite the fact that it was packaged as 'revolutionary', because we've known for a long time that a relatively flat trajectory is more economical.
• Secondly, minimal possible movement of the arms. That's not to say zero movement, because the arms play an important role in providing some rotational stability, but the movement must not be excessive. On this note, you see some absolutely bizarre arms carries among the elite runners, which you'd have thought would be corrected, but that only re-inforces that this is not an exact science.
• Third, a more acute knee angle during the swing phase. In other words, when your trail leg is coming through (eg. your right foot is planted on the ground and your left leg is catching up), then it's better to have that knee fully bent than straight. The reason for this is physics, relating to rotational torque and the force that is required of the muscles to bring the leg through. But the practical point is that the hamstrings come into play to reduce running economy, because they contribute to the flexing of the knee. One practical issue here is that when running slowly, it's almost impossible to bend the knee more than a few degrees - you'd be working so hard to bend your knee, the effect would be increasing your cost, not reducing it! So this is largely influenced by running speed.
  

Then there are a couple of other factors, which we'll touch on as we develop our discussions further in the next few posts.

But what is important to take out of the above list is that if you are a tall, skinny man, weighing next to nothing, with hips as wide as your shoulders, short arms, no body fat, and you wear a well-cushioned pair of size 6 shoes, you might have a good running economy!

The most important thing that jumps out from the above list is that there are some factors that one is born with (narrow pelvis, foot size, height, distribution of weight on the legs) and others that are improved with training and preparation, such as the kinematics like vertical oscillation and arm carry. Point is, great runners are born, and then trained. But everyone can run, and so as you read this, there is probably a great deal that you can do to improve your running economy, which would then translate into improved performance. But we'll discuss that in a separate post, later in the week.

Join us then!
Ross

Running Economy Part I

The Zersenay Tadese study - the most economical runner ever?

Yesterday we introduced a new series, Running Economy, inspired by this study, which was published just last week in the British Journal of Sports Medicine. It makes a great start to a series that we'll build on next week, looking at the importance of running economy to performance.

We must of course make the disclaimer that just as VO₂max does not by itself guarantee performance, so too running economy is one of many possible variables, both physiological and psychological, that come into play when one tries to understand just what is goes into determining performance. But it certainly seems to be an important one...we spoke yesterday of the growing awareness of running economy as a crucial determinant of performance, and of how little is known about it.

So it is perhaps fitting to begin our series with the very latest work, and then we'll deconstruct the theories as we progress.

The Zersenay Tadese Study

The title of the research article that was published last week was "The key to top-level endurance running performance: A unique example". The researchers, based in Madrid, Spain, had access to Tadese, the World Cross Country champion who put an end to the reign of Kenenisa Bekele earlier this year. He then followed this up with a win in the World Half-Marathon championships, where he beat world record holder Sammy Wanjiru, running 58:59, in a race where some time may have been lost due to tactical manoevuring in the middle part of the race!

Zersenay Tadese is a class act. Regular readers will know that I (Ross) am a particular fan of his, and recently picked him to be the next world record holder in the marathon, when he eventually makes the move up from the track. I think he might even have a more successful marathon career than Bekele. And if he gets the preparation right, Beijing 2008 might also see him challenge Bekele on the track. So it was with some personal interest that we discovered this article, courtesy George.

Looking at the study, it is always remarkable to have access to such a uniquely talented athlete, clearly at the peak of his 'game'. It's always been one of the big barriers to understanding the 'eternal mystery' of the dominance of the Kenyans that they've never really been studied in their prime. Most of the published work done on the East Africans comes from the labs of Bengt Saltin, and while those runners were certainly talented, they were by no means the best Kenyans in their best condition. And of course, there's a potentially crucial difference between the Kenyan who can run 27:30 for 10k compared to the one who runs under 27 minutes! So the fact that Tadese was tested during the month leading up to the World Cross Country Championships, and that he allowed the results to be published is a great coup for the researchers.

So let's take a look at the results...

Blood hematocrit

The first finding of interest is the hematocrit, measured one week before the Championships. It was "only" 43.7%. I say "only" because in another endurance sport, cycling, I suspect that many riders would not even get out of bed on pull on their jerseys if it was this low! In fact, the value of 44% is pretty much in the normal range, considering that he was doing a moderate to high volume of training at the time of testing (about 150km/week).

The authors suggested that this measurement, together with other findings we won't go into here, indicates "no manipulations to artificially increase blood oxygen transport capacity", and "no artificial stimulation of erythropoiesis". I'm sure sceptics are out there (they'd hardly report it if his hematocrit was 58%, would they!), but we'll go along with that one. Let's get onto running economy.

Running economy

We introduced the concept of running economy yesterday, but it bears repeating. Running economy is a measure of how much (or little, as the case may be) oxygen the runner uses for a given, sub-maximal speed. In theory, two runners can have the same maximal capacity for oxygen use (called VO2max), and then the one who is more economical at the sub-maximal speeds is likely to be the better runner.

So there are two measurements we need to look at here. The first is the MAXIMUM - the VO2max. The second is the oxygen use at sub-max, which tells us how economical Tadese is.

VO2max

Zersenay Tadese's VO2max was reported as 83 ml/kg/min. This is a very high measurement, but that's expected of a world class long distance runner. When compared to other world class athletes, Tadese's value 'disappears' into the crowd. In otherwords, if we lined up a group of athlete's VO2max values and asked you to pick the the two-time World Champion based on VO2max alone, there's a good chance you'd be wrong! Just as you would have been completely wrong when you had to guess that Derek Clayton could run a 2:08 marathon with his VO2max of "only" 69 ml/kg/min.

Of course, when it comes to VO2max, there's a lot of hype around the measurements. It has become something of an urban legend, much like the size of the fish you caught on your last fishing expedition which gets larger every time you re-tell the story! So depending on who you believe, Greg Lemond had a VO2 max of 92.5ml/kg/min, the Cross-Country skier Bjorn Daehlie was at 96 ml/kg/min in the off-season, and the physiologist who tested him predicted that he'd be above 100 ml/kg/min when he was "fit"! We're pretty sure you can relate your own stories of this super-human measurement!

Incidentally, while we're talking super-human, the Siberian huskies who take part in Alaska's Iditarod Sled Dog Race have been reported as having VO2 max values of 240 ml/kg/min! Eat your heart out, Bjorn!

Running Economy

So now we move onto running economy.

First things first – we have to understand what they are measuring. They have measured running economy as the total volume of oxygen needed to run 1 kilometer. This is really important, because there is evidence, shown in the Figure below, that this total volume does not vary too much with running speed. In otherwords, regardless of how fast you run, you use more or less the same volume of oxygen to run 1 kilometer! Of course, there will be individuals who don’t quite follow this trend, and so some runners will become more or less efficient as they run faster, but in general, it stays similar.

Figure showing schematic values of oxygen cost to run 1 km in three
different population groups. Note that the data are schematic only,
and represent pooled values for the three groups. Note also the general
absence of a change in economy as running speed increases.
Redrawn from Foster and Lucia (2006)

Now this might be confusing at first (certainly took some figuring out from our side – it has major implications for our understanding of fatigue, actually), because you’ve no doubt heard that the faster you run, the more oxygen you use. And this is still true – the trick is to understand the units that economy is being reported in. This is illustrated in the following example:

Take a runner who runs along at 4min/km, and uses about 200 ml/kg of O₂ to run 1 km. If we look at his O₂ use per minute, then we work out that he is using 50 ml/kg/min (because it takes him 4 minutes to run that kilometer and use those 200ml/kg of oxygen). If our runner increases his speed to 3min/km, if we assume that his total oxygen to run 1 km remains 200ml/kg (again, we acknowledge that some people will differ, but generally, as the figure above shows, this is the case). But now, he’s only taking 3 minutes to run the kilometer (and hence use those 200ml/kg of O₂). Therefore, his actual use of oxygen PER MINUTE is now 67 ml/kg/min!

So in fact, the use of oxygen PER MINUTE goes up with running speed, but the use per kilometer remains relatively constant. This is important (and has MASSIVE theoretical implications, but that is for another day). The other thing about this figure is that it creates a number of questions – why are the East Africans lower than the Caucasians, for example? But that’s all for the later posts in this series. Let’s get back to Tadese.

Tadese has one of the lowest total volumes of oxygen to run 1 kilometer ever reported. In the article, the authors report the following “normal” values for running economy, measured as ml/kg/km (that is, volume used to run 1 km)

• Frank Shorter – 192 ml/kg/kilometer (running at 3:06/km)
• Elite Kenyans (including Olympic medallists) – 192 ml/kg/kilometer (running 3:00/km)
• Elite Caucasians (Spanish runners) – 211 ml/kg/kilometer (running 3:09/km)

• Zersenay Tadese – 150 ml/kg/kilometer (running at 3:09//km and at at 2:51/km)

The size of this difference is astounding. We do have reports of runners who have been tested in this range, but we just need to get permission to publish the results (we’re working on that!). But let’s put this into context:

• Tadese is running along at 3:09/km, which is a 2:13 marathon pace.
• He is using 150 ml/kg of Oxygen to cover each kilometer.
  
• If we now convert this to a volume per MINUTE, we work out that he is using 47.6 mlO₂/kg/min. This is absolutely astonishing for how low it is!
  

We cannot emphasize just how significant this is – quite what it means, and the implication thereof is something we will tackle in another post, possibly even another series (we don’t want to go off on a tangent here!).

What is wrong with this picture?

But just think about something for a moment – Tadese has a VO2max of 83 ml/kg/min, and he runs at 3:09/km using only 48 ml/kg/min. Therefore, he is using only 57% of his “maximum” at this speed.

There is good evidence that athletes are able to run for 2 hours at about 80% of their VO2max. Now, if Tadese did this, he would be able run at 66 ml/kg/min. Given his Running Economy of 150 ml/kg/km (which is 'relatively' independent of speed - see Figure, and was similar for Tadese in the two speeds he was tested at), this would mean he could cover each kilometer in 2 minutes 18 seconds! Even if his running economy worsened quite a lot and he used up 180 ml/kg/km (a 20% increase), he'd still have it in him to run 2:45/km!

Quite clearly, this is not possible. So either Tadese becomes MUCH LESS efficient as running speed increases (which is somewhat out of the ordinary, as the figure demonstrates - slight changes, sure, but not so large), or something else is going on - there's something wrong with this picture. We need to address this, but as I've said, that's another can of worms!

The inevitable disclaimer...

I have no doubt that people will attack some of the assumptions we’ve made, and so we might as well declare right now – “We know, we've made some assumptions here, the key one being that economy (as measured per kilometer) doesn't change with speed, but we use this to illustrate a potentially profound point for our understanding of what limits exercise performance”. Think about it – if you’re running along at 80% of VO2max, then you have the capacity to use more oxygen. Yet you don’t. So how then, can oxygen be limiting, as you’ve probably read many times? Interesting one that…but that’s for another day…

Explaining Tadese’s extra-ordinary running economy

So now we move onto a mechanism – how do we explain this unbelievably low use of oxygen? Well, the authors put a few things out there:

• Very efficient utilization of oxygen by working muscles
• Training
• Muscle fibre distribution
• Genetic Factors
• And then the big one, anthropometric characteristics. That is, they measured the mass and size of the calf and found that Tadese had a significantly smaller calf muscle than the Caucasian runners, who had Running economies of 211 ml/kg/km.

With that, which I’m sure many of you are thinking is a very generic set of reasons and mechanisms, we’ll sign off today! But that’s on purpose, because in our next post on the series, we’ll look at what factors contribute to running economy in more detail – what is training, muscle fibre distribution, genetics? And then we can all compare ourselves to Tadese and work out why we’ll never be that economical!

Bye for now!

Ross