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Friday, November 02, 2007

Scientisits engineer a "Lance Armstrong mouse": How scientific and journalistic integrity goes bad

US scientists have successfully managed to 'engineer' a line of mice that display remarkable physical prowess and ability. In some English newspapers, it was referred to as "The Mouse that Shook the World", and of course, many have termed it Mighty Mouse.

Being scientists, we have no problem with that, and the achievement of the scientists, led by Professor Richard Hanson, in creating the mice by injecting a gene for an enzyme called PEP-CK is a remarkable one (we won't go into the details here).

But what is unfortunate is how the scientific and journalistic integrity of exercise science and physiology was then compromised by what can only be described as very bad and very scientifically inaccurate attempts to translate this information for the public, by both the scientists and the media.

Now, we have no issue with this - we feel very strongly at The Science of Sport that complex science should be 'packaged' in a more easy to understand, entertaining form, but unfortunately, what Professor Hanson and the media have done is compromise exercise physiology through their sensationalist explanations...

It is not a Lance Armstrong mouse

Take the following two statements, for example:

"...the physical performance of the supermouse can only be compared to supremely fit athletes like the cyclist Lance Armstrong, who won the Tour de France seven consecutive times from 1999 to 2005. The genetic alteration to a gene involved in glucose metabolism appears to stimulate the efficient use of body fat for energy production. At the same time, the mice do not suffer from a build up of lactic acid – which causes muscle cramps – a feature also seen in the best endurance athletes." (source)
"They are metabolically similar to Lance Armstrong biking up the Pyrenees; they utilize mainly fatty acids for energy and produce very little lactic acid," said Hanson" (Source)
A few points:

What does "metabolically similar" mean? An incorrect starting point

Firstly, this is pure conjecture, and irresponsible, incorrect conjecture at that. Professor Hanson has never monitored any cyclist cycling up the Pyrenees, let alone Lance Armstrong, and so the comparison is laughable. In fact, I doubt they even measured the metabolic characteristics of their mice. Can we define "metabolically similar"? The answer of course is no, because we don't even know what to look for. Perhaps the mice have similar oxygen consumptions, or lactate levels? Meaningless information, quite frankly.

It's not lactate - exercise physiologists have known this for a while

Secondly, the scientific basis for the argument is entirely incorrect. The lactic acid which is blamed as the cause of muscle cramping, is in fact a source of fuel and is in no way responsible for cramps. Poor lactic acid (or lactate, which is the more correct term) is blamed for many of the problems associated with fatigue during exercise. The truth is, it's actually used by the muscle as a source of fuel.

So in fact, when the scientists claim that Lance Armstrong produces less lactate (a claim made by Armstrong as well, incidentally), they are probably incorrect. If anything, Lance Armstrong's difference lies in the fact that he is able to USE lactate more effectively than untrained people. Without going into too much detail (this is something we can tackle in a future series, perhaps), lactate is produced as a result of a metabolic pathway called glycolysis.

The lactate is then released into the blood, and taken up by other muscles and tissues (including the heart, incidentally), where it is used as a form of energy. So what elite athletes can do is use lactate. As a result, when you measure the lactate levels, what you are measuring is the balance between release and uptake. For that reason, you cannot simply make the statement that the mice are "producing less lactate." Similarly, you cannot say this about Lance Armstrong.

Now the problem here is that in exercise physiology, this type of information is known by MOST people, but not necessarily by biochemists. So just as medical doctors delivering verdicts on dehydration are coming from their paradigm which may not be appropriate for exercise, so too biochemistry is not necessarily as cut and dried as this.

Oversimplifying human performance - Lance Armstrong is not different either

Finally, and perhaps most significantly, this entire sensational media report makes the startling assumption that Lance Armstrong himself is different from the rest of the population against whom he competes, which is not true from a scientific point of view. All this does is propagate this oversimplification of a myth that one athlete can be physiologically and vastly superior from others at an elite level. Clearly, Armstrong was superior on the bike - he won the race 7 times in a row, so from a results point of view, no argument, but that is not what I am referring to. Instead, I'm referring to the oversimplification of the reasons BEHIND that success. And I do not believe that this type of irresponsible reporting or translation of the science (by journalists or scientists who frankly should know better) does anything to help advance our understanding or appreciation of exercise science.

The reality is that to suggest that a cyclist is "unique" merely contributes to an inaccurate physiological stereotype. The most tested (and published) cycling teams in the professional ranks are Spanish teams, who have been extensively researched, with some very interesting data. The truth is that if we showed you a table of the results of 10 professional cyclists, including their VO2max values, lactate values, heart rates and "metabolic" markers, you would be completely unable to tell which of those cyclists is the best! Lucia et al, in 2004 in Medicine and Science in Sports and Exercise, published the results of their testing on the Banesto team, which included former podium finishers in the Tour de France and a winner of the Vuelta Espana, as well as domestiques and "back-of-pack" riders (in the pro peleton). And the most interesting thing of all is that the best rider, the one who achieved Grand Tour victories, had very average physiological data! It was some of the domestiques, the climbers, who were good for perhaps a few stage wins and some solid finishes, who produced the "best" results.

Now, from a scientific point of view, adopting the paradigm of the Mighty Mouse scientists, it would be an open and shut case to say who would win. But the results contradict this, for they suggest that there is something we cannot measure that accounts for success in competition.

As for the case of Armstrong, it is indeed unfortunate that highly educated people like Professor Hanson propagate myths and urban legends suggesting a "genetic superiority" because that is not what exercise physiology tells us. Unfortunately, most viewers of the Tour and of sport in general believe this, for it comes from an educated source. But the truth of the matter is that neither Lance Armstrong, nor any other athlete for that matter, possess characteristics that stand out from the rest of the elite sportspeople they compete against. What is the difference between Gebrselassie and Tergat? Well, 29 seconds, of course, but you cannot measure it! The difference between Asafa Powell and Tyson Gay? Maybe 3/100th of a second, also can't be measured physiologically!

This is in fact one of the most fascinating things in all of exercise science - what determines success? People will tell you its a high VO2max, good running economy, low lactate levels etc. All these are theories, undoubtedly contributing to the whole, but not one thing exists, or even a package of things exists, that can explain why Athlete A beats Athlete B. Often, the science would have predicted that Athlete B would win!

So the point is that this type of sensational science does little for the field of exercise physiology, and in this specific case, merely builds a false legend that perhaps should be examined somewhat differently.



Anonymous said...

If things were as simple as Professor Hanson suggests we wouldn't have races. We would just look at the charts and determine the winner in any individual sporting event. Further, I thought science has already proven that lactate is not a foe but rather a friend when it comes to athletic performance. This is a rather fundamental mistake for a scientist to make.

Keep up the good work!

Anonymous said...

The wiki article on Lance Armstrong states:

"Armstrong's most unusual attribute may be his low lactate levels. During intense training, the levels of most racers range from 12 μL/kg to as much as 20 μL/kg; Armstrong is below 6 μL/kg."

If you just take the data and recognize the role of lactate in the body, and if you assume that Lance Armstrong produces at least as much lactate as the average person, don't you get something like this?

**Lance wins a lot of races at least partly because he is able to utilize lactate, an important body fuel, better than most people.**

Here's what the researchers had to say about the mice:

"What is particularly dramatic is the difference in the concentrations of lactate in the blood," the researchers said. "At the beginning of exercise, the concentration of lactate was similar in two groups of mice, but by the end of the exercise period, the control group had elevated levels of blood lactate with little change in the levels in the PEPCK-Cmus mice."

If that explanation works for Lance, might it also work for the "mighty mice?"


Ross Tucker and Jonathan Dugas said...

Hi George and Bill

Thank you for your comments. George, you're quite right - this is the kind of over-simplification that the field of exercise science could do without. It's really just sensationalist science and only serves to propogate myths, about lactate, muscle cramps, fuel use, exercise performance, and Lance Armstrong. For unless Lance Armstrong is a genetically engineered human with the PEP-CK gene, the comparison is useless!!! So I agree, it's irresponsible for a leading scientist like this to come out with this kind of 'science'. I appreciate what they are trying to do, though - make the science understandable. But really, this pushed the limits of scientific credibility a little too far!! Thanks for the encouragement though!

Then to respond to the second question, it's a good one, Bill. So yes, ONE FACTOR that contributes to any athlete's ability to perform is their capacity to use lactate as a fuel. But the point is still that Lance is NOT unique in this regard!

I have in fact tested athletes who ride at power outputs ranging from 5 to 6W/kg (which is more or less what a Tour cyclist will produce) and they have lactate levels that are similar to this! If you look at that Lucia study (MSSE, 2004), you will see that the riders he tested were doing around 400W, some had lactate levels of 3mM!

Now that's the same, or better, than Lance Armstrong. So the statement that "MOST RACERS RANGE FROM 12 TO 20..." is not correct - there are many riders who are the same or lower than Armstrong, yet they did not win the race.

now, the reason for this is another debate entirely, and we could speculate wildly, and somewhat controversially. I know what I believe contributed to Armstrong's dominance! But this post is not about that - it's about what DID NOT contribute - it's NOT some genetic metabolic advantage that allows him to use lactate. And the sooner everyone realise that Armstrong is not this "genetic freak", the better for everyone's understanding.

Thanks for the comments!