Surprised I've seen no discussion of this VO2 Max study
Interested to see what people think about this.
www.ncbi.nlm.nih.gov/m/pubmed/22167716/
Here is a brief article about said study:
www.theglobeandmail.com/life/health...663/print/
The brain’s the boss when it comes to oxygen uptake
Eventually, your muscles can no longer get enough oxygen. It’s an immutable physical limit that kicks in during any sustained physical exercise and tells your body: “This fast – but no faster.”
At least, that’s the theory we’ve been working with since 1923. But a controversial new study from researchers on three continents suggests that the famous “VO2max” – the maximum amount of oxygen that you’re able to deliver to your muscles during hard exercise – isn’t really a maximum at all. Your heart and lungs don’t call the shots after all; your brain does.
The concept of VO2max was first introduced by Nobel Prize-winning physiologist A.V. Hill, who found that the amount of oxygen consumed by his muscles increased as he ran at a steadily increasing pace – up to a point. Eventually, his oxygen consumption would plateau, even if he continued to run faster and faster until he reached exhaustion. That plateau, he argued, represented his body’s “maximal oxygen uptake,” or VO2max.
In the decades since, VO2max has become a standard tool to assess aerobic fitness. Researchers measure it using an incremental test to exhaustion: On a treadmill or exercise bike, subjects start at an easy pace, and get faster every minute or so until they’re unable to continue, having reached a plateau in oxygen consumption shortly before failure.
So what causes this plateau? In the conventional view, there are three possibilities, according to Fernando Beltrami, a researcher at the University of Cape Town in South Africa.
“One is that the heart can’t pump any more blood,” he says. “The second is that the muscles are unable to extract any more oxygen from the blood. And the third is that the lungs can’t extract any more oxygen from the air we breathe.”
Over the decades, debate has raged among physiologists about the ultimate location of the bottleneck: heart, muscles or lungs? But the new theory, proposed by physiologist and author Tim Noakes (who is also Mr. Beltrami’s university adviser), suggests that the limit may not be physical at all.
In Dr. Noakes’s “central governor” theory, your decision to slow down or stop during self-paced exercise isn’t the result of an absolute physical limit. Instead, your brain applies the brakes proactively to prevent you from reaching these limits. After all, if you really did run to the absolute edge of your physical limits, Dr. Noakes is fond of pointing out, you’d be dead.
Last month’s issue of the British Journal of Sports Medicine contained eight different studies that, in various ways, offered support for Dr. Noakes’s still-controversial views. The most significant was a study led by Mr. Beltrami, with collaborators in Norway, Britain and Australia, that turned the standard incremental VO2max test on its head and used a “decremental” test instead.
Mr. Beltrami’s 26 volunteers started by performing a conventional incremental VO2max test. Then, on a separate day, half of them repeated the incremental test while the other half performed a decremental test. After a brief warm-up, the decremental test ramped immediately to a speed higher than the maximum speed reached in the previous incremental test. After about a minute – just before the subjects were about to fall off the back of the treadmill – the speed was decreased by one kilometre an hour. This process was repeated over and over, with the speed being lowered just before the subjects reached failure.
In the group that did two incremental tests, VO2max scores remained the same; but in the decremental group, VO2max scores increased by an average of 4.4 per cent. In other words, the subjects were suddenly able to transport more oxygen to their muscles, simply because the test structure was altered – a clear indication that it wasn’t a fundamental property of the heart, lungs or muscles that created the initial plateau.
The researchers reasoned that, since the subjects knew that the decremental test would become progressively easier, their brains would be less likely to pre-emptively apply the brakes in self-defence. Since emotional stress can affect blood flow and metabolism, that knowledge alone could alter their physiological response to exercise.
There was one further surprise: When the subjects did a final incremental VO2max test at the end of the experiment, the group that had previously performed the decremental test maintained their new higher max – a result that left even Mr. Beltrami puzzled. Whatever additional exercise capacity was unlocked by the novel decremental protocol somehow persisted.
For now, the study raises more questions than it answers. But it suggests that some of the limitations we encounter during hard exercise may actually be self-fulfilling prophecies – and that knowing your VO2max is less important than believing that you can go a little faster or a little farther.
Comments
Interested in what Al or Mike G have to say.
1) Noakes has laid his cards on the table, fully in support of his 'it's all in your mind' theory. Therefore, all studies he and his team conduct and cite are viewed through that lens. Doesn't make it right or wrong, but it is the bias through which he sees the world.
2) I would expect the decrement test to be a little easier, given that the hardest part comes at the LEAST fatigued moment. Not terribly surprised to see higher performance there. The interesting phenomenon is the 4% increase on the next test. Had there not been a control group, I would have believed that it was a 'learning how to take the test' phenomenon, but we can rule that out.
3) I'd be very interested to dig into the paper and see the variability in the results. I will try to do that some time soon, but haven't yet.
4) all that said, I'm inclined to believe that there's a lot to the 'it's all in your head' stuff coming out of Noakes' camp. I think that's the reason why many roadies are very successful with a basic plan of riding easy a lot with the occasional all-out town line sprint. I do believe that there are necessary physiological adaptations at LT, etc, but also believe that pushing yourself, all out, both from a muscle physiology perspective, as well as from a teaching your brain how to maximally recruit the motor units in the muscles. Long-winded way of saying I do agree that this is plausible.
More to come...
Why the test results are the 3rd time 4% higher - not sure, but if it would me i always volunenteer to be in the group which does only 2times the incremental VO2max test
Application to our training, well, maybe to do the hardest/longest interval with fresh legs and mind first.
That is what I do in the VO2bike ON time. do longest VO2 always interval first and as often planned and than i shorten duration for the remaining VO2 interval
a.) to keep overall time to recover between the overall as short as possible but as long as needed , b.) to get this "from here it gets only easier" in my mind.
On FTP and Run workouts i am do what I as I am told. But that is not max work
workout in week 7, 3 x 1mi, thinking "man, that was a tough workout. I'm cooked. I have no idea how I'm going get the 5k test done next week!"
then, having a great day on a test, exceeding your expectations
Followed by workout in week 9, 2 x 1mi, thinking "holy crap, I thought that workout two weeks ago was hard!!!"
A lot of our own limiters occur between the ears.
Tripped over this blog, need to go at the end of the blog, first part is about doping/law etc, but at the end
he has a nice summary his point of view regards the VO2 Max study.
Kai
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The "upside down" VO2max protocol
The other interesting story, one that has garnered some great discussion on our Twitter account, is the recent study that found that VO2max is increased when you do a reverse protocol that starts out at a high power output and decreases (as opposed to the normal progressive increase to fatigue). The implication of this finding is that the VO2 "max" concept is incorrect, which is something many already knew, but it calls into question the idea that oxygen delivery or use is limiting during maximal exercise. After all, if VO2max can be increased and then maintained simply by doing something different, despite maximal effort, then how was it the limitation in the first place? The implication of your answer to this question is rather important!
The study is therefore a hook for the idea that something else regulates performance, though it doesn't establish precisely what that is. There is the suggestion that the brain is in control, and that's so obvious many people will dismiss it as "too easy". But there are many reasons to suggest this, and I'll cover these in a blog post as soon as I can. The bottom line, regarding this study at least, is that it's fairly obvious, and not as outrageous as it may seem. But the reaction of people who see it tells the story of sports science and the VO2max theory, which has long been full of holes, but remains entrenched among many as the explanation for maximal performance. This is akin to proclaiming that the world is flat. Someone has to point out that it is round, and as obvious as this may be (the idea that the brain is command is equally obvious), this study adds to that realization.
Perhaps even more important are the implications of this. People make the incorrect leap that it's about "mind over matter". The idea that the brain controls exercise is not the same as saying that our mental capacities determine performance. This is obvious. It's not "mind" over matter, but "brain" over matter - it's still physiology, so let's not get too carried away with the idea that we can "believe" ourselves into being elite athletes. Certainly, psychology is crucial, and belief is essential, but the physiological limits still exist, and the regulation of performance is still physiological! Can we do more with the right mental approach? Of course, but that's a parallel area of performance management.
More to come...
Ross
I don't know how I missed this thread - I usually love this kind of stuff!
Regarding the comments quoted in Kai's post above: almost always, the conscious mind is a hindrance, not a help, when it comes to athletic performance. Learning how to "quiet the mind" by giving it something useful, but unobtrusive, to do is often the hardest thing for an athlete in training and competing.
Getting the mind out of the way allows the rest of the brain to better do its job of controlling performance.
For details on how I think about this, see this blog post of mine (it's about skiing, not triathlon.) http://bikrutz.org/triblog/?p=932
Back on this topic though, there is another long EN thread going on about what the optimal length of time for the VO2 sets. Yesterday I did 20 mins of "on" time as the following: 4x2.5', 2x2', 2x1.5', 3x1' http://www.trainerroad.com/cycling/rides/31744 I kept reducing the time of the sets (and the rest intervals) because I wanted to stay at 120% each time.
I wonder if an "interesting" VO2 set would be to do something like 5 straight minutes of "on" time, but do it something like the first minute at 123%, then 1' at 120%, then 1' at 117%, then 1' at 114%, then 1' at 111%? I'm totally making up the numbers here, but would follow the same concept as mentioned above. Essentially "tricking" the brain/body combination to work harder because there's always an "easier" target waiting for you at the end of the minute? In the final VO2 test above, these gains stuck, even for a traditional test.
Could one also do long FTP sets the same way? Say we break down a 15' FTP set into something like 105% for 5 mins, then 100% for 5 mins, then 95% for 5 mins? I used to do this back in my weight lifting days where we would do "supersets" of say bench press where you would load up the bar with a whole bunch of small'ish weights and go almost to exhaustion at say a starting weight of 225lbs, then your spotter pull 10lbs off each side and you would do a couple of reps, then they would pull 10 more lbs of each side and you would keep going and keep doing this all the way down to where we had big dudes in the gym grunting and screaming as they bench pressed a bar with nothing but 10lbs on each side. Couldn't do something this dramatic on the bike given the "time" required at each "rep", but no reason some modification of the same principle couldn't be figured out for VO2 or FTP sets.
But anyway, the basic idea was that people did some test to exhaustion - I am pretty sure on a bike. (Maybe a 20 minute cycling trial?) I can't remember exactly what it was, but it was something with a computer feedback, not a real outside ride.
Then, after a gap for recovery (next day?), they re-did the test - WHILE SHOWING WHAT THEY DID THE DAY BEFORE and tweaked the feedback on the computer. If they "cheated" the guy by just a few percent, the guy would struggle and match his old self (i.e., actually do a few percent better). But if they cheated the feedback by too much, the guy would give up at some point. Very interesting stuff. Maybe Al remembers enough details to drag up the thread.