Was 2:01:39 really a big breakthrough? After Breaking2, Ross Tucker predicted a 2:01:40!

I don't understand why Ross Tucker thinks the 4% means that runners should see a 4% improvement in their marathon times. Even if you just skimmed the study you'd realize that's not the case...The 4% refers to the improvement in running economy, in other words: the volume of oxygen consumed at a given pace. That does NOT necessitate a 4% decrease in marathon time.

gads wrote:

The relationship between efficiency and velocity are not linear and therefore an improvement in efficiency of 4% does not result in the same increase in velocity.

Really really basic sports science here guys. If you dont understand it you should refrain from spreading your pseudoscience based OPINION.

Yes, they are linear at small increments. Nike claims the shoes give you a 4% increase in running economy and if true, that would correspond to a 4% increase in speed at sub VO2 max speeds.

Kris Krinkle wrote:

I don't understand why Ross Tucker thinks the 4% means that runners should see a 4% improvement in their marathon times. Even if you just skimmed the study you'd realize that's not the case...The 4% refers to the improvement in running economy, in other words: the volume of oxygen consumed at a given pace. That does NOT necessitate a 4% decrease in marathon time.

What do you think being able to run 4% faster at the same VO2 and heart rate should translate to for a marathon time? According to the study, "When Hoogkamer made the necessary adjustments [mostly air resistance at 2:02 marathon pace], he pegged the actual performance-improvement level at 3.4 percent." That's still a lot higher than we are actually seeing at the elite level.

Jefe in the CO wrote:

File Tucker’s comments in the “why we can’t have nice things” folder.

Golf gets aerodynamic balls and trampoline faced drivers, swimming gets oxygenated water and sharkskin design suits, the big 4 sports in America have access to the world’s best trainers, nutritionist and gear, and excitement is generated.

We get a transcending, breakthrough performance (Although Monza was better) and all we get is Tucker complaining.

Let’s take our sport down a couple more notches by reverse engineering Mondo tracks to cinder.

Golf has restrictions on what type of balls and clubs you can use. Swimming outlawed some of the world record suits. Track needs to study these things.

So the actual test conducted for Nike at an independent lab had the athletes run at 5:30 pace while their oxygen consumption was measured. They did not run fast, they just required less oxygen.

Hardloper wrote:

Kris Krinkle wrote:

I don't understand why Ross Tucker thinks the 4% means that runners should see a 4% improvement in their marathon times. Even if you just skimmed the study you'd realize that's not the case...The 4% refers to the improvement in running economy, in other words: the volume of oxygen consumed at a given pace. That does NOT necessitate a 4% decrease in marathon time.

What do you think being able to run 4% faster at the same VO2 and heart rate should translate to for a marathon time? According to the study, "When Hoogkamer made the necessary adjustments [mostly air resistance at 2:02 marathon pace], he pegged the actual performance-improvement level at 3.4 percent." That's still a lot higher than we are actually seeing at the elite level.

4% increase in economy simply means you're using 4% less energy to run the same speed, right? It doesn't necessarily mean you can run faster at all as there may be other limiting factors when increasing speed. Mostly that's theoretical, though and what's more likely to happen is someone will be a little less than 2.4% faster.

Keeping in mind the results of the study on sub-elites, and only 8 of them I believe?, was a range of 2.7-5.3 percent. Either way, it would be shocking if elites benefited as much as sub-elites. It's unlikely Kipchoge would have gotten even a 2.7% increase in economy, but if he did than you'd probably see an increase in speed of about 1.6%.

Here's the thing guys: Nike probably already has or at the very least should have tested Kipchoge wearing the VF4% versus another shoe and has the actual data of how much his economy changed, if at all. It seems likely they would have tested this in the Breaking-2 buildup to ensure each of the 3 guys go going for it were wearing the best possibly shoe for their body.

Actual data ought to be available. My guess is his economy improves about 1% with the VF4%, resulting in a net speed increase around .6%.

Being a sub-sub-sub-sub-elite runner, my economy would probably improve more than 5.3%, especially as my body got more and more fatigued. For me in a marathon, I'd likely go from about 3:00:00 down to about 2:51:00, but that's because I'm not springy at all. My tendons lost their elasticity from all the miles I put in on the bike over the years. Kipchoge on the other hand is like a rubber band that has never been over-stretched.

Let me help y'all out wrote:

Hardloper wrote:

What do you think being able to run 4% faster at the same VO2 and heart rate should translate to for a marathon time? According to the study, "When Hoogkamer made the necessary adjustments [mostly air resistance at 2:02 marathon pace], he pegged the actual performance-improvement level at 3.4 percent." That's still a lot higher than we are actually seeing at the elite level.

4% increase in economy simply means you're using 4% less energy to run the same speed, right? It doesn't necessarily mean you can run faster at all as there may be other limiting factors when increasing speed. Mostly that's theoretical, though and what's more likely to happen is someone will be a little less than 2.4% faster.

Rate of O2 consumption (a proxy for energy) is directly proportional to speed at sub-VO2 max speeds which is why it is used in these studies. If you increase running economy 4% you should be able to increase speed by 4% or close to it - not sure where you get the 2.4% from? The truth is most likely Kipchoge does NOT get anywhere close to a 4% gain in running economy but more like 1%, which is what you're saying and what Ross Tucker is saying. But again, I don't know why you're converting from 1% to 0.6%.

"Keeping in mind the results of the study on sub-elites, and only 8 of them I believe?, was a range of 2.7-5.3 percent. "

did you just pull the numbers out of your ass?

"Among the 18 sub jects, the mean difference in energetic cost over the three velocities between the NP and NS shoes ranged from - 1.59 to - 6.26% and from - 1.97 to - 6.08% for NP versus AB, indicating considerable inter-individual variation in the amount of energetic saving the NP shoes provided."

sheesh, the study is free to download here

https://link.springer.com/article/10.1007/s40279-017-0811-2

If it were directly proportional to speed then why do I need to breathe when I’m not moving?

I’m not trying to be argumentative. Just saying I don’t agree with the premise that a 4% decrease of energy consumption at a give speed will net a 4% increase over that given speed once energy consumption is back to 100% of what it was before.

barely legal wrote:

"Keeping in mind the results of the study on sub-elites, and only 8 of them I believe?, was a range of 2.7-5.3 percent. "

did you just pull the numbers out of your ass?

"Among the 18 sub jects, the mean difference in energetic cost over the three velocities between the NP and NS shoes ranged from - 1.59 to - 6.26% and from - 1.97 to - 6.08% for NP versus AB, indicating considerable inter-individual variation in the amount of energetic saving the NP shoes provided."

sheesh, the study is free to download here

https://link.springer.com/article/10.1007/s40279-017-0811-2

The numbers I used were from articles I saw on the internets. Maybe they pulled the numbers of their arse? Either way, seriously thanks for posting the actual study. Very interested to check it out.

Let me help y’all out wrote:

If it were directly proportional to speed then why do I need to breathe when I’m not moving?

I’m not trying to be argumentative. Just saying I don’t agree with the premise that a 4% decrease of energy consumption at a give speed will net a 4% increase over that given speed once energy consumption is back to 100% of what it was before.

That's what's observed at sub-VO2 max speeds. As your speed increases from a light jog to a steady pace, your rate of oxygen consumption increases directly proportional to the speed, until you reach VO2 max (around 3k pace) after which you can still run faster, but you get your energy from other sources because your oxygen processing capability plateaus. Until that point the ratio of speed to oxygen consumption i.e. running economy is theoretically constant, which is why it's used in these studies. If running economy weren't constant across different speeds, measuring running economy would be pointless and you probably wouldn't see it in these studies.

Here is David Torrence's results as an example. Note that between 9.1 mph and 11.5 mph, both speed and oxygen consumption increase the same amount (26.4%):

barely legal wrote:

"Keeping in mind the results of the study on sub-elites, and only 8 of them I believe?, was a range of 2.7-5.3 percent. "

did you just pull the numbers out of your ass?

"Among the 18 sub jects, the mean difference in energetic cost over the three velocities between the NP and NS shoes ranged from - 1.59 to - 6.26% and from - 1.97 to - 6.08% for NP versus AB, indicating considerable inter-individual variation in the amount of energetic saving the NP shoes provided."

sheesh, the study is free to download here

https://link.springer.com/article/10.1007/s40279-017-0811-2

Interesting indeed. I see that the heel strikers got a significant advantage with the VFs versus midfoot/forefoot strikers, which Kipchoge clearly is.

The w/kg data looks pretty wild to a cyclist. 17w/kg was the average at 6:00/mi pace. Yet, 17w/kg is not sustainable for more than about 30 seconds by the best of the best kilo men (that's about a 1 minute race on the track). However, if you divide by four based on a concentric contraction efficiency of 25% that gives you about 4.25 w/kg which is sustainable until your brain can't take it anymore for the elite men. Factoring in the eccentric component, you get an output of about 6.5 w/kg. If only I could have the same eccentric component on my bike I'd win every grand tour assuming not crashing out or being assassinated.

Anyway, 1% increase in economy for Kipchoge seems reasonable to me based on reading the actual study. If this nets a .6-9% improvement as it ought to then I'd agree my hero didn't have that much of a breakthrough after all. Can we at least pretend this was earth shattering?

Thanks for the data and keeping things civil. From what I've read it sounds like economy is indeed linear, but the slope is not 1.0. From the studies I've quickly looked at the slope appears to be around .8-.9, which is probably why you get people saying they expect a speed increase of 3.4% from an economy increase of 4.0%

I could certainly accept that. Not that science is waiting with bated breath for me to do so.

there are material controls in skiing, bobsport, cycling, rowing and other sports. there is absolutely no reason why this should not be the case in running sports when shoe technology is becoming ever more sophisticated.

Just seen this now. First of all, if you've read my tweet on this as a conclusion or even suggestion that the supposed 4% improvement in running economy claimed by the Nike shoe translates to a 4% performance improvement, then you've misunderstood the point of that whole thread and discussion. At no point have I said that the 4% improvement in running economy (which I doubt is valid for Kipchoge anyway) translates to a 4% running performance. In fact, I've written plenty about that issue in the past - when the shoe first came out with the 4% concept, it was very obvious that the 4% claim of RE improvement would not provide anything like a 4% improvement in performance - the implications were ludicrous. I wrote on this at the time of the announcement, at the time of the Monza run, and have tweeted it when the study (Hoogenmakers) came out. So no, I'm not continuing to fail to appreciate this point. I'm at the front of the queue to point out the problem with it.

I think that Edgar Poe and Real Scientist, you're the ones who I think are not quite getting it. The point of bringing up the 4% in the thread is that this claim (based on the RE) sets the upper limit of what is *possible* as an advantage. IF the entire improvement in RE claimed by Nike (via Hoogemaker/Kram study) equates to performance, then that's what it would be. But this is clearly nonsense, as I've written numerous times. In fact, in the very next tweet, I've discounted this possibility, so I'm not sure what "continue to fail to realize" means. I think it suggests you've failed to appreciate the point is that the benefit, if there is one, is THEORETICALLY anchored at the upper end by the 4% improvement in one aspect of physiology (which itself is reductionist).

The lower limit for how much the shoe improve performance is obviously 0% (unless one wants to believe that they make runners slower, but I'd discount that for now, at least in elites). So, what you have is an upper limit of 4%, a lower limit of 0%, and the NYT study suggesting 1%.

The entire premise of the thread was to point out that if people are celebrating the human breakthrough aspect of the performance, they must discount the shoes, and vice versa Or they exist in some combination, but my point (and objection to the tech influence) is that we can't quantify the advantage - it's a range, so we don't know where we stand). But importantly, both cannot be true simultaneously . I think that when you have both taken this to suggest that I'm equating the 4% O2 cost reduction to a 4% time improvement, then you've missed that particular implication.

Also, just to then comment on the subsequent discussion - remember that economy and efficiency are not exactly the same thing (an issue that came up with Coyle tested Armstrong and attributed his improvements to GE). In the Hoogemaker study they report all the metrics - the W/kg, the O2 cost per kg per min and per kg per km and the energetic cost of transport, and every single one is 4% to 4.2% 'better off' in the Nike shoe.

So that's interesting for a couple of reasons. One is that a reduction of say 4% in O2 use per kg/min or per kg/km translates to a 4% reduction in total energy cost (measured in J/kg/m or in W/kg). That has implications for the translation of RE to performance, which is at the heart of what I consider your misunderstanding about my tweet (note that you're not wrong to question that association, just that it's irrelevant to the point I was making).

When you measure O2 cost and then convert it to a ECOT, you're working out the total energy used by the athlete. For cycling, this is easier to do - a guy rides at 400W (400 J per s of useful work), but is actually consuming say 2000 J per s of energy, because he's 20% efficient.

If you can improve this cyclist's efficiency by 1% POINT, then they go from 20% to 21%, and their total energy input remains 2000 J/s, but they'd now get 420 W of effective work out. That's a 5% effective change compared to the 400W initially, which is enormous. On the other hand, if you apply a 1% improvement to the useful work, the 400W, then it goes to 404W, but if the actual input (metabolic cost) remains the same, you've only achieved an improvement in efficiency of 0.2% points (because your effective power output of 404W is now 20.2% of the metabolic work of 2000 J/s. You'd arrive at the same point if you made this new cyclist produce 400W, and their measured metabolic work rate would be 1980 J/s. Still 1% better)

Point is, you have to be clear whether the improvement is 4% points or 4% in the case of the shoe, and whether the improvement is being applied to the metabolic cost, or to the effective power output (the useful work).

In the Hoogenmakers study, it is the metabolic cost that improves by 4%. You can see this because they measure the metabolic cost at a fixed running speed,. This is also why the W/kg values they report are are so high, above 13.5 W/kg - that's not power output, it's energy COST, the equivalent measure of the 2000 J/s in the cycling analogy.)

If we assume 38% efficiency as the poster below has, then that 14.13 W/kg measured in the adidas boost is 5.37 W/kg of effective work or actual running power output.

We know that the Nike shoe had an energetic cost of 13.57 W/kg (3.96% lower than the AB). If you now assume that the effective work is 5.37 W/kg (because they're running the same speed of 14km/h. This is analogous to the 400W earlier), then the runner in the Nike shoe is 39.6% efficient - they produce the same power with less cost. Which supports the calculation made below. And explains in part why the measured 4% improvement in cost doesn't become a 4% improvement in actual performance.

In any event, it's clear that the measured energy cost doesn't equate to measured energy performance, but it does set the upper limit for any advantage. Nike were clearly in no doubt about this when they named the shoe - they didn't name it the 4% and then assume that people would reduce the actual performance benefit in the way this thread has discussed. Therefore, the marketing message mattered, and that's worth using as a start point for the discussion. And again, to re-iterate, my intention was to stimulate people to think through the implicaitons if they are celebrating BOTH the athlete (which I think they should) and the shoe. Because those two things cannot co-exist - which is it? Is Kipchoge legitimately 1:18 to 1:40 faster than the batch of Kimetto, Kipsang, Makau (I exclude Bekele because he also had the shoe)? Or is the shoe legitimately 1:18 to 1:40 faster than its predecessors? Both can't be true, so in my opinion, people have to pick which one they're saying was the 'uniqueness' of the record.

And that's why I think the technology in the shoes should be regulated. For all of them - the adidas shoe that had the carbon plate, the Nike one, the next generation ones. When athletes are superior to their own contemporaries and we don't know why, that to me is a problem, and when it's possibly because the difference between Shoe A and Shoe B is greater than the difference between Athletes A, B and C, then I'd rather that be eliminated. It's difficult enough to know who is better with doping and the inequality of testing in different parts of the world.

Anyway, my two cents' worth, I think the debate is interesting and has no right or wrong answer.

Ross

Kris Krinkle wrote:

I don't understand why Ross Tucker thinks the 4% means that runners should see a 4% improvement in their marathon times. Even if you just skimmed the study you'd realize that's not the case...The 4% refers to the improvement in running economy, in other words: the volume of oxygen consumed at a given pace. That does NOT necessitate a 4% decrease in marathon time.

He doesn't - you've misunderstood the tweet. I've written many times that the 4% change in RE will not translate to a 4% improvement in performance. I only referenced that because that sets the very upper theoretical limit for the performance improvement. In the very next tweet in my thread, I've discounted this 4% claim (which was a strong marketing message, don't forget).

So no, I haven't. But you've misunderstood what I was getting at.

Just one other addition to my thoughts above, which I didn't include last night. This comes directly out of the Hoogenmakers study:

"How much of an improvement in running performance would be predicted from a 4% reduction in energetic cost? Hoogkamer et al. [9] established that percent changes in the energetic cost of running due to altered shoe mass translate to similar percent changes in 3000-m running performance, when both are evaluated at the same running velocity.. But, as recently summarized by Hoogkamer et al. [3], the energetic cost of overground running increases curvilinearly with velocity, due in part to air resistance. Such curvilinearity implies that a 4% average energetic savings observed should translate to ~ 3.4% improvement in running velocity at marathon world record pace (20.59 km/h) [3, 34]."

In other words, their own words are that the 4% improvement in RE should translate to a 3.4% improvement in performance. Not 1:1, but very close, and more than enough reason to start by saying 4% is the maximum theoretical limit to the improvement in the shoe. And that's why it was relevant and IMO correct to anchor the range of improvement possible at 1% on one end (NYT), to 4% on the other.

This 3.4% has ludicrous implications, however, because if it is true, then Kipchoge, Rupp, Bekele etc are all 4 min slower over a marathon in the next best shoes. I'm sure we all agree that Kipchoge and Bekele are not actually 2:05 and 2:06 runners.

Ross Tucker wrote:

We know that the Nike shoe had an energetic cost of 13.57 W/kg (3.96% lower than the AB). If you now assume that the effective work is 5.37 W/kg (because they're running the same speed of 14km/h. This is analogous to the 400W earlier), then the runner in the Nike shoe is 39.6% efficient - they produce the same power with less cost. Which supports the calculation made below. And explains in part why the measured 4% improvement in cost doesn't become a 4% improvement in actual performance.

Not sure what you mean by this. 39.6% is still 4% higher than 38%, so if an athlete consumed 13.57 W/kg, their usable power would go from 5.16 W/kg to 5.37 W/kg, a 4% increase. How do you go from 4% down to only 1%?

Put another way, if you assume 4% improvement in running economy (O2 consumption to speed) but only 1% improvement in speed, you're assuming the athlete consumes ~3% less oxygen, OR that running economy declines by ~3% with only a 4% increase, which contradicts the usual understanding of running economy. That's why I call BS on 4% running economy improvement for elite athletes... if true it would at least result in something close to 4% like the 3.4% mentioned in the study.