Wired Mag: Legal doping? Were Zoom Vaporfly 4% wearers twice as likely to negative split NYC?

Vaporfly Elite? wrote:

LetsRun.com wrote:

We wonder why he eliminated the elites (to get rid of DNFS??). We'll ask him and report back.

Why wouldn't they? The elites are wearing a completely different shoe! The Vaporfly Elite. The average runner can only get the Vaporfly 4%, right? The Vaporfly Elite is not available to the general public.

only the breaking2 athletes have the vaporfly elite. and probably Rupp and Mo. in fact I'd bet they aren't even producing those any more, just the 4% model.

I was thinking the same, i.e., that it would be hard to tell a Zoom Fly from the Vaporfly. Is there an obvious difference cosmetically? See that Mr. Thompson didn't respond. Not trying to be mean here, but dude you really embarrassed yourself with this miss on the shoes. And he disappeared on us here on LRC...

Abdoujaparov wrote:

OK. Not to completely rain on your parade but I know at least two of the runners shown in your chart as wearing the VaporFlys are wearing red ZoomFlys.

Abdoujaparov wrote:

OK. Not to completely rain on your parade but I know at least two of the runners shown in your chart as wearing the VaporFlys are wearing red ZoomFlys.

(...)

585 - definitely ZoomFlys

2261 - looks very much like ZoomFlys

3132 - definitely ZoomFlys

646 - Nikes but not even from this new range - this one is really random

610 - definitely ZoomFlys

I haven't checked them all but this is some bad science. You should fix or withdraw the article.

NicholasThompson, I would really like to hear your reply to this. Did you just through the Zoom Flys and the Vaporflys together? Could you take the article down and put it up again with the correct data?

It's hard to gain any insight from incomplete data. I ran 1:17:5x+1:14:5x in new balance shoes, bib would have been clearly visible and I wasn't tucked into a pack... Not on this list.

AndyDufresne2 wrote:

It's hard to gain any insight from incomplete data. I ran 1:17:5x+1:14:5x in new balance shoes, bib would have been clearly visible and I wasn't tucked into a pack... Not on this list.

Some of this has to do with how smart people run as well. I went out in 1:20 and faded but had I gone out in 1:22 I would have been more even. I think the humidity got to me in the last 4 miles. That has nothing to do with my shoes. The course, weather, pacing, etc., all matter. Take out mile 23-24 in NYC and some more people negative split.

shohohe wrote:

Abdoujaparov wrote:

OK. Not to completely rain on your parade but I know at least two of the runners shown in your chart as wearing the VaporFlys are wearing red ZoomFlys.

(...)

585 - definitely ZoomFlys

2261 - looks very much like ZoomFlys

3132 - definitely ZoomFlys

646 - Nikes but not even from this new range - this one is really random

610 - definitely ZoomFlys

I haven't checked them all but this is some bad science. You should fix or withdraw the article.

NicholasThompson, I would really like to hear your reply to this. Did you just through the Zoom Flys and the Vaporflys together? Could you take the article down and put it up again with the correct data?

Dude, it's a cluck bait article. It's not meant to be accurate.

What can I say? Slow day at work. When you re-read the article (and ignore the Brojos title to this thread), it appears the author does think the ZoomFlys are a less advanced model of the VaporFlys ( and share a model name).

So maybe yes, they were writing their clickbait based on a random sample of shoes a good chunk of which Nike has made no quantifiable performance claims about at all (not saying I buy the 4% science but pointing out that Nike didn't even extend that to the ZoomFlys).

It's just hilarious when people put together spreadsheets with links and start talking about regression analyses when they can't even be bothered to get the terminology right or correctly label their data set.

To an earlier poster, the main visible difference between the Zooms and the Vapors/4%s is that that Zooms have the flywire lacing system so show distinct lines running up to the laces on either side of the upper. In some of the race numbers I called out above that feature is very obvious, in others less so but in a number of those cases the runners are my teammates and I know what they ran in.

NicholasThompson wrote:

Thanks for posting this! I took the elites out for a couple reasons:

1) They have different pacing goals. Because they're trying to win, or get in the top ten, they care more about relative performance and they are more likely to be pacing against the group, not against the clock. The runners in the photos are much more likely to be trying to hit time goals. I figured it would make the data set a bit cleaner to just look at the latter group.

2) The question of whether the shoes help elites is interesting! But I was more interested in the question of whether they help slower folks.

I could though rerun the data pretty easily with them included to see if it shows anything different.

That's a good reason. While no data is concrete, this is a good sample. I don't think this should be written off.

I'm forming the opinion that the vaporflies definitely do help to some extent, but it's still fair. Shoes have changed and will continue to change over the years, but they're accessible to everyone.

The same discrepancies could probably be made if a bunch of runners ran NY in 1987 Pegasus vs 2017 Pegausus. Should we conclude that wearing 2017 Pegasus is cheating? Of course not.

Have you read the thread? This is a garbage sample.

Hey Nick,

Good to see you are still checking the boards. Putting on my epidemiologist hat, my first thought is to check the magnitude of effect and statistical significance. The odds ratio (i.e. the relative likelihood) of a negative split for those wearing Vaporfly shoes vs. those not wearing them was 2.72--a fairly high odds ratio--and the p-value was 0.051. Not half bad.

Next are the potential confounders, ie. factors that could be associated with both negative splits and wearing the Vaporfly shoes but that have no bearing on your actual hypothesis of interest. It seems that your biggest potential confounder here is general running savvy. Runners who are savvy might decide to give these new Vapor Fly shoes a try. They also might know how to pace themselves better. In your particular case, the effect of "savvy" can be tested. Look up the names of these runners in a database like athlinks and compare those who wore the Vaporfly in NY vs. those who did not. If Vaporfly wearers were not more likely to negative split in past marathons (those pre-dating sale of the Vaporfly), you can (mostly) rule out the "savvy" theory.

Finally, if you rule out "savvy", you or someone else would be justified in proceeding to a small controlled study, as suggested by others on the board. Given the magnitude of effect observed, it could be a small affordable study.

To wrap up, in my estimation, the results are definitely suggestive and will likely be followed up further by someone (if not necessarily you) given the magnitude of effect and the fact that it could be tested in a small(ish) study.

Best,

Steve

No, pedantry is garbage. Do you made the distinction that 2-3 of the 22 vaporflies are zoom flies. Right, that's still 19-20 that are vapors, and who have neg split.

Look, most studies like this can't be conclusive, because they don't take into account previous training, humidity effect on different runners, body composition, etc. You have to remove all variables. Having said that, you've got to take the study for what it is (a very broad pattern) and let go of being so pedantic.

It's not conclusive that the vaporflies have an advantage, but I'm of the "opinion" that they "likely" (not conclusively) do benefit to some extent. What extent that is, is not concluded yet.

The magazine added a bit to the story, making the shoes seem even more useful:

Update: After publishing, George Wu, a researcher at the University of Chicago Booth School of Business who has written several academic studies of runners, wrote to say that he had run a regression analysis on that data posted to determine the relationship between second- and first-half times. It turns out, in fact, that the Vaporflys appear to decrease finishing times by 4.43 minutes, controlling for first half speed. That result, he writes, is statistically significant by normal standards. You can see his data here.

This may say more about who buys what shoes. Are committed runners more likely to buy this type of shoe? That's definitely the impression Nike wants to give. I buy slightly more affordable trainers since I burn through so many pairs (or, well, maybe a half dozen a year). Figure other mid- to high-mileage amateurs do something similar, sticking with what works.

Statistically, this means nothing. Cross-sectional studies are next to worthless.

Before getting into p-values and sample size, how about discussing the chosen outcome: negative splitting? Why is this the chosen measure of performance? I suspect simply because it was easy to do with the NYC results data. A diff-in-diff would be far more interesting here. From there a cost effectiveness analysis comparing vaporflys ($250), zoomflys ($150), and all other shoes would be fascinating (~$100).

LetsRun.com wrote:

Why don't we have someone put on the shoes, hop on a treadmill and take their pulse?

Do same pace the next day in a separate pair of shoes.

The Kram Lab at Colorado did just that (along with some other physiologic markers) - they evaluated the energetic cost of the VaporFly and compared it to the Zoom Streak and Adios Boost at a few different running speeds. The subjects were 18 sub-31 min 10k runners.

Here's the abstract from their presentation at ACSM, but I suspect the full paper is to be published soon. There's no HR data in the abstract, but it'll probably be in the paper would likely track the oxygen consumption pattern regardless.

Maybe Rodger, Wouter, or Shalaya could weigh in. Certainly anticipating the paper

This is pure crap.

This "study" is a waste of time. Even if the shoes were proven to improve performance of everyone who wears them, isn't that the point of advancements in shoes? All of today's shoes are better than shoes 40 years ago, but that doesn't mean that today's shoes amount to "legal doping". I would suspect all manufacturers intend to improve shoe performance with every new model they develop. There is no standard for what shoes runners need to wear, and somebody with a 1lb shoe vs, someone else wearing lightweight racing flats doesn't mean the latter one is cheating.

Live to run wrote:

No, pedantry is garbage. Do you made the distinction that 2-3 of the 22 vaporflies are zoom flies. Right, that's still 19-20 that are vapors, and who have neg split.

Look, most studies like this can't be conclusive, because they don't take into account previous training, humidity effect on different runners, body composition, etc. You have to remove all variables. Having said that, you've got to take the study for what it is (a very broad pattern) and let go of being so pedantic.

It's not conclusive that the vaporflies have an advantage, but I'm of the "opinion" that they "likely" (not conclusively) do benefit to some extent. What extent that is, is not concluded yet.

I don't think working out with a few clicks that 5 out of a sample of 21 (24% and not 2-3 out of 22), are mislabelled is pedantry. I'd read a non scientific sample survey that didn't control for all the variables but my interests wanes when I realize the authors can't even recognize the product they're "analyzing."