Chicago Marathon 2019: Brigid Kosgei Running Form Analysis

I had the great good fortune to be in Chicago to see Brigid Kosgei set a new women’s marathon world record–in fact, to smash Paula Radcliffe’s record 17 years to the day after she set it. Not only that, I had my camera with me, so I have slow motion video and my analysis to share with you.

First, here’s my video and analysis of what you can see from the side:

Now let’s go a bit deeper.

I’ve written about her form before–most in-depth this past spring in my analysis of the 2019 London Marathon. What I wrote there still held true exactly the same way in this race. Still the large frontal plane pelvis movement with the narrow footfalls.

However today she looked a bit different from the side than she did in London 2019, and radically different than the previous year in London, when I also was on the course and captured high-speed video. Here’s my London 2018 video, cued to start just before she enters the frame:

I had to watch this video a number of times today to be sure it’s the same runner. However certain hallmarks are unmistakable, particularly how she uses her arms.

The differences that stand out starkly to me are that she appears to be sitting back in the 2018 video, and I’m by no means certain that her pelvis is over her foot at midstance the way it clearly was today. Her legs seem overall much more bent–at hip, knee, and ankle–than today. And her back is also quite different–much more neutral in a forward lean, whereas today her back was almost slightly arched throughout the gait cycle, though most noticeably at toe off. That was more pronounced earlier on in the race, but it’s still visible in my video.

In addition, her musculature seems different. It may just be that she’s a little more solid overall now than in 2018–a good thing, surely– but specifically it looks like her glutes and hamstrings are more developed now. And in conjunction with this, I see little sign of the pulled-in abdomen I wrote about as recently as this past spring, and which you can see really vividly in the photo on her Wikipedia page.

Since a pulled-in abdomen is incompatible with really developing and using your glutes and, to a lesser extent, hamstrings, this makes sense.

This is all a quite massive change. It’s pretty common for me to write about runners a few times over the years, and I usually end up just referring to earlier posts because they usually run with consistent form.

So what could explain Kosgei’s transformation?

Here’s the part of the post I hate to write. There’s another difference between her 2018 video and today, and you may have already spotted it too: the shoes. In 2018 Kosgei appears to be wearing normal racing flats, and today she was wearing Nike’s most recent Vaporfly.

The changes I saw in her form didn’t happen just today. Musculature doesn’t change in a day. But I think she was also wearing a version of Vaporflys in London 2019, and I gather she’s been running in them for a while.

I hate to write this for two reasons. The first is that I have so little data, it seems ridiculous to connect the only two data points I have–form change and shoe change–and suggest a causal relationship. I do it, though, while saying there could be a ton of other factors having especially to do with her training that I’m not aware of, because the design of the shoes could promote the kind of form change we see from her.

The second reason I hate to write this is that I hate those shoes. They shut off an important part of the body’s spring mechanism, namely the arch and big toe, and substitute a rigid plate that rocks a runner forward off the tip of her toes. In my experience, you can’t shut off a key part of how the body works in running without paying a price. It won’t happen right away, and the effects will probably vary somewhat from person to person, but the reckoning will come.

Also, they create confusion about the real meaning of the amazing accomplishments we’re seeing–world records broken, the 2-hour marathon barrier falling. Could the runners have done these things without the special shoes? Not knowing puts a damper on the celebration, to say the least.

But, all of that said, and bearing in mind as well that different people respond differently to shoes, it could be that the rocker helped Kosgei move farther forward relative to her feet and activate her extensors better.

Or it could totally have been something else, like a lot of uphill running or different drills, or stopping doing some kind of core work that was messing up her form.

But whatever it was, it worked for her, and she should stick with it. And if she could stop doing that extra little lift of her chest at toe-off, maybe she could even run those faster times–2:11?–she talked about in the press conference afterwards.

Meanwhile, if you think you may be sitting back a bit like Kosgei in 2018, don’t buy those effing shoes. Better movement can be learned, and that lasts a lot longer than any footwear. Here are some of my key hip extension lessons–click the image to try them for free.

Wondering who Jae Gruenke is and on what basis she does running technique analyses? Read this.

21 thoughts on “Chicago Marathon 2019: Brigid Kosgei Running Form Analysis”

  1. Hi
    I love the shoes… OK I run in sandals, but this isn’t about me.

    My question is this: when ‘they’ first ran track in spikes, what was the talk? Maybe this is the same…
    Maybe in 10/20 years all will be running in built up shoes with a plate of sorts built in for springing forward.

    Would love to test a pair… (because I feel the ground a little different to the normal runner. (because I run lots in sandals)

    • Thanks Dion. I want to try them as well just to see what the things I’m seeing feel like. But I don’t think the comparison to spikes is correct. Spikes don’t shut down an aspect of normal foot function. They add better grip, but otherwise your feet are supposed to still work normally. In reality they don’t because the toebox is too narrow, but that’s a design flaw that comes from modeling them on regular shoes, not a feature that’s supposed to help performance.

      Nike would love it if in 10 years the definition of “running” is “that thing you do in Vaporflys.” That’s what they’re aiming for–making them the default. But it won’t work because they cause too many problems, and people will eventually connect the dots. Plus they cost a friggin’ fortune, and one of the most common reasons people give for running is, “it’s a cheap sport.”

  2. Jae, I too have dislike for those shoes: Vapor Fly 4%, Vapor Fly Next %, and ENOS 1:59 % pod monsters…it surely does take away from the accomplishments IMO. Today, I competed in the NYRR Staten Island Half, I swear it could have been Easter with all those orange, lime green and now hot pink Nike % shoes!!! I passed and ran faster than many wearing those Nike shoes… in my 3mm drop Reebok Floatride RF Pros (got for $90 with discount and gift card) a true flat, no carbon, no slapping feet…natural mid foot strike with enough protection yet excellent ground feel and response. I tried the Vapor Fly 4%, a friend’s extra pair in a very short run and hated the marshmallow feel, and the 10mm drop/stack height (Next % are 8mm), made for an unnatural ride for me. Some I know, are having lower back and knee issues. I’m told by all I know who wear them ” you have get use to them” “they feel weird for a while, you get use to it”. Well, not me! I spent my $250 on the Balanced Runner Master Class…serving me well and benefiting my all round movement not just running-thank you Jae!

    • Now that you mention the “ENOS 1:59 % pod monsters”, did you notice the design? If my eyes are seeing this correctly, 3 carbon fiber plates, one of them splits the midsole. Unlike the Next%, there’s a carbon plate atop the midsole and one just above the outsole, too. If you look carefully at the design, it virtually creates a spring mechanism at the forefoot area. In my humble opinion, that takes some of the spark off the 1:59:40 26.2 miles time, of course that is for another discussion.

  3. Jae,
    Thank you for the great analysis of Brigid Kosgei’s form. You are correct that the new WR of 2:14:04 set by Brigid Kosgei in Chicago yesterday was set 17 years to the day after a world record, but not the 2:15:25 WR. Paula Radcliffe’s WR of 2:15:25 was set on April 13, 2003 in London. It had been the WR for for 16 years 6 months. The ’17 years ago to the day WR’ would refer to the 2:17:18 WR set by Paula Radcliffe at Chicago on Oct 13, 2002.

    Well done Brigid!

    Kind regards,

  4. Hi, in your article you wrote “Since a pulled-in abdomen is incompatible with really developing and using your glutes and, to a lesser extent, hamstrings, this makes sense.” Can you expand on this? I was always taught to tighten my core and pull in my abs when I run and I have the laziest glutes ever! I’ve been doing it wrong all these years? What can I do to fix it?

    • Great question, Jenna. The short answer is that abs and glutes are basically antagonists, so holding your abdominals contracted continually shuts your glutes off. But also it tends to tilt your pelvis upright instead of letting it tip anteriorly the way it’s supposed to when you run (something else you were probably told not to do). So your glutes aren’t put in a position where they can do their job. Type “glutes” into the search function in the upper right hand corner of this website and you’ll get a bunch of useful posts. But also do the free lessons I’ve linked to below and the Mind Your Running Challenge you’ll be invited to do afterwards, and you’ll be able to feel what to do to release chronic abdominal tension and start properly using your glutes. Understanding is good, but *feeling* is what you need to be able to do in order to improve your running.

  5. She was wearing an earlier version of the vaporfly in the 2018 video, not a huge difference except for a mildly lower drop and a bit more foam under the forefoot

  6. I am curious how much of Kosgei’s form changes from London ’18 to Chicago ’19 are due to her simply running faster. She ran Chicago 6 minutes faster than London, which is roughly 14 seconds per mile. That’s a big increase in speed and would require a longer stride, more anterior pelvic tilt, etc.

    • Rebecca, the movement strategy is too different to simply result from running faster. In fact, not knowing how to make the form changes that increase speed holds many runners back from faster speeds, and based on my 16 years of working with runners I’m confident the way Kosgei was running in London 2018 is not something she would have been able to spontaneously change by simply deciding (or training) to run faster.

  7. “Could the runners have done these things without the special shoes?”
    I thought the same.
    No doubt Brigid worked hard training for go out and win, but….what if, doing the same marathon with regular shoes? sandals like a Tarahumara? barefoot?
    minimalistic shoes?
    A long term doubt.
    Thanks for letting us share our thoughts about it.

  8. that’s an excellent summary Jae and, like you, I have little time for the vaporflyes.
    I think we’re beating around the bush, however. The changes in Brigid’s body you reference are simply not possible over the time course concerned by normal methods. they’re induced by another means. one that has cut a swathe through athletics and show’s no sign of abating

  9. I really appreciate all of your content! Do you think these super shoes are setting people up for future injuries? It would be great if you would do a series on running and aging because, you too, will someday lose the spring in your step. About 6 years ago I was hit by a car while running. For months I couldn’t properly use the left side of my body, resulting in muscle imbalance and a gait malfunction. The bones have healed but the spirit has not. As a result, relaxing is not an option, tight core, no spinal engine and hamstrings that always hurt. Thank you for telling me an anterior pelvic tilt is not a bad thing.

    • I’m sorry to hear about your accident, Katherine! I really recommend you find a local Feldenkrais practitioner for lessons–the Feldenkrais Method excels at helping people recover their ability to function after experiences like yours.

      On the subject of running and aging, Most of my clients and students are ages 40-80 and they tell me that my courses, coaching, and general advice are very effective for dealing with aging as a runner. 🙂 (I can help younger people too, but they generally still believe they’re invincible and just need to train harder.)

      I do think the supershoes set people up for future injury, especially since they tend to magnify asymmetry and interfere with the normal use of the muscles and fascia of the lower legs and feet. I hope they’re a fad that’s over soon.


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