2021 NYC Marathon Running Form Analysis–Jepchirchir, Korir

2021 NYC marathon champs Peres Jepchirchir and Albert Korir both had running form signatures that set them apart from the rest of their elite competitors. Runners of any level can benefit from understanding how their gait strategies worked for them.

At the time of this writing there doesn’t appear to be an official race highlights video, but here’s a wonderfully helpful video filmed by Kofuzi on the streets of New York.

As you may have noticed in many of my previous analyses, I pay a lot of attention to armswing, and in this race there was ample opportunity to watch the relationship between runners’ asymmetrical armswings and their asymmetrical leg function.

Many come to me concerned about one arm swinging across their body more than the other. That arm is almost never a real problem; the other arm, which swings more compactly and nearly always too much front-to-back (in the sagittal plane) is the real cause for concern.

Why? Because an arm can only swing that way when muscles in the shoulder girdle, upper body, and waist contract to make it do so. And chronically contracted abs and shoulder muscles on one side of the body interfere with the function of that leg–especially the ability to allow the leg to extend behind the runner and to come onto the toes before leaving the ground. So very often the leg on the side of the more constrained arm has pain or an issue such as runner’s knee.

This is a relationship that can work either way–the leg doesn’t function well so the arm swing gets affected, or the side and arm swing change, affecting the leg. I demonstrated this phenomenon from the perspective of how your arms affect your speed in this video.

The pattern was visible in runner after runner in both the men’s and women’s fields, including Molly Seidel, Laura Thweatt, Viola Cheptoo, Kenenisa Bekele, and Mohamed El Aarabi.

In nearly every case, the runner’s ribcage turned more towards the more sagittally-swinging, compact arm as the other arm swung farther across. In a race this is easy to see by just watching the movement of the runner’s bib. On the side each of them turned towards, the leg did not extend properly.

The exception is Albert Korir, who doesn’t fully extend either leg, but his left knee remains especially flexed. From the front or back, you can see he rotates his knee inwards to get off his leg without fully straightening his knee or ankle or coming onto his big toe.

Albert Korir approaching the finish line

His armswing is more or less symmetrical, fairly sagittal (neither hand comes to his midline), and has more “oomph” or snap on the upswing rather than the downswing. That last feature is very unusual for an elite runner and seems to function to create lift in late stance to help him leave the ground even though he’s stopping his leg action short.

You’ll notice his bib sits to the right even though it’s his left leg that extends less. This is because he turns more strongly to the right when leaving the left leg to compensate for the lack of extension.

I found myself wondering if he might be compensating for a leg length discrepancy–with the left leg longer–in running this way, but there’s no way to be sure.

Now let’s look at what’s so distinctive about Peres Jepchirchir, namely her upper body in comparison to second place Cheptoo and third place Yeshaneh. In this screenshot you can see how differently she organizes herself from the other two.

Peres Jepchirchir, Viola Cheptoo, and Ababel Yeshaneh

Her shoulders are rounded forward, upper back even slightly rounded (though it stretched out towards the end of the race), and head far forward. By contrast, Cheptoo and Yeshaneh hold their upper bodies more upright (Cheptoo most of all).

Jepchirchir’s form reminds me of Zersenay Tadese’s in this strong, almost slouching forward lean. In both cases, this organization allows the runner to maintain a fairly neutral spine, reduce drag, achieve a long stride length, and make running fast feel much easier.

In my experience, any effort a runner makes to pull their shoulders back or upper spine upright makes running significantly more work, even if they are moving as gracefully as Cheptoo and Yeshaneh.

As long as you can lean forward and relax your shoulders without making your whole spine a C-curve with the middle of your back moving backwards, Jepchirchir’s movement strategy will be the winning one when all other factors are equal.

1 thought on “2021 NYC Marathon Running Form Analysis–Jepchirchir, Korir”

  1. Everybody doesn’t move exactly in form to take on the situation , tall runner stroll upright, lean forward for a shorter runner could bring heaviness on the legs. Maybe not..


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