The Tokyo Olympics Women’s Marathon was exciting for more than one reason. From a running form perspective it was a treat to have the top three women–Peres Jepchirchir, Brigid Kosgei, and Molly Seidel–all running with such different form.
Take a look at this brief highlights video to see what I mean or find a highlights video viewable in your country on YouTube. (Unfortunately NBC Sports has opted not to allow their highlights video to be embedded, so I can’t post it here.)
Gold medalist Jepchirchir has what I think of as classic Kenyan form: a deep forward lean, hands coming to her heart with a dynamic, beating armswing, a long stride, and what looks like hard impact in each footstrike.
Her forward lean reduces drag and allows her to extend her legs easily behind her so she can get her body well past her foot before taking off into the air. Her dynamic armswing helps her apply force to the ground, increasing her elastic recoil, and her hard footstrike also helps her load her springs. Keeping her hands very close to her chest and moving her head forward make her lean possible.
Watching her run alongside her competitors earlier in the race, she seems to move her upper body much more than most, though some of that movement is actually just the vigorous tossing of her hair from side to side (which honestly has got to cost some energy, though I’ve never actually seen data on it).
Her countrywoman, silver medalist and world record holder Kosgei, has significantly different form. I’ve written about it extensively both before and after her transition to the super shoes, and captured high speed video in both the London marathon and her world-record run in Chicago. Take a look at that analysis here.
Kosgei’s elbows are bent more, bringing her hands higher up on her chest and keeping them in front of her rather than allowing them to pass to her sides. She’s more upright and her stride is narrower than Jepchirchir’s, almost as if she were on a tightrope.
These characteristics give her a more gliding action than Jepchirchir, without the visible hard impact of footstrike, and this is especially true because high arms like hers often lift the runner’s torso up a bit, activating the spinal extensor muscles more and preventing the weight from dropping onto the front foot as much. That sounds good but it may not be–a reduction in well-organized impact means less loading of the springs in a runner’s body.
Her narrow gait also contributes to the gliding quality, since she has to tip her pelvis significantly side to side to get over each foot.
As she fatigues, her asymmetrical habits emerge–a normal phenomenon and especially in evidence in this race as the heat overwhelmed many runners.
Kosgei’s habitual asymmetry is to adduct her left leg even more strongly than her right and hold her left shoulder forward, left arm completely in front of her. Make a note for future reference, folks–when she starts doing that, she’s fading.
Bronze medalist Molly Seidel’s form was yet again quite different from the other two women. Seidel leans much less than the two Kenyans (as is true of most American runners) and depends in part on internally rotating her thighs to help her pass her feet and get to toe-off.
In trying to understand exactly how her form was working for her (because before you ask what could be better about any runner’s form, you first need to ask what is good and how does it all fit together!) I looked at some of her race video from several years ago. Her basic form was the same but her arms were much lower and wider. She’s clearly worked on her armswing since then.
The really interesting thing about her form is that she runs with a metronmic core action–a rhythm that seemed more durable than any of her competitors’ and seems fundamental to her speed and toughness.
In the end, the best way to understand the essential differences in the three women’s form is to look at how each woman’s armswing brings her swing leg forward.
Jepchirchir’s hand beats downward along her sternum to swing her leg (on the same side of her body) forward. That action puts energy into the lateral trunk flexion and counterrotation that swings the leg for her.
Kosgei swings her elbow somewhat downward but mostly backward in an arc around her, rotating her upper body to drive the counterrotation of the pelvis and swing her leg forward.
Seidel beats her hand downward and back by the side of her waist, driving her hip and knee forward and slightly rolling her shoulder forward as it turns back (you might not see this but if you try it you’ll feel it), which helps shorten the swing side of her torso to bring the leg through. This is where that metronome action comes from.
Each woman’s arm and leg action fits together into a “type” of whole-body movement. Jepchirchir’s armswing is part of a forward leaning, rotating, and side-flexing trunk action that produces a long stride and a gait width just about as wide as the hip joints. Kosgei’s armswing is part of a fairly wide and very high figure-8 upper body action that generally produces a narrow, tightrope-style gait. And Seidel’s fairly low, wide arm action is part of a trunk action that keeps the weight in the middle, between the two legs, and tends to internally rotate the legs to bring support underneath the center of mass.
With all this in mind, go back to 3:15 in the Tokyo Olympics Women’s Marathon highlights video and watch the end of the race–how each woman’s form becomes more pronounced as they approach the finish line and how strongly they contrast with each other. It’s a dazzling show.
Very interesting analysis. However it is simply not true that a forward lean reduces air resistance. The reduction is infinitesimal (perhaps 1 sec. in a marathon). Reduction in frontal area with a 5 degree lean is less than 4 parts in 1000 (it’s just the cosine of 5 deg.). And the effect of air resistance at 2:20 marathon pace is a small fraction of the forces the runner must overcome. As far as I can tell, the reason for a forward lean is simply to place the centre-of-mass over the foot at the point of impact.
Thanks for your comments, Tony, and for your email correspondence on this subject as well. I’m very interested to hear what you think of Pugh’s work on the subject of drag! As for the other functions of a forward lean, they include better extensor and glute recruitment, better breathing, better core action and thus weight shift, and a better ability to open up the stride behind the runner, producing a longer stride length without overstriding. There are probably more as well, but those are the top ones.