Geoffrey Mutai in Slow Motion

Check out this video of Geoffrey Mutai running in slow motion. This was taken at mile 21 of his recent record breaking effort at the New York City Marathon:

Look at that. Just like buttah.

This reminds me of some interesting physics of running that I learned recently.

According to basic Newtonian physics, an object moving at a constant velocity and direction will stay at a constant velocity unless another force acts on it.

Marathon runners move at a constant horizontal velocity for many miles at a time, and therefore during this time the net horizontal forces acting on them must be zero. In the case of a very efficient runner who is not over striding and braking on each step, the horizontal forces pushing them away from their direction of movement are likely to be very small, mostly limited to the forces of air friction. Therefore, the amount of forward horizontal force required to overcome this friction and maintain constant speed is very small.

What this means is that almost all the forces applied to the ground by an efficient runner are vertical. All Geoffrey is doing in this video as he glides over the ground is just pushing directly into the ground to keep himself airborne.

He is not pulling or pushing himself forward, he is just staying afloat, cruising on the constant velocity and inertia he attained in the first ten to fifteen meters of the race. In essence, he is like a ball bouncing over the ground in arced parabolas. Watch the vid again with this in mind and see if you can appreciate the bouncing quality of Mutai’s running.

I should mention that these ideas are based on an influential study done by Peter Weyand a few years ago, which found that vertical ground reaction forces are the limiting factor in top speed running.

I couldn’t help but think of these principles of physics last time I went for a run. It was strange and counterintuitive to think that I didn’t need to push or pull myself forward with each stride, and that instead all I needed to do was push straight into the ground and just kind of bounce along the road. I’m not sure a witness would have noticed a difference in my stride when I held this idea in my head, but it made a real difference to me.

And distracted me momentarily from the fact that on many levels, I really hate running. (But I’m learning to like it.)

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10 Responses to Geoffrey Mutai in Slow Motion

  1. Look at the barefoot running “cult” or pose running. Whether you actually run barefoot or not, both of these ideas emphasize running form and technique. In particular they both talk about not bouncing up and down as much as moving over the ground. Well worth checking out. Pose technique talks about just keeping yourself from falling, similar to what you talked about above.

    (While I am a big fan of barefoot running, I personally think the greatest benefit of the recent barefoot craze is not getting rid of shoes, but shifting the focus from shoes to technique… which is why I so enjoy your articles on movement: you emphasize technique, efficiency, etc.)

  2. Interesting point. I think that Danny Dreyer talks about this (running and Newtonian physics) in his Chi Running book: Just start moving and falling forward and the rest is just floating… Dont’t try to push, just move your legs through as relaxed as you can and keep you posture as stable as you can.

    On might add that the arch of the foot is constructed like some kind of spring and thus the bouncing-ball analogy is quite adequate (for midfoot/forefoot strikers).

  3. This “floating” idea is also present in sprinting:

    Pose method posits that running is just the consumption of gravity. Speed, and distance are irrelevant by products of controlled falling. The only real difference between 100m spring form, and 100 mile ultra-marathon form is the height to which you pull your foot under your hip, and the amount you lean forward (thus consuming more or less gravitational leverage).

    Compare the sprinters to Geoffrey Mutai.

    I agree with K. Speed and power are the products of movement. If you want to get fast, you first need to learn HOW to move. Perfect technique allows you to take full advantage of the free forces that are given to you. Gravity being the big player. Good technique makes movement seem effortless, which is typically the word we use for top athletes in all sports: They make it look easy.

  4. K, BG and Devin,

    Thanks for the comments (and the great video.) I am not very familiar with Pose or Chi running as I haven’t read the books. I have seen some quick summaries on the internet (as well as some minor criticisms by some sources I respect.) I am personally a fan of barefoot running as it seems to instantly correct my running form and make everything feel very natural. I would guess that for all three methods, there are pros and cons and it depends on the individual.

    One way or the other, I find the current debates on running form to be very interesting and plan to read and write more when I get a chance.

  5. What a moment of grace. I was plodding along, straining my body, hurting myself trying to lose weight. I then did some research on running form and ran into barefoot running. I totally agree with K, the key is in the technique, not shoes. I needed to protect my feet because of a medical condition, so I chose vibram five finger shoes. But the technique is nothing less than phenomenal. I went from a laborious painful experience to one with little physical discomfort and grace. It also allowed me to increase my miles and therefore increase my weight loss that now stands at 40lbs. As a myofascial therapist, I believe that barefoot running with or without shoes is the best technique for the body and the most efficient physically and dynamically. Thanks for the post Todd

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