Misunderstanding energy leaks when sprinting in the transverse plane

Posted on May 8, 2017


[client is dumbbell bench pressing and obviously tired]


[client rests with weights down at their chest]

Me “If you want to rest that’s no problem, but rest with your arms straight up rather than at your chest. It will make it easier than coming up from a dead stop.”

Rocket scientist client from MIT “Oh, let me tell you about potential energy.”

Me “Let me tell you about the stretch reflex!”

Planes of motion,

planes of movement


  • forward / backward = sagittal
  • side to side = frontal
  • twist = transverse

Energy leaks are wasted motion. One school of thought out there, which seems to be increasing in popularity, is when running any movement not in the sagittal plane is an energy leak. One book phrases it as “Energy that should be used for propelling the body forward is leaked into the compensatory rotational movements.”

There is a gigantic problem with this line of thinking.

The fastest people EVER don’t adhere to this energy leak philosophy! That’s Ben Johnson, Maurice Greene, Asafa Powell, Tyson Gay, and Usain Bolt (twice), all significantly turning their knees inwards. Their knees are moving in the frontal and transverse plane. Not only the sagittal. (So are their arms (and torso)!)

In this one race, Powell lane 8, Justin Gatlin 7, Gay 6, Bolt 5, all doing it,


(If you want video quality.)

This is not cherry picking. This is damn near all the fastest people of all-time. The only ones not here are people I didn’t go searching or didn’t find video for.


To hammer this home, the knees turning in like that mean the hips are turning in. The hips are the most powerful part of the body. The most powerful part of the body is energy “leaking”!

And you can’t say “Well, those guys are great over 100 meters. But what about just their start? I bet there are people who start faster than them, and they do so because their knees don’t cave in.”

Ben Johnson has as good a start as anybody, and his knee is whipping in like that. It’s probably turning the most.

notable 100 meter sprint performances splits

Seen in the reaction time (RT) and 0-10 meter split. (The yellow highlights are where Usain Bolt stand out.)

Maurice Greene also has -that’s present tense- the world record in the 60 meters. Donovan Bailey has the world record in the nobody-cares-about-anymore 50 meters. His knees turn in too:

There are of course some who automatically go “They could have run faster then!” Even Michael Johnson, former world record holder in the 200 and 400 meters, has been on the BBC and such talking about how much faster Usain Bolt could run if his technique were more “efficient.”

“He’s very raw. He’s not a very clean sprinter; if you look at him from a biomechanical standpoint. Ultimately if he were to really be focused and committed on cleaning up his technique he could probably run 9.4…”

That is, if Bolt stopped rocking side to side so much. Johnson was an endurance athlete. Not a sprinter. 200 and 400 meters are endurance events. (The 100 is mildly one too.) He never came out of the blocks like these 100 meter guys are, and perhaps that’s where his disconnect occurs. Do marathoners run with their knees turning in like that? No. Do 100 meter guys run at top speed -60 meter mark- with their knees doing that? No. Coming out of the blocks, as fast as a human can do so, is different.

Second, whenever you give a quick, easy way the fastest people ever can run faster

– > Cleaning up technique is easier than e.g. getting stronger, and notice Johnson say “if he were to really be focused” as if that’s all that needs to change. “Just try harder!” He even says in the BBC video how he could make corrections by “tomorrow.”

we have to seriously question if there is fruit hanging that low. Once in a blue moon we come across innovations like this, but it’s awfully rare. More so in events which have been around over a century with millions of dollars attached to them.

Olympic lifters do this too!

Pyrros Dimas world record,


Nijat Rahimov, a current world record holder,


Sagittal exercise, yet we’re seeing frontal and transverse movement again. Tons of olympic lifters do this. One exception is the Chinese. They seem to actively avoid it. We’ll come back to this.

While my rocket scientist client was thinking this,

Potential Energy = mass * height * gravity

Where in his mind because holding the weights above your head means it will take more energy as the weight is at a greater height to start, he’s forgetting the body has this element:

Band tendon muscle analogy full stretch GIF

Where that potential energy is a good thing. It will give a greater stretch reflex! Drop a ball off a 10 inch elevation and it doesn’t bounce as high as if you drop it off a 20 inch. The act of holding your arms straight in this does take some effort from the body,


but anybody with some lifting experience will tell you that difficulty is less than what it takes to lift a weight from a dead stop on your chest. What’s one way we purposely make an exercise harder? By pausing halfway or at the bottom!

This is where too narrow of a mechanics mindset causes us to go astray when applying things like F = ma in its strictest sense to the body. It’s like telling somebody Work = Force * Distance. Ok, now hold a weight in front of you and don’t move. You’re not moving the weight any distance…does that mean you’re not doing any work? Of course not. We aren’t that simple, nor is physics.

-> One thing you learn if you take higher level math and physics classes is all the complexity is taken out of the intro classes. Even high school AP physics. It’s a gentler way of getting people into the topic. For instance, in introductory physics you learn about projectiles, force, etc. One thing never mentioned? The fact all those things travel through air, which can impart its own force!

So yes, when a machine is going down a track, going side to side wouldn’t appear to be very beneficial. But humans are not hunks of metal. We’re more like balls of bands.

And what’s the strongest one we have? The gluteus maximus. A muscle which extends, externally rotates, and abducts the hip.

hip extension

What are all those sprinters doing when the bring their knee up and in like that?

Flexing, internally rotating, and adducting the hip. They’re doing the opposite of what the glutes do.

-> Actually, part of the glutes are contracting when hip internal rotation and flexion occur simultaneously. Anatomy ain’t that simple either!

Because what band would we want to elicit the strongest reaction from when we’re trying to generate the most force we can in the quickest amount of time? We’d defer to our biggest band- the gluteus maximus.

This is likely one reason Chinese lifters can get away with not having the knees move like others do. Though they seem to get their knees out. (Which is still not pure sagittal movement.) They don’t need the stretch reflex in lifting like sprinters do coming out of the blocks. It’s not as elastic of an activity. There could very well be other things they’ve found with this technique too. Biggest thing which comes to mind is reduced injury risk. When the knees turn in like that under an axial load, we start playing with fire when it comes to the knees’ longterm health. Perhaps the Chinese have found their lifters can handle more loads in training by not having the knees cave in as much.

Regardless, the point is seemingly going the wrong direction can not only be ok, but is often advantageous when it comes to humans moving quickly.

-> Notice powerlifters will never go through their squat in a knees-in-to-out motion. Powerlifting is a slow event.

While we’ve gotten fairly specific here, this is kind of remedial. What do you do when you throw a ball? You move sideways and backwards (you cock your arm and rotate your body). When we jump we go down to go up. (Watch many basketball players leap off two feet. You’ll see their knees turn in too.)  Steph Curry shoots a basketball like this-

If you watch tutorials on how he shoots, or you can even see his right hand above, his hand starts on the side of the ball then pushes forward. Where we then get into all the nuances of timing, comfort, and simply what works for somebody.

Hunks of metal do this too!?

In middle school shop class we had an assignment to build a CO2 race car. It’s a fun assignment many middle schoolers do.

While all my classmates were excited to make their car look cool, paint it up a certain way, I wanted to win this thing. I made my car a horizontal cone, with the least amount of paint possible. My teacher saw it and goes “Whoa. Talk about aerodynamic! Nobody’s done that before. Going to be tough to beat.”


Add wheels and that’s what my car looked like.

I got second damn place. Me and my teacher were both confused. I don’t remember what the other car looked like, but it’s not much further into life where you see things like this,

That’s a spoiler and vortex generators on a wing. Where adding material, adding weight, adding pieces of metal sticking up into the air, can improve performance! Aerodynamics isn’t as simple as my 13 year old self thought.

-> One of the highest end car designers in the world discussing how if a car is too clean / polished, it gets slower, as air can stick to it more easily.

With humans the examples of this are endless. As Charlie Francis said decades ago, you mess with these nuances at your peril, and you better be positive the change is worth it. Not everybody is going to, or should, look the same when they move. (<- Ironically, Michael Johnson was said to have flawed technique!) Even more so when we’re talking the limits of a person / world class performance.

What’s more likely- the fastest people ever are all running wrong, that billions of years of evolution has lead to flawed locomotion despite one of the fundamental points of evolution being to ambulate while expending the least amount of energy, or some people have a misunderstanding of what “proper” running form is? That proper form for one person may not be for another?

-> That Michael Johnson is pissed Usain Bolt is so much better than him, and he wants to make himself feel better by implying Bolt is merely that gifted, yet lazy and or not focused.

Maybe Usain Bolt does turn in more than the optimal stretch reflex would necessitate. Is it worth screwing with if he can be the fastest person of all-time without messing with his form? He was born with scoliosis. He’s 6’5.” There are genuinely no sprinters near his level who have a similar body. Do we know what that level of speed and scoliosis are supposed to look like? What are the tradeoffs of making the change?

When an airplane is at cruising altitude, we want it going strictly forward, right? We wouldn’t want to go up and down as we flew. Then why do we purposely allow room for the wings to bend upwards and downwards?

“That’s wasted movement!” Yeah, but it’s a smoother ride for everybody on board. Does acute performance go down? Yes. But it’s marginal, and in exchange you get a stronger material. (At least that’s what this says. I’m only a casual airplane fan.) If your barometer is chronic performance? Such as how long the material lasts? Furthermore, say fuel costs were a tad higher with that wing bending -I find conflicting thoughts on this- but do you make that money up by having more passengers on board because you’re known to have smoother rides?

So maybe Usain Bolt could run faster if his right shoulder didn’t dip so low.

But maybe he has scoliosis and not allowing that shoulder dip would be more stressful to his back. Maybe he could have run a little faster, but maybe his career would have been years shorter.

And that making that change could have taken a year (think how long it took Tiger to change his swing), in a sport where a year is like 20% of your career.

And do you fuck with 9.58, jogs of under 10 seconds, nobody close to your best time, three dominant olympics and not much issue staying healthy???

Knowing what not to change is just as important.

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