Butt kicks at top speed;

How the hell can some elite sprinters kick their own asses as they run and still be so fast?

Isn’t that a wasted motion? I sure as hell can’t run that way.

You can’t possibly be getting as much of a forward knee drive from the hip flexors, and it screws up the lower leg from setting itself up for a true pawback action.

It leads to a more vertical action. And also lead to longer ground contact time with the foot.

It looks damn poor technically.

I can’t understand how it works for them but it does.

I don’t see Maurice Greene doing that; he has very strong pawback, forward knee drive and his shin whips out at the end of the forward knee drive setting him up for a perfect pawback.

Would these elite sprinters be running faster if they changed thier technique? I would say no.
I can’t figure out how it works for them so well.(not that it really matters)

Be very careful about what you see elite sprinters doing at top speed. Some of it is an optical illusion. For example, there has been much discussion about full extension at the ankle, with some people asserting that elite sprinters don’t do it. Yet, when full speed and slow motion versions of the same video clip are played next to each other, one can clearly see that they do indeed extend fully at the ankle, but it’s so fast, you can’t see it at full speed.

With regard to recovery and pull-through be very careful about consciously imitating the action you see in elite sprinters, because you might end up over exaggerating the motion and screwing up your technique.

Your observation relates directly to a lesson I learned when training with Charlie in April. I had always been self conscious of pulling the ankle of the swing leg over the supporting knee. The problem was that the motion was too exaggerated, resulting in an exaggerated knee lift, which caused me to lean slightly backwards, caused the support leg to deflect a little and the hips to drop, as well as reducing stride frequency due to the excess range of motion in the support leg.

Charlie changed my technique so that now it subjectively feels like I’m just stepping over the support ankle about mid shin, but in fact the ankle of the swing leg is passing over the support knee. It’s just that the motion is so quick I don’t notice.

It’s the same with the “pawing action”. Subjectively, it should feel like you’re just stamping your feet up and down. There’s hardly any preception of horizontal movement. If you do feel a pawing back action, you’re spending too much time on the ground.

The key lesson, which I’ve repeated many times, is that there is often a big difference between what you subjectively feel and what you are objectively doing. And this is where a good set of experienced eyes watching you becomes so crucial.

Another example is the perception of speed in a relaxed state verus a tense state. When you are relaxed, the movement subjectively feels slower even though it’s faster. Because there is less neurological “clutter” from unnecessary muscle activity, you are more aware of the details of your movements. This is why most people run their fastest times when they think they’re only going 90%.


Thanks for the insights, you make some very interesting points.

My biggest problem right now is probably ankle joint extension.

Personally I am running purely biomechanical. I am not saying this is the best for everyone, but after recovering from a stress fracture which kept me out more or less for 2 years, I find that biomechanics work better for me, and it boils down to 2 primary things;

#1 The Pawback; to initiate the pawback you begin with the leg in front of the body (at flight phase) after the shin whips out from the forward knee drive. You contract the leg (the pawback leg) in a manner that involves a very quick pulling motion backwards and down; and you only contract at the very top 1/5th to 1/4th of the movement, after that you (after you have gotten the momentum of the leg to switch direction) you simply allow the momentum you created from the top of the pawback to drive the leg down. BUT YOU DO NOT CONTINUE TO APPLY FORCE THROUGH THE MOVEMENT, THE ONLY USABLE FORCE IS AT THE TOP, NOT AS YOU GET CLOSER TO THE GROUND AND ESPECIALLY NOT AT GROUND CONTACT. There are almost no braking forces this way. All sprinting actions are performed in this manner.

Here is the key to this point; Since you have already contracted the pawback leg when it was in front of you, by the time the foot hits the ground, you will get a stretch in your achilles which will then lead to a rebound and ankle extension. I see no way to apply any force at all to the track (when at top speed) because all force has been applied before the foot hits the ground. Once the foot hits the ground all forces are stabilizing and rebounding of the achilles.

This is strictly from a biomechanics book. Bear in mind that World Class sprinters may be a lot faster then anyone will ever get with this type of sprinting form. But the difference in my sprinting, and my training partners sprinting has been astronomical.

All actions in sprinting are elastic. And only require contraction to initiate whatever sprinting action you are doing, you don’t follow through.

Do I try to apply extra ankle extension or do I rely on stretch and rebound only?

The other primary action is the forward knee drive phase. (comes from the hip flexors!) After the pawback and support phase, the moment after the foot breaks ground contact, from the point that the foot is farthest behind you the knee is whipped forward forefully, and again the contraction is as dynamic as possible, meaning that you are only applying force at the very beginning of the forward knee drive. (or the beginning 1/4th of the movement)

When you combine this with arm actions, you are getting the basics of biomechanical/scientifically efficient sprinting.

The only problem is what looks like better form may not actually pan out in real life. I would say the two sprinters that really use the closest I have seen to this form to be; Maurice Greene and Darrell Greene. (football payer)

A lot of other sprinters technique looks dowright horrible, even those running under 10.1, when compared to this style.

And the usable forces at top speed are arm action, pawback, forward knee drive (hip flexors) and ankle extension which is more or less stablilizing and stretch/rebound of the achilles. Do you have time to contract the ankle in the 1/10th of a second the foot is on the ground? I think not.

And if so, how in the world do you ever train for such a quick ankle joint contraction???

That is my main question.

What I am saying is that none of these actions are ‘forces applied at ground contact’ all occur during flight phase.

Arm action will drive your ankles into the track harder, allowing a much greater stretch/ rebound of the achilles, the only possible usable forces applied to the track would be after the stretch/rebound of the achilles and after the landing forces shift from going into the track to coming off the track; if you applied the forces too soon you would be working against gravity.

I hate to say it but I don’t see how anyone can be that quick to really use ankle drive to their advantage at top speed. :confused:

So try to apply that force after your support phase, and after you have gotten that stretch/rebound of the achilles. (THE TOTAL GROUND CONTACT TIME IS ONLY 1/10TH OF A SECOND; YOU NOW HAVE ABOUT 3/100THS OF A SECOND TO APPLY THE FORCE OF YOUR ANKLE USING YOUR CALVES.)

Yeah, right :cool:

Nothing is so simple that it can’t be complicated beyond comprehension.

You’ve given a very detailed analysis of the biomechanics of sprinting, but how does that translates into coaching proper technique?

My starting point would be: Pump the arms, step over with the ankles.

Don’t get me wrong. Your biomechanical analysis is impressive, and I’m not in a position to challenge it right now. But, this goes back to my point about the objective facts of what is occuring biomechanically versus what you actually use as subjective coaching cues.

Taking your biomechanical analysis for granted arguendo, none of these actions or motions are consciously executed by the sprinters. They just happen as a consequence of what the sprinters consciously do, which subjectively may feel very different. That was my point.

This touches on Charlie’s (by now) cliched phrase “paralysis by analysis”. If you attempt to coach a young sprinter by explaining sprinting technique to him/her in terms of your analysis, the likely result is a tight athlete.

It would be nice you hear from pierrejean on this topic, as he seems to be our top biomechanics stud.

Yeah, and i´m very anxious to see the Helsinki Biomechanic Work

As Flash pointed out, what you see or what you want to do, and what you feel are all different sometimes in sprinting.
I don’t think there is a correct biomechanical model for all sprinters. Just look at the difference between Gatlin, Powell, kim, etc etc. However, it goes without saying that that certain things are common to all of them.
Moreover, I don’t believe one set of cues will work for sprinters. For example Charlie says step over the opposite knee, Tellez says push up with the stride.

Well look at Lauren Seagraves course on drills to do for speed; they are absolutely pathetic. I have no idea how anyone can run fast trying to transfer that onto full speed sprinting.

All the actions are vertical. Sprinting is horizontal.

You go to a track meet and you see all these kids doing these same stupid drills.

I am seriously starting to wonder if the people who the drills actually work for are just freaks of nature and that particular set of drills just works for them, and they are that 1 in 100,000 that can actually benefit greatly from them.

Its strange. There is a Biomechanical/Kinesiologically correct form of sprinting accepted by scientists that is somewhat universal. Do the fastest sprinters in the world use it? No. (maybe a couple)

Does it work for me and the athletes I have trained? Yes. Does Seagraves drills produce the kind of speed the biomechanics training does? No, and the difference I see is about 6/10ths off the 100M.

Sprinters who butt kicks at top speed are generally the ones who have proportionnaly longer femur, and/or the ones who have the more quad flexibility.
If you have the chance to watch Christine Arron during her glutes massages, you will notice 2 ecchymoses because of these butt kicks. I should ask Lauryn Williams to show me hers to see if she has the same syndrome :cool: :stuck_out_tongue: