Motor Skill Acquisition: Method of Amplification of Error

You ever had the experience where no matter what you said or did with an athlete, the desired motor output was not achieved?

In other words, your coaching sucked was ineffective in guiding the athlete towards hitting the correct positions?

Be honest, I know I’m not alone in this. And I know I’m not the only one who has taken this as a personal failure and a personal challenge.

Well, my friends, today, unlike the other days, the story has a happy ending. And where does the story begin?

Method of amplification of error.



The athlete presented a very simple, very common movement error: incomplete knee extension during the first step of acceleration. So I went through the normal checklist of coaching cues.

First up was video feedback. Slo-mo film with the ol’ iPhone, and thanks to the nifty screen share feature and the good fortune of having a compatible TV, within seconds of completing the rep we’re watching it on the big screen. Below is what we’re looking at.

We note a significant bend in the back knee, as opposed to a fully extended knee, indicating he is shortchanging his first step by decreasing the time of force application, resulting in a lower impulse, resulting in a slower starting speed.

No bueno.

I talked about wanting to see a straight line through the ankle, knee, hip, shoulder, and ideally the ear if I’m getting really picky, at toe off, as in the pic below.

The athlete understood the instructions, and off we went to the track for the next rep.

Same result.

And the next rep…

Same result.

A reminder to hit that straight line position.

Same result.

So I move on to the next item in the coaching checklist, external cueing.

“Big, powerful first step, like a rocket taking off.”

Same result.

Another external cue, and another, same result.

I move to internal cueing–heck, why not, right?

“Build a lot of pressure in your front foot. Push it hard down and back.”


I’d never had an athlete not hit the correct posture by this point. Clearly I was not coaching this kid effectively.

Then a conversation sparked the thought that would ultimately help this athlete (and me) overcome this challenge.



I’m lucky enough to hang out with Mike Studer twice per week. By hang out, I mean he’s my boss and he treats patients at the clinic I work in (one of three he and his wife own) twice per week.

Still, feels like hanging out. I prefer to think of it that way.

To say the absolute least, Mike is sharp. He’s a world leader in motor learning and skill acquisition, particularly in the neurologic rehabilitation realm. And although I don’t work with those with neurological pathologies like he does, the underlying principles of motor learning apply to both populations equally. They look different in practice, but the theory and principles are the same.

Mike frequently retrains gait. Gait is arguably the most difficult aspect of motor behavior to alter. It is autonomous and second nature, emanating from a central pattern generator (CPG). Very difficult to change. Yet, he does it frequently and successfully in his neuro clinic alongside several other neurologic rehabilitation specialists.

Sprinting is not terribly unlike walking in the sense that is largely automatic. It’s not like a deadlift or power clean, a movement that needs to be taught: people intuitively know how to run. Thus, effecting change in a sprint cycle can be very difficult. So I asked Mike about methods he’s used to retrain gait and other autonomous patterns, and the method of amplification of error (MAE) was one he suggested.

MAE is essentially where you provide constraints that exaggerate the movement error to the point of hyperbole. You make it really, really bad–the exact opposite of what you want to see.

This, in turn, provides the athlete context for what really, really bad feels like, developing an increased sensory understanding of the movement. It also breaks the athlete out of the autonomous nature of the movement you are trying to change, similar to an internal cue, which in and of itself is valuable to re-training an ingrained motor pattern.

From there, the idea goes, the athlete can use this newfound information of what really bad feels like to do the exact opposite, resulting in the desired behavior.

It is, essentially, sensory re-training.

Quickly executed movements (roughly 300ms or less) are not subjected to movement correction via sensory feedback because processing sensory feedback takes longer than the movement itself. These rapid movements are produced by the CPG and are considered a generalized motor program (GMP), or a cluster of neurons that fire together to produce movement.

The athlete I was working with could not tell after the rep whether he achieved full extension or not. He lacked the sensory awareness to feel it. Utilizing MAE gave him additional sensory context he could use to intuitively understand when he was and was not achieving the desired motor outcome–full knee extension.

So what did the actual drill look like? Peep the video below.

I cued him to take the tiniest first step possible, understanding that would mean essentially no knee extension.

Along the same line of thought, I figured if amplifying the error provides sensory context, so too should doing the movement too well…that is, exaggerating the movement in the opposite direction of the error. So, after several reps of the tiny steps, I asked him to cover as much ground as possible with his first step, essentially resulting in a bound to start his acceleration.

Not an effective way to accelerate, but an effective way to provide sensory context around the first step.

Immediately after a few reps of the bound-looking starts, we returned to our acceleration reps. I instructed him to find the middle ground and achieve that mythical posture we’d been chasing for several sessions.

Like magic, he got there.

Ok, so it wasn’t exactly a fully straight knee, but it was much better than where we started.

I was pumped. He was finally able to hit the posture, and I had finally succeeded in this coaching challenge.




Hindsight being 20/20, I should have known to go a sensory re-training method from the get go. Instead, I got caught up in the stupid traditional S&C thought process, wondering if it was a strength issue, a mobility issue, a cueing issue, a whatever else issue…

I lost sight of the fact that all motor outputs are the result of sensory inputs.

This doesn’t discount strength and mobility as limiting factors. Of course not.

But they aren’t the ONLY factors, and they definitely aren’t the most important ones in relationship to motor learning.

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