Wednesday, April 06, 2005

Half-Pipe Theory of Motor Skill

Drop a ball into a half pipe at your nearest skate park. What happens to the ball? It rolls down to the bottom of the pipe and then goes up the other side, stops, rolls back down to the bottom and back up the other side again. Pretty soon the ball will come to rest in at the bottom of the half pipe.

Now kick the ball lightly up the original side of the pipe. After some backing and forthing, the ball will again come to rest at the bottom of the pipe. Try it again, but kick it harder, this time up the opposite side first. Again after some backing and forthing the ball comes to rest at the bottom of the pipe.

As long as you don’t kick the ball hard enough for it to escape the half-pipe, the ball returns to the bottom of the pipe no matter which way you kick it or how hard you kick it.

Some motor control and learning researchers think your joints and muscles may act sort of like that half-pipe when it comes to motor skills. Over time you settle into a particular half pipe. For example after some experimenting, you learned to walk. Your particular gait represents your own special walking half-pipe. You don’t have to think about it at all. You just walk along and if you get bumped one way or the other, or if someone trips you (not enough to knock you down) after some backing and forthing, you resume your normal gait.

Your tennis game may be like this too. As players learn we form our own tennis half-pipes. The half-pipes constrain our stroking patterns. Initially it’s not too tough to move from one half-pipe to another. The walls are pretty low. Over time those walls get higher and steeper. It gets harder to kick your ball out to another half-pipe. Your strokes become grooved.

This is a good story with a dark side, or a bad story with a bright side, however you’d like to think of it. Once you settle to the bottom of a high-walled half-pipe, you can pretty much count on coming to rest at the bottom of that particular pipe. Take some time off. Play a lot. Take lessons. Whatever you do, your tennis strokes, after some backing and forthing, return to the bottom of the same old half-pipe.

For Andre Agassi, this is a very pleasant situation. For others it’s not so pleasant. Andre, no matter how much you bump him, returns to the bottom of a half-pipe that works very, very well for tennis. Others return to the bottom of half-pipes that don’t work so well for tennis. Maybe the bottom of one half-pipe swings across the ball rather than through it. Another half-pipe may tend to pull up too quickly on forehands. Try as you might to kick yourself out of that particular half-pipe (or however much you pay someone to kick you out of it), you seem to return to the bottom of the pipe. Sure you may get up the walls pretty far during a private lesson, but all too quickly, after some backing and forthing, you return to the bottom of the same half-pipe.

So why is this good news? Because if you’ve been playing for a while, you can probably count on your strokes to be “grooved” in their half-pipes. You can count on them. They are not fragile. The game would be very, very difficult if every time you went out to play you never had a clue which half-pipe you were in. This isn’t to say that you’ll always play well. Playing well is a different story. What I’m describing is your stroking pattern. Your motor control.

The bad news, as I alluded to before, is that improving (moving to a “better” pipe, a pipe more in Agassi’s neighborhood) is very difficult. To get up the wall, out of one pipe and into a better pipe takes tremendous energy. This can be very frustrating because you can practice, take lessons, and work on your strokes with tremendous energy, only to find yourself, after some backing and forthing, still at the bottom of the very same pipe. Someone else may not work at their strokes at all and sure enough, they also return to the bottom of their half pipe. You work at your strokes. They don’t. Yet you both have not permanently changed your strokes. Talk about frustration.

This isn’t to say that your half-pipe is permanent. With focused practice it is possible to get out of one pipe and fall into another one. Some people may be better at scaling the walls than others. Some people’s pipes may have lower walls than others. Whether you’ll succeed at moving to another half-pipe will depend upon many factors, mostly unknown at this point, at least unknown to me.

My hope is that as instructors we can come up with more effective ways of helping people go from one half-pipe to a better one. There’s no reason to think that’s not possible.

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