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Biomechanics Research: Variation in Human Movement

Is variability in human movement a problem?

Soon after you start playing a game of darts, you realize that you cannot always hit bullseye. Actually, even if you are a professional darts thrower, you still cannot hit bullseye every time. Similarly, even the best basketball player misses some free throws despite thousands of hours of practice. When we talk about more fundamental activities, like walking, you are actually a professional. You have practiced this task for years and years. In walking, you are as good as Michael Jordan is at basketball. However, when you observe your steps on snow or sand, you can see that they are never exactly the same. The same holds true with every task. Variability is practically a fact of life. Bernstein (1967) called it “repetition without repetition”.1

Until recently, scientists believed that variability is simply noise in the system, something we want to eliminate it in order to become perfect dart throwers, free-throw shooters, etc. An analog is a radio dial which we tune to eliminate whatever noise exists in order to listen to the beautiful, crystal voice of our favorite singer. However, is this true? Is variability simply bad for you? If yes, then why can we not get rid of it completely?