How do we learn a movement skill?

Degree of Freedom:

We each have approximately 230 joints within our body, most of these joints have one possible path of movement or ‘degrees of freedom (eg. Elbow).

Yet more complex joints (shoulder & hip) each have upwards of three degrees of freedom (flexion/extension, IR/ER, adduction/abduction).

We have somewhere in the region of 244 degrees of freedom within the body, controlled by 630 muscles.

The capacity for different movement types, patterns and complexities is vast.

When first learning a new skill, the most effective solution involves ‘freezing’ degrees of freedom. ‘Freezing’ essentially involves reducing the number of potential movement solutions available to simplify the choice problem.

Instead of our joints moving independently, the brain moves them together in a rigid, block-like way.

When a movement skill is new, it’s easier for the brain to move the shoulder, elbow, wrist as one unit than it is to move them independently of one another.

The way the brain ‘freezes’ a joint to reduce range of motion is by utilising a coactivation strategy.

Essentially this involves activating both the agonist and antagonist muscles around a joint. This is similar to what happens when we ‘limp’ when walking.

We are putting the foot on the accelerator and the brake at the same time.

As we begin to learn a movement skill, we start to release or ‘free’ degrees of freedom. We may start to flex the knees, move the trunk, rotate the wrist. Our joints and segments start to move independently of one another.

When this ‘freeing’ occurs it is evidence of an improvement in both movement skill and movement variability.

From learning to walk to learning to dance, the body undergoes this same method of initially reducing movement variability by creating a rigid, yet easily controllable system…to increasing movement variability by creating fluid and flexible movement which can easily adapt to changing task and environment constraints.

Higher skilled movers have more movement variability. Meaning they can execute the same outcome or end result with more consistency, but do so using slightly different motions at each joint with every repetition.

Less skilled movers have more variability in outcomes and results, but move in a similar way at each joint with each repetition.