How Structure Affects Function

This blog is focused on the central nervous system - how it affects the way we move and feel, and what we can do to change its function in that regard. But that doesn't imply that the structure of the body is unimportant, or that good movement is “all in your head.” The structure and health of the musculoskeletal system are essential for quality movement, just as a mechanically sound car is required for safe driving.

Further, the structure of the body has significant effects on how the nervous system performs many functions, including motor control. In fact, certain motor control options are impossible without the right structure.

Moving well and moving often

Many people who are focused on the importance of building good movement patterns would agree with Gray Cook's idea that we should "move well before moving often."

For example, one should learn how to do a bodyweight squat with good form before loading up that squat with heavy barbells. And someone should not go out and run a full marathon without first ensuring their gait pattern is not concentrating excessive stress into some vulnerable area. From this perspective, the order of progression is to first develop good movement patterns, and only then load the patterns to develop strength, power, endurance, etc.

But it should be remembered that sometimes the opposite progression is needed - strength, power or endurance must come first in order to support the desired movement patterns. This is because every movement pattern requires some minimum baseline of strength, power or endurance, and that baseline might not be there.

For common every day activities like walking, sitting and standing, these minimum levels are pretty low. But some people fall below them, and in these cases strengthening will change movement patterns. A study on strength training in nonagenarian women shows that it increases gait speed, which indicates better function and less risk of falling. Strength training may also improve gait patterns in cerebral palsy patients who are particularly weak.

In more demanding activities, strength, power and fitness are far more likely to be limiting factors on what movement patterns are available. For example, if you don't have sufficient strength in a one legged squat position, you will not be able to execute a wide variety of advanced soccer techniques, regardless of your level of coordination. What might appear to be a skill issue is actually a strength/power deficit.

Soccer - Barclays Premier League - Wigan Athletic v Liverpool - DW Stadium

Dynamic systems - why structure affects function

A dynamic systems perspective on motor control implies that it is not dictated solely by movement programs stored in the brain. Instead, the intelligence which creates movement patterns lives in the system as whole. They emerge from the complex interactions of millions of different variables in the body and environment, including the structure of the skeleton, connective tissue and musculature. If we change the structure of the body, we will necessarily change the motor patterns used to control it.

Imagine you are accustomed to driving a Ferrari. First, can I borrow it? Second, imagine you are now driving a 1973 Pinto, with poor acceleration, loose steering, crummy brakes. New patterns of driving will emerge very quickly. You will soon be driving slower around turns, allowing more time to stop, and waiting for larger gaps before merging lanes. These new driving behaviors will emerge naturally without any conscious intention to change.


Or consider the much happier reverse situation, where you switch the Pinto for a Ferarri. Suddenly, a whole range of new driving behaviors are available to you. It won't take long for you to start exploring them and using them. In either case, the decisive factor causing the change in driving patterns is not your driving skill, but the structure of the car.

We can imagine making similar transitions in the structure of the body. What if you lost 20 pounds of fat, gained 10 pounds of muscle, improved the health of a major joint, or healed an old injury? You would be presented with a whole new range of movement options, some of which would be more effective and efficient. You would quickly improve motor control without any deliberate efforts at motor learning.

Lessons from infant development

Esther Thelen performed some fascinating experiments on infants that resolved an apparent paradox with regard to their stepping behavior, which appears early, disappears for a while, and then reemerges later. The prevailing theory was that changes in stepping behavior were due to the infants somehow acquiring then losing the motor control programs required for stepping. But Thelen showed the decisive factor was the relative strength to weight ratio of the limbs. She was able to prevent and enable the stepping behavior by weighting or unweighting the legs. In other words, changes in relative strength caused immediate changes in the system which creates motor control.


I think it's a good idea to spend time working on improving movement patterns, and to avoid heavily loading patterns which are likely to create too much stress in local areas. At the same time, we should recognize that in some cases, one of the quickest and easiest ways to change motor control is to change the structure of the body which we are trying to control.

If you enjoyed this article, here are some others addressing similar topics:

The Difference Between Motor Learning and Exercise

Dem Bones: Skeletal Structure and Movement Function