Efficiency

Efficiency seems to be something nature strives for. I read a line recently that struck a chord: nature looks to do the most with the least. This of course applies to movement as it does to everything else. Whether we realize it or not, we look to maximize our efficiency when we move. We might limit our range of motion to get somewhere faster, or elongating a tendon might be more time consuming than keeping it stiff. Both are in the name of efficiency. Another way to look at this metric is through the lens of energy expenditure. It feels more efficient to move faster and limit joint excursion, however distribution of load requires joints independently of one another and that takes time.

Rotation seems to be one of the most effective and efficient ways to absorb and produce energy. In order to do this, joints and tissues as a whole must be able to move with respect to each other. That is what allows for sufficient energy storage and then release. Each individual joint can accumulate a certain amount of energy storage and over the course of an entire movement. Every joint compounds on the one before until a massive amount of energy can be returned to the environment.  That is the most efficient way to make use of our movement capabilities.

That being said, there are times when we may want to sacrifice efficiency for performance. A powerlifter maxing out, a sprinter looking to set a new record on the 100-meter dash, a baseball pitcher reaching max velocity. Joint movement is as limited as possible, while still creating high levels of energy output. We could look at the spine as a point of reference. If we are only walking, preferably every joint moves with respect to another. Rotating, level by level, in an energy efficient way. In the examples listed above, joints are actually limited in their movement so they can behave like one unit. That one unit is now capable of producing an enormous amount of energy simply due to it behaving like it is one single mass versus many.

Efficiency seems to be what the natural world is seeking. There are different ways to measure this, and depending on the context, we can judge what is more or less efficient. If daily movement is of priority, then ensuring joints move relative to one another is the best solution. High-performance activities require a trade of energetic efficiency to produce high forces/velocities. We can manage our energetic output based on what we value most at the time. There are consequences however. Joints moving independently limits performance, but if you keep everything moving together as one unit then energetic expenditure is massive and health may be sacrificed.

Austin Ulrich, Physical Therapist