[This blog was written past Matt Jessee. Matt is a former Athletic Development Intern at Able-bodied Lab and is currently earning his Masters Degree in Exercise Science with an accent in Neuromechanics from the Academy of Mississippi – Ole Miss.]

At Athletic Lab, all athletes are exposed to a variety of intensities. This is by design to get the most out of your training plan. Training heavy or explosive movements is not only fun, but necessary according to the size principle. Yes, size really does matter. This concept is based upon intensity levels and motor unit of measurement recruitment patterns.

Let's starting time have a expect at a couple of definitions:

Intensity, in this case, volition be divers equally a percent of maximal speed, or strength. Therefore to make something more intense would crave an increment in speed, strength, or both.

A motor unit is a motor neuron and the muscle fibers information technology innervates. It consists of both a neuron (nerve cell responsible for stimulating a muscle jail cell) and the muscle cells themselves. Each type of motor unit of measurement possesses different characteristics.

Well-nigh people have heard the terms fast and slow twitch muscles. This refers to the specific characteristics of the different motor units. Muscles comprise some combination of all three fiber types (not just i motor unit is responsible for the whole thing).

Individuals are genetically predisposed to which type of fiber is more ascendant throughout their muscles; however, that doesn't mean you lot should ignore training beyond all intensities. This chart will highlight some of the primary differences between fast and ho-hum twitch classifications.

size principle chart

The size principle states that motor units will be recruited in order of size from smallest to largest depending upon the intensity. When because the diverse backdrop of the motor units this makes sense. The small units don't produce much force, they are tiresome to human activity, and they are resistant to fatigue. The larger units produce a lot of forcefulness, they react quickly, but they are easily fatigued. This allows for smoother, more controlled movements. It besides ensures that the body acts as efficiently as possible from an energy standpoint.

To better empathize this information technology helps to think of muscular functions. For example, postural muscles have to stay active all day long. They take a higher concentration of slow motor units, which can stay active for long periods of time, and they won't tire out easily. They volition exist able to maintain the pocket-sized forces necessary to proceed yous upright, but they aren't capable of producing the large forces that are required for sport performance, or demanding tasks.

When a lot of strength or speed is required, all motor units will be recruited, especially the larger, faster Blazon IIx. If performance is the ultimate goal, and then these motor units should exist trained regularly to ensure adaptation. When trained, the neural pathways become more efficient (faster) and are better able to synchronize with other motor units (more forcefulness). The muscle fibers themselves will modify gene expression, becoming stronger every bit a result. Most people never consider these principles, become to the gym day after mean solar day, and neglect to leave their condolement zone during training. This is not the case at Athletic Lab. Our programming is but another case of scientific discipline coming together operation evolution.