Adaptations to Fitness

While we are working on our fitness goals, it is beneficial to know how we are getting better in addition to how to get better. There are a few ways the body adapts to fitness: neurological changes, increased motor unit recruitment, increased cardiac output, hypertrophy.

When you first start exercising, the first 2-4 weeks of strength gains is attributed to neurological adaptations. Just like when you learn any new skill, new neurological pathways are created to make it easier on the body. Think back to when you learned how to snatch. It was difficult at first (it may still be difficult for some!) but after practicing it became easier and easier. This is because the initial neuro pathway got deeper and deeper and less thought was required to perform the new skill, and in this case the snatch.

After those 2-4 weeks, most gains are attributed to increased motor unit recruitment. A motor unit is the combination of the motor neuron and the muscle fibers it innervates. Think of a plug in an outlet. After time, our body is able to recruit more motor units (add plugs in outlets) to increase the force output of a specific muscle or muscle group. With more motor units the muscle is stronger (light is brighter!).

The next adaptation stems from increased stroke volume (amount of blood pumped from the heart). Cardiac output is heart rate x stroke volume. With a higher stroke volume, more blood is pumped to muscles = more oxygen delivery = greater capacity to do work!

Finally, the one some of us all love: hypertrophy. This occurs when the muscle cells increase in size (giving you bigger muscles). This takes about 6 months from when you start strength training, and contrary to what we all think, actually is the least responsible for strength gains.

All of these adaptations are present in CrossFit and all are important to our fitness goals. Think of how you have progressed from day one to now and what has been going on in your body since then. This cycle is not permanent, though. Neuro adaptations are just the beginning, but the beginning can start at any point. You can go back and learn a new movement such as kipping pull ups, cycling toes to bar, etc. We are always adapting!

-Coach Robbie