Body Basics: Adaptation- Part 1
Stimulate, Adapt, Recover.
These are the basic 3 processes of exercise and fitness that we've been focusing on. When the topic was introduced, it was to help people gain a very simple understanding of their bodies and what is happening when they hit the gym (or what is not happening). If you haven't read the Body Basics post, or the second post on Stimulation, go back and read those first.
As we progress, it's important to understand what happens when your body is introduced to a stress. Those stresses we talked about were mod
ified through Volume, Intensity, and Variance. Those are very broad topics, so we need to dig a little deeper as to how muscle responds to 3 types of training that all have the ability to be modified by these 3 stresses (the flow chart for this will be great!).
Before we start digging in, you need to know that there are 3 muscle fiber types, what they are responsible for doing, and their primary functions. Those 3 types are:
Type 1A: This is also called slow-twitch muscle fiber, and is responsible for a large amount of movement throughout daily life. It isn't very strong, it contracts at a slow rate, but of the 3 muscle fiber types, it does not get tired easily. This is mostly due to its use of oxygen in creating ATP (energy), which is the most efficient way to create energy. In order to get oxygen to the muscle cell, it also has a large number of blood vessels throughout it. If we were to look at your Thanksgiving Turkey, this is the red meat, which you may notice a lot of in the turkey's legs. This is due to the amount of oxygen the muscle receives, which should not be surprising, since farmed turkeys really only walk around. If you examine that turkey leg closely, you'll actually be able to see the blood vessels that are intertwined throughout the meat.
Type 2B/X: This is also called Fast-Twitch muscle fiber. It produces a lot of force (meaning it's strong), it's larger in size, it doesn't create ATP using oxygen, and it gets tired very quickly. This is the bodybuilder's muscle. If you see an individual who has a large quantity of muscle mass, this is the muscle you see. It's strong, and can do a lot of work....for a short period of time. It primarily uses an energy pathway called the Phosphocreatine cycle (or as some people call it, fast glycolysis), which means that it breaks down elements within the muscle cell to produce energy. This energy process is very fast, but doesn't create lots of ATP, and can only be utilized for a few seconds. If you're looking at your Thanksgiving Turkey, this is the turkey breast. It's white meat, and if you look at the muscle fibers (the long stringy pieces of meat), they're very thick in size. You'll also notice that there is very few blood vessels throughout this muscle.
Type 2A: Often times, this is mentioned before Type 2B, but I think it's appropriate to end on, being that it has qualities from both Type 1A and Type 2B muscle fibers. These are what I like to call "fitness fibers". This type of muscle is strong, but also fairly fatigue resistant. It utilizes both phosphocreatine and oxygen for energy production (not at the same time, but it can do both types). It's also capable of having some size, but does not achieve the size of Type 2B fibers. This is the person at the gym who has some muscle mass, is probably a little leaner, but seems to be able to go for hours on end. They can lift a lot, they can run very far, and people point to them when they visualize their fitness goals. I call it the "fitness fiber" for that reason: It can do everything. If you're looking back at that turkey, this is the slightly darker white meat. I would say it almost looks pink, but I have issues seeing colors and won't go as far as to claim what color it actually is. It has a decent amount of blood vessels in order to receive oxygen, but doesn't always utilize that energy pathway, so it doesn't have quite as much as Type 1A.
These are the 3 muscle fibers type. In part two of adaptations, we'll break down the 3 stimuli you can utilize, and how the muscle fibers will respond to each one, in order for you to maximize your training.