The Science Behind Muscle and Muscle Tissue

In order to better understand what happens during a work out, it helps to understand the basic foundations of your body and the science behind it. Since your muscles are the very substance upon which your workouts exist for, a discussion of what your muscles are made of and what makes them tick is in order.

Muscles are made of muscle fibers, which are thin, long cells that are mostly made of protein. When we lift a weight or put resistance on our muscles, our brain sends a signal to the muscle fibers to contract. The more that muscle fibers contract at the same time, the more powerful the contraction.

After a muscle contraction, there is always a relaxation in the muscle. When fibers contract one after the other, the muscle stays contracted.

What does this have to do with your workout, you say? Try to hold a five or 10-pound weight until your muscles shake. Soon, you will be unable to hold the weight because the muscle will contract after receiving oxygen and then relax and give up when there is no more oxygen left to give it. This is the effect you have when you lift weights to muscle fatigue and/or muscle failure. This phenomenon is an important step in muscular development and growth. In fact, the primary purpose of lifting weights is to purposely tear down muscle tissue. Rest in between workouts is the buildup and recovery phase of the muscle and is called the Principle of Overload.

When you work out, you make your muscle fibers bigger by increasing the number of muscle fibers and this makes your muscles stronger.

There are two types of muscles fibers that everyone is born with, although in different amounts of each. Slow Twitch (Type I) muscles and Fast Twitch (Type II) muscles. Fast twitch muscles are broken down into type IIA and type IIB. Everyone is born with their muscles mixed with these two types of muscle fibers, about 50/50 each on average.

Without getting too scientific and basically stated, slow twitch muscle fibers are meant for endurance activities such as marathons because there are extended muscle contractions. These type fibers fire slower but are in it for the long haul. They assist us when running marathons or other distance runs.

Fast twitch muscle fibers, however, are used for sprinting and activities that require a burst of energy because the fibers fire more quickly.

Although many researchers believe we are born with a 50/50 ratio of fast and slow twitch muscle fibers, there are researchers that believe certain athletes are gifted in specific sporting events based on which fibers are predominant.

For example, a sprinter may be considered to posses about 80% fast twitch to 20% slow twitch fibers. Conversely, a marathon runner that does not have to run very fast but run distance may be considered to have more slow-twitch fibers.

Research is currently being conducted to test whether fast twitch fibers can be changed into slow and vice-versa. In the quest to discover why some athletes are faster or have more endurance than other athletes, researchers are continuously testing athletic strength and power, in addition to speed and endurance.