Muscles are one of those things that most of us take completely for granted, but they are incredibly important for two key reasons:

• Muscles are the "engine" that your body uses to propel itself. Although they work differently than a car engine or an electric motor, muscles do the same thing - they turn energy into motion. 
• It would be impossible for you to do anything without your muscles. Absolutely everything that you conceive of with your brain is expressed as muscular motion. The only ways for you to express an idea are with the muscles of your larynx, mouth and tongue (spoken words), with the muscles of your fingers (written words or "talking with your hands") or with the skeletal muscles (body language, dancing, running, building or fighting, to name a few).

Muscles are incredibly sophisticated. They are efficient at turning fuel into motion, they are long-lasting, they are self-healing (muscle tissue is capable of regeneration) and they are able to grow stronger and remember specific motions (techniques) with practice. They do everything from allowing you to walk to keeping your blood flowing!

When we think about muscles involved in training and competing we think about the muscles we can see and feel, e.g. the biceps in your arms, the calf and quads in your legs and the pecs in your chest i.e. Skeletal Muscles

• Skeletal muscle is the type of muscle that we can see and feel. When a body builder works out to increase muscle mass, skeletal muscle is what is being exercised. Skeletal muscles attach to the skeleton and come in pairs -- one muscle to move the bone in one direction and another to move it back the other way. These muscles usually contract voluntarily, meaning that you think about contracting them and your nervous system tells them to do so. They can do a short, single contraction (twitch) or a long, sustained contraction (tetanus).

As a competitor what important bits do we get from this:

• Muscles turn energy into motion - to allow us compete.
• Muscles are self healing* - to allow us to recover.
• Muscles can grow stronger and remember specific techniques, with practice - to allow us improve.
• Muscles MUST receive instruction from the Nervous System**  - to enable all of the above functions.

*Although skeletal muscle is considered to be Voluntary muscle, it still needs to be told what to do by the brain. 

**The brain controls all of these functions by the constant sending and receiving of messages via the bodys vast network of nerves.