A Brief Overview:
Muscles are the powerhouse of the body, and of obvious importance in any sort of physical activity. Skeletal muscles are the most well known, and are responsible for all voluntary movements. There are other types of muscles that control basic body functions such as breathing, pumping the heart, and digestion, and these will not be discussed here.
Breaking it down:
Skeletal muscles are actually fairly complex in structure. Think about a muscle being one of those Russian stacking dolls made out of wood that has a slightly smaller doll inside of each. Each muscle is made up of lots (and I mean lots) of muscle fibers, or muscle cells. Each muscle fiber contains lots (and I mean lots) of myofibrils; on each myofibril is a series of repeating patterns called sarcomeres, and this is where the magic happens.
When your brain sends a signal to the muscle to contract (called an action potential), a chemical neurotransmitter (sort of like the nerve/muscle ambassador) bonds these microscopic filaments together. This process converts electrical energy from the brain into chemical energy where nerve and muscle meet. A series of chemical reactions produce enough mechanical energy to generate the power required to move your bones, skin, and anything else that can’t move by itself.
All of this is initiated not in the muscle itself, but in the brain from the motor cortex. It’s common to mistake the muscles as the generating force behind movement, because it happens so fast, and mostly without conscious thought. We’ve even created terms like “muscle memory” to imply that muscles are not only responsible for movement, but remember it. Not so! The only part of your body that remembers anything is the brain – without it, muscles are just lumps of protein and goo.
When muscles are subjected to an overload, i.e. worked beyond their capacity, the muscle fibers can become torn. In exercise, these microscopic tears result in the recruitment of specialized cells that repair the fibers and contribute to an increase in muscular strength and size. This small amount of tearing is, in part, why you might feel sore after a lot of strenuous activity.
If the stress on the muscle is far beyond what it can handle, fibers may become torn more severely, resulting in a strain. Hamstring and calf sprains are common in jumping sports, including dance.
- These articles, written for Dance Advantage, give further insight into the unique properties of muscles:
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