How do muscles work?

We have about 650 of them in our bodies. They make possible every move we make, even when we are sleeping. Yet, how many of us really appreciate our muscles? How many of us even bother to keep them in good shape? How many of us, rather, take them for granted with little or no consideration to the vital role they play in our lives.

Too many people today neglect their bodies, including their muscles. The result, of course, is muscular pain, breakdown, and inefficiency. In order to avoid being among those who suffer from muscular neglect, let’s take a minute or two to analyze just what our muscles do for us?

Muscles can lift things – one moment a feather, the next a 100-pound bag of cement. In both cases, the nerve fibers contract completely. How then does the muscle know how to exert the correct amount of force to lift light or heavy objects? Well. A muscle is made up of many bundles of muscle fibers. Each of these bundles of fibers is called a motor unit. Each unit has a motor nerve that branches out at its tip.

Each muscle fiber, therefore, has its own nerve ending to stimulate it. An electrochemical impulse is transmitted by chemicals from the nerve ending to the fiber, causing the fiber in that motor unit to contract. Depending on the type of load to be lifted, a differing number of motor units will be recruited into the contraction process. So, for the feather lift, only a few motor units would be required, whereas for the cement many units would be needed.

So, the central nervous system is constantly making decisions as to how many motor units are required to lift a certain item. The more fibers that contract the bigger and harder the muscle will be. For instance, lifting your bicep to scratch your nose doesn’t require the recruitment of many motor units. Consequently, your bicep will remain soft. But, if you curl a weight up to your shoulder, your bicep will contract forcefully and become hard and will bulge.

The finesse with which we are able to control our muscular strength is dependant on the number of fibers within each motor unit. The fingers have relatively few fibers within their motor units – sometimes less than 10 – and this allows fine fingertip control. The large thigh muscles of the upper leg, however, are not capable of such delicate control. Typically each motor unit will contain in excess of 100 fibers.

Skeletal muscles are composed of fast-twitch and slow-twitch fibers. The slow-twitch fibers are designed for slow and steady use whereas the fast-twitch ones are for quick bursts of energy. People with more fast-twitch fibers are unusually quick in their movements. The proportion of fast and slow-twitch fibers in the body is determined at birth.

The muscles within our bodies need stimulation in order to maintain their function. A well-toned muscular system will not only make it easier to perform everyday physical tasks, but it will also leave you feeling mentally alert and ready for action. So, appreciate what you have in your muscles – and treat them with the respect they deserve.

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