Muscles

by Johnny Nguyen, BS, FIT Exercise Director 

The goal of the first single cell organism is movement, by internal fluid mobility and by external displacement. Along the way, movement became more complex for the sole purpose of survival, and so the single cell morphed into multiple cells, and this continued for millions of years until what we end up with are billions of cells in each of us, doing their magic to keep us breathing in the air, erecting skyscrapers, driving in rush-hour traffic, and walking into the sunset on a white-sand beach.

The magic that facilitates locomotion originates in the system of nerve cells, the center of them packed tightly into a global complex of neural network called the brain, descending from which is a spinal cord that moderates information to and from the thousand of nerve tentacles that sprawl into almost every corner of the body, some of which directing our legs to walk along the ocean.

The nervous system is the master that tells our body and all its organs what to do and how to do it. Some of these organs include the heart, liver, kidneys, and muscles, the very drive-system that allows mobility.

Without muscles, we’d be a sack of bones, tissues, and blood. This is as exciting as being a vegetable. Sadly, though, many people who are stuck in a sedentary lifestyle aren’t too far removed from a vegetative state. Muscle wasting comes with advancing age and is hastened by inactivity, leaving the body to resemble a sack of, well, potatoes. And to make the situation more burdensome, our society is in the business of convenience, and as such we enjoy the reward of getting more from doing less, but it ultimately promotes an inactive lifestyle that brings on prematurely deconditioned muscles. Therefore, it is important in our culture to keep muscles healthy and functional through physical training.

From hunting and gathering to walking everywhere as part of a day’s work, if we consider that movement was such a natural part of human evolution, then health clubs and gym memberships seem so contrive in the grand scheme of humanity; but they are for the most part good medicine for a society that weaves so tightly into its social fabric the living room couch. So get up, get to the gym and work those muscles.

There are three types of muscle tissues. They are smooth, cardiac, and striated.

Smooth muscles are considered involuntary muscles, because they generally don’t listen to what we consciously tell them to do. These muscles go on about their business, digesting food within the intestines and moving along undigested material, transporting air within the bronchi while turning away unwanted guests, routing blood within the vessels and directing how much goes to where, and guarding the doorway to the soul by adjusting the size of the iris in the eye. And it’s good to know that smooth muscles also control the bladder so we don’t pee our pants. These muscles do their work silently, and they can keep going long after we’ve fallen asleep.

Cardiac muscle is found only in – you guessed it – the heart. Like the muscle in our legs, the cardiac muscle responds positively to exercise, increasing not only in fiber size but also, as a whole, enlarging the cardiac chambers, favorably allowing the heart to achieve a lower work rate and greater stroke volume while under load. The cardiac muscle is also involuntary, automatic and rhythmic, and the only muscle that doesn’t take a coffee break for the duration of your entire life. There is no other muscle that has greater endurance than the one you have beating in your chest.

Striated muscle tissues are known in Gray’s Anatomy (the book, not the television show) as “striped muscles,” because of their compartmentalized structure. Each muscle fiber resembles a locomotive train, sectioned the entire length of the fiber. Muscle fibers are packaged in bundles within bundles, all the way down to the microscopic level where they house contractile filaments called actins and myosin. When triggered by a nerve impulse, a sequence of chemical reactions occur, ending ultimately in these contractile filaments clawing at and sliding over each other to create a mechanical contraction. A twitch occurs and then a movement, and we skillfully negotiate the gentle slope on the white-sand beach. Striated muscles are voluntary. Unless we’ve had one too many shots of tequila, we can control striated muscles at will.

Because striated muscles originate from, attach to, and, therefore, move the skeleton, they are often called skeletal muscles. Both the muscular and skeletal systems give us our humanly shape, and while the skeleton gives the muscles leverage to pull on for mobility, the muscles give the skeleton the load it needs to build and maintain its strength and density. Strong muscles help to produce strong bones, and strong bones allow the muscles to work optimally – a symbiotic relationship that we’d be wise to nurture and strengthen through physical activity.

About 700 skeletal muscles are found in the human body, and a healthy person can control them without consciously activating a single one. Generally, we just focus on a task, and the body automatically selects the appropriate muscle or groups of muscles to do the job. Whether it’s pouring a glass of water, carrying a grocery bag or snatching a barbell, muscles are recruited to various degrees. And while most of us may think that carrying grocery is an easy task now, this won’t be the case in our golden years when carrying even our own bodyweight becomes challenging, because without continued conditioning, muscles naturally weaken with age, and diminish. As much as it is poetic to age gracefully, it is the ability to walk into the sunset on a white-sand beach without a walker that creates a far more poetic scene. Exercise gives us this chance to enjoy the last few warm days in life’s late season.

Until then for many of us, exercise keeps our muscles strong, lean, and functional, protecting us from injury, and exercise ultimately helps us to defend against the ravages of disease. Give us our health clubs and gym memberships.