Muscle is my health engine. I love how it looks and I love how it feels. I like the sensation of muscular power and strength and I especially like what muscle gives me, confidence and personal pride. Muscle allows all of us to perform a great range of recreation and physical activity. Without muscle none of us could move.

Muscle serves the body in many ways, including the generation of heat (thermogenesis), the utilization of stored bodyfat and glycogen as fuel, stability of body position and posture, regulation of organ function, the elimination of waste through peristalsis, the circulation of blood and the endogenous (internal) production of amino acids required for immune cell replication.

The human body is comprised of three types of muscle tissue that function in different ways, skeletal, cardiac and smooth. Skeletal muscle constitutes the majority of the body’s total muscle pool (50%) and is the one that typically gets most of the attention. 640 individual skeletal muscles are attached by tendons to 206 bones. Skeletal (and cardiac) muscle is also called striated muscle because of the presence of alternating dark and light bands.

Muscle Composition

Muscle is predominantly water as in 72% water, 22% protein and 4% fat. What remains is 2% inorganic material. Fat is 15% water, 12% protein, 70% fat and 3% inorganic material. The structure and function of muscle and fat are not the same. They operate and act independent of each other.

A muscle cell is called a myocyte. A fat cell is called an adipocyte. They’re two different types of cells. One cannot turn into the other. You can certainly gain or lose both, but a fat cell cannot transform into a muscle cell and muscle absolutely does not turn into fat.

Skeletal muscle is also defined based on characteristics of function. These include excitability, contractility, extensibility and elasticity. Excitability describes how a muscle can receive and respond to stimulus from the nervous system. Contractility refers to the fibers’ ability to contract or shorten, such as when you make a muscle by squeezing your biceps.

Extensibility is defined by muscle stretch and its ability to extend through a range of motion. Elasticity relates to muscle recoil and how efficiently muscle can return to its original shape after contraction or extension.

Individual muscle fibers are separated, surrounded and protected by bands and layers of connective tissue. A special sheath called fascia surrounds each fiber, and deep fascia connective tissue holds muscle together and separates them into functional groups and bundles. A muscle fiber is actually a single muscle cell comprised of an outer membrane called the sarcolemma.

Think of a major muscle group like your chest or back. Large muscles consist of hundreds and even thousands of independent muscle fibers called vasiculi, which are nicely bundled and wrapped up like a newborn baby in a blanket. Each fiber is internally packed with additional bundles of finer myofibrils. Myofibrils are the contractile elements of skeletal muscle.

Electron micrographs of myofibrils reveal even finer column like structures called myofilaments. Myofilaments consist of thousands of functional units strung together in long chains. Each unit is highly functional and is arranged in compartments called sarcomeres.

There are two types of myofilaments, thick and thin. Thick myofilaments consist mainly of the protein myosin. Thin myofilaments consist mainly of the protein actin. Special bands, zones and lines, identified by letters like A, I, H, Z and M, describe regions specific to the myofilaments myosin and actin, where they overlap and how they interact and interconnect at different points.

Nerve cells that stimulate muscle fibers are called motor neurons and a single motor neuron, including all the muscle fibers it stimulates, is called a motor unit. The process of muscle contraction involves the recruitment of a least one or more motor unit. The ability to recruit motor units depends on the health & condition of our neuromuscular system and is a primary determinant of muscle contraction, muscle force and complete muscular development.

Sliding Filament Theory

The mechanism of muscle contraction is based on a sliding filament theory model originally proposed by Hansen and Huxley in 1954. According to this model muscle contraction occurs as thin filaments slide or pass over thick ones. The filaments themselves do not shorten in length, but simply slide past one another, causing whole muscle bundles to shorten, change shape and become thicker.

Roll up one of your shirt sleeves. Extend your bare arm straight out in front of you. Bend your elbow and bring your fist towards your face. Now contract your bicep with force. Notice how your bicep gets thicker and larger (you hope).

As the filaments slide past each other it causes the muscle to change shape and rise up into a ball. Myosin cross-bridges attach to and pull on actin filaments causing them to slide inward. As the filaments slide and sarcomeres shorten, the entire muscle eventually shortens or contracts, and it all happens because we willed it to.

All or Nothing

Skeletal muscle fibers contract according to an all or nothing principle initiated by thought. Our brain (if we use it) is what makes us human. An electrical impulse strong enough to elicit a contraction response produces maximal contraction of an entire motor unit or none at all. All or nothing!

This principle relates beautifully to human achievement. Throw yourself into whatever you’re doing and don’t hold back. Dive in! Go for it! Don’t look back. Make the decision to either do it or not. All or nothing!

If you put yourself and everything you are into any project, big or small, including your full potential, you can do anything. We are limited by ourselves. Did you know that desire itself is the only evidence you need to achieve your goal? Believe and achieve. Enter the science of epigenetics.

If we want to be well, we have to know what wellness is. Next we must understand how to achieve wellness and finally, we have to apply the work that leads to wellness as an outcome. It’s all about action. You can’t build health (or muscle) without action and effort.

The concept of all or nothing is inherent in the discipline of sport and elite exercise training. You have to know what you want and go after it, like a hungry animal. The entire mechanism is driven by your own desire, energy and effort, and you get back whatever you put in. Call it karma, give and take, divine recycling, reaping and sowing. cause and effect or as Thomas Paine warned the British in New York, "As you do so, so shall you be done by".

I call it courage, honor and integrity (CHI).

Photo by Nicole De Khors from Burst

As always, stay well and live free!

Dr.C