NASM CHAPTER 2 Continued

Well friends we finally made it.

To the part everyone is concerned with.

Building MUSCLE!

Well not really more like the anatomy of muscles and why they do the things that they do.

So there is three types of muscle

• Skeletal- These get the most attention. Why? Because they are what drive athletic performance. Examples of them would biceps, quadraceps
• Cardiac- The most important muscle. Because without the heart beating you are literally dead.
• Smooth- Digestive system uses a lot of these. Like in the esophagus, and I am not a doctor but I think the eyes use smooth muscle as well

When you are thinking of a skeletal muscle, I want you to think of a wire. Stuffed with smaller wires inside, with a layer of insulation. Or think of a bunch of spaghetti noodles wrapped up in a tortilla. The spaghetti noodles are stacked and packed tightly on top of each other.That is a muscle, the more sciency terms Are:

• Fascia- Which is the first layer that surrounds completely the different strands of muscle. The Tortilla.
• Epimysium- Is a more concentrated version of the Fascia. The spaghetti example,imagine that each strand of noodle has a tiny wrap of a tortilla.

Both the Fascia and the Epimysium connect to a Bone. Forming a Tendon. (Remember T=B to M)

Let’s keep using the spaghetti noodle example. Each noodle (or Muscle fiber) is called a Fascile.

Each Facile is covered in another connective tissue wrapping called the Perimysium. In the tiny spaces between the tightly packed noodles (Fascile) there is another connective tissue called the Endomysium.

See look I did add a picture today! It is just because I am a visual person, and this will help me learn.

To find out how muscles move and contract we need to look at the microscopic level.

Using the Spaghetti idea, think of a single noodle. Now think about that noodle microscopically. We see layers of fibers. We look into one of those fibers and see a Myofibrils This is the microscopic level where all the action occurs. Inside that Myofibrils we see even myofilaments. Myofilaments have two pieces which pull against each other to form contractions.

• Actin- Are thin, and they are the filled with different binding sites.
• Myosin- Are Thick and are full of extending anchors, to lock with the binding sites of the Actin.

Please be aware that the combination of Actin and Myosin is called a Sarcomere

Now these two pieces have a strong affinity towards each other, but that is not always good. Imagine if all your muscles were flexed and locked at all times. You would not be comfortable this is where two protein structures come into play.

• Tropomyosin- When the muscle is relaxed this blocks the binding sights on the Actin.
• Troponin- Acts conversely to Tropomyosin, and actually helps guide the myosin to bind with the Actin.

So these two protein structures will balance each other out, unless there is a stimulation to offset the balance. (This is good, because it creates contractions)

Please note that a muscle can only contract and relax. It can not extend. This is why skeletal muscles are somewhat balanced. ie The bicep to the Tricep.

That stimulation we talked about is where the nervous system comes into play. It has a Motor Unit on each and every Muscle Fiber. These Motor Units flood the muscle with chemicals called Neurotransmitters. They also generate an electrical impulse called the ACTION POTENTIAL Which disrupt the balance of tropomyosin and troponin, and thus the Sarcomere contracts.

The primary Neutrotransmitter is ACh or Acetylcholine.

So way back before we had powerful enough microscopes we wondered how muscles could generate so much force. Scientists were stumped until they asked mathematicians about how such a small thing could propel something.

What those mathematicians proposed was The Sliding Filament Theory. Which describes how Actin and Myosin slide past each other. This would later be found to be true.

MUSCLE FIBER TYPES

There are two types of muscle fibers.

• Type 1 (Slow Twitch)- Which can be referred to as Red Fibers. These guys are built with tremendous amounts of blood flowing capillaries, mitochondria (THE POWERHOUSE OF THE CELL), and Myoglobin (Which helps supply oxygen.) Therefore these are great for long term contractions, which provide stabilization and posture control for the body.
• Type 2 (Fast Twitch) These are great for explosive burst of energy.

Type 2 can be further subdivided into

• Type IIx- Fatigue quickly, they have a low oxidative capacity, but are high energy outputs
• Type IIa- Have a slightly higher oxidative capacity. Which means they do not tire out as quickly. Actually TYPE IIa is a nice in between muscle fiber between TYPE 1 and TYPE IIx.

So remember how I said MUSCLES CAN NOT Extend?

As trainers we must be able to classify the muscles being utilized in an exercise and which ones are not. To help us clarify this, we group muscles together.

• Agonist- is the Primary mover. Say you are doing a chest press. You’re agonist muscle is the pectorals.
• Synergist- Assist the primary mover. In the chest press examples the triceps are the synergists.
• Stabilizer- Stabilize the primary and the synergist muscle groups are activated. During the chest press the weight has to go from the arms down to the chest. this weight is transferred through the rotator cuffs of the shoulders
• Antagonist-These guys oppose the primary mover. IE agonist vs. the Antagonist. So during the chest press the posterior deltoid is pulling back against the pectorial muscles.

So there you have it the skeletal muscular system in a real rough nut shell. To know more, become a medical professional. Or use wikipedia, I wont judge.