BEGINNERS' LIBRARY ( Part I )

BEGINNERS' LIBRARY ( Part I )

* You don't have to have a degree in Human Bio or Phisiology or be a neurologist to become a bodybuilder. Regardless, the following are very important for you to know as they can and will help you put on serious mass and strength in no time without the help of drugs *

This is a far superior version of Beginners' Library. The information I had given in my old article is insufficient. Accordingly, I have decided to write a series of more complete articles. I have also provided two links where you can actually see how muscles contract.


So, How do muscles contract?

When a signal ( electrical signal ) gets to the nerve endings which lie next to the ends of fibers, a chemical transmitter, Acetylcholine, is released, and it travels across the small gap between the nerve and the muscle which is known as Neuromuscular Junction. Then, Calcium ions are released from the sarcoplasmic reticulum increasing the amount of calcium in the region of the filaments. Calcium ions combine with the troponin in the thin filaments, and troponin is stopped from inhibiting the myosin-actin interaction allowing the thick and thin filaments to interact, then, contraction takes place. When the "command" for contraction ceases, the release of calcium ions ends and, by an active process using the energy from ATP splitting * ATP splitting is convertion of ATP into ADP + P for energy *, calcium ions are pumped back into the sarcoplasmic reticulum. As this process lowers the level of calcium ions in the sarcoplasm, the calcium ions dissociate from the troponin and the myosin-actin interaction is inhibited. As a result of this inhibition, tension produced by the muscle diminishes.

I see that this science jargon has confused you greatly.

Let me make is simple for you;

Basically, inside the muscle fibers, the signal stimulates the flow of calcium which causes the thick and thin myofilaments * thick and thinn myofilaments are what are called actin and myosin proteins, to be precise* to slide across one another.

When this occurs, it causes the sarcomere * a sarcomere is made up of thick and thin myofilaments * to shorten, which generates force. When billions of sarcomeres in the muscle shorten all at once it results in a contraction of the entire muscle fiber.


For better idea, go to the links below;

http://www.youtube.com/watch?v=JvOyQMxbc78&NR=1

http://www.youtube.com/watch?v=EdHzK...eature=related

In the second video, you can see the blue colour nucleus on the myofibril, right? Those beautiful blue guys are the ones that express genes. To build bigger fibers, they are supposed to express genes.

It can be Slow Twitch, Type I gene or it can be Fast Twitch, Type II a or Type II b. It depends on what twitch the original fiber is.

Remember that the genes they express can be changed with training. REMEMBER THIS LAST POINT, OK? This is how you can become fast twitch dominant.



There is a super cool website which tells you all about these with super cool animated pics. But, for now, you have a sound knowledge of how contractions take place. So, I won't be pasting that link here.


The process repeats as we keep on lifting.

This whole process of muscle contraction relies heavily on substrates such as Calcium, Sodium, and Potassium to name a few. With continuous signals, the concentration of these substances decreases.




Types of Fibers


There are many types of fibers Type X, Type Xb, Type IIb, Type II ab, Type II a, hybrids of type II a and Type I, Type I and blah blah blah.


But, it is ok, you don't have to know all of them. Let's take a look at the three main types of fibers.


Slow Twitch Fibers ( Type I fibers ) = Fatigue resistant, Smallest and Weakest. Easy to activate. Red in colour.



Fast Twitch Fibers ( Type II a fibers ) = Not as fatigue resistant as Type I fibers, but bigger than them, stronger. Not as easy to activate. Red in colour as well.


Fast Twitch Fibers ( Type II b fibers ) = Least fatigue resistant, Biggest and Strongest. Hard to activate. White in colour.




Motor Units


Motor Unit ( MU ) = A motor neuron and All the fibers this neuron innervates.


Largest MUs = Largest neurons and largest muscle fibers ( Type II b )


Medium MUs = Medium neurons and medium muscle fibers ( Type II ab and Type II a )


Smallest MUs = Smallest neurons and smallest muscle fibers ( Type I )


Large motor neurons usually contain larger number of muscle fibers, whereas small motor neurons control less number of fibers.

When a motor neuron is activated, all the fibers it control will be used. If it controls 1000 fibers, all 1000 fibers will contract ( twitch ).


Motory neurons send signals to make muscle fibers contract ( twitch ). The faster the signals are sent, the faster the fibers contract ( twitch ) and the more force they produce. Sending signals is known as Firing.


Large motor neurons can fire faster than small motor neurons.

There is a range to how fast they can fire, which is known as Fire Rating or Firing Frequency.

The faster a neuron fire, the faster the fibers it control will contract.

The faster a fiber twitch, the greater the tension on this fiber, hence, the more force output.


When a neuron reaches its limits, it will drop out. Means, it stops firing and all the fibers it controls will stop contracting.





Types of Contractions


The contraction of a muscle does not necessarily imply that the muscle shortens; it only means that tension has been generated. Muscles can contract in the following ways ( I won't include stuff like Polymetric here ):

1. "Isometric contraction"

This is a contraction in which no movement takes place, because the load on the muscle exceeds the tension generated by the contracting muscle. This occurs when a muscle attempts to push or pull an immovable object.

OR

It can also be that the load and force output of our muscles are equal.

2. "Isotonic contraction"

This is a contraction in which movement does take place, because the tension generated by the contracting muscle exceeds the load on the muscle. This occurs when you use your muscles to successfully push or pull an object.

Isotonic contractions are further divided into two types:

a. "concentric contraction"

A contraction in which the muscle decreases in length against an opposing load, such as lifting a weight up.

b. "eccentric contraction" * Refer to my first two articles for more info *

A contraction in which the muscle increases in length as it resists a load, such as lowering something down.

During a concentric contraction, the muscles that are shortening serve as the agonists and hence do all the work. During an eccentric contraction the muscles that are lengthening serve as the agonists (and do all of the work).

For example, while doing chin ups, biceps serve as agonists as the body moves up and down, hence, triceps are antagonists and while doing dips, triceps are agonists and biceps are antagonists.

When an agonist contracts, in order to cause the desired motion, it usually forces the antagonists to relax. This phenomenon is called "reciprocal inhibition" because the antagonists are inhibited from contracting.