Sequence of a Muscle Contraction

Initiation of a Muscle Contraction

1) A contraction is initiated in the central nervous system, which is composed of the brain and brainstem. The contraction can either be voluntary or involuntary. We will only be focusing on voluntary contractions, which involve skeletal muscle

2) A motor neuron in the ventral (front part) of the spinal cord is activated, and a new action potential is then generated, which is passed outward in the ventral root of the spinal cord.

3) As the action potential travels down the motor neuron axon it arrives at the pre-synaptic terminal

4) The action potential causes voltage-gated Ca2+ channels to open. The causes Ca2+ to enter into the pre-synaptic terminal

5) The rise of intracellular Ca2+ triggers synaptic vesicles filled with acetylcholine (ACh) to pass readily through pre-synaptic membrane into the synaptic cleft.

6) The ACh vesicles travel across the synaptic cleft, which is only 50 nm wide. The bind to acetylcholine receptors, namely nicotinic acetylchoine receptors (nAChR), the nAChR are found within the sacrolemma, which is the outer surface of a muscle cells.



7) An new action potential is then generated and depolarizes the transverse tubules (t-tubules), which lie along the sacrolemma

8) A depolarization of the T-Tubule causes Ca2+ release from the sacroplasmic reticulum (SR)

9) Ca2+ binds to the tropnon-tropomysion complex in the actin filaments. This releases the inhibition that prevented actin from combining with myosin

10) During muscle action, actin combines with myosin-ATP. Action also activates the enzyme myosin ATPase, which then splits ATP. The energy from this reaction produces myosin crossbridge movement and creates tension.

11) ATP binds to the myosin crossbridge; this breaks the actin-myosin bond and allows the crossbridge to dissociate from actin. The filaments then slide past each other and the muscle shortens.

12) Crossbridge activation continues when Ca2+ concentration remains high enough (due to membrane depolarization) to inhibit the troponin-torprmyson system

Contraction Termination

- ACh at the neuromuscular junction is broken down by acetylcholinesterase (AChE), and this terminates the stream of action potentials along the muscle fiber surface.

- The SR ceases to release calcium ions, and immediately starts to uptake all the calcium ions that have been released.

- In the absence of calcium ions, a change in the configuration of troponin and tropomyosin then blocks the action of the myosin molecule heads, and contraction ceases.





- Kurt Kuhn - www.FUSIONBodybuilding.com

***WBFF Launch Party*** - April 4th Fluid Nightclub

I hope everyone in the GTA can make this - it's gonna be wicked!!!

WBFF LAUNCH PARTY APRIL 4TH FLUID NIGHTCLUB!

Launch of Paul Dillett's
WBFF - WORLD BODYBUILDING FITNESS FEDERATION

Sponsered By: FAREMON PERFORMANCE APPAREL.


www.FUSIONBodybuilding.com

What are Decanoate Esters?

There have been new products making there way into the market place containing decanoate esters. I have done my own investigation and although the intentions of bonding such ingredients such as creatine and other amino acids with decanoate ester sound quite interesting – is it more effective in terms of delivery and is it safe?

I asked a friend of mine – Androgenic - Shawn D. Wells, MPH, RD and Chief Scientific Officer of MAN Sports Inc. to look into this…

***Androgenic Reviews - The Deca Esters***

Chris/Gym God PM'd discussing the validity/efficacy of the decanoate esters. So I decided to turn it into full-blown review as the ******* products are becoming more visible and even had a booth at the Arnold Classic. Let's start of by using the term "deca ester" sure sounds good to the newbie...much like using Test-, -bol, -drol, -strol, or even the classics like "extreme", "X-treme", "hardcore", "ultra", etc.

Back to decanoate. It is an ester that Test or Deca (hence its name...from the nandralone) can be bound to. With test, I talked to Bill Llewelyn last weekend and he stated Cypionate or Enanthate are the best forms for efficacy.

Most steroids are bound to propionate, enanthate, decanoate, cypionate, etc. These slow down the quick release steroids like test. susp. or winstrol that require more frequent injections. Some other IM injection drugs use these esters such as Haldol (psychoactive) or Prolixin (psychoactive).

Decanoic acid is a carboxylic acid (carboxyl group, polar, forms hydrogen bonds with each other, reacts with bases)...when a salt or ester (organic compound in which an organic group replaces the hydrogen in a hydroxyl group) is made it is then called decanoate. Esters are similar to salts except with a general salt it is a cation (+) and anion (-) union. Esters are present all through nature and most of the smells you know from fruits, plants, etc. are the ester molecules.

Now, the question of Creatine bonded to "deca" or other amino acids has been asked. Since more than half of the molecular weight is in fact the decanoate ester and not the creatine...you'd have to hope that this form is more than 2x as effective (and that doesn't factor in cost at all...CM can just be dosed higher for pennies). So, is it more effective? Well, the ester makes it lipophilic (use van de Walls forces and basically its means "likes fat"). Therefore, this specific ester has a longer half-life endogenously due to it being attracted to the fatty tissue/adipose.

OK, now you may be thinking it’s a long acting form of arginine, creatine, or tyrosine. Although, this is a point worth discussing - is that even what you desire? The longer acting it is, the more (dramatically more) would be needed to be dosed to ellicit an acute response such as NO type effects. Besides that issue, if long-acting is what you desire...here's the kicker...

Decanoate, is meant to be injected. All the data I have presented is as such. It is fully illogical to extrapolate those chemical properties of IM medications and steroids to creatine and amino acids take orally. Further, creatine and amino acids have great absorption rates (depending on the scenario endogenously). Its value is poor, its science is worse. You will have to use more than twice as much to get the same effect as creatine monohydrate or Arginine HCL or Tyrosine HCL alone.

Stupid. You betcha. Wait, it gets better. Besides overpaying for oil cans with half as potent pills there's safety issues.

http://www.sciencelab.com/xMSDS-Decanoic_Acid-9923668Here's the MSDS on decanoic acid a.k.a capric acid (not bonded, but then it does become unbonded internally, breaking apart from the creatine, arginine or tyrosine)...so I am unsure as to how much of an issue this is. Further, the MSDS is talking about the acid as a liquid. Nonetheless, it lists it as hazardous to skin, eye, inhalation and ingestion. It says it has proven carcinogenic effects? Hmm.

The LD50 (lethal dose for 50% of the tested animal) is 3-4g/kg or 300-400g. That's extrapolated and not converted for metabolic differences. So, huh, again. This would equate to less than 1kg of creatine decanoate.

I've had trouble finding any of the IM esters toxicity/safety data to extrapolate the consumption of the bound salt. Nevertheless, here we stand.

Why would you use this product at all?

It’s rhetorical and deeply sarcastic. Bottom line is don't use this garbage and be offended that these companies continue to try and scam you.

Shawn D. Wells, MPH, RD Chief Scientific Officer - MAN Sports, Inc.

In Awe of Dawe

Kerrie Dawe - Team ASN Click Here> ASN.com.au




Chris Belanger - VP Sales www.FUSIONBodybuilding.com

CORTISOL - What Bodybuilders Need to Know!

Background Information

Cortisol, also known as the ""stress hormone"", because of its response to stresses such as: emotional, trauma, infection, surgery, and perhaps the most common to bodybuilders, the stress of physical exertion.

Coritsol is a steroid hormone. It is a four ringed structure like testosterone, but has a far different impact on the body. Coritsol, when released into the bloodstream, reacts throughout the body to control the body’s supply of carbohydrates, fats and proteins. It also suppresses the immune system, preparing us to carry on in the face of life’s various stresses.

Coritsol is released by the adrenal cortex, which is located above the kidneys. Parvocellular neurosecertory, cells that are found in the anterior pituitary gland in the brain, control the adrenal cortex and determine whether a stimulus is stressful or not, as defined by the release of cortisol. These neurons lie in the hypothalamus, namely in the periventricular zone of the hypothalamus and release a peptide called corticotropin-releasing hormone (CRH) into the blood. CRH travels the a short distance into the anterior pituitary, where within a small time frame, it stimulates the release of corticotropin, or adrenocorticotropic hormones (ACTH). ACTH enters the blood stream where it stimulates cortisol release.

Blood levels of cortisol are, in general, regulated. As mentioned earlier, cortisol is a steroid, whose precursor is cholesterol. Thus, cortisol is lipophilic, or a "fat-loving" molecule, which can easily pass through membranes and readily cross the blood-brain barrier. In the brain, cortisol interacts with specific receptors that lead to the inhibition of CRH release, ensuring that circulation cortisol levels do not get too high. Interesting enough, neurons with cortisol receptors are found throughout the brain, and not just in the hypothalamus.

Cortisols Effects

Once cortisol is released into the blood stream, it has the potential to decrease amino acid transport into the cell. This decreases anabolism and stimulates protein breakdown, where amino acids are the result, this happens in all cells except the liver. The circulation delivers these freed amino acids to the liver for gluconeogenesis -- the creation of glucose from a non glucose source. Coritsol also serves as an insulin antagonist, by inhibiting glucose uptake and oxidation.

In instances where there are elevated and extended levels of serum cortisol, this can lead to excessive protein breakdown, tissue wasting and negative nitrogen balance. All of which are counter productive to bodybuilders.

Bodybuilders go to the gym to build their muscles, which is named hypertrophy. They must stay in a positive nitrogen balance for muscles to grow. Insulin is also important as it helps drive much needed nutrients into the cell, especially after a workout. There is discussion that two supplements, glutamine and phosphatidylserine are used to produce an anticortisol effect, however, I believe all this comes down to a matter of personal opinion. To keep your cortisol levels low, there are a few choices, two of which are, you could resort to medication or try to stay relatively stress-free. Generally speaking, the less stress there is, the lower your cortisol levels, but keep in mind, there are times when being stress free is difficult, namely after a workout.


- Kurt Kuhn - www.FUSIONBodybuilding.com