Thread: Creatine FAQ
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Old 04-05-2006, 05:48 PM
EricT EricT is offline
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Default Creatine Cycling

Q: Is there any benefit to cycling creatine? Does my body become accustomed to the creatine and become less efficient at using it?


A: Lyle Mcdonald:

I don't think so. The usual arguments (and there is research behind the concepts but not, in my opinion, the interpretations) regarding creatine cycling are that chronic use causes down-regulation of the transporter and down-regulation of the body's natural synthesis of creatine. Both are logical effects of keeping the body saturated with an outside source. But so what? As long as your muscles stay supersaturated, you should get whatever effects are going to occur (in terms of energy production, increased leverage from water storage, and the rest).

A: Blood&Iron:

This is a good question and one that, unfortunately, does not have a clear-cut answer. A few years back researchers decided to take a look at what happens during long-term creatine supplementation. (1) The study found that chronic administration of creatine does, indeed, lead to a down-regulation of the creatine transport protein, which is responsible for the uptake of creatine into cells (It should also be remembered that creatine supplementation leads to the down-regulation of endogenous creatine production. (2)) The authors hypothesize that since human muscle has an upper limit for creatine content, the down-regulation occurs to prevent the accumulation of excessive intramuscular creatine. They conclude that to prevent this down-regulation, athletes should use creatine for no more than 3 months straight before taking at least a month off. The problem is, as the authors themselves point out, that the down-regulation of the creatine transporter occurs to prevent the accumulation of excessive intramuscular creatine. So, while the endogenous production and uptake of creatine will indeed be down-regulated, this should only result, not in a (substantial) decrease of intramuscular creatine, but in an end to further increases in intramuscular stores. If, however, you remain unconvinced, I suggest trying both protocols to test for yourself whether cycling has merit. In my experience, it does not.

References

1. Guerrero-Ontiveros ML. Wallimann T. Creatine supplementation in health and disease. Effects of chronic creatine ingestion in vivo: down-regulation of the expression of creatine transporter isoforms in skeletal muscle. Molecular & Cellular Biochemistry. 184(1-2):427-37, 1998 Jul.

2. Wyss M. Kaddurah-Daouk R. Creatine and creatinine metabolism. Physiological Reviews. 80(3):1107-213, 2000 Jul.


A: Robert Thoburn:

Brief Intro

Before I start, I’m going to assume that not everyone who reads this article is familiar with the use of creatine supplements.

Your body produces creatine. As we’ll see, the vast majority of it ends up inside your muscles, just as it does in animals. Thus, creatine can also be obtained from the diet, as by eating animal muscles--beef, for instance.

In a nutshell, creatine is typically used by bodybuilders and like-minded fitness enthusiasts to: (1) increase lean body mass (a 2-4 pound gain is not unheard of); and (2) increase the capacity of their muscles to perform intense work, like firing out a heavy set of squats or bench presses at the gym. The latter may be due to the enhancement by creatine supplementation of muscle fiber relaxation (i.e., your muscle fibers can relax more quickly during contraction, thereby increasing their power output) and resistance to fatigue (i.e., your muscle fibers can generate a given amount of force for longer).

Getting ‘accustomed’ to creatine

Now back to your questions. Simply put, the answer is that yes, your body does become ‘accustomed’ to creatine and begin to use it less efficiently with prolonged supplementation.

To understand how this may occur, let’s start at the biological target of your creatine supplements, your muscle fibers.

The bulk of your muscle is made up of muscle fibers. Making these muscle fibers bigger is the ‘Holy Grail’ of cosmetically-oriented bodybuilders like you and I. These fibers are also the site of ~95% of your creatine stores.

Once your muscles are saturated with creatine, you’ll start peeing more of it out.

Unfortunately (depending on your perspective), your muscle fibers can only hold so much creatine. Once they’re full (such as after ‘loading’ with creatine), adding more creatine to your diet than is required to maintain this level is a waste: You’ll just end up peeing more of it out (see Snow and Murphy, 2001 and references therein).

‘Cycling’ creatine: Is there a basis for it?

Unlike some bosses, your muscle fibers don’t have an ‘open door’ policy. Not when it comes to nutrients, anyway. That is, creatine can’t just come and go as it pleases.

There’s a lot more creatine inside your muscle fibers (i.e., intracellularly) than outside (i.e., extracellularly). Thus, if anything, the tendency is for creatine to exit the muscle fiber rather than enter it. Transporting creatine inside therefore requires work.

The work of transporting creatine into your muscle fibers is performed by at least one type of transporter, which is actually a protein. For our purposes, you can think of this protein transporter as a ‘gateway’ that spans the membrane that encloses the muscle fiber. Many such gateways are distributed throughout the muscle fiber membrane, providing numerous possible sites for creatine uptake.

Work requires energy. The energy used in transporting creatine inside your muscle fibers ultimately comes from adenosine triphosphate (ATP). ATP can be broken down to release energy. Some of this escapes as heat, and some is free to be used to perform work, such as creatine transport. The creatine transporter also seems to be dependent on the presence of certain minerals (e.g., sodium, chloride; possibly magnesium, calcium).

As your muscle fibers fill up with creatine, the activity of the creatine transporter seems to rise briefly, and then fall. This so-called ‘down-regulation’ may be most pronounced in your fast-twitch (a.k.a. type II, or ‘white’) muscle fibers -the fibers, incidentally, that tend to be the most responsible to your muscle-building efforts.

Is there any use in ‘cycling’ creatine?

The fact of the matter is that the proposed benefits of creatine ‘cycling’ have not been proven.

As many of you already know, when creatine is transported into your muscle cells, it is attached to a phosphate group to become phosphocreatine (PC). When PC is broken down, it releases energy that can be used to very quickly re-synthesize ATP, without the need for oxygen. Thus, PC allows your muscle cells to produce lots of force in short ‘bursts’, such as is requiring during an intense iron-pumping workout.

PC levels may fall with long-term creatine use (van Loon et al., 2003) and this may be due to transporter down-regulation (van Loon et al., 2003). Dr. Theo Wallimann (Lourdes et al., 1998) therefore suggests consuming creatine for no longer than 3 months at a time, followed by a 1-month ‘creatine-free’ period to avoid complications of creatine transporter down-regulation.

Note, however, that no studies have been performed to demonstrate the superiority of one method of creatine ‘cycling’ versus another (or vs. not cycling at all). Wallimann seems to base his advice on rodent studies, cell studies, and reports of neuromuscular disease linked to defects in creatine transport.

An alternative to cycling might be to simply consume smaller amounts of creatine each day so as to gradually build your muscle creatine levels up to the point of saturation. Thereafter, consume as little creatine as you need to maintain your gains.

How much is that? About 2 g creatine per day. Interestingly, though one study found 2 g to be inadequate to prevent PC levels from falling to pre-supplementation values following the loading phase, the gains in lean body mass and exercise performance realized by the subjects were maintained (van Loon et al., 2003)!

Think about it this way: Consuming, say, 20 or more grams of creatine day is going to expose your body to more of this substance than the human species ever encountered during virtually its entire evolutionary history. Does it not seem reasonable to suggest that a more moderate intake of creatine might be more efficient, if not safer, in the long-term?

Oh, and remember that at least in the first 24 hours of supplementation, creatine transport into muscle will be accelerated by consuming creatine with carbohydrate (e.g., dextrose) (see discussion in Snow and Murphy, 2001).

Creatine isn’t just for Bodybuilders

Finally, it’s worth pointing out that creatine supplements aren’t just for bodybuilders, men, or others hoping to improve body composition, muscular strength and power. In fact, creatine may soon be recommended for a variety of neuromuscular disorders (e.g., Huntington’s disease). Parkinson’s patients may also benefit.

For those concerned about diabetes, short-term (i.e., 1 month) creatine supplementation does not seem to negatively affect blood sugar control (glucose tolerance) or insulin action (Newman et al., 2003). Some studies suggest it may actually improve glucose tolerance under certain conditions (see references in Newman et al., 2003).

References

Lourdes M, Guerrero-Ontiveros, Wallimann T (1998). Creatine supplementation in health and disease. Effects of chronic creatine ingestion in vivo: Down-regulation of the expression of creatine transporter isoforms in skeletal muscle. Mol Cell Biochem, 184: 427.

Newman JEN, Hargreaves M, Garnham A, Snow RJ (2003). Effect of creatine ingestion on glucose tolerance and insulin sensitivity in men. Med Sci Sports Exerc, 35: 1.

Snow RJ, Murphy RM (2001). Creatine and the creatine transporter: A review. Mol Cell Biochem, 224: 169.

Van Loon LJC, Oosterlaar AM, Hartgens F et al. (2003). Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci, 104: 153.
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If you act sanctimonious I will just list out your logical fallacies until you get pissed off and spew blasphemous remarks.
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