I have some questions about creatine that i need cleared up for my debate at UNiversity.
O.k first I want to make sure I have it right;
During muscular contractions ATP uses a phosphate for energy and then the ATP turns into ADP, Then this ADP goes for a “little ride” and along comes creatine with a phosphate in tow and the phosphate reattaches to the ADP forming ATP.
Question 1. Is creatine used only to transport phosphate?
Question 2. The fact that your taking creatine orally, does this mean that your own creatine stores are no longer produced by the body? Is there a feedback mechanism here?
Question 3. What’s the problem during the kreb cycle (if I have it right in the beginning) Do “run out” of creatine or phosphate first?
I realize these questions are probibly pretty basic but I would appreciate if anyone could help me out.
1)Energy is released when the phosphate bonds are BROKEN. Adenosine doesn’t “use” the phosphate (per se), but acts as an energy “carrier”. It’s all a LITTLE more complex, but you get the idea. Also…creatine (in the form of creatine phosphate) is the muscles FIRST and QUICKEST source of energy. However…these stores are RAPIDLY depleted. Also…creatine falls under the class of supplements known as “Cell Volume Optimizers” in that via osmotic gradients, it “pulls” water into the INTERcellular space, thereby a)helping to maximize cellular function and b)“pump-up” the muscle cells.
2)JB,Bill and the guys can help a little here, but I THINK research has suggested that there IS a negative feedback, which is why it is often recommended to cycle creatine. However…the production by the body supposedly returns to “normal” levels fairly quickly.
3)The Kreb Cycle only INDIRECTLY has anything to do with creatine metabolism. It represents the primary mode in which glucose is metabolized in the body. This leads to ENERGY production, which is “stored” in the form of ATP (or more correctly, in the form of the “Adenosine/Phosphate Bonds”. Hope this helps!
Lion King…you da man! Great work, buddy. I’ll see what I can throw into the mix to maybe clear any murky waters or add some fluff to the mix.
Greg…hey, buddy, good questions. Man, I love talking physiology! Here goes: 1. The ATP-PCr energy system is anaerobic and as the King stated it pretty much is involved in activities lasting 3-15 seconds. ATP is the body’s storage form of energy via the breakdown of fuels’ molecular bonds. Phosphocreatine (PCr) is broken down by Creatine Kinase into Creatine, an inorganic Phosphate and Energy. The Phosphate and Energy bind with an ADP molecule to form ATP. Like Mufasa mentioned, PCr stores are rapidly depleted. 2. I’m not too keen on this one. I’d like to hear one of the gurus take this one. 3. The Krebs Cycle is a component of cellular respiration or oxidative phosphorylation (metabolism). The ATP-PCr system isn’t directly relation to the Krebs. At rest, oxidative processes restore the broken PCr bonds. It’s important to note that although PCr stores are rapidly depleted, ATP production continues via other methods.
The human body produces about 2 grams of creatine per day. If you take more than two grams (from foods, or the supplement) your endogenous creatine production will stop. Guess what, if you are not vegetarian, you are eating about two grams of creatine every day. Don’t worry about that, you don’t have to supplement with creatine to shut down your own creatine, and anyway, the body can restart producing creatine easily.