May 20, 2001
1- Featured Article:
How does creatine make us stronger?
This Month’s Featured Article:
How does creatine make us stronger?
There are two principal ways to increase our strength. The first is to increase the amount of force-generating muscle mass we have. In other words, the more muscle you have the stronger you will be. Another way is to increase our energy stores. You have more energy, so you can work harder. Creatine does the latter, or increases the amount of energy in our muscles. Later on this may lead to an increase in new muscle proteins, so these two processes are not entirely mutually exclusive.
Within all cells energy is stored in the form of a molecule called Adenosine TriPhosphate, commonly abbreviated as ATP. ATP is simply Adenosine with a tail of Three Phosphates.
ATP can be considered the energy currency of cells. In muscle cells ATP pays for movement. The more powerful the movement, the more expensive it is. Our muscles typically have about 5 seconds worth of ATP in their checking account. Therefore, all out efforts can only last a few seconds before breaking the bank; exhausting our ATP reserves.
To reiterate, we pay for exercise with ATP. In keeping with our currency analogy, think of creatine as an emergency loan to exercising (spending) muscles. Creatine rapidly recreates ATP during exercise. However, in order to do this, creatine must first be energized with a phosphate group. This renders a modified form of creatine called phosphocreatine (PCr), Creatine with an attached Phosphate group.
Phosphates = Energy?
If you’re thinking that energy appears to be associated with the presence of phosphates, you’re right. In actuality, it’s the energy within phosphate groups that the cell uses. ATP liberates this energy by releasing a phosphate group. This energy is then harnessed by the cellular machinery that causes movement. After losing a phosphate group ATP becomes ADP (Adenosine DiPhosphate). However, in order to maintain exercise intensity, ADP needs to be reconverted into ATP.
How does the cell do this? PCr donates its own phosphate group to ADP in order to reactivate ATP. This occurs while we are still exercising. In this manner ATP is re-energized and can continue to pay for movement.
Why doesn’t the cell just store more ATP?
Good question. ATP is a large, heavy molecule. The cell can’t store too much of it. For example, it is generally said that the human body (at rest) contains approximately 100 grams of ATP at any one instant. However, during the day a sedentary person might consume as much as 3/4 of his/her body weight in ATP. Think of it. Doing nothing, I go through 140 pounds of ATP in a single day. Now that I have given my weight away, let me give you another example. If I were to run a marathon, which I wouldn’t, I would go through that same amount in a matter of hours!
PCr, on the other hand, is smaller and lighter. The cell can store much more of it. By using PCr as an intermediate phosphate donor the cell increases its capacity to store high-energy phosphates. We generally have about 4-6 times more PCr in our muscles than ATP.
Take Home for ATP and PCr
In theory, the more creatine our muscles contain, the more PCr they should have stored and the longer our ATP supply will last before becoming exhausted.
Does bulk always lead to strength?
In past issues of the Creatine Newsletter we spoke about muscle volumizing. It may be a good idea to review them here.
The muscle growth that results from “traditional” training is a relatively slow process. Muscle growth in this instance takes weeks and is the result of new muscle proteins being produced. Blood flow to our muscles also increases, which would also serve to increase muscle size. Our strength increases because we have more force-generating proteins and more blood feeding our muscles. This process is known as hypertrophy.
On the other hand, muscle volumizing is the swelling of our muscles with water as a result of a creatine load. Although our muscles increase in size, and you may feel more pumped, this isn’t the source of our increased strength. We now know that creatine makes us stronger by extending our muscle energy capacity. Furthermore, muscle volumizing is very rapid. Volumizing can be observed right after commencing loading, which is much too fast to involve the creation of new muscle tissue. It’s just water.
Therefore, it isn’t size that makes us stronger, but more energy and new muscle proteins.
But, doesn’t muscle volumizing per se have an effect on strength?
Maybe…. Some studies have shown that volumizing itself may stimulate the production of new muscle proteins. However, these experiments were conducted on isolated muscle cells raised outside the animal. On the other hand, similar studies have failed to show an effect.
Biochemical markers of muscle protein production, however, do increase after a few days of creatine supplementation. Whether this is attributed to creatine per se or an indirect effect of the increased exercise capacity conferred by creatine remains to be seen.
It is largely agreed upon that creatine supplementation increases the availability of ATP to exercising muscles. This effect would give you more energy during repeated bouts of intense exercise with sufficient rest periods. Why?….., because it is during the rest periods that our PCr stores are replenished and this can take a few minutes.
Although it also possible that creatine use increases muscle protein production, this effect remains to be clearly demonstrated experimentally.
Therefore, creatine increases our energy stores and may induce the production of new muscle proteins.
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