Sunday, 2 June 2013

Creatine and ATP

Before reading about creatine it is important to know a little about ATP:

Adenosine triphosphate (ATP) acts as an energy source for the majority of cellular functions within the human body.

ATP is a highly unstable molecule which is readily hydrolysed to ADP and inorganic phosphate (Pi) by the enzyme ATPase. This hydrolysis releases vast quantities of energy which can be utilised by cells to perform work e.g. muscle contraction when weightlifting. ADP is then converted back to ATP using energy that is released by consumption of food. We perform this conversion of ATP to ADP and back again constantly.

The average human has about 0.2 moles (101 grams) of ATP present in their body at any given moment yet uses up approximately the same weight of ATP as their body weight during the course of a day. How this occurs is discussed in more detail in the post about creatine.

I'm sure most of you have already heard of this popular exercise supplement but just in case you haven't:

Creatine is a naturally produced amino acid that is formed in the liver, kidneys and pancreas.
Most people produce around 1-2g of creatine per day.

It is involved in the production of ATP, a molecule which is of vital importance for energy production within cells.

Creatine can be obtained through diet, for example eating red meat.

95% of creatine in stored in skeletal muscle, with the remaining 5% scattered around the body but primarily found within the brain, heart and testes.

While there are some concerns as to the safety of creatine supplementation, these appear to be in the minority. In fact, the European Food Safety Authority has stated that oral consumption of creatine at a rate of 3g per day is considered "unlikely to pose any risk". However, they advise against a high 'loading phase' which is sometimes suggested by those using the supplement. The purpose of a loading phase is to take in as much creatine as your body can hold (each person has a genetic preset amount of creatine which can be retained) and then the maintenance phase begins after this. This is because the body will naturally tend to return to a more normal concentration of creatine but will do so at quite a slow rate, the maintenance phase requires much less creatine per day (usually 2-5g per day) compared to the loading phase (up to 24g per day), though these figures depend on which supplements you are taking.

How creatine works:

Muscle fibres store ATP but in small amounts. We typically have enough ATP in our muscle fibres at any given time to contract at maximal effort for 3 seconds. If you are a seasoned bodybuilder then you may have enough to contract for 6 seconds. However, if we couldn't make more ATP rapidly then we wouldn't be able to move very fast or for long periods of time. That's were ATP synthesis and creatine come together. In order to replenish the ATP molecules as quickly as possible, muscle cells contain creatine phosphate which is a high energy compound. This molecule donates a phosphate group to ADP (when ATP breaks down to release energy for the cell to work, ADP + inorganic phosphate group is formed) in order to reform ATP. Creatine supplementation is useful in that it creates the maximum level of creatine phosphate that a muscle can hold. This maximises its ability to reproduce ATP from ADP and creatine phosphate. The benefit of this is that the increased ability to produce energy allows us humans to sprint faster and longer, or lift heavier weights for more repetitions. By working at a higher level of exertion we cause more minor damage to our muscles which is then repaired, causing greater gains in strength and size.

Creatine itself also increases muscle cell mass. This is thought to occur by firstly attracting water molecules into the cell and by causing an anabolic reaction to form more proteins. Elevated levels of creatine has also been shown to correlate with more satellite cells which repair muscle fibres, meaning that creatine also speeds up the recovery process of cells.

So far I have only covered the physical benefits of creatine supplementation, but there are also mental gains as well. As mentioned before, some creatine is also stored in the brain and it has been shown that creatine supplementation can improve cognitive performance and also reduce the effects of sleep deprivation. In the case of sleep deprivation, the brain loses creatine levels and when these are increased by supplementation levels of mental performance are maintained for longer.

When taking creatine:

Creatine in powder form is stable but once dissolved in water will begin to degrade and form creatinine. Creatinine is a waste product and if ingested will be removed from the blood stream by the kidneys and so has no productive use. This is quite a slow process, but all the same if you are adding water to creatine then it is recommended that you drink the resulting solution within 48 hours of it being made. This prevents significant accumulation of creatinine.

Creatine also degrades at a temperature of 303 degrees celsius which means that boiling water can be added to creatine powder in order to dissolve more of it.

Many people gain 6 to 10lbs during the first 2 weeks of starting creatine supplementation and strength gains usually start to occur after the first week. If you don't work out however, you will experience little to no strength gains, but you will still gain weight from the water retention, as water is drawn into the cells by the creatine.

It is generally recommended that you consume at least 4 litres of water per day when using creatine. Also, creatine can be more effectively absorbed in the presence of simple sugars and a very effective and popular juice which can increase absorption is grape juice. This can increase absorption by around 60%!

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