Sports Nutrition Bible

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Energy (ATP)

I was going to start off by talking about Protein, Carbs, Fats etc... but before we go into that i think it's important to explain how the body produces energy. Once you understand how the body produces energy, you will hopefully be able to see for yourself the importance of nutrients.

So....Energy!

Energy is produced by the splitting of a chemical bond in a substance called Adenosine Triphosphate (ATP from here on...). ATP is produced in every cell of the body from the breakdown of carbs, protein, fat and alcohol (booze )

Ok so, what's ATP then?

It's a small molecule with an adenosine backbone with 3 phosphate groups attached. Basically think of a daddy long legs with only 3 legs (on the same side) and a body. The body is the adenosine backbone and the 3 legs are the phosphate groups (hope that makes sense).

What's this got to do with energy?

Energy is released when one of the phosphate groups splits off. So basically the poor daddy long legs only has 2 legs now. Now it has become adenosine diphosphate or ADP. Some of the released energy is used to carry out work (muscle contractions etc...) while the rest (in fact most of it) is given off as heat. That explains why you feel warm when you exercise. Anyways, once this happens ADP is converted back into ATP and a continual cycle takes place, in which ATP forms ADP and then becomes ATP again...

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The Bodys a radiater. . Great Thread good lad ono.

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continued....

ATP and ADP

So the body can only store very tiny amounts of ATP at any one time. Basically there is just about enough to keep up basic energy requirements while you're resting. Obviously when you start exercising, the demand for energy suddenly increases, and the supply of ATP is used up within seconds.

As more ATP must be produced to continue exercising, more fuel must be broken down.


So where does this fuel come from?

Well namely...

Carbohydrate
Protein
Fat
and Alcohol

When the above is eaten, they are broken down (in the digestive system) into their various constituents or building blocks. Then they can be absorbed into the bloodstream.

Carbs are broken down into small, single sugar units: glucose, fructose and galactose. Fats are borken down into fatty acids and proteins are broken down into amino acids. Alcohol is evil and is mainly absorbed into the blood.

The ultimate fate of these 4 components is energy production.

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How is energy measured?

The short answer is.....in calories. I won't bore you with the science of it. Basically that's all you need to know. CALORIES is the answer

Energy Value of Different Food Components

1g provides...

Carbs 4 calories
fat 9 calories
protein 4 calories
alcohol 7 calories

So basically, 1 gram of carbohydrate contains 4 calories, as does 1 gram of protein. 1 gram of booze contains 7 calories while 1 gram of fat contains 9 calories. Easy.

So from that list, you can gather than fat is the most concentrated form of energy. However, that doesn't make it the 'best' form of energy for exercise.

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How is energy produced?

The body has 3 main energy systems in which it can call upon depending on which type of physical activity is being undertaken. These are...

The ATP-PC system

The Anaerobic glyolytic/Lactid Acid System

and...

The Aerobic System


The ATP-PC System

This system uses ATP (as explained before) and phophocreatine (PC, hence the name 'ATP-PC') that is stored in the muscle cells, to generate energy for maximum bursts of strength and speed which last up to around 6 seconds. 20m sprint or near max lift at the gym are examples of maximum bursts.

Phosphocreatine (PC from here on...) is formed when creatine (which is a protein as it happens) is linked to a phosphate molecule. The job of PC is to regenerate ATP rapidly. When the creatine and the phosphate seperate, the free phosphate bond transfers to a molecule of ADP (remember the daddy long legs with only 2 legs). Once this happens, a new ATP molecule is formed (The daddy long legs with 3 legs, curtosy of the added phosphate bond).

Unfortunately the ATP-PC system is in very limited supply. Infact it can only provide around 4 calories of energy. After this, ATP must be produced from other fuels. When this happens other systems take over....

Anaerobic Glycolytic System

This system is activated as soon as you start high intensity activity. It dominates in events lasting upto 90 seconds. 400m-800m sprint is an example of this type of activity.

Anyway, in order to meet sudden large demands for energy glucose bypasses the energy producing pathways that would normally use oxygen. Hence the term 'anaerobic.'

After 30 seconds of this type of exercise, this system contributes up to 60% of your energy output. After around 2 mins, it's contribution falls to around 35%

This system uses carbs in the form of muscle glycogen or glucose as fuel. Glycogen is broken down into glucose, which because of the lack of oxygen present, quickly forms ATP and lactic acid. This is quite ineffective as muscle glycogen dwindles away quite rapdily. Fatigue will also set in due to the build up lactic acid.

lactic Acid and the 'burn'

Just to dispell a myth, it's not actually the lactic acid that causes the 'burn' feeling you can get during or after maximal exercise. The feeling is actually caused by the build up of Hydrogen Ions and acidity. Nice
I'll go into lactic acid later on at some point.....i'm sure


The Aerobic System

This is quite similar to the anaerobic one except ATP is generated from the breakdown of carbs and fats in the presence of oxygen. The process is slower (which means ATP isn't produced as rapidly) but it can produce larger amounts so it's all good.

The aerobic system comes into play after the previous 2 in this topic have pakced in, which only takes a couple of minutes. So after a few minutes energy supply dwitches to the aerobic system.

Basically without going into too much detail, the aerobic system provides the energy required for sub maximal, prolonged exercise.

Fats can be used to produce energy in this system.One fatty acid can produce as much as 200 ATP molecules which makes fats an even more efficient energy source than carbohydrates (glucose can create upto38 molecules of ATP in the same conditions). However fats can only broken down under aerobic conditions when energy demands are quite low. Carbs are more versatile in the sense that they can be broken down in anaerobic conditions.

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Creatine

So i talked about Phosphocreatine earlier on. I explained that PC consisted of a phosphagen molecule and creatine. So,although most of you have probably supplemented or at least heard of creatine, i'd like to give you a brief breakdown of what the compound actually is.

So....What is Creatine?

It's basically a compound that's made naturally in our bodies to supply energy. It's mainly produced in the liver from 3 amino acids:- glycine, arginine and methionine. From the liver it's transported in the blood to the muscle cells where it is combined with phosphate to make phosphocreatine. Just like magic.

The muscle cells turn over around 2-3g of creatine a day. Once PC is broken down into ATP (energy, remember) it can be recycled into PC or converted into a naother substance called creatinine, which is then removed via the kidney in the urine (pee )

Creatine is typically obtained (in diet) from beef, fish and pork. The typical person stores around 120g of creatine. 60-70% is stored as PC while the remainder is sotred as free creatine.

Supplementation

While i'm on the subject, i might aswell go into the supplementation of creatine. I'm sure most of you have tried creatine monohydrate before, or CEE maybe...Probably with decent results.

The most common course of action is to saturate your muscles with a loading phase of creatine, followed by a maintenance phase. This method is effective, but it's not actually the best way of doing things. In fact it's quite a costly way of getting creatine into your muscles.

What should i do then?

Seen as though around two-thirds of this creatine (20g per day) actually ends up in your urine (wee) with only the remaining one-third ending up in your muscle cells.

To reape maximum benefits of creatine supplementation, a better idea would be to take smaller doses spaced throughout the day. The key is to try to slow down the absorption from the gut. This gives the maximum chance of all the creatine ending up in your muscle cells and not in your urine. To do this, try taking only 6g daily (instead of the 20g - for the loading phase), but instead of consuming it at once, in shake format, sprinkle it on your food. Sprinkle 1g at a time over the course of 6 meals which would give you a total of 6g per day. This will actually produce effects equivalent to taking 20g a day. After that, maintenance should only be 2g per day.

Not only will this method save you money, it will also produce less water retention which can only be a good thing. This loading strategy can be repeated every 8-12 weeks.

Cycle length

The maximum effectiveness, it's proposed that creatine is best taken is cycles lasting 3-5 months, followed by one month off cycle.

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Lactic Acid - The Lactic Acid Shuttle

Contrary to popular belief, lactic acid produced by the muscles is not a wasted by-product. Infact it constitutes a valuable fuel (once exercise intensity is reduced).

Once intensity is reduced or stopped completely, lactic acid has two possible fates. Some may be converted into pyruvic acid, when then can be broken down into ATP (in the presence of oxygen). So basically lactic acid produces ATP and can be a valuable fuel for aerobic exercise.

The other fate is....

lactic acid may carried away from the muscle (in the bloodstream) to the liver where it can be converted back into glucose, released back into the bloodstream or stored as gylcogen in the liver. This mechanism for removing lactic acid from the muscle is called the lactic acid shuttle

This also explains why the muscle soreness brought on by hard training is not due to lactic acid. In fact, the lactic acid is usually cleared within 15 minutes of exercise.