# Glycogen depletion



## zoco (Nov 23, 2010)

Glycogen depletion


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## Barker (Oct 1, 2009)

Cheers for that mate, sort of knew the majority but it halped clear a few things up!


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## aka (Jun 25, 2010)

thanks


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## chezzer (Apr 17, 2008)

thanks


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## CrazeUK (May 17, 2010)

Cheers pal


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## SoulXedge (Mar 15, 2010)

Good reading! Thor a would copy and paste so people don't have to be redirected:

Our body uses glycogen as a primary source of energy. Glycogen is actually the storage form of glucose (carbohydrates) in animals and humans.It is stored in the liver and muscles.When there is no glycogen available, the body will reach for its secondary energy source - stored fat and muscle protein.

An average person has to do about 30-40 minutes of moderate intensity cardio in order to burn the stored glycogen.This means that if you do cardio for an hour, you are burning fat only the last 20 to 30 minutes, while the first 30-40 minutes you are only depleting your glycogen stores.

There are a few ways to burn mostly fat when you do your cardio workout:

-Do morning cardio or fasted cardio sessions.When your body goes longer periods without food (like fasting or 8-9 hour sleep) it depletes glycogen in order to sustain itself.This is why morning cardio will burn mostly fat.It is a good idea to take a protein shake or BCAA prior to the workout to prevent muscle breakdown.

-Work with weights before the cardio session.Weight training is a glycogen depleting activity and it is a good practice to do your weight workout before the cardiovascular workout.

-Modify your diet and lower the amount of carbohydrates you are consuming.This way the body will not have excess carbohydrates that can be stored as glycogen, so even light activities will burn fat.Many diets are built around the idea of reduction of carbs - just take the Atkins diet for example (lots of protein and fats, but almost no carbs)*

Knowing what glycogen is and how your body uses it will certainly help you maximize your cardio sessions to burn the maximum amount of fat, but this is not the only factor that comes into play when trying to lose fat.* Below are a few other tips that will help you to lose fat.

-Keep a training journal and record your meals and the calories for each meal. The journal will help you tailor your meals and workouts for you and help you find out what works best for you over time.

-Avoid empty calorie sources such as fruit juices, sodas and sweets.Eliminating empty calories can be the easiest and quickest way to cut calories out of your diet.

-Drink about a gallon of water everyday! Water helps metabolize the fat and drinking cold water is actually a calorie consuming process.In order to be absorbed, water will first be heated by the body, burning calories in the process.

-Don't be lazy.Even small things matter.Walking the dog or climbing the stairs will also add up to the whole fat burning process.

*


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## zoco (Nov 23, 2010)

I noticed a big difference since I started fasted cardio, even with light cardio sessions


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## SoulXedge (Mar 15, 2010)

X2 fasted cardio really gave me some major changes!


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## defdaz (Nov 11, 2007)

So many parts of that are just plain wrong.

Basically there are two ways to provide energy to the muscles during exercise - anaerobically or aerobically. Anaerobic energy provision is caple of providing large amounts of energy quickly but over a short period of time whereas aerobic energy supply is only able to provide a lower amount but over a long time period. It's the intensity of the exercise (ok and initial glycogen store levels) that dictates what fraction of the energy being supplied comes from anaerobic or aerobic systems.

Even during your weights session you will be getting some of your energy aerobically - yes, weights do burn fat!

Fat can only be utilised aerobically. Fat oxidation rates do increases slightly as exercise intensity increases, up to a certain point - above this the rate drops. However - it is key to understand that whilst fat oxidation rates, and thus energy provision from fat does increase up to the 65% mark, the actual percentage of energy being provided by fat burning is constantly dropping as intensity increases. So you need to think about whether reaching that 65% (or whatever) V02 mark (or % heart rate, whatever guide you're using) is worth it in terms of the increased glycogen depletion that will occur during the higher intensity. For me, a lower intensity, a nice fat burning rate (not far off maximum) and a higher glycogen level after my cardio is preferable.

Glycogen depletion does affect fat oxidation rates - I'm not arguing this fact, but fat oxidation does occur during low intensity exercise even with full glycogen stores.

So, the point I was trying to make is this:

Fat burning begins immediately! In fact it never stops - ~60% of your energy is provided by fat at rest. All this crap about having to deplete your glycogen levels first is just t*ss. Sure initial glycogen levels in the target muscles does affect fat oxidation rates but not to the point where no fat oxidation occurs. Just crazy talk.

And how does the writer think that training chest or any upper body muscles will affect glycogen levels in your legs and so improve your results from your cardio? Very odd. They sound as if they detest glycogen! As bodybuilders we need to love the stuff. LOVE IT. 

http://jap.physiology.org/content/98/1/160.short - max fat oxidation was at 61% max heart rate (for me at 36 this is just 112bpm).

http://www.bioscience.org/1998/v3/d/holloszy/d1027.htm - a lot of useful information, bit old now

http://www.informaworld.com/smpp/content~db=all~content=a713776167 - during a 1500m run aerobic contribution was 80% (though what fraction of this is from fat or carbs is not specified)!

http://jp.physoc.org/content/241/1/45.short

http://www.ingentaconnect.com/content/adis/smd/2001/00000031/00000010/art00003

http://www.biochemsoctrans.cn/bst/031/1270/0311270.pdf

http://jap.physiology.org/content/80/3/876.short - just another study showing that even during sprint / low duration exercise that aerobically derived energy provision is high.


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## dtlv (Jul 24, 2009)

defdaz said:


> So many parts of that are just plain wrong.
> 
> Basically there are two ways to provide energy to the muscles during exercise - anaerobically or aerobically. Anaerobic energy provision is caple of providing large amounts of energy quickly but over a short period of time whereas aerobic energy supply is only able to provide a lower amount but over a long time period. It's the intensity of the exercise (ok and initial glycogen store levels) that dictates what fraction of the energy being supplied comes from anaerobic or aerobic systems.
> 
> ...


Totally agree, glycogen = friend not foe, both for exercise performance and fat burning. Excellent post :thumbup1:


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