Fuel and Running – Part 2 – Maximising Glycogen Stores

As mentioned in the previous post, runners use both carbohydrates and fats during a run.

We won’t be talking about protein because protein is only broken down during extreme cases.58d054bbb9c5b14b3eceef810e7bef0c

The percentage of which fuel a runner uses depends on the INTENSITY of the run (which will be discussed in another post!). For now, we will focus on the FUEL.


We are all familiar with carbs – the rice, the breads, the noodles. The very food group people try to avoid when they want to lose weight (Not all carbs are “bad”. You just have to find what is right for you!).


They are stored in the body as glycogen and broken down to glucose when the body needs it.


There are limits as to how much glycogen you can store in your liver (about 100-200g) and muscle tissues (about 400-500g). It takes about 120 minutes of running to deplete your glycogen stores.

As discussed, low glycogen stores and blood glucose levels have ill effects on running performance which would either require you to slow to a walk or STOP completely.

Maximising Glycogen Stores


In runner’s vocabulary, it’s called CARBO-LOADING. Carbo-loading involves significantly increasing carbohydrate intake a few days prior to a race. There is evidence that higher pre-exercise glycogen levels delay fatigue.


Although there are a few limitations on the studies performed on carbo-loading, it is safe to say that runners will benefit from it prior (final 3 days) to racing or running longer distances (especially when it comes to speed and performance).

When and How Much?

Carbo-loading takes place during taper week, 3 days before the big day (NOT one week).

Some people begin carbo-loading a week before the big event and takes this opportunity to “EAT ALL YOU CAN” (not a good idea unless you plan to ruin your race day performance).


The recommended amount is 8-12g per KG per day.

For me (45KG), that is about 450g of CARBS PER DAY, equivalent to about 40 slices of bread. BREAD MONSTAHHHH! Even if you’re a big eater, it is not easy to consume the recommended amount of carbs.

When I was preparing for SCKLM 2014, I wrote down every food and drink consumed. I had to have a sense of what I was putting into my mouth. I calculated exactly how many grams of carbs (in everything) to make sure that I ate the right amount. Even then, I was always on a mini binge at night because I hadn’t eaten enough. Runners can opt to drink (sports drinks, milk etc) their carbs if eating is too much to handle.

I did not practice carbo-loading before race day but I recommend that you try at least once to get the feel of it.

Does it Work?

In my experience, carbo-loading WORKS (for a marathon)! I did not hit the wall when I ran my first marathon. Training and carbo-loading done right? Probably. If anybody is interested, I can share what I had during the carbo-loading phase.


You often hear people “carbo-loading” for every race regardless of the distance. Is it necessary? Carbo-loading is unlikely to be effective for events below 120 minutes. You would have sufficient energy to fuel your run and the excess weight gained during the carbo-loading phase will in fact SLOW you down.

Although carbo-loading during the final 3 days leading up to race day is needed to top off glycogen stores, how you replenish your stores on a day to day basis is probably more important. What you eat DURING training will allow you to recover and ensures that you reap the benefits of your training.

If you’re a serious hard core runner (training up to 2 hours a day), you are effectively depleting your stores during training. The amount of carbs needed on a day to day basis is near the amount required during carbo-loading.FullSizeRender

Runners NEED to EAT!

Now you know that it is important to start off with a full tank!

You wouldn’t drive your car on empty, hey? 😉

Next up, how to reduce dependence on your carbohydrate stores.

Till then,

Keep Running!

8 thoughts on “Fuel and Running – Part 2 – Maximising Glycogen Stores

  1. This blog is funny and informative at the same time. Keep it up!
    Carbo-loading is a little tricky for me as I have high cholesterol.

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