COMRADES MARATHON – THE FINAL DAYS – Race Week Eating / Carbo-Loading Debate

by Mark Wolff

So in the previous blog on preparation for Comrades Marathon (if you haven’t read it just click here) I touched on basic guidelines to adhere to around the taper weeks.

In this blog I am going to focus on actual race week which is the week leading up to race day. Its the one week that if managed correctly it can make a big difference on race day.
We already discussed the positive benefits of sleep in leading up to race day and its something that I will briefly re-emphasize on doing all the way up until race day. However in this blog the focus will revolve more around nutrition.

Race week is one where stress levels are higher and sometimes forgotten and last minute preparations can cause a few panic stations among the masses leading to the neglect of areas that are actually important.

Eating well in race week is important not just from a recovery and energy perspective, but also for health. Any foods you consume which you are intolerant to have the potential to ruin your race. Over the years I have seen many athletes succumbing to stomach bugs in race week, which no only weaken you but can also lead to dehydration and severely compromised gut bacteria. If this does happen, your race if you actually manage to get to the start line will start off on the back foot. Its the last thing you need. Focus on foods that you know sit well with you and do not compromise. Do not try anything new. Avoid soups and sauces or anything that you cannot completely identify the ingredients of and make sure you can know exactly what you are eating and play it safe. You have spent months training for Comrades the last thing you want to do is ruin it all in a day.

As far as meals go keep them smaller and frequent and ensure a nice balance of healthy carbohydrates, fats and lean proteins. Lets take a look at carbo-loading which can be a highly debatable subject.
I often hear athletes speaking about carbo-loading without really understanding what the purpose is or how it is achieved. The term carbo-loading is widely used and its purpose is to top up glycogen stores prior to an event in order to maximize muscle and liver glycogen which of course is the quickest source of easily accessible fuel during exercise.

The human body has two primary fuel tanks glycogen and fat. Glycogen you can compare to rocket fuel, it is the main source of fuel when the body is oxygen deprived and is quickly converted to aid the production of ATP (Adenosine triphospate) which of course is what fires our muscles for motion. Our glycogen stores are capable of approximately 2000 Calories of fuel storage. As you can see the glycogen fuel tank is limited in that it cannot last very long and over time will deplete. The other primary fuel tank fat is much larger in that it can harness around 40 000 Calories of fuel. Fat though takes much longer to be converted into ATP molecules and a nice portion of oxygen over time is required to do this. This is where the debate comes in. In shorter higher intensity events glycogen will be a primary fuel source and so the larger the tank and the more it can be spared through the consumption of carbohydrates the longer it will support the effort. Click here to check out my animated video explanation on the fuel tanks to get a better understanding, of how they work.

However we are talking about Comrades Marathon and this is not a race performed at a very high intensity. Its a pace controlled event meaning that breathing should be regulated and more oxygen should be made available to the system. Controlled pacing allows the fat fuel tank to become highly accessible and with a higher rate of fat oxidation during exercise a higher percentage of glycogen will be spared.

Exercise will of course use a percentage of both glycogen and fat however pace will determine which of the two is most used. The question itself of is carbo-loading necessary is now begging to be answered. My answer in short is I do not feel its a major necessity. Why? Because you are in a week where training is at its lowest and by eating healthily constructed meals your glycogen stores will top up nicely over time. If they are topped up to a fraction higher than usual will it make a huge difference over a 90km run? For the average person highly unlikely. If its an elite athlete an percentage gains are the difference between win or loss that is an entirely different debate.
A runner has a higher risk of gaining weight by over ingesting carbohydrates prior to an event and that will just lead to a bit of a tougher day out.
Glycogen does have weight and for each gram of glycogen you would expect to see it bound to 3-4grams of water. So glycogen topping up can certainly lead to higher water retention and a higher weight. If its purely glycogen weight that is not a terrible thing but if its more than just glycogen weight you can land up in a spot of trouble.

Now its one thing saying you are carbo-loading but the question I will ask next is have you done this repeatedly in training ? Do you know exactly what to do and how to do it? Most athletes don’t.

There are 3 types of carbohydrate loading regimes which most athletes utilize. The classic, modified and 1 day regime.

Classic Regime

The classic regime is a complete carbohydrate depletion from 6 – 4 days out from the event with high intensity training to drop the glycogen stores and then reintroducing a high carbohydrate regime to replenish and top them up. Its quite a dangerous regime in that unless you know the timing intimately well you might not top them up in time and secondly doing intensity work the few days before leading up to the event with the lower carbohydrate intake can lead to fatigue.

Modified Regime

A more popular carbohydrate loading regime is the modified regime. Exhaustive training is done 6 days out from the event but along with the introduction of a moderate carbohydrate diet and then gradually building to a higher carbohydrate diet closer to the event is a safer play. However unless you have done this before I would not recommend it.

One Day Regime

In this carbo-loading regime no exhaustive training takes place and there is an increase in carbohydrates a few days out with a large carbohydrate intake the day before the event. Again this needs to be tried and tested.

If you havent experimented with the above before then my suggestions for macronutrient eating during the week is simple.

1. Overall calorie intake MUST drop in line with reduced training volume. Overeating causes weight gain.
2. Ensure you are eating an adequate amount of protein daily prior to the event. I would suggest 1.2 – 1.4 grams/kg of bodyweight and split 3 hourly. It of course also ensures you maintain nitrogen balance.
3. Slightly increase your  carbohydrate intake however in the form of low insulin spiking carbohydrates (Low GI).
Remember the GI index is measured to a 50 gram carbohydrate serving so if you consume in excess of this the GI index does not apply and you would need to look at the Gylcemic Load (GL) in order to ensure you do not trigger an excessive rise in blood sugar post consumption.

If you want to increase the carbohydrate meal the day prior to the event I would suggest eating a slightly higher carbohydrate meal for lunch the day before but keep the night time meal smaller for the sole purpose of being able to get a better nights sleep and avoiding digestive discomfort.

Pre-race nerves can cause havoc with the digestive system and signs of
– Nausea,
– Diarrhea,
– Stomach Cramps and
– Appetite Reduction can easily occur.

There are a few things you can do to deal with this.
Keep Fibre Intake Low
Avoid high fibre foods such as bran, high fibre-breads, cereals and dried fruit rather go with low fibre foods. An example would be white bread as opposed to brown seed or whole wheat bread loaf.
Avoid heavy cruciferous vegetables which can cause flatulence and stomach discomfort

Liquid Food
If you are battling with your appetite in race week then opt for more liquid type meals which can help when your appetite is suppressed. Smoothies, porridges, cereals and soft dense foods are perfectly fine, just ensure you understand the composition.

Acid vs Alkaline
Food type can of course play an important role on digestive acids and trigger stomach issues. The best thing you can do is stick to more alkaline type foods in race week to lower acid levels and keep the stomach happy as well as assisting in the reduction of any inflammation in the body. Caffeine is acidic and can lead to irritability. If you do battle in race week with irritable bowels then keep caffeine to a minimum or even eliminate it.

Hydration is without a doubt a crucial part of race week. Proper hydration is key to arriving at race day completely hydrated and ready to tackle the event. Remember every day during race week you are losing fluid in the form of sweat, urine and faeces and its important to keep topped up. I advocate consuming a hypotonic drink during race week to maximize hydration and this can be consumed daily to ensure the pull through rate is efficient. To understand more about hydration and hypotonic drinks click here
Alcohol in race week is an absolute no! It pulls fluid from the system it dehydrates you and it is completely counteractive to what you are trying to achieve. Save the alcohol for after the event please.

I hope this helps you mentally prepare for the week ahead. You now have time to plan your nutrition and hydration for race week and if you follow these simple guidelines you cannot go wrong.


all the best


Mark Wolff is a certified sports nutritionist and an endurance nutrition and physiology expert with over 20 years experience. An endurance multi-sport athlete with a triathlon, mountain biking and weight lifting background, he works extensively with professional and amateur athletes in a variety of sports disciplines as well as those just wanting to change their lifestyles. He firmly believes that a person can only reach their full potential when their health and nutrition is down packed. Mark’s focus on nutrition and physiology is not just on training and racing, but he places major emphasis on recovery, immune system health, emotional stability, stress management and performance. Mark is co-founder of 32Gi, a sports nutrition company, focused mainly on health and endurance nutrition.

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1 comment

The TRUTH about Carbo Loading | 32Gi June 5, 2018 - 5:10 am

[…] Mark, it’s been extremely helpful and you do have some great visual representations of the different regimes, the classic, the modified and the one day regime which I’ll put a link […]


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