2-3 Days to Go – what’s this ‘carbo’ loading business?

Well firstly ‘carbo’ means carbohydrates which are the most efficient form of energy for the body and the major fuel for high intensity endurance exercise. Carbohydrates foods are all broken down into glucose during digestion. Glucose is stored in the muscles as ‘glycogen’ and it is this store that fuels your muscles during exercise. The levels of glycogen in your muscles are directly related to your diet. Regrettably, we don’t have a never ending store of glycogen in the body. In fact, a typical athlete can only store up to 2000 calories (approx.) of energy as carbohydrate, versus a competitive requirement of 2,800 calories for a marathon.

Endurance exercise beyond 2-5 hours  clearly place large pressure on carbohydrate stores. When your muscles own supply of energy runs out, your body relies on blood glucose to top up your energy stores. This emphasises the importance of eating sufficient carbohydrates before, during and after your marathon to provide glucose to the exercising muscle, prolong performance and enhance recovery time.  Athletes are frequently found to have inadequate intakes of carbohydrate, which during prolonged exercise will result in nausea, light-headedness and onset of fatigue.     

So in the last few days before the marathon it’s all about the carbohydrates. They are the fuel to make those muscles last as long as they can.

The ‘loading’ refers to loading your muscles with enough carbohydrate to build up your muscle glycogen to help you get to the end of the race. Many people still use the old fashioned carbohydrate loading plan which is based on using a 3-4 day depletion period where training was hard and carbohydrate intake was low followed by 3-4 days of high carbohydrate intake or ‘loading’ and reduced exercise. However, this style of carbohydrate loading is a very difficult regimen to follow and often leads to fatigue.

More recent research has now shown that the depletion phase is not required to build up the muscles glycogen stores. In fact, carbohydrate loading in the 36-48h after your last exercise session and resting over that period can build up your muscle glycogen effectively and is more manageable.

So what should you be eating in the last 36-48 hours?

To carbo load effectively, men should try to aim for 10g of carbohydrate per kg of their body weight per day. Women should aim for over 7g of carbohydrate per kg of their body weight per day. This level of carbohydrate intake requires careful planning, particularly for those of you trying to fit it all in around your full time work, commuting and family life.

It is therefore useful to adopt a grazing type eating pattern, with plenty of nutritious carbohydrate snacks between regular meals that are based around carbohydrate foods such as bread, cereal, potatoes, pasta and rice, in addition to all sorts of beans, peas and lentils, fruit, and low fat dairy products. This may mean you have to eat up to 8 times a day so organisation and thinking ahead are key!

The rest days during this carbohydrate loading period before the marathon are vital, not only for recovery of muscles, but also to allow maximum replenishment of glycogen stores.  

The following is an example of the diet for a runner weighing 70kg and contains 700g of carbohydrate (or 10g carbohydrate per kg body weight):

Breakfast    
Large bowl (75g) low-fibre breakfast cereal 200mls low fat milk; 1 medium banana, 3 tbsp of raisins, 250ml orange juice
Snack        
Cereal bar, 1 lt sports drink
Lunch        
2 sandwiches (4 slices of bread) with meat & salad; 125g tub of low-fat fruit yoghurt. 1 pint milk
Snack        
Banana smoothie made with 200mls low-fat milk, medium banana and honey, cereal bar, 2 large handfuls of dried fruit e.g. dates/apricots
Dinner    
1 cup of pasta sauce with 8 heaped tablespoons of cooked pasta (tomato based sauce), 1 large bread roll, 60g turkey, 2 glasses of cordial, 1 portion of grapes (85g)
Late Snack    
2 slices of toasted bread and jam
1lt sports drink

On the day – how can you possibly eat with the nerves!

Many people will opt for a lie in rather than ensure they have a good carbohydrate based breakfast or others just can’t physically face solid foods before a big race. What you have to remember is that breakfast is just what it says on the tin – you are breaking a fast! If the last time you ate the night before the race, was at say 11pm, and didn’t eat any breakfast, your muscle and liver glycogen will already be depleted.

For your breakfast choose a high G, low fat, low fibre, low protein meal. So the aim is to maximise the carbohydrate delivery to your muscles whilst reducing abdominal discomfort. You should aim to get 150-300g carbohydrate through your breakfast. The following examples contain approx 150g carbohydrates:

o    2 large bowls breakfast cereal + 300mls low fat milk, large ripe banana, low fat fruit yogurt
o    4 slices toast with large tin spaghetti, large ripe banana
o    2 rounds thick bread sandwich with meat, low fat yogurt
o    2 rounds jam sandwiches, low fat yogurt
o    4 heaped tablespoons raisins/sultanas & 1 pint low fat milk & 150g low fat yogurt

If you get nervous and your stomach is clenched, try to get up earlier and eat 2-3 hours before the race but no earlier. Avoid eating in the 1-2 hour window before the race so your body has fully digested the food. Choose more compact sources of carbohydrates such as yogurts, dried raisins or sultanas and cereal bars. For those who cannot stomach solid food at all, then take carbohydrates in the form of liquids such as milkshakes or milk with milk with added dried milk powder.

The F factor - Fluids   
The main aim of hydration is to replace losses of fluids and electrolytes, and to provide a source of carbohydrate. The human body is 75% water. Relying on thirst or voluntary intake of fluids will not be enough to maintain hydration status. By the time you feel thirsty you may have already lost 1.5L fluid from your body. You need to be well hydrated coming into your marathon, during it and then avoid dehydration afterwards by replacing your fluid losses.

So aim for 500mls of water in the 2 hours prior to the marathon and, for those who can  manage it and have tried it before, take 300ml-600mls in the 15 minutes prior to your marathon. This effectively loads some water on board for your body to absorb before you get to your first water station. This needs some practice though so do not attempt it for the first time before this marathon!

For those who cannot tolerate solid carbohydrates, isotonic sports that contain approx 6-8% carbohydrates provide fuel and fluid. One 500ml isotonic drink will typically contain 30g carbohydrate.

Every athlete is different and some can take on board a lot of fluid whilst others find it difficult. Ideally you should have used your training months to work on your fluid intake and fine-tune your hydration strategy for events. The best way to match your fluid losses is to measure your sweat loss during training. This means weighing yourself in the same lightweight shorts and singlet pre and post exercise (towel dried after exercise). Then you need to replace 1.5 times your weight loss. Ideally keep your weight loss to 1kg maximum by drinking regularly throughout the race.

What about during the race?
The key to nutrition during the marathon is not to leave it too late. Don’t wait until you start to notice a decline in your pace or start to feel thirsty…at this stage it’s too late to reverse the damage. Start as you mean to go on. Some runners are so keen to keep with the lead pack that they ignore the water stations early in the race for fear of dropping their pace. But ultimately, their pace will drop without adequate carbohydrates and fluid.

So as a guide, your aim is to get in 30-60g carbohydrate and 150-250ml fluid per hour. If you aim to take 200-250ml of isotonic fluid per 5km fluid station, this should provide adequate carbohydrate and fluid. Avoid over drinking, especially women and those who are slower as this can overhydrate you which is not a good thing either.

And after the race – ah sure it doesn’t matter….on the contrary!

What you eat after your marathon is extremely important for those athletes who have training next week and a race schedule ahead and for those whose first marathon this is, or even for those for whom this is a first and last marathon. Adequate carbohydrate and protein will help the muscles to recover and heal and minimise injury. So don’t just head for the bar! Ideally have a carbohydrate and protein containing drink or food within 30 minutes of finishing your marathon.

Aim to take 1g carbohydrate and 0.1-0.2g protein per kg of your body. The following are examples of post race snacks containing 80g carbohydrate and 16g protein:

Then eat your carbohydrate rich meal within 2 hours of this post race snack. And remember to drink 1.5 times every kg of body weight loss through sweating.

So, hopefully you have been practising all the above before this marathon! Don’t try anything mad like taking energy gels for the first time. Stick to what you know you can tolerate and try all the above in your training for your next marathon!!  And Good Luck!

© Richelle Flanagan, BA, MSc, Pg Cert, MINDI