Carbo-loading principles

Carbo-loading for the marathon was pioneered in the 1970s by athlete Ron Hill, who experimented with something he called ‘the diet’. A gold medal winner for the marathon in the 1970 Commonwealth Games, winning in two hours and nine minutes, he credited part of his success to his nutritional preparation.

'The diet’ centres around two distinct phases, namely depletion and loading.

• Depletion — this phase involves eating minimal or almost no carbohydrate, but while maintaining high hydration levels and stocking up on protein. This causes carbohydrate stores to run down and become depleted when running.

• Loading — immediately following the depletion phase, the runner switches to the loading phase. During this phase, protein intake is reduced and carbohydrate intake is increased markedly. Hydration is still maintained at a high level.

• The net effect — the effect of this is that carbohydrate fuel tanks in the liver and muscles super-compensate for the depletion phase and maximize their store of glycogen so that the runner starts the race by running with a near full tank.

Advocates of carbo-loading claim it provides the following:

• Plentiful supply of running energy
• Avoids the ‘wall’
• More energy in the final few miles

Detractors of carbo-loading advise that a modified carbo-loading system is just as effective, and comes without the associated side effects which include:

• Nausea
• Tiredness
• Hunger pangs
• Reduced immune system functioning
• Irritability
• Subsequent bloating
• Poor pre-race fuel stocks

Clearly, carbo-loading has its good and bad points, but it can be modified from the full-blown version oultined earlier. Runners can either employ a full-blown, modified or basic version of carbo-loading.

Use our comparison table below and see which system of carbo-loading will suit you:

Carbo-loading — the realbuzz comparison

Assuming that your race is on a Sunday, start the program with a run of approximately 10 miles (16.1km) on the preceding Sunday, at the same time as your planned race but at a much slower and easier pace. The remainder of your training during this final week tapers towards the big day and the focus is on your nutrition and hydration.

• Full blown carbo-loading system

Description: Nil carbohydrate during depletion phase.

Depletion phase — Sunday to Thursday 12.00 (noon)

1. Starting after your last 10 mile (16.1km) run, completely eliminate any form of carbohydrate.
2. Eat plenty of protein, salad, cheese etc. and keep hydration levels very high.

Loading phase — Thursday 12.00 to Sunday morning

1. On Thursday morning, complete a short run of approximately 4 miles (6.5km).
2. Post run, immediately start eating large quantities of carbohydrate.
3. Focus on complex forms, for example: pasta, whole-grains and rice.
4. Keep hydration high and include small quantities of protein.

Notes: Eat a normal pre-race breakfast, by now you should be feeling very full.

Pros: Could result in a personal best run
Cons: High risk, hard to adhere to, and end result could be low fuel stocks if insufficient fuel consumed during loading phase.

• Modified carbo-loading system

Description: Small quantities of carbohydrate eaten during depletion phase.

Depletion phase — Sunday to Thursday 12.00 (noon)

Similar to the full-blown system but, include a small amount of carbohydrate, for example: breakfast cereal each morning.

Loading phase — Thursday 12.00 to Sunday morning

Exactly the same as for the full-blown system:

1. On Thursday morning, complete a short run of approximately 4 miles (6.5km).
2. Post run, immediately start eating large quantities of carbohydrate.
3. Focus on complex forms, for example: pasta, whole-grains and rice.
4. Keep hydration high and include small quantities of protein.

Notes: eat a normal pre-race breakfast, by now you should be feeling very full.

Pros: Lower risk, the ability to super-compensate may be slightly less but should still result in good carbohydrate stocks.
Cons: May not maximize fuel stores as well as the full-blown system.

• Basic carbo-loading system

Description: Carbohydrate allowed in slightly reduced quantities from normal intake.

Depletion phase — Sunday to Thursday 12.00 (noon)

After your 10 miles (16.1km) run, decrease your carbohydrate intake slightly.

Loading phase — Thursday 12.00 to Sunday morning

In the last three days before your race, increase your carbohydrate intake.

Notes: Prepare exactly as you would for any race.

Pros: No risks or side effects and easy to adhere to.
Cons: Does not invoke the super-compensation technique so fuel stores are unlikely to be at absolute optimum.

Fuelling your running

For the novice, the basic carbo-loading system is most suitable. However, as your experience grows, you may like to try more advanced methods of fuelling up. Clearly there are risks associated with the full-blown system and the possibility that your fuel stocks may not reach maximum if you fail to load sufficiently in the final days. However, if you get the timing right, the benefit of a completely full tank is certain to make the difference as your race progresses.

One option is to experiment with the modified system for your next running event. The risk of experiencing any side effects is lessened, yet there are still significant benefits to enjoy. If you find that it works for you, you can then decide if you really want to go and try the full-blown method or simply stick with method that has served you well before.