Carbohydrate Loading - Melbourne Marathon

Yet another topic that can have more opinions than participants. I'll keep things relatively simple. This is my plan as it relates to me. It is the carbohydrate loading plan I have followed many times over the years. I have tried other modifications, and results seemed to be at least less than optimal. Mainly I follow the guidelines from the Australian Institute of Sport. There is a lot of evidence, research and practice behind these guidelines. They are well tested. However, there is a little bit of extra detail to go beyond these guidelines.


AIS - Carbohydrate Loading Fact Sheet.


Depletion

Starts on Monday with a run of approximately 80-90min, which includes 30min at or above marathon pace. This should tap slightly into the stored muscle glycogen, and set up the body for some mild to moderate carbohydrate depletion.


My diet from Monday to Wednesday will be relatively low in carbohydrate. The focus will be on protein dominant foods. The calories will also be relatively low for me. I should feel moderately hungry throughout this phase, but not like "death warmed up" as used to be the norm in the earlier, more drastic depletion phase of past.

It has been argued that the depletion phase is not necessary. Muscle glycogen stores can be enhanced with just 2-3 days of the loading phase itself. However, there is some evidence that the stores can be even higher (the difference of 150mmol/kg/ww to 200mmol/kg/ww). It could be one of those 1%'ers that means the difference in the final kilometers of the marathon.


Loading

Thursday to Saturday will be three days of loading up on carbohydrates. I have reprinted the list from AIS link above. This will be very close to what I eat. My weight is 63kg, so getting in 630g carbohydrate, is 10g/kg, which is about spot on. Remember this is a short term diet, for a very specific goal.

Breakfast
3 cups of low-fibre breakfast cereal with 11/2 cups of reduced fat milk
1 medium banana
250ml orange juice


Snack
toasted muffin with honey
500ml sports drink


Lunch
2 sandwiches (4 slices of bread) with filling as desired
200g tub of low-fat fruit yoghurt
375ml can of soft drink


Snack
banana smoothie made with low-fat milk, banana and honey
cereal bar

Dinner
1 cup of pasta sauce with 2 cups of cooked pasta
3 slices of garlic bread
2 glasses of cordial


Late Snack
toasted muffin and jam
500ml sports drink

This sample plan provides ~ 14,800 kJ, 630 g carbohydrate, 125 g protein and 60 g fat

Hydration

There are two main reasons to ensure appropriate hydration. The first is it will aid the storage of muscle glycogen. About 2mg of water is stored with every 1mg of carbohydrate. The second is hydration status can play a big role during the marathon. Quite simply, becoming dehydrated results in a reduction in performance, and it is almost impossible to maintain adequate hydration during the event. So I plan on doing the most I can prior to race to day to get my hydration up to scratch. This does not mean that I will just drink lots and lots of water. There are plenty of problems that can also cause.

The drinking plan is simple. Each day I will drink about 500ml of electrolyte/hydration formula. This aid the body's absorption and potentially enhance distribution throughout all the compartments. On top of this I will drink water with every meal, and a bit in between. The main guide will be that my urine is nearly clear a few times a day. During the loading phase, I will need to drink a bit more each day compared to usual. It is not about going over the top and trying to hyperhydrate. The plan is to ensure I am properly hydrated, and this can take a few days to achieve. The science isn't strong here, but the theories make sense to me.

Expectations

Not much during the depletion phase. Just a little bit of hunger, and probably a lot of thinking about food, purely because I am placing some restrictions on my diet. Things change in the loading phase. The first day is usually very easy to eat the required amount, but day 2 the appetite typically falls, and this day becomes a struggle. Then on the final day before the race, my appetite usually skyrockets. At this same time I would expect to have gained about 2kg from the increased glycogen and water stored. I usually feel pretty light on this day and into race morning. This is usually coupled with the look of leanness with a hardness to the muscles. Physically and metabolically some switch seems to get flicked on the day before the race.