Your carbohydrate store: glycogen reserves
The human organism has an amount of accumulated fat that provides almost infinite energy. It is true, however, that these fats - a fundamental fuel for endurance - can only burn, i.e. provide energy, in the presence of glucose, the small molecules that make up carbohydrates. Carbohydrates reserves, are, on the other hand, limited. They can be accumulated in the liver or between muscle fibers and are called glycogen.
Muscle glycogen is the most abundant and important for performance. The decrease in training in the days preceding the race will help to maintain a good "supply" of it. This is also why there is no need to exaggerate with carbohydrates in the days before the race. The glycogen is also accumulated in the liver to constitute a necessary reservoir to maintain supplies of glucose to all organs of the body, especially the brain, during the day and night.
How to replenish glycogen tanks for the days before the race
The question therefore arises: if glycogen reserves are fundamental, how can they be supplied in view of a competition as the Ironman or the Ironman 70.3? Since your daily diet already contains carbohydrates, maintaining the same amounts of carbohydrates
, together with a sharp reduction in exercise before the race is useful way of fill up your tanks with glycogen.
There's more. The same reduction in training sessions and their intensity in view of the race could also reduce hunger. It is important, therefore, to know how to listen to your body, without exceeding with the amount of food. The risk, in fact, would be to strain your digestion and gain weight.
Carbo-load: how important are carbohydrates?
It is therefore advisable to have the glycogen reserves full at the start of endurance races as it can significantly play at the advantage the overall performance, by obtaining an increase in the exhaustion time of about 20%, reducing the time required to complete the distance by 2-3% and, lastly, to reduce the perception of fatigue. It is therefore clear that the amount of carbohydrates consumed in the days before the race are pivotal to build up the reserves of muscle glycogen, while those consumed in the hours close to the race help also to optimize the reserves of liver glycogen.
Carbo-load: from a classic to a more moderate and equally effective protocol
These advantages were firstly recognized in 1960 by Swedish researchers who defined the protocol of glycogen supercompensation
as a strategy useful to saturate the reserves of liver and muscle glycogen.
The protocol was immediately adopted by the greatest athletes of endurance disciplines. Despite helping to accumulate significant amount of muscle glycogen, it did not take long to show some potential disadvantages:
- Hypoglycaemia during the low carb period
- Practical problems in consuming large volumes of food
- Gastrointestinal problems (diarrhea due to high intake of protein and fat on low carb days)
- Low recovery capacity in low carb day
- Mood disorders in the low carb period (apathy, lethargy, irritability, mood on the ground)
- Increased body weight (saturated reserves = +2 kg, as each g of carbohydrate binds 3 g of water)
The moderate model
From a classic protocol, we now move on to a moderate model, still in use today by athletes and that is declined in 3 strategies
depending on the daily habits of the athletes. Each of these strategies guarantees the saturation of glycogen reserves.
Let's see them in detail:
- Mixed diet with 50% carbohydrate intake
- Diet "poor" (but not free!) of carbohydrates (25%) for 3 days, followed by 3 days of diet rich in carbohydrates (70%), similar to the previous approach
- Mixed diet for 3 days (50% carbohydrate) followed by 3 days of moderate carbohydrate intake (70%)
The protocol changes, but the result in terms of quantity of saturated glycogen is similar and the disadvantages are reduced: in the carbohydrate loading model the quantity of saturated glycogen was 211 mmol/kg ww against 204 mmol/kg ww of the moderate model, considering the maximum capacity of muscle glycogen around 150-250 mmol/kg ww.
And that's not all. There are also two further aspects to consider: the first is that the moderate tapering phase model leads to a reduction in the volume and intensity of training, a factor that already allows itself a saving of glycogen as highlighted in the lines above. The second aspect is that endurance performances such as cycling granfondo or long triathlon races start in the early hours of the morning. The alarm clock, therefore, and with it the breakfast stands on the borderline of time between night and dawn. This means, in practice, low appetite with only a small amount of liver glycogen to be replenished.
How to eat in the 3 days before a long race
Knowing the strategies on how to feed yourself in the 3 days before a long race is a great first step towards a race without fear of running into unpleasant situations. Here are my tips:
- Carbohydrates: 5-7 g carbohydrates/kg/day to be divided into each meal and snack (women may also take a smaller amount as they are already used to a low-carbohydrate diet)
- Protein: maintain a protein intake of not less than 0.3 g/kg per meal
- Attention to fibres: reduce the intake of vegetables, fruit, legumes, whole grains until it is eliminated
- Avoid fasting: consume the snacks avoiding to stay long hours fasting
- Hydration: hydrate, considering that each g of carbohydrates binds 3 g of water (see boiled rise/pasta)
- Cocoa: to stop the training of the days before the race and keep the muscles oxygenated
A practical example of pre-competition feeding
Here is an example of what you could do in the days before the race to optimise your glycogen tanks:
- Olympic Triathlon 51.50 (1500 m swimming + 40 km cycling + 10 km running): on the last day before the race, increase your usual carbohydrate intake and slightly reduce protein, eliminate fruit and vegetables;
- Ironman 70.3 - (1900m swimming + 90 km cycling + 21 km running) the last 1-2 days before the race increases your usual intake of carbohydrates, keep your protein intake constant and eliminate the consumption of fruits and vegetables;
- Ironman - (3800m swimming + 180 km bike + 42.195 km running) in the last 2-3 days increases your usual intake of carbohydrates, keep constant that of protein and eliminate that of fruits and vegetables.
Remember - There are scientific guidelines that can provide useful information especially when combined with field experiences alongside athletes, but every individual is different. Therefore, each athlete will have to develop his/her own pre-exercise routine. The long training sessions and/or conducted at the same intensity of competition are a valuable study to develop and promote a strategy of nutrition and integration.