In general, the composition of the diet is recommended based on the model of so-called food pyramid.
The base of the pyramid is occupied by bread, cereals, rice and pasta; above is a band equally occupied by vegetables and fruit, yet always on top in white meat, fish and dairy products, the apex of the pyramid , so with a contribution minimum, fats, red meats and sweets.
course, depending on the characteristics of the individual, the type of sport and level of fitness, diet will vary.
DIFFERENCES BETWEEN SPORT
An optimal diet should provide the necessary components and supply the energy needs. There are great differences among sports in terms of energy expenditure.
For example, for a two-day ascent of Mont Blanc takes about 9000 kcal, an Alpine stage in the Tour de France may take well into 6000 kcal a day, a triathlon race around 5000kcal. Even when energy consumption is so high it is necessary respect the rule of "balance", even if this happens in a longer time. In the presence of caloric deficit on the provision, the person loses weight, especially at the expense of fat mass, but also lose muscle protein structure.
endurance sports
in endurance sports is the main fuel represented by fat. Of these there is usually a great willingness in the body, by contrast are relatively limited stocks of sugar. They are present in muscle and liver as a polymer called glycogen (about 200 g in muscles and also in the liver) and as free glucose in the blood (at a concentration of about 0.1g / dl). Even during a test of endurance (marathon trip to the mountains) there is always, compared with a preferential use of fat, some use sugar.
For example, for a period that lasts 3 hours, about '86% of the consumption of oxygen is to oxidize fats and glucose from the plasma, only 14% is used to oxidize the substrate already present in the muscle. The common case is the scarcity of sugar that occurs with the framework of hypoglycemia. For this reason, it is important to replenish the stocks of sugar. Hypoglycemia leads to typical symptoms: extreme fatigue, nausea, fainting, headache. This condition should be prevented, in turn introducing sugar to compensate for the losses. Often, more than the depletion of sugars, there is the problem of dehydration. In this case it is useful to take every 20 min. about 100-120 ml of a beverage containing glucose at a concentration of 3-5% and salt in a concentration sufficient to compensate for those lost by sweating. When the body is approaching the condition of hypoglycemia in the liver implements a particular pathway that, starting dall'aminoacido branched alanine, allowing the synthesis of glucose.
strength sports
In this case, the main problem lies in the fact that training of this type induces muscle hypertrophy and you need to supply the body with a protein that allows the deposition of new matrix proteins. The proteins come from meat, from cheese, milk, cereals (wheat) and some legumes (beans, peas, lentils, chickpeas). The need for media, in terms of protein, 1g is per kg per day. Weight lifters, bodybuilders, gymnasts tend to take even 3 g / kg per day. The physiology research on this topic do not confirm this need. Surprisingly, the protein needs are slightly higher in athletes who engage in endurance tests which easily cover 20-30 km per day in training.
pre-race diet
During the work there is a progressive muscle depletion of glycogen stores that are present in muscle and liver, already after one hour of the race, the decrease in muscle glycogen may be 50%. Furthermore, the rate at which glycogen is metabolized depends on power output, in fact, if the subject is also used in part via the anaerobic glycogen consumption is 18 times faster than the simple aerobically. So the fact of delivering more power you pay for staying with the fuel tank dry. This is the main cause of all races scoppiature a strong aerobic component of long duration. Here, then, the need to maximize your glycogen stores before the race.
pre-race meal (the night before the race): increasing the caloric intake coming from carbohydrates to 75% (normally 50-55%)
Reinstatement of carbohydrates after the race
After a long race and carbohydrates should be challenging. The recommended dosage is 50-75 grams of carbohydrate every two hours. The drinks are rich in sugars are indicated for the restoration after the race. If the carbohydrate is optimal, stocks are reformed at a rate of 5% per hour. So it takes 20 hours for a complete refreshment of glycogen stores. The rate of resynthesis is still variable between subjects and certainly decreases with advancing age.
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