Body Composition in Soccer (Ukázka, strana 99)

(WHO), all essential amino acids can be found in soy (fermented soy, tempeh); moreover, in a full-scale and balanced meal (combination of legumes with cereals), the amino acid content is similar or often even higher than recommended for animal protein (Hammer et al., 1999).

In terms of timing the protein intake in a soccer player’s diet, it is necessary to divide protein consumption into several servings during the day, predominantly at dinner due to protein’s contribution to optimal recovery after the load. Protein must be consumed on a daily basis.

Protein together with carbohydrates help to optimize glycogen stores and, immediately after the load, a balance of carbohydrates and protein is required (Section 7.1).

7.3 Lipids In chemistry, lipids are referred to as esters of moderate to long chain carboxylic acids. They are natural substances from animal and plant sources. They can be in liquid or solid state.

They are saturated and unsaturated acids. Unsaturated fatty acids are divided into two major groups: omega 3 fatty acids (ALA, alpha-linolenic acid; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid) and omega 6 fatty acids (LA, linoleic acid; AA, arachidonic acid). Alpha-linolenic and linoleic acid are essential fatty acids which must be obtained from food.

Currently, we consume much more omega 6 than omega 3 fatty acids, in ratios of 10:1 or even up to 20:1, despite the recommended ratio of 5:1 for these fatty acids in our diet.

Boisseau et al. (2002) include an analysis of Mono Unsaturated Fatty Acid (MUFA), Poly Unsaturated Fatty Acid (PUFA), and Saturated Fatty Acid (SFA) intake, which reveal a substantially higher percentage of energy intake from SFA (25.6%). This is connected to the olive oil use as the main additional fat, whose use has been seen in the Mediterranean population (Moreno et al., 2002). A high portion of MUFA to total energy intake (13%) has been found, while there is a lower PUFA intake (5%), which is connected to the non-existent use of vegetable oils which contain PUFA, and mainly to a low daily fish intake (2% of total energy intake), compared to consumption of meat, poultry, and meat derivates (12% of total energy intake). The content of omega 6 fatty acids in different types of food has increased as a result of modern agriculture, which offers everyone an excess of cereal products, mostly from wheat, soy, and 98 Ukázka elektronické knihy, UID: KOS528526

other plant sources with a high proportion of omega 6 fatty acids. As a result, the content of omega 6 has increased in many foods including meat, eggs, and dairy products from animals that were fed mainly by cereals.

Generally, in practice, an optimal proportion of lipids in children at pre-school and school age should amount to 30–35% of total energy intake. Although a greater reliance on fat as an energy source during exercise has been described among young athletes (Bar-Or, 2001), there is no data to suggest that adolescent soccer players require a higher lipid intake than adults (Bar-Or & Unnithan, 1994). However, Iglesias-Gutiérrez et al. (2005) report a lipid intake of 38% and cholesterol intake of 385 mg in young soccer players (n = 33, aged 14–16 years). The food intake of these adolescents was based on cereals and derivates; meat, fish, and eggs; milk and dairy products; biscuits and confectionery; and oil, butter, and margarine, which provided 78% of total energy intake, 85% of proteins, 64% of carbohydrates, 90% of lipids, and 47% of fiber.

If a long-term intake of lipids is lower than 27% of the total energy intake, clinical changes related to vitamin A deficiency will appear (Nevoral et al., 2003). Due to inconsistent available literature, where the recommended amount of lipids in soccer players’ diets is about 15–20% in order to maintain optimal body composition, in terms of fat mass proportion, we have to emphasize that qualitative distribution of fats is more important than the quantity of fats, considering that foods containing monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) are basics for a healthy diet (Hu et al., 2002).

Therefore, a well-designed nutrition intervention would be advisable for optimizing performance, and especially for promoting healthy eating habits in adolescent soccer players.

7.4 Vitamins and minerals Vitamins and minerals are often overlooked in athletes’ diets; however, without complex nutrition, which also includes these components, optimal sport performance is not possible. The need for vitamins and minerals in a soccer player’s diet depends on training intensity and frequency, as well as on the player’s age and gender. Generally, it is not recommended to supplement vitamins and minerals in children because their well-balanced diet should cover the amount required for optimal body growth development. Sport, also at the performance level, and 99 Ukázka elektronické knihy, UID: KOS528526

physical load of children are not proven reasons for supplementation since vitamins are catalysts and they are not burned during exercise like carbohydrates. The available studies are contradictory on this point.

Collins et al. (2019) do not recommend using nutritional supplements in children or adults because the important vitamins and minerals should be obtained from food in a balanced diet.

Iglesias-Gutiérrez et al. (2005) report that in young elite soccer players (n = 33, aged 14–16 years) all vitamins and minerals were above recommendations except folate, vitamin E, calcium, magnesium, and zinc.

None of the soccer players in this study reported the use of supplements during the food-recording period. However, 76% of them admitted sporadic use of vitamin, mineral, or vitamin-mineral supplements, especially iron supplements (64% of individuals), due to medical advice (72%), their own decision (16%), or both reasons (12%).

High intravascular hemolysis during training can lead to higher iron losses (Resina et al., 1991). The authors observed iron deficiency (low ferritin levels) without anemia in 48% of the players, although diet provided sufficient amounts of iron (143% of the dietary reference intake) (Food and Nutrition Board, 2002). This condition has often been described among adolescent athletes (Constantini et al., 2000) and is probably related to the increase in myoglobin mass that occurs during adolescence due to high muscular development (Eichner, 2000).

There is no study that would explain the need for supplementation of vitamins and minerals due to increased physical activity (load). It is necessary to realize that the need for supplements is individual, depending on individual athletes’ metabolisms or eventual health complications (problems with nutrient absorption); therefore, it is not possible to give general recommendations for the given age category, or, specifically, for elite soccer players.

In practice, up to 80% of athletes use nutritional supplements to add vitamins and minerals. However, supplementation will never replace a balanced diet and is also useless unless one of the factors from the triangle load-diet-recovery does not work.

The basic vitamins necessary for optimal functioning of the organism are shown in Table 13. The body does not produce vitamins and we have to consume them through food or supplements, optimally daily, in the recommended amounts (Table 16). Vitamins are not a source of energy for soccer players, but they are catalysts that regulate biochemical reactions in the body. Without vitamins, the human body cannot work optimally.

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