Nutrition

Disregarding many aspects of nutritional intake it seems confirmed that physically active human beings (and therefore athletes/players) have a higher need for calories to meet their “basic” demands and/or to achieve and maintain an ideal bodyweight and body composition (16 - see references below).

With the game intensity and volume in hand it seems questionable what and how much footballers should eat to maintain health status.

Generally, our food consists of macronutrients and micronutrients, which are the two major parts that are made of different compounds and finally used in digestion.

Macronutrients
The four principal classes of macronutrients providing food energy to humans are: carbohydrate, fat, protein (and alcohol) (24).

The energy from the nutrients is “measured” in calories and not only the total amount but also the different percentages for the macronutrients are important.

Carbohydrate is the primary fuel substrate during soccer (18), and consequently high dietary intakes of 60- 70% of total calorific intake have been recommended for athletes (11) and footballers.

However, existing literature with regards to a) the amount of calories consumed by footballers and as a consequence b) dietary recommendations for specific groups are limited.

1) Jacobs stated the (average) daily food intake of professional Swedish footballers and presented a total of ~4900 kcal of which 47%, 30% and 14% derived from carbohydrates, fats and proteins. However, the authors stated that these players did not meet their dietary requirements during in-season.

2) French youth football players (13-16 years of age) consumed 2352 to 3395 kcal/day. When adjusting for weight the energy intake ranged from 38.8 to 55.5 kcal/kg/day. However, the researchers also stated that these amounts were not adequate for this group (16).

3) Russell & Pennock (28) reported a daily calorie intake of ~2800 (±164) in young (17 year-old) professional English footballers which was not sufficient to cover the estimated energy expenditure of ~3600 kcal. However, the diet itself and the recommended percentage of the macronutrients seemed adequate. The intake of carbohydrates, proteins and fats were 56, 16, and 31% of the daily intake respectively (28).

4) Rico-Sanz (25) stated that the daily caloric intake of 17-year old Puerto Rican Olympic football team members was ~3,952+/-1,071 kcal, of which ~53% (8.3 g/kg body weight) was from carbohydrates, 32% from fat, and 14% from protein. Furthermore, Rico-Sanz cited Lemon (17) who stated a protein intake of 1.4-1.7 g/kg body mass per day for footballers.

Mullin et al. (20) provided a formulae to estimated caloric intake for athletic populations:

Energy requirement (kcal/day) = Players weight (pounds) ×35-50 kcal under intensive training

Clark et al. (9) stated 7-10 g/kg body mass for daily carbohydrate intake.

Research was also conducted in female players and Fogelholm et al. (13) reported daily energy intake of 2131 ± 400 kcal with a 111 ± 450 kcals energy deficit in normal weight female soccer players.

Martin et al (18) stated a relative energy intake of 31 kcal/kg/day which falls below the recommendations for female soccer players of 47-60 kcal/kg/day (12). However, carbohydrate (~54.8%), protein (17%) and fat (29%) intakes were in line with recommendations (18) in international female footballers. Fluid intake of 2466 ± 1350 ml/day was sufficient to meet baseline recommendations (18). In the same publication, following guidelines were published for daily carbohydrates and protein intake: 4.0-6.0 g/kg body mass of carbohydrates and 1.2-1.4 g/kg body mass of protein (11). Furthermore, the carbohydrates should be 60-70% of the daily caloric intake with the proteins accounting for 12% and fats for 18-28% (29).

Micronutrients
There seemed to be very limited research with regards to micronutrients, despite reported iron deficiency in close to 50% of adolescent footballers (14).

While major aims of nutrition are similar in youth and adults, one specific issue needs to be taken care of when youth players are targeted.

In developing players, the feeding cycle must cover the power requirements and nutrients to harness physical growth and maturity (6), physical activity (4), which (obviously) adults have already completed.

As a result, special attention should be given to nutrients related to growth (zinc, iron, foliate and calcium).

Recommendations were given with regards to protein consumption (16, 20):

Mullin et al. (20): Protein requirement (g/day) = Weight (pounds) x 0.9-1.0 g during intensive training

Leblance (16) suggested between 1.98 to 2.20 g/kg/day of protein intake for youth footballers.

However, Boisseau et al. (7) reported a nitrogen loss of 1.04 g/kg body mass per day, which resulted in a recommended daily allowance protein of 1.4 g/kg body mass per day.

Scientific investigations also exist about the effect of nutritional supplementation on performance (27).

In 1987, Leatt et al. (15) investigated the supplementation of glucose polymer on glycogen depletion during a soccer match. The players consumed 0.5 liters of a 7% glucose polymer solution 10 minutes before the game and at half-time. Muscle biopsies indicated that the supplementation slowed the muscle glycogen depletion in the experimental group (15).

A similar dose was used in semi-professional/former professional (2) and male university football players (3). The 6.4% carbohydrate-electrolyte solution supplementation seemed to be effective to slow-down fatigue compared to the control group. The ingestion of the carbohydrate-electrolyte solution during the Loughborough intermittent shuttle run test enabled the players (with compromised glycogen stores) to better maintain the passing and sprint performance, compared to the control group which were given water only (3). Furthermore and in the second study, there was a 3% reduction in the Loughborough soccer passing test from before to after exercise in the carbohydrate-electrolyte trial, whereas in the placebo trial the reduction was 14%. The skill performance during the simulated football activity appeared to deteriorate in the last 15– 30 min of exercise. However, providing 52 g/hour carbohydrate during exercise showed a tendency to better maintain skill performance (2).

Russell et al. (26) also showed that carbohydrate supplementation attenuated decrements in shooting performance during simulated soccer match-play.

Additional other research also suggests that carbohydrate ingestion (6.0 – 8.0%) improve sprint time, motor skill (22), and soccer-specific skills (10, 23, 30) such as dribbling and kicking accuracy. The ingestion rate was 30-60 g/hour before and during intermittent exercise (27).

However, a honey-sweetened beverage did not positively affect any football performance (1).

Bishop et al. (5) utilized carbohydrate supplementation to investigate immune response of football players. The authors concluded that in contrast to prolonged continuous strenuous exercise, carbohydrate feeding has minimal influence on the immune response after football-specific intermittent exercise protocols.

Vitamin C and E supplementation was tested in football players during pre-season (31). The results in this study showed that the supplementation may reduce lipid peroxidation and muscle damage during high intensity efforts, but did not enhance performance (31).

Interestingly, there seems to be evidence that protein intake in excess of ~1.7 g/kg body mass per day will not aid more in building and repairing muscles (19).

Education about nutrition seems key (21), not only to get reliable data (8), but also to improve performance and well-being/health of (especially youth) footballers.

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