Nutrition in young players - Part 1

In adult athletes a correct energy balance is crucial to optimize training, recovery and match performance. In young athletes these aspects should remain secondary, the primary objective being the maintenance of appropriate growth and maturation. Research performed up to now on diet manipulation and physiological impact of training is limited by ethical issues concerning their potentially negative effects on growth and maturation processes (1)

In the past few decades the number of young athletes approaching sports aiming at higher level competition has been increasing considerably. This expansion has been favoured particularly by the improvement of specific training means. Training and enhanced physical activity are important, although their impact on the growth process of young athletes has not yet been fully understood. Most of the present knowledge on the adaptations to training and nutrition is  based on studies performed on young university or college students, or on middle-aged or older adults. The present study demonstrates that the energy expenditure and metabolism of adolescents can differ from those of the adults and, therefore, many of these recommendations cannot give any clear and exhaustive view of the real nutritional needs of young athletes (2-3)

The caloric expenditure during the growth stages varies according to the maturation periods, changing from a phase of higher caloric expenditure in early childhood and childhood to a progressively decreasing expenditure in late childhood and adolescence, corresponding to a slower growth rate (5) . In view of this, primary institutions like F.A.O. / O.M.S. / U.N.U. have defined the caloric requirements recommendations according to age. Table 1 gives the caloric recommendations for physically active boys and girls.

 

Journal of Sports Medicine

Age (years)	Boys (kcal/day)	Girls (kcal/day)
6-7	1800	1650
7-8	1950	1775
8-9	2100	1950
9-10	2275	2125
10-11	2475	2300
11-12	2700	2475
12-13	2925	2625
13-14	3175	2725
14-15	3450	2855
15-16	3650	2875
16-17	3825	2875
17-18	3925	2875
Table 1: Daily energy requirements according to age for boys and girls performing high level physical activity From  FAO/WHO/ONU, 2004 [4]

 

In the reference paper “Sport Nutrition For Young Athletes”, 2013, the Canadian Paediatric Society  explains how a correct energy balance in young athletes can improve performance, lower the fatigue of continuous training, reduce the percentage of injuries, optimize recovery (6). The balance between caloric intake and expenditure plays a key role in maintaining muscle mass (7, 8) and also regulates excessive caloric intake that can lead to obesity (9). In Table 2 the recommended caloric intake for boys and girls according to age is reported.

 

Recommended daily caloric requirements  (kcal/day)

Age (years)	Boys	Girls
4-6	1800	1800
7-10	2000	2000
11-14	2500	2200
15-18	3000	2200
Table 2: Hoch AZ, Goossen K, Kretschmer T. Nutritional requirements of the child and teenage athlete. Phys Med Rehabil Clin N Am 2008; 19(2):373-98.

 

The position of the Italian institute on this issue is available freely on the website sito della Società Italiana di Nutrizione Umana S.I.N.U. (http://www.sinu.it/html/pag/tabelle_larn_2014_rev.asp). As an example, the following table illustrates the age range 6 -17. A comparison of the different European and American institutes shows a good consistence of the recommendations for the daily energy intakes favouring  proper growth and maturation.

 

LARN FOR ENERGY
Age	Weight	MB	ENERGY REQUIREMENTS FOR A LAF OF:
(Years)	(Kg)	(kcal/day)	25° pct	Average	75° pct
Male
6	23.3	1030	1480	1640	1770
7	26.2	1100	1580	1750	1880
8	29.5	1180	1690	1870	2010
9	33.2	1260	1810	2000	2150
10	37.2	1320	2210	2300	2460
11	41.7	1400	2340	2440	2610
12	46.9	1490	2490	2600	2780
13	52.7	1590	2670	2780	2970
14	58.7	1700	2840	2960	3170
15	63.5	1780	2990	3110	3330
16	66.6	1840	3080	3210	3430
17	68.2	1860	3130	3260	3480
MB: Basal metabolism; LAF: Level of physical activity; pct: percentile25 MB and energy values are rounded to 10 kcal/day Age according to birth date: e.g., 4 years means the time period between the 4th and 5th birthdays Body weight according to the average values per age reported by Cacciari et al. (2006). For 1,5 years the value has been calculated by interpolation MB estimated by the equation of Schofield et al. (1985) LAF values (25th percentile – average – 75th percentile) were chosen according to the expected distribution in the children and adolescent population (SACN, 2011) equal to: < 3 years 1.35 - 1.39 - 1.43; 3-9 years 1.42 - 1.57 - 1.69; 10-18 years 1.66 - 1.73 - 1.85 Energy requirement obtained by increasing the DET by 1% to take into account the energy deposited in newly synthesized tissues The reported values are given as an example and are not regulatory.

 

Specialist magazines and TV programs very often give advice on the importance of balanced diets but in everyday practice common people are not able to apply these concepts. They lack the quantitative bases to plan the diets for their children and themselves. In this article we are not going to discuss qualitative details of nutrition for young players (this aspect will be illustrated in the coming article “Nutrition in Young Players” Part 2), but rather examine quantitative aspects and, therefore, the main issues concerning proteins, fats and carbohydrates will be reported, together with quantitative recommendations for their correct balance in daily diets.

 

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Proteins are fundamental to the growth process in that they supply all the necessary amino acids, help the development of the skeletal muscle resulting from physical activity and contribute to improve muscle recovery in training pauses.

On average, adult athletes have a quite higher demand for protein intake compared to sedentary adults (10) A general recommendation is an intake of between 0.8 and 1.2 grams of protein per kg of body weight (for instance, for a boy weighing 60 kg values should range between 48 gr and 72 gr daily). The American College of Sports Medicine and the American Dietetic Association recommend for active adults daily intakes between 1.2 and 1.8 gr/kg of body weight (corresponding to 70-110 gr/day for a boy of 60 kg weight) (11,12). This recommendation seems to be adequate also for young athletes (13,14), also because during infancy the growth process and the consequent synthesis of new tissues lead to an elevated demand of amino acids (15).

It is recommended that this daily protein intake is supplied by “whole” foods (16) and not by protein supplements, although the latter are often perceived as essential for growth and building muscles, and for achieving peak performance (17,18,19). The idea that supplements are necessary has been well investigated in adults, but a study carried out on young football players at High School has pointed out the mistaken beliefs concerning the choice and practical usefulness of protein supplements compared to food (20). This wrong idea may originate from the lack of knowledge in nutrition of young athletes who gain information from specialised newspapers and magazines (advertising), from friends and coaches. The advice for young players is to take protein from whole foods such as egg, fish, meat, dairy products, soya, etc. that are well known sources of amino acids providing full support to growth and development of young athletes.

 

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FATS

In terms of caloric requirements most of the sources recommend a lipid intake of about 25% (maximum 30%), that is the same for both sedentary and active individuals (21). An intake higher than 30% should be avoided for it could favour obesity (e.g., a boy of 16 and 60 kg weight with a diet of 3000 kcal/day, a lipid requirement of 25%, that is 750 calories, i.e., about 85 gr/day). Dietary fat (and deposited fat) play an important role not only in favouring healthy growth and maturation processes but also for the absorption of fat-soluble vitamins A, D and K and for the synthesis of cholesterol and sexual hormones (25).

Beside leading to obesity and overweight of young people, excessive lipid intake may start the pathogenesis of cardiovascular disease, which becomes full-blown in adulthood but begins during the growth process as a result of wrong nutritional choices (22, 23, 24) of parents and environment (family, school, etc.). Therefore, it is essential not only to quantify added fats such as oil, butter, etc,, but also to be aware that fats are present  also in fish, meat, cheese, etc, and must be duly considered in order to avoid exceeding the individual daily threshold.

 

Fats per 100g food (Average data varying according to product quality and brand)
MEAT	Beef (steak)  Chicken (breast)  Raw ham  Bologna	15.32 g 0.40 g 18.52 g 35.8 g
FISH	Canned tuna in oil  Salmon (slice)  Sole (frozen)	8.2 g 10.43 g 1.93 g
CHEESE	Grana cheese  Asiago cheese  Ricotta	28 g 21.3 g 7.9 g
CEREALS	Oatmeal  Pasta  Rice	7.5 g 1.5 g 0.5 g
Other foods	Potato chips  Rusks  Biscuits (e.g. Macine)  Mc Donald's (Big Mac)	32.2 g 5.5 g 21 g 26 g
The nutritional values reported here were obtained from USDA (United States Department of Agricolture) database on nutritional values, and INRAN database on foods compositions

 

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CARBOHYDRATES

The sources of carbohydrates for the body are glycogen stores (sugar stored as a reserve) present in the liver and muscles, and carbohydrates taken from food entering the blood stream after digestion. Carbohydrates requirement varies considerably according to several factors such as kind of sport, practise intensity level, gender and environmental conditions. All these variables make it difficult to give a single recommendation, suffice it to say that an increasing training intensity raises the carbohydrate demand and expenditure, which means that the more frequent are weekly intense training sessions, the higher is the carbohydrate daily intake needed. As an indication, at least 50% of the total daily caloric intake, or between 3 and 8 gr/kg body weight daily are recommended (26, 27)

Young athletes demonstrated to be unable to store glycogen in muscles as their adult counterpart, and the utilization of the same carbohydrates by young athletes results to be less efficient and fats remain the primary fuel (28). This inability to store glycogen must be taken into account because it may lead to an accelerated fatigue increase during intense prolonged training as a result of the lack of blood glucose ready for use. To this purpose the possibility of introducing exogenous sources of carbohydrates during training has to be considered.

Coming back to the example of the boy aged 16 some practical considerations can be made on his recommended daily caloric intake and macronutrients breakdown.

 

Boy aged 16, 60 kg weight, 3-4 weekly training sessions and match on the weekend
3000 kcal
Proteins	About 90 g	1.5 g for 1 Kg weight
Fats	About 85 g	25% of daily calories
Carbohydrates	About 480 g	8 g for 1 Kg weight

 

In a forthcoming article we are going to discuss the second fundamental aspect of nutrition, that is the quality of our foods.

 

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Bibliography

[1] John Eric W. Smith, Megan E. Holmes, and Matthew J. McAllister

Department of Kinesiology, Mississippi State University, P.O. Box 6186, Mississippi State, MS 39762, USA

 

[2] J. Aucouturier, J. S. Baker, and P.Duch´e

“Fat and carbohydrate metabolism during submaximal exercise in children” 

Sports Medicine, vol. 38, no. 3, pp. 213–238, 2008.

 

[3] J. S. Harrell, R. G. Mcmurray, C.D. Baggett,M. L. Pennell, P. F. Pearce, and S. I. Bangdiwala

“Energy costs of physical activities in children and adolescents”

Medicine and Science in Sports and Exercise, vol. 37, no. 2, pp. 329–336, 2005.

 

[4] Food and Agriculture Organization of the United Nations, United Nations University, and World Health Organization

Rome, 17–24 October 2001, Food and Agricultural Organization of the United Nations, Rome, Italy, 2004.

 

[5] R.M.Malina, C. Bouchard, and O. Bar-Or

Champaign, Ill, USA,2nd edition, 2004

 

[6]1. Hoch AZ, Goossen K, Kretschmer T.

Nutritional requirements of the child and teenage athlete.

Phys Med Rehabil Clin N Am2008;19(2):373-98.

 

[7] Dietitians of Canada, the American Dietetic Association, and theAmerican College of Sports Medicine.

Can J Diet Pract Res 2000;61(14):176-92.

 

[8] Meyer F, O’Connor, H, Shirreffs SM ; International Association of Athletics Federations

J Sports Sci 2007;25 (Suppl 1):S73-S82.

 

[9] American Academy of Pediatrics, Committee on Nutrition and the Council on Sports Medicine and Fitness

Pediatrics 2011;127(6):1182-9.

 

[10] K. D. Tipton, A. E. Jeukendrup, and P. Hespel

“Nutrition for the sprinter”

Journal of Sports Sciences, vol. 25, supplement 1, pp. S5–S15, 2007

 

[11] S. M. Phillips and L. J. C.Van Loon

“Dietary protein for athletes: from requirements to optimum adaptation”

Journal of Sports Sciences, vol. 29, supplement 1, pp. S29–S38, 2011.

 

[12] N. R. Rodriguez, N. M. Di Marco, and S. Langley

“American College of Sports Medicine position stand. Nutrition and athletic performance”

Medicine & Science in Sports & Exercise, vol. 41, no. 3, pp. 709–731, 2009.

 

[13] N. Boisseau,M. Vermorel, M. Rance, P. Duch´e, and P. Patureau- Mirand

“Protein requirements in male adolescent soccer players”

European Journal of Applied Physiology, vol. 100, no. 1, pp.27–33, 2007.

 

[14] F. Meyer, H. O’Connor, and S. M. Shirreffs

“Nutrition for the young athlete"

Journal of Sports Sciences, vol. 25, supplement 1, pp. S73–S82, 2007

 

[15] D. Nemet and A. Eliakim

“Pediatric sports nutrition: an update”

Current Opinion in Clinical Nutrition and Metabolic Care, vol. 12, no. 3, pp. 304–309, 2009.

 

[16] C.H.Murphy, A. J. Hector, and S. M. Phillips

“Considerations for protein intake in managingweight loss in athletes”

European Journal of Sport Science, vol. 15, no. 1, pp. 21–28, 2015.

 

[17] B. H. Jacobson and S. G. Aldana

“Current nutrition practice and knowledge of varsity athletes”

The Journal of Strength & Conditioning Research, vol. 6, no. 4, pp. 232–238, 1992.

 

[18] B. G.Wiita and I. A. Stombaugh

“Nutrition knowledge, eating practices, and health of adolescent female runners: a 3-year longitudinal study”

International Journal of Sport Nutrition and xercise Metabolism, vol. 6, no. 4, pp. 414–425, 1996.

 

[19] S. S. Jonnalagadda, C. A. Rosenbloom, and R. Skinner

“Dietary practices, attitudes, and physiological status of collegiate freshman football players”

Journal of Strength and Conditioning Research, vol. 15, no. 4, pp. 507–513, 2001.

 

[20] M. C. Duellman, J. M. Lukaszuk, A. D. Prawitz, and J. P. Brandenburg

“Protein supplement users among high school athletes have misconceptions about effectiveness”

Journal of Strength and Conditioning Research, vol. 22, no. 4, pp. 1124–1129, 2008.

 

[21] J. W. Smith and A. Jeukendrup

“Performance nutrition for young athletes” in Nutrition and Enhanced Sports Performance: Muscle Building, Endurance, and Strength

S. D. N. Bagchi and C. K. Sen, Eds., pp. 523–529, Elsevier, 2013.

 

[22] R. J. Bloomer, M. M. Kabir, K. E. Marshall, R. E. Canale, and T. M. Farney

“Postprandial oxidative stress in response to dextrose and lipid meals of differing size”

Lipids in Health and Disease, vol. 9, article 79, 2010.

 

[23] C. Bouziotas, Y. Koutedakis, A. Nevill et al.

“Greek adolescents, fitness, fatness, fat intake, activity, and coronary heart disease risk”

Archives of Disease in Childhood, vol. 89, no. 1, pp. 41–44,2004.

 

[24] L. T. Mahoney, T. L. Burns, W. Stanford et al.

“Coronary risk factors measured in childhood and young adult life are associated with coronary artery calcification in young adults: the Muscatine study”

Journal of the American College of Cardiology, vol. 27, no. 2, pp. 277–284, 1996.

 

[25] A. H. Lichtenstein, E. Kennedy, P. Barrier et al.

“Dietary fatconsumption and health” Nutrition Reviews

vol. 56, no. 5, part 2, pp. S3–S28, 1998.

 

[26] L. Bonci

“Sports nutrition for young athletes”

Pediatric Annals,vol. 39, no. 5, pp. 300–306, 2010.

 

[27] P. M. Nisevich

“Sports nutrition for young athletes”

IDEA Fitness Journal, pp. 65–67, 2008.

 

[28] J. Aucouturier, J. S. Baker, and P.Duch´e

“Fat and carbohydrate metabolism during submaximal exercise in children”

Sports Medicine, vol. 38, no. 3, pp. 213–238, 2008.