Department of Human Biometry and Biomechanics, Vrije ......Department of Human Biometry and Biomechanics, Vrije Universiteit Brussel, Brussels, Belgium Page 1 of 32 International Journal

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Nutritional habits of Flemish adolescent sprint athletes

Dirk Aerenhouts, Marcel Hebbelinck, Jacques R. Poortmans, and Peter Clarys

Department of Human Biometry and Biomechanics, Vrije Universiteit Brussel, Brussels,

Belgium

Page 1 of 32 International Journal of Sport Nutrition and Exercise Metabolism @ Human Kintetics, Inc.

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Abstract

Purpose and methods: To investigate dietary habits of Flemish adolescent track and field

athletes using a 7-day weighed food record. Besides adequacy for growth, development,

and physical performance, dietary health aspects were considered.

Results: Twenty-nine girls and 31 boys, with minimum 2 years of track and field training

practice, were recruited. All subjects had daily breakfast (♀: 22.5 ± 5.5% of total energy

intake (TEI); ♂: 19.8 ± 7.3%). Fruit in girls and juices and sports drinks in boys were

consumed mostly between meals (♀: 21.3 ± 8.1% of TEI; ♂: 24.3 ± 10.1%). Soft drinks

contributed considerably to energy intake between meals in both sexes. Protein intake (1.5

± 0.3 g/kg.day for both sexes) was within the recommended daily intake (RDI) for strength

athletes. Mean daily carbohydrate intake in girls was lower compared to boys (♀: 5.1 ±

1.1g/kg; ♂: 6.0 ± 0.9g/kg) with mono- and disaccharides contributing 26% to TEI in both

sexes. Total fat intake was above 30% of TEI in more than half of the subjects and only 10

subjects had a saturated fat intake below 10% of TEI. Fiber intake (♀: 23.7 ± 7.9g; ♂: 29.1

± 11.2g) was far below the Belgian RDI. Intake of vitamins and minerals were generally

low, despite micronutrient supplementation in 37.5% of the subjects.

Conclusion: Only few athletes reached all nutrient RDI’s. Unhealthy food habits with

regard to refined sugars, fat and micronutrients were observed. These adolescent sprinters

should be encouraged to consume more non-sweetened beverages, fruits and vegetables.

Keywords: energy intake, nutrient intake, track and field

Page 2 of 32International Journal of Sport Nutrition and Exercise Metabolism @ Human Kintetics, Inc.

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Introduction

The importance of a well balanced diet meeting the energy, fluid and nutrient demands is

well described (Petrie et al., 2004; WHO, 2005; Meyer et al., 2007). In adolescent athletes,

energy intake needs to cover physical activity, growth and physical development. During

the adolescent growth spurt 15 to 25% of the adult height is achieved, 45% of the skeletal

growth is acquired (Rees and Christine, 1989) and around 26% of bone mineral is accrued

(Baily et al., 1999). Few studies cover the nutritional needs of young athletes during that

period (Meyer et al., 2007).

Reports on the most recent dietary surveys of non-athletic Belgian adolescents (Paulus,

2001; Matthys et al., 2003; Pynaert et al., 2005; Mullie et al., 2006) and adolescents from

other countries (Samuelson, 1996; Decarli, 2000) revealed that intakes of total fat, saturated

fat, mono- and disaccharides were too high, whereas iron intake was far below the RDI,

especially in girls. Pynaert et al. (2005) and Mullie et al. (2006) stressed the importance of

breakfast and snacking habits on total energy intake (TEI) and macronutrient intake. One

might consider that athletes are more conscious concerning their eating habits, which may

differ from the general population (Cavadini et al., 2000).

Athletes in general are advised to consume a diet rich in carbohydrates providing more than

55% of TEI or 6 to 10 g/kg.day (Burke, 2001; American College of Sports Medicine

(ACSM), the American Dietetic Association (ADA) and the Dietitians of Canada (DC),

2000). Strength athletes have protein needs between 12 to 15% of TEI (Maughan and

Burke, 2002) or 1.2 to 1.7 g/kg.day following ACSM, ADA and DC-guidelines. Anaemia

and iron deficiency is generally recognized as the main nutritional problem in adolescents

(WHO, 2005). Due to the expansion of erythrocyte mass and muscular development, boys

have high iron requirements. However, girls are usually expected to have up to 15% higher

iron needs due to onset of menarche. Iron deficiency is more common among adolescent


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athletes regularly involved in strenuous exercise, which may reduce performance capacity

and recovery (Raunklar and Sabio, 1992). Because of the skeletal development and bone

mass acquisition during adolescence, calcium requirements reach maximal levels at that age

(Baily et al., 1999). Moreover, physical activity and appropriate intakes of fruit and

vegetables have a beneficial effect on bone mineral accrual during childhood and

adolescence (Whiting et al., 2004; Vatanparast et al., 2005). Hence, adolescent athletes

should be advised to consume a well balanced diet maintaining and optimizing health and

performance (Economos et al., 1993; Meyer et al., 2007). In an athletic population,

snacking habits can help to achieve adequate intake of energy and nutrients (Burke et al.,

2003).

The aim of the present study was to describe the energy and nutrient intake pattern of a

selection of the Flemish top track sprint athletes aged 12 to 18 years and to formulate

advice for an adequate and healthier diet.

Methods

Subjects

The present collection of data on the diets of a selected group of adolescent sprinters,

training at least 2 years, was part of a study in which nutritional and biometrical data, as

well as biomechanical data from the sprint start are being collected longitudinally. In

cooperation with the Flemish Athletics League (VAL), 120 athletes were selected and

invited to participate in the study. The selection was based on in- and outdoor track sprint

discipline rankings. Only 60 of the 76 responders were retained (29 girls and 31 boys aged

12 to 18 years). Participating athletes and their parents were given detailed information

about the study. They were asked to give written informed consent, in accordance with the

university’s ethical committee.


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Study design

Data were collected in late spring of 2007 (mean temperature 16°C and 75% humidity). All

athletes were in preparation for the summer outdoor competitions. Subjects completed a 7-

day food record in order to estimate mean daily intake of energy, macronutrients, vitamins

and minerals. The subjects were clearly instructed to maintain their normal eating pattern

and to report all foods as accurate as possible considering preparation and/or composition

of foods, time of the day and portion size. For the latter they were asked to weigh off the

items, using their personal weighing scale. When not feasible, household measures were

given to make an estimate of the portion size (Health council, 2006). During the same week

the subjects completed a physical activity questionnaire using a 7 level intensity scale in

order to calculate their physical activity level (PAL). The basal metabolic rate (BMR)

(Harris and Benedict, 1918) was calculated and multiplied with the obtained PAL value to

estimate total energy expenditure (TEE).

Girls: BMR = 655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 x age in years)

Boys: BMR = 66 + (13.7 x weight in kg) + (5 x height in cm) – (6.8 x age in years)

Subjects were asked to weigh themselves before breakfast of day 1 when they started

recording as well after day 7. Within two weeks after completion, the records were checked

by the investigator in the presence of the athlete and at least one of the parents. Additional

information was obtained where necessary and the subjects were questioned concerning

specific nutritional habits in function of training and competition. In case of incomplete

recording, the food record was excluded for analysis. During the same visit

anthropometrical data were collected. Standing height was measured to the nearest 0.1cm


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using a wall-mounted stadiometer. Weight was measured with the TANITA-TBF 410,

accurate up to 100grams, and fat mass and fat free mass were estimated by the underwater

weighing method using the formula of Siri (1961).

Fat percentage = (495/uwd*) – 450 *: under water body density

Residual long volume was estimated based on the height, weight and sex of the subject, for

gastro-intestinal gases the volume was fixed to 100g.

Analysis of the food records was done by the same investigator using the Becel nutrition

software program BINS 3.0.1, based on the Dutch (NEVO 2001) and Belgian (NUBEL

2004) food composition databanks. The ratio between estimated total energy intake and

BMR (TEI/BMR) was used as a tool to detect under-reporting. In a non-dieting population

the cut off value of 1.1, suggested by Goldberg et al. (1991), was used to exclude under-

reporters. To our knowledge, a detection method for over-reporting in a dietary survey does

not exist.

Nutrient intakes of girls and boys were compared to the recommended dietary intakes

(RDI) of the Belgian Health Council (2006) and those proposed by the American College of

Sports Medicine, the American Dietetic Association and the Dietitians of Canada (2000).

Comparisons in nutrient intakes were made between subjects having reported to consume

soft drinks or not.

Statistics

Statistical analysis was performed with SPSS 15.0. The significance level was set at p <

0.05. The Kolmogorov-Smirnov test was used to test for normality and t-tests were used to

compare between and within groups. One sample t-test was used to compare intake values


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with reference values. Correlations between intake patterns, anthropometric values and age

were calculated using Pearson or Spearman procedures.

The study was approved by the Medical Ethical Committee of the Vrije Universiteit

Brussel.

Results

Two girls with incomplete recordings and 1 girl and 1 boy with a TEI/BMR below 1.1 were

excluded. Table 1 shows age and main anthropometric characteristics of the included

subjects (n = 56).

[Insert Table 1 about here]

Boys had a lower body fat percentage and were taller and heavier than girls (Table 1). Body

fat percentage correlated significantly with age in girls (r = .45; p < .05) but not in boys (r =

.17; p = .22).

All adolescents were active in athletic sprint disciplines ranging from 60m indoor to 400m

outdoor sprint and hurdles. Six girls and 8 boys were involved in regular resistance training,

ranging from once every two weeks to 3 times a week (mean frequency ♀: 1.8days/week;

♂: 1.2days/week). During the week of reporting, both girls and boys were active in sports

of moderate intensity on 2 to 7 days, with a mean daily duration of 100 ± 40min in girls and

95 ± 35min in boys. Seventeen girls and 19 boys reported high intensity sports at least once

a week (mean duration ♀: 95 ± 65min; ♂: 96 ± 49min). Twenty-four girls and 25 boys

weighed themselves at the start and after the week of recording. There was no significant

difference between the 2 measurements (♀: pre = post: 54.9 ± 7.2kg; ♂: 62.2 ± 9.3kg vs.

62.3 ± 9.3kg). TEI (♀: 2007 ± 380kcal; ♂: 2643 ± 361kcal; p < .001) as well as TEE (♀:


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2581 ± 275kcal; ♂: 3117 ± 473kcal; p < .001) were lower in girls compared to boys. TEI

did not match TEE in both sexes (each p < .001).

All subjects had daily breakfast. There was no difference between girls and boys in energy

intake from breakfast (♀: 456 ± 141kcal; ♂: 526 ± 221kcal). Both a warm meal and a bread

meal were taken for lunch or diner. In the case of training or competition in the afternoon, a

bread meal was generally preferred for lunch. For breakfast, 54% of the girls and 67% of

the boys chose regularly for cereals, in the other case, bread was chosen. For breakfast as

well as for the bread meal, both full grain (♀: 75 ± 55g/day; ♂: 136 ± 110g/day; p < .05)

and white bread (♀: 60 ± 39g/day; ♂: 61 ± 51g/day) were consumed. Boys consumed

significantly more full grain than white bread (p < .01). Chocolate paste (♀: 11 ± 11g/day;

♂: 19 ± 19g/day; p < .05), cheese (♀: 20 ± 15g/day; ♂: 21 ± 25g/day), meats and sausages

(♀: 19 ± 15g/day; ♂: 20 ± 18g/day) were the most popular bread garnitures.

Energy derived from food and beverages between meals was significantly lower in girls

compared to boys. This accounted for 33% of the TEI difference (437 ± 191kcal vs. 635 ±

272kcal respectively; p < 0.01). The relative contribution to TEI was similar between both

sexes (♀: 24.3 ± 10.1%; ♂: 21.3 ± 8.1%),(Figures 1,2). Macronutrient composition of

breakfast and snacks showed no differences between the two sexes.

Fruit snacking accounted for 59 ± 26% in girls and 49 ± 32% in boys of total fruit intake.

More fruit was consumed between than during meals in both sexes (p < .001). Mean daily

fruit consumption was significantly lower than the RDI of 250g/day in boys (p < .05) but

not in girls. Total daily fruit consumption tended to be higher in girls compared to boys (♀:

262 ± 160g, ♂: 180 ± 157g; p = 0.06). Fruit contributed significantly more to total energy,

fluid and mono- and disaccharide intake in girls than in boys. In both sexes, mean vegetable

consumption was roughly 3 times lower than the RDI of 300g/day (♀: 101 ± 59g; ♂: 108 ±


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74g). Not one girl or boy reached the RDI for vegetables and only 11 girls and 4 boys

reached the RDI of 250g for fruit.

Girls consumed 62 ± 29% of total milk intake during breakfast and 15 ± 22% between

meals. In boys this was 71 ± 27% and 11 ± 19% respectively. In both sexes, significantly

more milk was consumed during breakfast than during the rest of the day (p < .001 each).

Boys consumed significantly more soft drinks than girls (217 ± 202ml vs. 69 ± 86ml; p <

0.001) which accounted for 9% of the difference in TEI. This resulted in a significantly (p <

.01) higher relative contribution from soft drinks to TEI, fluid, mono- and disaccharide

intake. After excluding subjects who did not report soft drinks (10 ♀ and 4 ♂), girls

consumed 53 ± 39% and boys 58 ± 30% of soft drinks between meals. Non-soft drink

consuming girls had a lower body fat percentage (14.2 ± 3.6% vs. 18.0 ± 3.9%; p < .05)

compared to the soft drink consuming girls. Non-soft drink consuming boys had higher

carbohydrate (61 ± 5% vs. 55 ± 5%), fiber (40.3 ± 17.4g/day vs. 27.4 ± 9.3g/day) and lower

fat (25 ± 5% vs. 31 ± 5%) intake compared to soft drink consuming boys (all p < .05). Girls

consumed 45 ± 42% and boys 34 ± 38% of total fruit juice intake during breakfast (p > .05),

and 22 ± 34% for girls and 41 ± 40% for boys between meals (p < .05). Girls consumed 50

± 54% and boys 91 ± 27% of total sports drink intake between meals (p > .05).

Different kinds of pasta (♀: 64 ± 55g/day; ♂: 55 ± 62g/day), boiled or mashed potatoes (♀:

39 ± 30g/day; ♂: 66 ± 72g/day), fried potatoes (♀: 21 ± 23g/day; ♂: 32 ± 26g/day) and rice

(♀: 13 ± 15g/day; ♂: 20 ± 30g/day) were consumed during the warm meal. Additionally,

different kinds of meat (♀: 42 ± 22g/day; ♂: 73 ± 30g/day; p < .001), poultry (♀: 28 ±

18g/day; ♂: 27 ± 23g/day) and fish (♀: 17 ± 18g/day; ♂: 14 ± 16g/day) were chosen.

[Insert Figure 1 about here]


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[Insert Figure 2 about here]

Seven girls and 8 boys had a specific nutritional strategy towards training. Plain water and

isotonic sports drinks were most consumed before and during training. Immediately after

training, only the boys drunk plain water and ate carbohydrate-rich food (e.g. banana or

bread) as part of a replenishment strategy. Prior to competition, 13 girls and 21 boys had a

specific nutritional strategy, mostly right before or in between heats. Pasta, bananas and

other easy digestible carbohydrate rich foods were consumed within the last 2 hours before

start of the competition. Between series, mainly plain water and isotonic sports drinks were

consumed. Immediately after competition, only 4 girls and 7 boys had fluid and

carbohydrate replenishment strategies.

Table 2 shows mean macronutrient intakes. Only 3 girls and 6 boys reached the RDI for

fluid intake as suggested by the Belgian Health council of 2006.

Eleven girls and 22 boys had a protein intake between 10 and 15% of TEI, whilst the rest of

the group (15 ♀ and 8 ♂) had a protein intake above 15 energy%. Eleven girls and 18 boys

had an intake between 1.2 and 1.7 g/kg.day and none of the subjects had an intake below

1.0 g/kg.day.

In 11 girls and 17 boys carbohydrate intake was above 55% of TEI. In 4 girls and 3 boys,

intake of carbohydrate was beneath 50% of TEI. Expressed as g/kg.day, 18 girls and 14

boys did not reach an intake of 6 g/kg.day. Subjects not reaching a carbohydrate intake of

55 energy% had a total fat intake between 34.1 and 39.9 energy% and a saturated fat intake

between 13.2 and 17.8 energy%. Energy% from fat was too high in 15 girls and 16 boys.

For 2 girls, intake from fat accounted for less than 20% of TEI. In 20 girls and 26 boys

intake of saturated fat exceeded 10% of TEI. Only 1 girl and 5 boys had a mean daily


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cholesterol intake above 300mg. A significant negative correlation of -.91 (p < 0.01) was

found between total fat intake as a percentage of TEI and total carbohydrate intake

percentage. Fiber intake was generally low with only 4 girls and 4 boys reaching the

Belgian RDI.

Only 1 girl and none of the boys reached all RDI’s proposed by the Belgian Health Council

for macronutrients, fiber and fluid. When fiber intake was not considered, 2 girls and 1 boy

reached the remaining RDI’s. When both fiber and fluid intake were not considered, 5 girls

and 4 boys reached the RDI for all macronutrients.



Calcium intake appeared to be low in most of the subjects, especially in girls. Mean sodium

intake was high (♀: 2692 ± 560mg; ♂: 3421 ± 821mg; p < .001) and only 1 girl and 1 boy

did not exceed the upper limit of 1600mg/day (Health Council, 2006). In none of the

subjects the Ca/P ratio reached the RDI of 1, a value of 1.3 is considered as optimal (Health

Council, 2006). In 3 girls and 8 boys the ratio was even below the lower limit of 0.5. For

potassium, 2 girls and none of the boys had an intake below the lower limit and 13 girls and

24 boys had and intake above the upper limit. Vitamin intake was generally low, except for

vitamin C in boys. Ten girls and 11 boys reported dietary supplement intake ranging from

individual up to multiple vitamin or mineral supplements. Only 1 boy took an amino- acid

supplement. In girls, the supplement contained iron (n = 5), magnesium (n = 1), vitamin E

(n = 1), ß –carotene (n = 1) and vitamin C (n = 4). In boys, the supplement contained

calcium (n = 6), iron (n = 7), magnesium (n = 8), potassium (n = 2), phosphorus (n = 2),


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vitamin E (n = 8), ß –carotene (n = 2), vitamin A (n = 8) and vitamin C (n = 9). Only after

supplementing iron, 5 girls reached the RDI of 20mg/day. The girl and 8 boys who took

supplementary magnesium already had an intake above the RDI of 250mg/day through their

diet. In the case of vitamin E, one girl and 5 out of 8 boys reached the RDI through

supplementation.

Discussion

The present investigation reports the estimates of food intake and energy expenditure from

60 adolescent top sprint athletes. These adolescent athletes, involved in regular physical

exercise of high intensity, probably have higher nutritional demands than their peers.

However, most nutrient intakes were compared to the general Belgian RDI’s for

adolescents due to lack of reference RDI values for this specific population. The

longitudinal care of the subjects gave confidence to the completion of a food diary. As

suggested by Goris and Westerterp (2000) and Scagliusi et al. (2003), subjects in dietary

surveys appear to improve reporting accuracy after confrontation with earlier results of

reporting, as is the case in this study. Body weight did not change before and after the

recording in both sexes. Nevertheless, TEI did not cover energy needs, which suggests

underreporting food intake and overestimating energy expenditure. Indeed, as shown by

Klesges et al. (1990), aerobic activities can be overestimated by over 300%.

Despite the use of a 7-day food record that minimizes within subject-variability (Willet,

1998), standard deviations of some nutrient intakes are considerable. This can be explained

by a high variability in consumption of food items. For other nutrients, the nutrition

software, based on the Belgian and Dutch food databanks, indicated incomplete results due

to lack of reference values. Therefore, unsaturated fatty acids, selenium, copper, zinc, B-

vitamins and vitamin D were not discussed.


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All subjects had daily breakfast, delivering 22.5 ± 5.5% of TEI in girls and 19.8 ± 7.3% of

TEI in boys. In a study on non-athletic Flemish adolescents by Matthys et al. (2003 and

2007) 16.9% of the girls and 13.2% of the boys never ate breakfast which contributed only

14.9% to TEI in girls and 15.7% in boys. Daily breakfast use among Belgian adolescents

was found to be even lower in a study of Mullie et al. (2006), 40 to 61% of the girls and 33

to 52% of the boys did not have daily breakfast. Decarli et al. (2000) found that breakfast

contributed 19% to TEI in Swiss teenagers which is closer to the results of the present

study. In our athletes, food consumption between meals accounted for 21.3% and 24.4% of

TEI in girls and boys respectively. Mono- and disaccharides made up the greatest part of

energy intake between meals (♀: 50.2 ± 15.4%; ♂: 47.8 ± 13.2%). These findings are

similar to those of Burke et al. (2003) on elite Australian athletes and of Matthys et al.

(2003) and Decarli et al. (2000) on non-athletic adolescents. In the study of Decarli et al.

(2000), snacking contributed significantly more to TEI in girls (23.0%) than in boys

(20.4%).

For the group studied, it appears difficult to reach the RDI’s. Only 6 athletes reached the

RDI for fluid intake. Insufficient fluid intake can negatively affect health and performance

(Sawka et al., 2005). As argued by Petrie et al. (2004) and Casa et al. (2000) recuperation

and tissue repair/development requires at least an euhydrated status. Dougherty et al. (2006)

reported impaired repeated sprint times in young basketball players being dehydrated for

2%. Hoffman et al. (1995) observed that anaerobic power output was 19% lower when

drinking had not been possible during a basketball game.

Both boys and girls had a mean daily protein intake of 1.5 g/kg, which is likely to be

sufficient considering ACSM, ADA and DC-guidelines and recent findings on Belgian

adolescent soccer players (Boisseau et al., 2007). Subjects who needed to increase their

carbohydrate intake should lower their total and saturated fat intake. Saturated fat


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contribution was generally too high but cholesterol intake was within acceptable limits in

almost all subjects. Quite similar patterns were detected by Paulus et al. (2001) and Matthys

et al. (2003) in non-athletic Belgian populations. These similar findings can partly be

explained by an inadequate consumption of fruits and vegetables and unhealthy fat sources.

The RDI for fiber in Belgium (age 9 – 13: ♀: 25g, ♂: 30g; age 14 – 18: ♀: 30g, ♂: 40g)

differs from that established by the American Academy of Pediatrics Committee on

Nutrition (0.5g/kg body weight) or the RDI for children suggested by Williams et al.

(1995), (age + 5 to 10g/day). Using the lower limit as proposed by Williams et al. (1995),

16 girls and 23 boys in our sample would have had a sufficient fiber intake. Boys generally

had less difficulties in reaching the RDI for the selected micronutrients. This is probably

due to the greater quantities consumed and not due to a healthier composition of the diet.

On the contrary, girls generally choose healthier food as shown by the consumption of fruit

and soft drinks. In this respect, our results confirm previous findings by Paulus et al. (2001)

and Mullie et al. (2006).

Over one third of the subjects (37.5%) regularly took vitamin and mineral supplementation,

indicating concern about an adequate nutrient intake amongst these athletes. In a study of

Loosli and Benson (1990) 43% of gymnasts and even 60% of dancers took supplements. In

our athletes, closer analysis revealed that especially in boys some micronutrients were

supplemented while intakes were already within the RDI (e.g.: iron, magnesium,

phosphorus, vitamin C). Athletes need to receive better information about the use and

possible (dis)advantages of supplementation. As stated by Meyer et al. (2007), an

appropriate dietary intake rather than use of supplements (except when clinically indicated)

is recommended to ensure young athletes to participate fully and safely in athletics. The

low calcium and the high phosphorus intake may influence bone health negatively (Whiting

et al., 2004). However, it has been shown that weight bearing activities have a positive


15

effect on bone mineral density (Baily et al., 1999; Andreoli et al., 2001; Prouteau et al.,

2006). Dairy products are considered a good source of calcium. Recent publications (Karp

et al., 2006; Wilkinson et al., 2007; Hartman et al., 2007; Shirreffs, 2007) indicate that low-

fat milk would be a very suitable recovery drink after endurance and resistance training.

Therefore, skim milk may be a welcome variation in sports drink utilisation. However,

Hunt and Johnson (2007) showed, at least in adults, that established calcium requirements

may be too high.

In the present study, a higher intake of mono- and disaccharides between meals was mainly

due to consumption of fruit and beverages such as fruit juices, sports drinks and especially

soft drinks. Soft drink consuming boys tended to have a less balanced diet with lower

carbohydrate and a higher fat intake. Girls consuming soft drinks had a higher body fat

percentage compared to non-consuming girls (p < .05). This may negatively affect physical

and sprint performance capacity. Only a limited number of athletes (30%) reported the use

of sports drinks, mainly in function of competition. As sports drink utilisation may

positively influence performance and recovery, a well considered use of sports drinks may

be advised to these adolescent athletes. However, it should be kept in mind that most sports

drinks have erosive effects on dental enamel, as demonstrated by Venables et al. (2005).

To conclude, all subjects had daily breakfast which is a remarkable difference with other

studies on non-athletic peers. Most of our tested adolescent athletes had a too high intake of

saturated fat and mono- and disaccharides whilst intake of minerals and vitamins was

generally low. This may be partly explained by a low fruit and vegetable intake. The study

indicated a non efficient use of supplements. If carefully chosen, snacks can have an

important contribution in reaching the RDI for almost all nutrients. Cereal and fruit bars

with little or no added sugars, fruit, juices and water are good examples, whereas cookies,


16

candy and soft drinks should be limited. Strategic use of sports drinks should be encouraged

to improve fluid intake, performance and recovery. Better information regarding

supplementation and sports drink use is required. In general, the diet consumed is slightly

better compared to non-athletic peers. Nevertheless, improvement towards a healthier and

appropriate sports nutrition should be facilitated in these young athletes.


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24

Acknowledgements

The authors wish to thank all participating athletes, their parents and the Flemish Athletics

League for their cooperation.


25

Figure 1-Contribution to TEI of breakfast and food consumption between meals and their

respective composition in girls (n = 26).

Figure 2-Contribution to TEI of breakfast and food consumption between meals and their

respective composition in boys (n = 30).


26

Table 1 Age and anthropometric characteristics girls (n = 26) boys (n = 30)

age (years) 15.7 ± 1.6 15.7 ± 1.9

height (cm) 168.0 ± 6.0 ** 174.5 ± 9.4

weight (kg) 54.7 ± 7.3 ** 61.2 ± 9.4

bodyfat (%) 16.5 ± 4.1 *** 9.3 ± 3.4

Results are presented as mean ± standard deviation. Comparison between girls and boys

using an independent t-test (** = p < .01; *** = p < .001).


27

Table 2 Mean daily intake of fluid, macronutrients and fiber

RDI girls (n = 26) boys (n = 30)

fluid (ml) 2201 ± 808 2482 ± 635

fluid ml/kg body weight (b) age +

sex dependent

40.8 ± 16.0 §§

3 (11.5%)

40.6 ± 9.2 §§

6 (20.0%)

protein (g) 78 ± 15 ** 92 ± 17

protein energy% 10-15% (b)

15.7 ± 2.0 **

11 (42.3%)

14.1 ± 1.8

22 ( 73.3%)

protein g/kg BW 1.2-1.7g (a)

1.5 ± 0.3

11 (42.3%)

1.5 ± 0.3

18 (60.0%)

total carbohydrate (g) 273 ± 54 *** 362 ± 54

total carbohydrate energy% > 55% (b)

54.6 ± 4.3

11 (42.3%)

55.7 ± 5.1

17 (56.7%)

total carbohydrate g/kg BW 6-10 g (a)

5.1 ± 1.1***,§§

8 (30.8%)

6.0 ± 0.9

16 (53.3%)

polysaccharide (g) 143 ± 26 *** 193 ± 48

polysaccharide energy% 28.7 ± 3.5 29.4 ± 4.9

mono/disaccharide (g) 127 ± 35 *** 167 ± 37

mono/disaccharide energy% 25.3 ± 4.6 26.0 ± 6.5

total fat (g) 69 ± 17 *** 91 ± 21

total fat energy% < 30% (b)

29.9 + 4.8

11 (42.3%)

30.3 ± 5.0

14 (46.7%)

saturated fatty acids (g) 28 ± 8 *** 37 ± 10

saturated fatty acids energy% < 10% (a,b) 12.2 ± 2.4 §§ 12.2 ± 2.5 §§


28

6 (23.1%) 4 (13.3%)

cholesterol (mg) < 300mg (b) 187 ± 45 **,§§

25 (96.2%)

234 ± 72 §§

25 (83.3%)

alcohol (g) 0.4 ± 1.0 0.3 ± 1.0

total fiber (g) (b) age +

sex dependent

23.7 ± 7.9 *,§§

4 (15.4%)

29.1 ± 11.2 §§

4 (13.3%)

In italic = number of subjects reaching the RDI. (a) RDI according Joint Position Statement

of the American College of Sports Medicine, the American Dietetic Association and the

Dietitians of Canada (2000). (b) RDI according the Belgian nutritional recommendations

(Health Council, 2006). Comparison between girls and boys using an independent t-test (*

= p < 0.05; ** = p < .01; *** = p < .001). Comparison to the RDI using a one sample t-test

(§ = p < 0.05; §§ = p < .001).


29

Table 3 Mean daily intake of selected micronutrients

girls (n=26) girls reaching

RDI

boys (n=30) boys reaching

RDI

Ca (mg)

+ S (♀:0, ♂:6)

911 ± 304 §

911 ± 304 §

3 (11.5 %)

3 (11.5 %)

958 ± 340 §

971 ± 347 §

10 (33.3 %)

12 (40.0 %)

Fe (mg)

+ S (♀:5, ♂:7)

11.6 ± 2.6 ***,§§

20.6 ± 27.4 **,§§

21 (80.7 %)

22 (84.6 %)

15.8 ± 3.7 §§

24.7 ± 29.1 §§

26 (86.6 %)

26 (86.6 %)

Mg (mg)

+ S (♀:1, ♂:8)

293 ± 85 **,§§

294 ± 86 ***,§§

14 (53.9 %)

14 (53.9 %)

358 ± 75 §§

371 ± 84 §§

28 (93.3 %)

28 (93.3 %)

Na (mg) 2692 ± 560 ***,§§ 1 (3.9%) 3421 ± 821 §§ 1 (3.3%)

K (mg)

+ S (♀:0, ♂:2)

3087 ± 783 *,§§

3087 ± 783 *,§§

11 (42.3%)

11 (42.3%)

3616 ± 749 §§

3617 ± 749 §§

6 (20.0%)

6 (20.0%)

P (mg)

+ S (♀:0, ♂:2)

1342 ± 328**,§§

1342 ± 328 **,§§

24 (92.3%)

24 (92.3%)

1636 ± 359 §§

1638 ± 358 §§

29 (96.7%)

29 (96.7%)

vit A (µg)

+ S (♀:0, ♂:8)

713 ± 281

713 ± 281

13 (50.0%)

13 (50.0%)

643 ± 245

816 ± 427

13 (43.3%)

16 (53.3%)

ß-carotene (µg)

+ S (♀:1, ♂:2)

2128 ± 1213

2209 ± 1259

/ 1851 ± 1193

1898 ± 1239

/

vit C (mg)

+ S (♀:4, ♂:9)

129 ± 69 §§

208 ± 278 §§

19 (73.1 %)

20 (76.9 %)

132 ± 64 §§

185 ± 173 §§

28 (93.3 %)

28 (93.3 %)

vit E (mg)

+ S (♀:1, ♂:8)

7.0 ± 1.9 §§

7.2 ± 2.5 *,§§

1 (3.9%)

2 (7.8%)

7.1 ± 2.5 §§

10.2 ± 6.9

4 (13.3%)

9 (30.0%)

RDI according to the Health Council, 2006 (age and sex dependent). + S = intake values

with supplements included (number of girls and boys supplementing). Comparison between


30

girls and boys using an independent t-test (* = p < 0.05; ** = p < .01; *** = p < .001).

Comparison to the RDI using a one sample t-test (§ = p < 0.01; §§ = p < .001).


21,7%

30,4%

34,3%

13,4%

21,3%

56,2%

22,5%

BETWEEN MEALS

LUNCH & DINER

BREAKFAST

protein

total fat

mono/disaccharide

polysaccharide

15,3%50,2%

7,3%

27,1%

total fat

polysaccharidemono/disaccharide

protein

Figure 1


31,4%

12,4%

34,0%

22,3%

24,3%

19,8%

55,8%

LUNCH & DINER

BREAKFAST

BETWEEN MEALS

protein

mono/disaccharide

polysaccharide

total fat

47,8%

7,0%

18,1%

26,7%

mono/disaccharide

protein

total fat

polysaccharide

Figure 2


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