NUTRITIONAL STRATEGIES: SATIETY, WEIGHT LOSS

AND SUPPLEMENTATION IN SPORTS

Scientific director: Enrico Arcelli

Calories: should we still count them? 2

Losing weight without losing lean body mass 4

Soy proteins in weight loss and sports 12

Beverages for athletes 20

Fatigue in football 37

Gastrointestinal disorders in long-distance runners 45

Sports anemia 51

table of contents

2

calories:

should we still count them?

The final conclusions of the round table of the 2nd

International Congress “Science in Nutrition”

(Rome, March 2010), organized by the Paolo

Sorbini Foundation for Nutritional Science, stated

that “calorie” is an "antiquated" term that is the

result of laboratory experience with calorimeters

and has no correspondence in physiology. The

calorie is the quantity of heat needed to increase

the temperature of one gram of water by 1°C, but

said quantity of heat depends on the initial tem-

perature and it is difficult to measure precisely.

Moreover, the International System of Units envi-

sages, instead of the calorie, the use of the joule,

the unit of measurement for thermal energy as a

function of temperature, which, in turn, is measu-

red in degrees. In general and in theory, the

quantity of heat can be expressed in units of

energy, but the human body does not behave like

a machine that burns calories.

It is a complex system of cells that regulates ther-

mal energy and hence body temperature by using

sophisticated metabolic mechanisms, the activity

of hormones (e.g., thyroid hormones) and other

body activities that do not simply depend on the

calories in food. For all these reasons, about 60%

of daily calorie intake is not used for metabolism.

In practice, when assessing different types of

food, you need to consider the glycemic index and

glycemic load. These physiological parameters -

which have been a part of scientific language for

a few decades now - refer to the quality and quan-

tity of food. The assessment of glycemic index and

load provides information to keep blood sugar

and carbohydrate metabolism under control. A

meal of foods with a high glycemic index and load

includes many carbohydrates that are quickly

assimilated. This entails a fast increase in blood

3

sugar and hence in insulinemia. This condition

stimulates the body to store energy as fat instead

of burning it to produce energy.

As underscored by Dr. Silvana Hrelia (Department

of Biochemistry at the University of Bologna) at

the round table, starting from the assumption

that lay people do not have a clear picture of the

scientific advances in the field of nutrition, it is

important to spread simple concepts and ideas to

reap positive results for well-being. It would

improve the chances of solving the obesity pande-

mic, also among children, and preventing chronic

pathologies (e.g., cardiovascular diseases, diabe-

tes and metabolic syndrome). Advertising messa-

ges that are harmful to the health of young peo-

ple must stop, and the language used must chan-

ge as well. It must be clear that it is not enough to

count calories without being aware of the real

meaning of the term, which 50% of Italians do not

know. Some use this unit of measurement for

mathematical calculations without knowing that a

diet low in calories is not enough to lose weight

and especially that such a diet is not enough to

lose weight well. The great majority of people do

not know that food with a low glycemic index

favors a feeling of fullness and is the first step

towards a healthy lifestyle. Prof. Enrico Arcelli

(Department of Sport, Nutrition and Health

Sciences at the University of Milan) added that

obesity is a risk factor for early mortality and that

two and a half hours of sports a week are not

enough to obtain optimal benefits (also in terms

of weight loss), but are enough to reduce the risk

of infarction and cardiovascular diseases by a

quarter.

In the field of nutrition, it is difficult to find an

agreement among all those involved, but there is

consensus on these rules: strike a balance

among the various types of nutrients; increase

the intake of vegetables and especially those with

a deep color - definitely not potatoes - and eat

seasonal fruits and extra-virgin olive oil regularly.

As for proteins, they are very important and you

should prefer leaner varieties, such as fish, poultry

and low-fat cheeses, ham (after removing fat) and

bresaola. In conclusion, it should be borne in

mind that 200 kcal derived from a certain food (for

instance, one rich in carbohydrates with a high

glycemic index) are not equivalent to those of

another food (for instance, one containing lean

proteins), as they have different effects on the

body, starting from blood sugar, insulinemia and

satiety.

4

- 1 -

losing weight without

losing lean body mass

This article discusses weight loss in sports,

namely the actual reduction in body fat without

reducing lean body mass. This objective can be

achieved by following those types of diets, such as

the Zone diet, that provide adequate quantities of

all nutrients, in a balanced relationship, and

ensure hormonal balance, while providing for

maximum physical efficiency, no feeling of hun-

ger and optimal training conditions. This way

there is a tangible loss of body fat while maintai-

ning muscle mass intact.

However, this article does not deal with those

practices, such as saunas and hypoglycemic

diets, that are carried out during the hours or

days before a competition and that do not affect

body fat but do cause dehydration or a reduction

in glycogen reserves.

LOSING WEIGHT IN SPORTS: WHY?

There are several reasons why athletes wish to

lose weight. Some athletes, like bodybuilders, do

it for aesthetic reasons; reducing subcutaneous

fat improves muscle definition. Other athletes do

it because competitions in their sports are divi-

ded into different classes based on body weight

(see Table 1); these sports include weight-lifting,

combat sports (boxing, judo, martial arts, etc.)

and rowing (lightweights and coxswains).

However, it also can be beneficial to lose weight

in sports with no classes with weight limits, since

lower body weight affords lower energy expendi-

ture (suffice it to mention here middle-distance

runners, mara thoners, race walkers, triathle-

tes…), or a better power-to-weight ratio (in parti-

cular, jumping competitions in athletics, the

open weight rowing class, artistic and rhythmic

gymnastics, and figure skating, etc.).

5

For instance, every kilo of extra weight leads to a

loss of about 1.5-2 cm in the high jump. If you

consider that the unit cost of running is equal to

about 200 ml/kg/km (Margaria, 1938), you can

calculate that in an athlete who initially weighs

65 kg, an extra kilo of fat leads to a worsening of

about 3-4 s in a 1500-meter runner who normal-

ly covers the distance in 3 min and 45 s; 12-14 s

in a 5000-meter runner whose regular time is

about 14 min and 30 s; and 25-30 s in a 10,000-

meter runner whose regular time is about 30 min

(Arcelli, 1990). In marathon racing the loss

amounts to 2-3 min (Table 2). Even in those

sports in which the movement is done by a hor-

se's muscles (showjumping, horse racing) or the

wind (sailing), a lower body weight is to be prefer-

red. On the contrary, in sumo, athletes focus their

efforts on increasing body weight (even reaching

extremely high levels of body fat), because the

technical characteristics of this sport do not

favor lighter athletes.

Table 1 - Weight classes and limits in rowing, weight-lifting and combat sports.

ROWINGMEN kg WOMEN kgLightweights 72,5 Lightweights 59Open weight > 72,5 Open weight > 59Coxswains 55 Coxswains 50

JUDOMEN kg WOMEN kgSeniors 55 Seniors 48“ 55-60 “ 48-52“ 60-66 “ 52-57“ 66-73 “ 57-63“ 73-81 “ 63-70“ 81-90 “ 70-78“ 90-100 “ > 78“ < 100

KARATEMEN kg WOMEN kgSeniors 55-60 Seniors 45-50“ 60-65 “ 50-55“ 70-76 “ 55-61“ 76-83 “ 61-68“ 83-90 “ > 68“ > 90

BOXINGMEN kg WOMEN kgLight flyweight 48 Light flyweight 44Flyweight 51 Flyweight 46Bantamweight 54 Bantamweight 48Featherweight 57 Featherweight 51Lightweight 60 Lightweight 54Junior welterweights 64 Junior welterweights 57Welters 69 Welters 60Middleweights 75 Middleweights 64Super middleweights 81 Super middleweights 69Heavyweights 91 Heavyweights 75Super heavyweights > 91 Super heavyweights > 81

WEIGHT LIFITINGMEN kg WOMEN kgSeniors 56 Seniors 48“ 62 “ 53“ 69 “ 58“ 77 “ 63“ 85 “ 69“ 94 “ 75“ 105 “ > 75“ > 105

ASSESSING BODY FAT AND CALORIE DEFICIT

Therefore, whoever wishes to reduce his or her

body weight in the medium term without reducing

efficiency must set eliminating body fat and not

fat-free mass - muscles, glycogen, water, etc. -

as the main goal. It must be borne in mind thou-

gh that just 36-48 hours are necessary to repleni-

sh water and glycogen stores, while it takes much

more time to recover any muscle mass that is

lost. The first step in planning weight loss in an

athlete is the calculation of body fat. There are

various ways to analyze the body's composition,

among which: skin fold caliper test, bioelectri-

cal impedance analysis, methods based on the

use of infrareds, DEXA (Dual-emission X-ray

absorptiometry) and hydrostatic weighing. It is

possible to have an idea of the ideal weight for

the athlete examined if you consider also what

the literature says about body fat in athletes in

specific sports. Now you can determine, for

instance, whether a certain athlete can actually

reach a given body weight (in particular, a weight

that allows him or her to reach a specific weight

class). If the results indicate that it is possible,

you can plan the progressive loss of excess fat

by combining training with diet to reach the

required deficit in the daily energy balance

(Kinney, 2004). Having said as much, it is clear

that the time factor is essential in planning a

reduction in body weight (Golay, 2000).

According to Orlandi (2009), the energy balance

restrictions - compared to what are the actual

calorie needs regardless of the limits that calories

have as a reference - can be divided into three

different levels:

• daily deficit of 1000 kcal or more: it can have

damaging effects on athletic performance and

should not be considered at all (Giorgino, 1979;

Arioli, 2009);

• daily deficit between 500 and 1000 kcal a day:

this level of restriction can be effective only in

specific situations and in specific athletes;

• daily deficit of less than 500 kcal a day: by far,

this is the preferred level for athletes, especially

because it gives a reduction in body weight that

6

Table 2 - Worsening in performance in marathon running, inminutes and seconds, based on finish time and body weightwhen - all other conditions being the same - there is a 1 kgincrease in body fat (Arcelli, 1990).

can be more easily achieved through the loss of

body fat alone (i.e., without altering the subject's

muscle mass).

QUALITY AND QUANTITY OF CARBOHYDRATES

Still, despite the calorie deficit, an athlete who

wishes to lose weight should never suffer a lack of

nutrients. In particular, the intake of proteins and

carbohydrates must never fall below certain daily

quantities. Athletes engaged in intense training

must have a protein intake of around 1.5-2

g/kg/day in order to avoid having a negative

protein balance (Tarnopolsky et al., 1988;

Chesley et al., 1992; Lemon et al., 1992.)

Protein breakdown can exceed protein synthe-

sis, which can lead to a loss of lean body mass,

even when there is a sharp drop in carbohydra-

tes in the diet. Therefore, athletes must always

rely on a minimum daily intake calculated as the

sum of:

• quantity of carbohydrates needed by the cen-

tral nervous system and other tissues and

organs that do not have their own energy reser-

ves (about 1 g every kg of body weight or slightly

more);

• quantity of carbohydrates consumed by

muscles during physical activity (to be calcula-

ted individually for each athlete).

If these quantities are not reached, the body must

produce glucose through gluconeogenesis, a pro-

cess that entails the breakdown of body proteins

and the use of the branched-chain amino acids

that they contain. The final result is a reduction in

lean body mass and especially in muscle proteins.

On the other hand, the choice of what types of car-

bohydrates should be eaten is also extremely

important. The weight loss phase can last several

months and the time during which the resulting

body weight needs to be maintained can be much

longer. Hence, you need to bear in mind that

during these periods there are two main factors

that counter diet maintenance: a drop in the

resting metabolic rate and an increase in appetite.

Generally speaking, there is no drop in resting

metabolic rate during weight loss - at least in

most athletes who regularly do a lot of training;

there can be, however, an increase in appetite

during diet restriction phases. When choosing

foods, you need to consider not only their calorie

content (the only element considered in the past),

but also the capacity of given foods to increase

appetite more or less quickly.

7

As for carbohydrates, you should especially

choose those with a low glycemic index (see

Sport Nutrition Report 1, 2010, pg. 6-12); the

quantities should always involve a moderate

glycemic load. A high glycemic load would make

the levels of insulin in the blood rise; hyperinsu-

linemia favors an increase in the fat contained in

adipocytes, but also leads to an early onset of

appetite (Sears, 2006) as a consequence of the

rapid drop in blood glucose to below baseline

levels, which takes the name of reactive hypo-

glycemia.

Among the foods that supply carbohydrates,

those with a low glycemic index often have a low

caloric density; that is to say they supply few

calories while having the same weight (and/or

volume). Being free to eat as much food as one

likes while having to eat mostly those with a low

caloric density, such as vegetables (and even

genuine whole-grain cereals) allows subjects to

lose weight more easily without any sort of defi-

ciency (Poppit and Prentice, 1996; Rolls and

Bell, 1999).

THE ROLE OF PROTEINS AND HORMONES

Proteins, unlike carbohydrates with a high

glycemic index, favor satiety. According to

Paddon-Jones et al. (2008), it is important for

anyone who wishes to lose weight to eat a reaso-

nable amount of proteins at every meal because

they: (a) promote maintenance of lean body mass,

(b) increase energy expenditure (thermal effect of

foods) and (c) increase the feeling of fullness.

As for fullness, first of all, it should be considered

(see box at pg. 10) that you have short-term full-

ness (or satiation) that occurs while you are still

eating (or immediately after) and long-term full-

ness (or satiety), which refers to a longer period

of time without appetite in the hours following

your last meal. Besides psychological factors or

other more complex factors, there are over

twenty peptide hormones that act on the various

centers in the hypothalamus that modulate hun-

ger and satiety. Among these hormones, suffice it

to mention the following four that favor satiation

or satiety, either indirectly (by acting on the

receptors of the vagus nerve, which, in turn, is

connected to the hypothalamus), or directly once

they reach the hypothalamus through circulation:

• PP (pancreatic polypeptide): gastric distension

leads to its production by the pancreas in the

cells arranged along the edges of the islets of

Langerhans; its levels remain high only for few

hours;

8

• CCK (cholecystokinin): it is a hormone secreted

by the duodenum and jejunum (it tells the body

to stop eating) once foods rich in proteins and

fat have been eaten; this is the reason why both

are more satiating compared to carbohydrates;

• GLP-1 (glucagon-like peptide 1): it, too, regula-

tes the intake of food; it is produced in the

ileum especially as a result of eating carbohy-

drates and fats, but also milk proteins and,

in particular, those found in whey;

• PYY (peptide YY): it is produced by L cells in the

intestine (especially in the ileum and colon); its

levels rise 1-2 hours after meals and remain

high for about 6 hours, thereby limiting the

onset of appetite during this period; it is espe-

cially the proteins in food that make it rise.

When you are eating, the blood levels of these

hormones rise after a short while; they reach

the hunger and fullness centers and send

signals to the brain that can be either fast (trig-

gering satiation) or slow yet long-lasting (trig-

gering satiety). Vegetables (those with a low

caloric density and low glycemic index - not

potatoes) favor satiation because, by generating

gastric distension, they trigger the production of

PP. Proteins, instead, above all favor satiation

through CCK as well as satiety as a result of PYY.

THE ROLE OF LEUCINE

When the objective is to lose fat without losing

lean body mass, leucine plays a key role (it is one

of the branched-chain amino acids; the other two

are valine and isoleucine). According to Layman

9

Figure 1 - Various hormones contribute to determining fullness:two of these, PP and CCK, favor satiation (i.e., short-term full-ness), while the other two, GLP-1 and PYY, favor satiety. They acton the hunger and fullness centers of the diencephalon eitherdirectly (through circulation) or indirectly, i.e., by acting on thereceptors of the vagus nerve, which, in turn, is connected to thehypothalamus

(2009), if a lot of carbohydrates are consumed,

especially those with a high glycemic index, the

fat accumulated in adipocytes tends to increase,

while the intake of a certain quantity of leucine

helps lose weight and maintain muscle mass.

Leucine has a double action: on the one hand, it

acts on the hypothalamus and triggers the

feeling of satiety (Cota et al., 2006; Zhang et al.

2007); on the other, it acts on muscles, thereby

favoring hypertrophy. In both cases, leucine's

action takes place thanks to the intervention of

m-TOR (Morrison et al., 2007). In order to lose

fatty tissue only and ensure total well-being,

according to Layman (2009), each main meal

should include a quantity of at least 30 g of

proteins, which is equal to about 2.5 g of leucine

if the proteins are of good quality.

This way, the concentration of leucine in blood

reaches the limits needed to stimulate weight

loss without losing muscle mass. On the con-

trary, carbohydrates should be less than 40 g

(Layman, 2009).

CONCLUSIONS

When an athlete wishes to lose weight, it is

important to determine - well outside the compe-

titive season - which weight loss targets can be

reasonably achieved and how long it will take to

reach these targets.

The choice of the diet to be followed must

undoubtedly be customized, considering the

principles discussed in this article. A regimen

such as the Zone diet seems to be very suitable to

reach these goals.

10

There are two forms of fullness wich are defined as

satiation and satiety.

Satiation is the short-term fullness that develops

during meals. When the stomach is full, the nerve

"sensors" on its walls send signals that stimulate

the secretion and circulation of PP, a hormone that

reduces appetite.

Satiety refers to long-term fullness, namely that

fullness that lasts several hours and keeps the fee-

ling of hunger from returning. If you reach the time

of the next meal without feeling too hungry, you eat

less. In general, foods rich in proteins - having the

same amount of calories - give longer satiety com-

pared to foods rich in carbohydrates.

SATIATION E SATIETY

REFERENCES

Arcelli E.: Che cos’è l’allenamento. Sperling & Kupfer Editori, Milan,1990.

Artioli G.G., Iglesias R.T., Franchini E., Gualano B., KashiwaguraD.B., Solis M.Y., Benatti F.B., Fuchs M., Lancia A.H. jr.: Rapid weight-loss followed by recovery time does not affect judo-related perfor-mance. J. Sports Sci., 23: 1-12, 2009.

Chesley A, MacDougall JD, Tarnopolsky MA, Atkinson SA, Smith K.Changes in human muscle protein synthesis after resistance exerci-se. J Appl Physiol., 73(4): 1383-1388, 1992.

Cota D., Proulx K., Smith K.A., Kozma S.C., Thomas G., Woods S.C.,Seeley R.J.: Hypothalamic mTOR signaling regulates food intake.Science, May, 12, 312 (5775): 927-930, 2006.

Equipe Enervit: Indice e carico glicemico. In “Sport Nutrition Report2010”, pg. 6-12, 2010.

Giorgino R., Scaldapane R., Lattanzi V., Cignarelli M., Various typesof reducing diets. Minerva Med., 70 (51): 3475-3491, 1979.

Kinney J.M.: Nutritional frailty, sarcopenia and falls in the elderly.Curr. Opin. Clin. Nutr. Metab. Care, 7 (1): 15-20, 2004.

Layman D.K. : Dietary Guidelines should reflect new understandingsabout adult protein needs. Nutr. Metab. (London).: Mar 13;6:12,2009.

Lemon PW, Tarnopolsky MA, MacDougall JD, Atkinson SA. Proteinrequirements and muscle mass/strength changes during intensivetraining in novice bodybuilders. J Appl Physiol., 73 (2): 767–775,1992.

Margaria R.: Sulla fisiologia e specialmente sul consumo energeticodella marcia e della corsa. Atti Accademia Nazionale dei Lincei,1938, serie VI, 72-99.

Morrison C.D., Xi X., White C.L., Ye J., Martin R.J..: Amino acids inhi-bit Agrp gene expression via an mTOR-dependent mechanism. Am JPhysiol Endocrinol Metab., Jul, 293(1): E165-171. 2007.

Orlandi C.: Gestione e controllo del peso e della muscolatura dell'a-tleta, Convegno Nazionale SIAS – Palermo, 13-14 novembre 2009.

Paddon-Jones D., Westman E., Mattes R.D., Wolfe R.R., Astrup A.,Westerterp-Plantenga M.: Protein, weight management, and satiety.Am. J. Clin Nutr., 87 (5): 1558S-1561S, 2008.

Poppitt S.D, Prentice A.M.: Energy density and its role in the controlof food intake: evidence from metabolic and community studies.Appetite, 26(2):153-174, 1996.

Rolls B.J., Bell E.A.: Intake of fat and carbohydrate: role of energydensity. Eur. J. Clin. Nutr., 53: S166-173, 1999.

Sears B.: Prevenire con la zona. Sperling & Kupfer editori, Milan,2006.

Tarnopolsky M.A., MacDougall J.D., Atkinson S.A.: Influence of pro-tein intake and training status on nitrogen balance and lean bodymass. J Appl Physiol., 64 (1): 187-193, 1988.

Zhang Y., Guo K., LeBlanc R.E., Loh D., Schwartz G.J., Yu Y.H.:Increasing dietary leucine intake reduces diet-induced obesity andimproves glucose and cholesterol metabolism in mice via multime-chanisms. Diabetes, Jun, 56 (6): 1647-1654, 2007.

11

Soy is a legume native to Asia; for many Asian

populations it has been a staple foodstuff for

over 5,000 years. Compared to other legumes, it

is easier to digest and richer in proteins: in soy-

beans, proteins account for over 35% of the dry

weight. They have a good amino acid profile with

a biological value near 75.

It should be borne in mind that the proteins iso-

lated from soy are much more effective compa-

red to the proteins ingested with the whole bean

or with soy-based foods. Thanks to the high con-

tent of glutamine, arginine and branched chain

amino acids as well as to new extraction and

processing methods, they have a higher protein

quality score in the new index (PDCAAS) develo-

ped by the World Health Organization (WHO).

The PDCAAS (Protein Digestibility Corrected

Amino Acid Score), adopted by the FDA - Food

and Drug Administration - and FAO, classifies

protein quality considering both the content of

amino acids and digestibility. The maximum

PDCAAS score is 1.0; it is given only to casein,

whey proteins, the proteins of whole eggs, albu-

men proteins and, indeed, the proteins isolated

from soy (see Table 1). Beef has a score of 0.92,

followed by soybeans with 0.91; then come kid-

ney beans and rye (0.68), whole wheat (0.54),

lentils and peanuts (0.52); at the bottom of the

ranking you find seitan, which is composed of

wheat- derived proteins, with a score of 0.25.

Several epidemiological studies have shown that

people who regularly consume a higher quantity

of soy-based foods have a lower risk of develo-

ping some pathologies. The beneficial effects of

soy proteins are mainly associated with the pre-

sence of isoflavons and, in particular, daidzein

- 2 -

soy proteins

in weight loss and sports

12

and genistein. These substances, for the very

fact of being of plant origin and being able to

bind with the same receptors of estrogens, are

defined phytoestrogens. A substance that is

even more effective than daidzein and genistein

is equol, a molecule that - as a result of the

action of certain strains of bacteria - is formed,

starting from phytoestrogens, in the intestine of

20-30% of people living in Western countries

and in a higher percentage in the inhabitants of

Asian countries. Equol has a very intense

antioxidant activity (Setchell and Clerici, 2010).

In particular, soy proteins are very effective in

fighting dyslipidemias; according to a meta-

analysis by Zhan and Ho (2005), they can reduce

total cholesterol, LDL cholesterol and triglyceri-

des, while significantly increasing HDL choleste-

rol. Other studies published more recently have

provided further data on the efficacy of soy pro-

teins in reducing blood lipids in overweight and

obese adults (Balk et al., 2005; Reynolds et al.,

2006). Jenkins et al. (2009) compared the effects

of proteins in a vegetable diet (which included

soy proteins) with those of a high carbohydrate

diet and those of a vegan diet in both male and

female overweight and hyperlipidemic subjects.

The team of researchers showed that, besides

benefits in terms of weight loss, those on the diet

including soy proteins witnessed significantly

higher reductions in the concentrations of LDL

cholesterol and total cholesterol.

According to Sirtori and Lovati (2001), the habit of

eating soy is associated with a reduced incidence

13

Table 1 - PDCAAS score, namely the biological value of the dige-stibility corrected amino acid content of proteins. As you can see,only 5 proteins have a maximum score of 1: casein, whey pro-teins, egg proteins, albumen proteins and proteins obtainedfrom soy.Source: Normal and Therapeutic Nutrition, 17th ed., Corinne H.Robinson, Marilyn R. Lawler, Wanda L. Chenoweth, and Anne E.Garwick. Macmillan Publishing Company, 1986.

of cardiovascular diseases. Already back in 1999,

even the U.S. Food and Drug Administration

authorized that the following wording be put on

the labels of products containing soy proteins: “25

grams of soy protein a day, as part of a diet low in

unsaturated fat and cholesterol, may reduce the

risk of heart disease." Soy phytoestrogens are

similarly capable of influencing enzymes involved

in the regulation of cellular proliferation, thereby

inhibiting the increase in the number of neopla-

stic cells; for this reason, the regular consump-

tion of soy reduces the risk of some forms of can-

cer such as colon cancer (Bennink, 2001), prostate

cancer (Rowland, 2004; Hwang et al., 2009) and

breast cancer (Wu et al., 2008). Moreover, in

women, soy reduces the disorders associated

with menopause and the risk of osteoporosis

(Alekel et al., 2000; Scheiber et al., 2001;

Lydeking-Olsen et al., 2004). Soy proteins also

have antioxidant properties (Park et al., 2010) and

very beneficial effects on type-2 diabetes, espe-

cially in women in menopause (Jayagopal et al.,

2002). Another recent study (Pipe et al., 2009) on

men and women with type-2 diabetes has compa-

red the effects of the proteins isolated in milk and

the proteins isolated in soy and has shown that

with soy proteins the levels of LDL cholesterol are

significantly reduced.

SOY PROTEINS AND WEIGHT LOSS

Soy proteins have the ability to generate a greater

feeling of satiety compared with other widely

consumed high-quality proteins (Anderson et al.,

2004; Semon et al., 1987). Their main component

is beta-conglycinin, a peptone that, as proven by

studies on animals, is very effective in stimulating

the release of cholecystokinin (CCK), a hormone

that triggers satiety (Nishi et al., 2003). For this

reason, adding soy proteins to weight loss diets

aimed solely to reduce body fat is considered to be

an effective method to improve the feeling of

satiety, weight control and diet quality.

The role of soy proteins in weight loss has been

the subject of three recently published articles

(Westerterp-Plantenga et al., 2009; Cope et al.,

2008; Velasquez et al., 2007). These articles

argue that when hypocaloric diets - followed by

adults to reduce body fat and control weight - are

based mainly on the consumption of soy proteins,

the effects are equivalent to those of diets based

on the intake of other types of proteins. These

benefits are probably due in part to the metabo-

lic effects of soy on the metabolism of glucose

and lipids (Veldhorst et al., 2009). However, no

study has been carried out to investigate into the

effect of hypocaloric diets containing soy proteins

14

15

in children. It has been observed that soy proteins

can reduce weight and body fat even in rats and

mice (Nagasawa et al., 2002; Iritani et al., 1996).

There is also clear evidence that, in case of wei-

ght loss, diets with a high protein content and

particularly those containing high-quality pro-

teins help to preserve fat-free mass (FFM)

(Noakes, 2008; Layman, 2004). In turn, this

improves the metabolic profile of the diet and

increases the reduction in insulin levels and the

size of LDL particles (Westerterp-Plantenga et

al., 2007).

Several studies have proven that in adults, during

a period of planned weight loss, soy proteins pre-

serve fat-free mass just as well as dairy products

and mixed protein sources (Li et al., 2005;

Lukaszuk et al., 2007; Anderson et al., 2007; St-

Onge et al., 2007). While, on the one hand, the

mechanisms of this effect are not entirely clear

yet, on the other, it has been suggested that

these actions are the result of hormonal respon-

ses to an increased intake of proteins and/or a

reduced intake of carbohydrates (Westerterp-

Plantenga et al., 2007; Layman, 2003).

Table 2

THE BENEFITS OF SOY

Soy provides proteins in greater quantities and with

a better quality compared to other plants;

provides healthier lipids, such as monounsaturated

fats, polyunsaturated fats and phospholipids such as

lecithin;

provides less saturated fats and less cholesterol;

has a lower glycemic index: for a mixed composi-

tion, the glycemic index is 18 (as opposed to 100 for

glucose);

favors a balanced diet: the properties and compo-

nents of soy are beneficial to balanced nutrition;

is a good source of vitamins and minerals, and par-

ticularly vitamin E, iron and potassium;

helps bring down the level of cholesterol in blood,

thanks to the action of phytosterols as well as of

lecithin, a substance that also acts on circulation by

keeping cholesterol suspended and not allowing it to

build up on arterial walls;

regulates satiety, as proven by recent scientific

research;

acts on fat-free mass: many studies have documen-

ted the benefits of proteins obtained from soy on the

increase in fat-free mass;

mitigates the disorders associated with the men-

strual cycle and menopause in women: soy isofla-

vons rebalance both excess estrogens, which are the

cause of the premenstrual syndrome and the lack of

estrogens during menopause by restoring the cor-

rect hormonal levels;

lowers the incidence of colon, breast and prostate

cancer;

helps prevent osteoporosis.

SOY AND EXERCISE

Some data in scientific literature suggests that

soy proteins can be a useful nutritional supple-

ment to compensate the needs of a training pro-

gram (Brown et al, 2004; Candow et al., 2006;

Lukaszuk et al., 2007; Philips et al., 2009).

Soy proteins as a part of diet have the ability to

influence physical performance for a series of

reasons, particularly due to the high intake of

high-quality proteins and elements with a phyto-

chemical effect, such as isoflavons, and to the

action of some peptides that are formed during

digestion. A series of studies carried out by the

Ohio State University have shown that the con-

sumption of 40 g of soy proteins every day for

3-4 weeks can improve post-training recovery by

accelerating the recovery of muscle functions

that were involved in physical exercises and by

inhibiting muscle soreness (Rossi et al., 2000;

Hill et al., 2004; Box et al., 2006). Studies have

also assessed the inflammatory state, oxidative

stress and muscular damage in blood tests.

Another interesting finding regards the intake of

soy proteins, which after training have led to

a partial reduction in blood levels of cortisol,

a hormone correlated with stress (Disilvestro,

2005). Besides these effects, soy proteins favor

post-training recovery and increase muscle

mass and strength through stimulation during

training (Bazzoli, 2002). A study carried out on

women who regularly did aerobic exercise and

had an intake of 40 g of soy proteins over a

period of 4 weeks showed that oxidative stress

was sharply reduced, while this was not the case

in the control group, which had consumed only

whey proteins.

Many athletes tend to avoid soy proteins becau-

se they think that their biological value and effi-

cacy are lower than whey proteins when it comes

to increasing muscle mass. Research has shown

that, in actual fact, soy proteins and the associa-

ted antioxidants can contribute to increasing fat-

free mass (Kalman et al., 2007). Antioxidants are

agents that are either exogenous, namely absor-

bed through a correct diet, or endogenous, i.e.,

produced by the body (Rossi et al., 2000). They

act against the muscle damage caused by the

oxidant reactions of free radicals. The benefit of

the proteins isolated from soy is that they con-

tain a mix of antioxidants, among which isofla-

vons, saponins and copper. The latter is an

essential component in a number of antioxidant

enzymes (Box et al., 2006). The production of

free radicals by the body is especially intense

16

during exercise and the resulting oxidative

stress seems to contribute to muscle damage

and fatigue (Hill et al., 2004). Said damage and

sense of fatigue could slow down muscle reco-

very between training sessions thereby reducing

the progress made during physical training. As a

consequence the increase in fat-free mass

promoted by a specific training program could

be limited.

This has been confirmed in a research study to

assess the increase in lean body mass in two

groups of university students (Disilvestro, 2005).

They associated overload training with the con-

sumption of protein bars; in one group the bars

contained soy proteins, while in the other they

contained whey proteins. Both groups showed

an increase in fat-free mass, but the data collec-

ted in the phases following exercise demonstra-

ted that the group that consumed only whey pro-

teins showed the presence of perioxidative fac-

tors.

Table 3

THE BENEFITS OF SOY IN SPORTS

Soy proteins:

• favor the loss of body fat, without losing effi-

ciency, in athletes who need to lose weight;

• favor the increase of muscle mass and

strength;

• allow, in the same training conditions, the

reduction of inflammation and oxidative

stress; cortisol levels are also lower;

• favor recovery in the phase following trai-

ning; there are less muscle aches and less

fatigue.

17

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19

Water is very important in sports. In several

sports events and particularly in those that last

more than a few dozen minutes and/or that are

held in an environment that leads to abundant

sweating (i.e., with high air temperatures and

high humidity and irradiation levels), it is absolu-

tely essential that athletes reach the start of the

competition without any water deficiency and

that, during the competition, at least part of the

water lost through sweat (and if necessary,

minerals as well) is integrated. Even a moderate

loss of water by the body leads to a sensitive

worsening of performance and, if this loss is

even greater, it can be dangerous to health.

WATER LOSS BY THE BODY

Humans can survive without food for a few

weeks provided that they can drink fluids. They

cannot resist for more than a few days without

water: even when fasting in a cool environment,

humans need a daily intake of more than half a

liter of water. The human body is continuously

losing water, even though there are substantial

differences from one day to another. Save for

pathological cases, the routes through which

water is lost are the kidneys (the quantity of

urine increases when you drink more water than

needed), the digestive system (stools can be

more or less rich in water depending especially

on the food eaten; diarrhea and vomit can sub-

stantially increase the loss of water and mine-

rals), skin (through sweat and insensible perspi-

ration) and the lungs (a substantial amount of

water vapor can be eliminated through the

airway especially above a certain altitude). It

should also be borne in mind that every day the

glands of the stomach and intestine (especially

- 3 -

beverages for athletes

20

in the first section) secrete a large quantity of

fluids, on average between 7 and 10 liters; in

a normal individual, however, these liquids are

almost entirely reabsorbed by the large bowel.

Even in the glomeruli of the kidneys, an enor-

mous quantity of what is called first-intention

urine is produced every day, totaling almost

a few dozen liters. However, if the production of

adiuretin (anti diuretic hormone -ADH) by the

pituitary gland is normal, most of it is reabsor-

bed by renal tubules and only a small quantity

(even less than a liter) becomes urine and is eli-

minated as such by the body.

In order to have a correct (fluid balance), water

loss (output) must be compensated by the intake

of water (input). A substantial part of the input

(exogenous water) does not come from bevera-

ges, but foods. Very few foods are completely

dry, while some fresh foods (fruit, vegetables,

meat, fish…) contain percentages of water of

over 70% or even 90%. In the body, the combu-

stion of carbohydrates, fats and proteins produ-

ces other water called endogenous (or metabo-

lic). Every 100 g of carbohydrates used to produ-

ce energy yields 55 g of water; every 100 g of

lipids gives 107 g; and every 100 g of proteins 41

g. For an accurate calculation of the level of

dehydration in an individual who is engaged in a

prolonged effort that produces a lot of sweat, it

is necessary to take into account endo genous

water as well.

However, according to McArdle, Katch and Katch

(1998), its role is of scarce relevance in the fluid

balance of an athlete.

THIRST

The onset of the feeling of thirst depends on

several factors such as local factors (dryness of

the mucosa of the mouth and pharynx) or psy-

chological factors (watching others drink a beve-

rage, for instance, causes or worsens thirst).

Intense physical activity in an athlete during a

competition, on the contrary, can eliminate or

ease it. That's why when you are sweating inten-

sely during physical activity you need to drink

even if you are not thirsty. Anyhow, the feeling of

thirst depends on centers located in the hypotha-

lamus that regulate the intake of water. These

centers receive information from various recep-

tors such as the osmoreceptors, the volorecep-

tors and baroreceptors. Then there is a hormo-

ne called angiotensin that directly stimulates

thirst centers when there is a drop in the volume

of extracellular fluids. Most of the factors (osmo-

21

receptors, voloreceptors, baroreceptors, angio-

tensin) intervene and stimulate the thirst centers

when conditions in the body have already chan-

ged. In athletes, for instance, this happens when

they have already lost a substantial amount of

sweat that can even exceed 1% of body weight.

The interruption of the stimulus to the thirst cen-

ters by these factors takes place anyway with a

certain delay compared to the moment when,

following thirst, the individual has started to drink.

In some cases the stimulus is blocked only when

the fluids have passed the stomach, reached the

intestine, passed into blood, reached extracellular

fluids and thus redressed the imbalance that

triggered the stimulus in the first place. Dryness

of the oral mucosa, on the other hand, is usually

remedied at the very moment in which an indivi-

dual drinks. This avoids the intake of an excessive

quantity of water as would be the case if you con-

tinued to drink until all the other factors stopped

stimulating the thirst centers. The feeling of a full

stomach and tense stomach walls - such as the

feeling after rapidly drinking a large amount of

water - is another element that leads to the

inhibition of thirst centers.

The thirst stimulus is qualitatively non-specific;

that is to say, it does not provide information on

the type of beverage that an individual should

drink. When a primitive man felt thirst, he had

just one beverage to quench it: water. Nowadays,

however, people feel the same stimulus, but they

can choose from several beverages to quench

thirst and, at the same time, solve any issues of

restoring water and mineral levels.

In the case of an athlete, it is important that these

fluids are integrated as well as possible and,

in order to do so, you need certain knowledge and

experience. Once you have rationally chosen the

type of beverage, thirst can provide useful infor-

mation (though not always very accurate) on the

quantity that an individual should drink of said

beverage. Though there are substantial differen-

ces between one case and another, it can be

stated that the production of about 700 g of sweat

is all that is needed to trigger thirst. It should be

noted that in a sedentary person this is more or

less the quantity of fluid loss that can already lead

to a drop in efficiency, while in athletes the quan-

tity, according to some, is more than double.

THERMAL BALANCE

While performing any type of physical activity,

the muscles involved produce heat (metabolic

heat) and the quantity depends above all on the

22

energy consumed. The environment, too, gives

heat to an athlete's body (irradiated heat) and

particularly the sun, but also hot surfaces such

as tarmac previously warmed by the sun.

However, the increase in body temperature

above certain values reduces the body's perfor-

mance. Fortunately, the body has some mecha-

nisms by means of which - at least until environ-

mental conditions are not too unfavorable - its

temperature can be cooled down (Fig. 1).

Some of these mechanisms consist in the tran-

sformation of the water into vapor that leaves

the body in the form of sweat and, to a much

lesser extent, insensible perspiration (disper-

sion of vapor through skin without the interven-

tion of sweat glands) and also by means of to the

latent heat of vaporization (elimination of water

vapor through the respiratory system). Every

gram of water that leaves the body in the form

vapor burns almost 0.6 kcal. For the purpose of

thermoregulation, maximum efficacy of the three

mechanisms is achieved when air is dry. On the

contrary, when air is humid they are less useful

and, in particular, only a small percentage of

sweat produced can evaporate while the remai-

ning amount soaks clothing or falls to the ground

in drops.

Another two mechanisms (defined as convecti-

ve) are based on the heating of the air in contact

with skin and with the mucosa of the respiratory

system respectively. The film of air that is near

our skin and the air we inhale and exhale is hea-

ted. This way, a part of the body's heat is dispel-

led. The effectiveness of convection reaches its

maximum when there is a great difference (gra-

dient) between air temperature and the tempe-

rature of the skin (or mucosa).

If air temperature is higher than the temperatu-

re of the skin or mucosa (which happens if you

are playing a sport in an environment in which

air temperature is near or above 40°C), theseFig. 1 - Some of the main factors involved in the thermal balan-ce of an athlete engaged in physical activity.

23

mechanisms do not dispel heat from the body,

but actually add heat. Another way to dispel body

heat is what can be defined as conduction,

although the term is not very precise. It occurs

when there is contact between a fluid and the

body, as is the case when you are drenched in

fresh water (just think of sports in water or even

of athletes when they pour water over their

body), run a sponge soaked with water over your

skin, or even when you drink a cool liquid, which,

as it flows in the mouth, jaws, esophagus and

finally the stomach, comes into contact with the

mucosa, which has a temperature higher than

that of the liquid, and yields heat to the liquid

until it reaches the same temperature.

It should be borne in mind that athletes benefit

from a small rise in body temperature (e.g., the

internal temperature rise from the normal 37°C

to 38°C) that occurs during warm-up before trai-

ning or the competition. However, if the tempe-

rature rises even more, there are negative

effects on enzymatic systems and on the proces-

ses that are taking place inside the body (Åstrand

and Rodahl, 1970). An internal body temperature

of more than 40-41 °C can be tolerated for just a

few minutes (Åstrand and Rodahl, 1970) and is

hence incompatible with sports.

SWEAT

Sweat is a saline solution whose composition

varies from one individual to another and even

within the same individual in different situations

(see Table 2). These differences in the concentra-

tion of minerals are linked, among other things,

to the "training" characteristics of the small

organs that produce sweat, namely sweat glands

Fig. 2 - Schematic overview of the production of sweat by a sweatgland, composed of a gland proper and by a duct through whichsweat reaches skin surface. This duct is depicted with a straightline and minimum length, while it actually is not only very long,but it is also wrapped around the gland proper until it forms asort of ball. The sweat gland first produces sweat, which has aconcentration of minerals very similar to that of plasma. Alongthe gland duct, though, electrolytes, especially sodium andchloride, are reabsorbed. In sweat, therefore, these ions have aconcentration that is much lower than in the plasma. This sameconcentration in the sweat of an acclimatized athlete is lowerthan that of a non-acclimatized individual (see Table 2). In thegland duct, calcium and magnesium re-absorption is a bit lowercompared to that of sodium and chlorine; the re-absorption ofpotassium is minimal or none (Arcelli, 1989).

24

(Fig. 2). As soon as it is produced, sweat (which

can be defined as first-intention sweat) has a

concentration of electrolytes that is similar to

that of blood plasma, that is to say it is isotonic.

During the passage through the gland duct,

however, a great amount of electrolytes is reab-

sorbed, especially some of them. The sweat that

reaches the skin’s surface is hypotonic and

contains fewer ions compared to plasma and

extracellular fluids, even less than one-third or

one-fourth of chlorine, sodium, calcium and

magnesium. However, potassium often has a

concentration similar to (or slightly lower than)

its concentration in plasma. It should be borne

in mind that an athlete who trains for a few days

in an environment that causes intense sweating

undergoes a gradual adaptation in the produc-

tion of sweat from at least three points of view:

• the concentration of ions in sweat is lower (see

the values of the last and second-to-last

column in Table 2);

• there is an increase in the body surface wet

with sweat;

• there is an increase - even very significant - in

Main mechanisms by which heat is dispersed from an athlete's body.

• Heat lost through the evaporation of sweat on skin surface (60%).

• Heat lost through diffusion of vapor through skin or insensible perspiration (2%).

• Heat lost through the elimination of vapor through the airways or latent heat of vaporization (6%).

• Heat exchanged by convection between the body surface and ambient air (30%).

• Heat exchanged by convection between air inhaled and airway mucosa (2%).

The values in brackets refer to the percentage contribution of the various heat dispersion mechanisms

during a marathon (Arcelli, 1989). The evaporation of sweat from the skin surface becomes quantitati-

vely more important when air temperature is high (or rather, when the skin-air thermal gradient is

low). The heat exchanged by convection increases when high air humidity makes it more difficult for

sweat to evaporate (see Table 1).

HEAT DISPERSION DURING SPORTS

25

the quantity of sweat secreted by sweat glands

every minute.

The first two factors make it possible, in the

same environmental conditions, to transform a

higher percentage of sweat into water vapor and

to reduce the quantity of sweat that is wasted.

This is beneficial to an athlete because, in order

to dispel the same quantity of heat, a smaller

amount of heat is needed while losing less water

and minerals from the body. The percentage of

sweat that evaporates decreases with the rise in

air humidity (especially in cases in which it is

necessary to rapidly eliminate large quantities of

heat) through the evaporation of sweat (especially,

when air temperature is high and hence heat dis-

sipation through convection is reduced). The

third type of adaptation is also beneficial, it

allows sweat glands to produce a greater quan-

tity of sweat per unit of time. For an athlete who

needs to compete in a hot or hot and moist

climate, another extremely effective mechanism

is the body's ability to resist higher dehydration

rates.

Table 1 - Thermal balance of an athlete.

The thermal balance of an athlete doing physical exercise (B) is given by:

B = M + R - Es - Ep – Er ± Cv - P – Cd

In this formula the various symbols are:

M: metabolic heat, produced by muscles;R: irradiation heat that reaches the body especially with sunrays;Es: heat lost by the body through the evaporation of sweat;Ep: heat lost by the body through insensible perspiration, i.e., through the diffusion of vapor across theskin without the intervention of sweat glands;Er: heat lost through the elimination of water vapor through the airway (latent heat of vaporization);Cv: heat exchanged by convection between the surface of the skin and ambient air - the film of air in con-tact with the skin warms up if air has a temperature below that of the skin (this mechanismdispels heat from the body); if, on the contrary, the air has a very high temperature (near or above 40 °C),it warms the body;P: heat exchanged by convection between air inhaled and airway mucosa;Cd: heat exchanged by conduction, for instance, when the body comes into contact with cold water (eventhe water in a sponge) or when you drink a cool liquid.

26

This too happens after a few days (or few weeks)

of training in an environment that leads to the

production of large quantities of sweat. In this

period, the body's water (which is already greater

in a trained athlete) tends to further increase: in

a trained and acclimatized athlete the quantity

can even be over 5% more than that of a seden-

tary individual with the same percentage of body

fat. Anyhow, it should be stressed that even with

the same level of effort and environmental condi-

tions, the quantity of sweat lost by different ath-

letes differs: in situations in which some produce

less than a liter of sweat per hour, others can

even produce up to 3 liters (Murray, 2000).

Therefore, everyone needs to drink at a schedu-

led frequency according to their own needs

(Nadel, 1980).

DEHYDRATION AND ITS CONSEQUENCES

When an athlete competes in an environment

with high temperatures and high levels of humi-

dity and irradiation, there is a first phase (begin-

ning just a few minutes after the start of activity)

Table 2 - Electrolytes contained in plasma and sweat.

The following are the concentrations of the main electrolytes contained in plasma, in the sweat of an indi-vidual at rest, in the sweat of an athlete who is not used to physical exercise in an environment that leadsto intense sweating (“non-acclimatized athlete”) and, in the last column, in the sweat of a trained athletewho is used to practicing sports in a hot and moist environment (“acclimatized athlete”). It can be clearlyseen that the sweat produced in this last case has sodium and chlorine concentrations (and even calciumand magnesium concentrations) that are between three and four times lower compared to plasma levels.Only the concentration of potassium remains constant or is slightly reduced.

The values are expressed in grams per liter. Horta (1986).

Electrolyte Blood plasma Sweating at rest Non-acclimatized athlete Acclimatized

Sodium 3,25 1,85 1,38 0,92

Chlorine 3,70 3,10 1,50 1,00

Potassium 0,20 0,20 0,20 0,15

Calcium 0,10 0,04 0,04 0,03

Magnesium 0,04 0,01 0,01 0,01

Total 7,29 5,20 3,13 2,11

27

during which there is an increase in the quantity

of blood in the skin due to dilation of blood

vessels in the subcutaneous area and to the

increase in cardiac output. A greater quantity of

(metabolic) heat produced by muscles and possi-

bly of heat absorbed by the body due to irradia-

tion reaches the skin, whose temperature rises,

thereby favoring the dissipation of heat by

convection. As stated above, the greater the diffe-

rence between air temperature and skin surface

temperature, the more effective this heat disper-

sion mechanism is. At the same time, there is an

increase in the production of sweat, which is the

prerequisite for increased heat dispersion through

the evaporation of water in this saline solution at

skin level. However, when the body has lost a

large amount of sweat (depending on the degree

of acclimatization, there are differences between

one athlete and another in the level of dehydra-

tion that can be borne, as already mentioned

above) several changes occur in the body. First of

all, there is a rise in internal body temperature.

After 20-40 minutes (but even less in extreme

climatic conditions), the body's dehydration leads

to a reduction in total blood volume. As for blood,

since sweat is characterized by lower concentra-

tions of plasma electrolytes, it witnesses an

increase in the concentration of minerals and

some of them in particular. This imbalance can

lead to muscle cramps, especially in individuals

who have a predisposition and/or are less trained.

Still, if an athlete continues to maintain a high

intensity of effort and does not provide for

adequate rehydration, the consequences can

affect the entire body. At a certain point, the body

reduces the production of sweat; at the same

time, it reduces the quantity of blood that reaches

the skin. The possible purpose of these two adap-

tations is that the latter is an attempt to allow as

much circulating blood as possible to reach the

most important organs for the survival of the body

(central nervous system and heart). However,

both the reduction in sweat produced and the

decrease in the supply of blood to skin reduce the

body's ability to dispel heat. Body temperature

can rise to above 41°C. In this case, heatstroke

ensues. At the same time, there can be a drop in

blood pressure, especially due to a reduction in

blood volume. All this makes it extremely difficult

- and dangerous to health - to continue the effort.

In U.S. football (a sport in which, among other

things, players wear gear to protect them against

injuries but which makes heat dispersion more

difficult) there have been cases of death (even

among young children) during practice in hot and

28

moist climates - in most cases, the coach had

prohibited players from drinking.

In athletes who recover most of the water lost,

these negative effects do not occur and, if they do,

they are greatly mitigated: the temperature rises

less (if the beverage is cool, the conduction

mechanism can cool down the body's temperature

by a few tenths of a degree Celsius); the reduction

in blood volume is more limited; the reduction in

sweating is not as great; cardiac output is not

reduced to the same degree, while heart rate

increases by a lesser degree; the flow of blood to

the skin remains high; and so on. Acclimatization,

too, plays an important role in that the negative

effects discussed above occur later on.

RESTORING WATER AND MINERALS

The foregoing implies that when climate condi-

tions are such that there is a major production of

sweat it is absolutely necessary to drink before

and/or during and/or after a competition or trai-

ning session, depending on the characteristics of

the effort. It is important to choose the most

appropriate beverage, and this is especially true

for the beverage drunk just before or during the

physical effort: it must remain in the stomach for

as short a time as possible and it must be rapidly

absorbed in the intestine. If it is known before

starting physical exercise that it will last more

than a few dozen minutes and lead to intense

sweating (high levels of air temperature, humidity

and solar irradiation), it is important to drink

more than usual, especially in unfamiliar condi-

tions.

Some associations recommend drinking before

sports activities. The American College of Sports

Medicine (1996) recommends drinking about 500

mL of fluids two hours before physical activity to

favor adequate hydration and have enough time to

eliminate excess fluids. The recommendation of

the American Dietetics Association (2000) is very

similar: 400 to 600 mL of fluids two hours before

physical exercise. The National Athletic Training

Association (2000) states that, in order to ensure

adequate pre-exercise hydration, athletes should

drink about 500-600 mL of water or a sports

drink, 2-3 hours before exercise and 200-300 mL

of water or sports drink 10-20 min before the

start of the competition.

At any rate, the quantity of fluids that should be

drunk as soon as the warm-up is completed

and before the start of the effort depends on

29

30

the ability to support the presence of the beve-

rage in the stomach without feeling discomfort.

It also depends on the type of effort involved.

Running, for instance, implies vertical jolts at

every step and hence concentrated beverages

are not indicated, as, on the other hand, they are

for cycling.

As regards the quantities of fluids that can be

taken during exercise, the American Dietetics

Association (2000) recommends drinking

between 150 and 350 mL at intervals of 15-20

min, while the National Athletic Training

Association (2000) states that fluid replacement

must be equal to the quantity lost through urine

and sweat, thereby limiting weight loss to less

than 2%; in general, this can be achieved with

200 to 300 mL of fluids every 10-20 min.

It is impossible, though, to indicate precise

quantities for every athlete, because the volume

of fluids to be drunk depends on the volume of

Many years ago Jacobs (1980) had already stated

that dehydration does not seem to have a negative

impact on performances of less than 60 seconds;

there is no effect on results in sprints, throws,

weight-lifting and so on. It can actually be surmi-

sed that in trials having a very short duration,

during which it is advantageous to have a lower

body weight (for instance, high jump), being

slightly dehydrated can be an advantage. In conti-

nuous competitions lasting more than a minute or

in most cases over 10-15 min, be they cyclic (run-

ning, race walking, cycling…), or acyclic (tennis,

team sports…), the loss of water can have negati-

ve consequences on performance when it exceeds

certain quantities. For instance, every liter of

water lost corresponds to an increase in heart

rate (about 8 bpm), a drop in cardiac output and a

rise in internal temperature by about 0.3°C. These

elements help explain how a careful management

of hydration - before and during a competition -

can affect the performance of athletes in these

sports in climate conditions that cause abundant

sweating.

CONSEQUENCES OF WATER LOSS ON PERFORMANCE

31

fluids lost; the latter, in turn, is affected by

several factors. Moreover, it should be added

that the possibility of replacing lost fluids varies

during a competition depending on the sport.

In team sports, for instance, it can be done

during intervals and breaks in the match; in

marathons and race walking at refreshment

stations; and so on.

As regards the quantity of beverage needed each

time, it should not bloat the stomach too much.

The maximum quantity that does not cause any

disturbance varies from one individual to

another, also depending on the type of sport.

Therefore, every athlete should find the one

most fit to him/her. In more demanding climate

conditions, the production of sweat by the body

can amount to 20-40 grams per minute. This

clearly shows how high the intake of fluids

should be, although the intestine does not

absorb more than a certain quantity of water

per minute, not even when the beverage is the

most suitable one. It should always be borne in

mind that when clothing is soaked with sweat,

the quantity of beverage sipped should be grea-

ter than that needed to quench thirst.

During training sessions, an intake of fluids

might be needed that is even greater than that

needed during a competition. In some periods

of the year (for instance, during the pre-season

of some football and basketball teams), there

are often two daily training sessions and they

last quite a while, even more than a match. The

continuous production of sweat, which takes

place even outside of a training session if the

weather is hot or hot and humid, can lead to a

substantial loss not only of water, but also of

minerals in just a few days. It should be borne in

mind that a “casual” diet - that is to say one

based on the available foods and personal

tastes - does not necessarily restore the content

of minerals in the body to normal levels. Some

muscular problems (such as cramps) can be the

result of this imbalance between intake (with

food) and loss (through sweat). That's why it can

be useful to regularly replenish the body with

some of the electrolytes contained in sweat

especially during those times of the year when

loss is greater, namely when it is hotter.

THE "IDEAL" DRINK FOR ATHLETES

Drinks for athletes should have certain well-defi-

ned characteristics especially with regard to the

time of consumption.

32

Those who do sports lasting more than a few

minutes, if continuous, or for more than 20-40

minutes if these alternate moments of intense

activity with moments of rest (as is the case in

team sports and tennis), it is absolutely neces-

sary to know whether the intake of water during

exercise or during the day is enough to make up

for fluids lost during the day. In order to avoid

worsening performance, it is very important to

be well hydrated during practice (and even more

so during a competition), that is to say, to be in

a state of euhydration. If someone is dehydra-

ted, there is a worsening in performance. All

this applies in particular to the hottest periods

of the year and, above all, to professional athle-

tes during high load periods, when they train for

many hours every day.

The most important information on the state of

hydration can be obtained from bioelectrical

impedance analysis, but one's body weight can

be very useful provided it is always measured in

the same conditions, especially in the morning

on an empty stomach, before breakfast and

after voiding stools and urine.

A drop in weight by a few hectograms compared

to the day before must always be considered as

a possible state of poor hydration.

The first urine of the morning should be exami-

ned too: it must be abundant and, above all,

quite clear; its specific weight should be of 1020

or less. Watch out, though, for very abundant

and almost transparent urine: it could be a sign

of the difficulty to retain fluids due to a poor

intake of sodium and hence of a situation of

ineffective replacement, as signaled by the

American College of Sports Medicine (see the

article “Exercise and fluids replacement” in

issue #2 of 2007 of Medicine & Science in

Sports & Exercise, pg. 377-390). In order to

reduce the useless loss of sweat, avoid staying

too long in the sun and in the heat when it is not

necessary and also avoid physical exercise

when it is not required by the sports activity.

SOME TIPS FOR MAINTAINING PROPER HYDRATION IN THE HOTTEST PERIODS OF THE YEAR

33

Drinks to be taken before exercise

The drink should be consumed 20-40 minutes

before the competition or training session so that

it does not give rise to problems later on when the

physical effort has started. For instance, if it were

very rich in carbohydrates, which lead to a rise in

blood sugar and hence in insulinemia, it could

inhibit the use of fatty acids during exercise and

even cause what is known as reactive hypoglyce-

mia. Both problems occur when high quantities of

carbohydrates are ingested and rapidly assimila-

ted, as is the case of some drinks that contain

large quantities of glucose, sucrose or maltodex-

trins (at a high concentration). Consider that 300

mL of a sports drink containing 6% of carbohy-

drates with a high glycemic index (for instance

18 g glucose, maltodextrins, sucrose) can already

lead to significant insulin stimulation, thereby

having negative effects on the ability to oxidize

fats during exercise.

Drinks to be taken during exercise or right

before it

Like the one taken during exercise, the drink to

be taken right before a competition or training

must provide in the shortest time possible for

the replenishment of what has been lost in

sweat. Therefore, it must pass quickly through

the stomach and then be absorbed rapidly in the

intestine. If possible, it should also supply a

certain quantity of carbohydrates to the body.

The time a drink spends in the stomach depends

on its concentration of carbohydrates. A quick

passage through the stomach is possible when it

contains 5% or less and, at the same time, does

not contain too many minerals. At the same con-

centration (1 g of carbohydrate for every 100 g of

water), a drink containing fructose or maltodex-

trins passes more quickly compared to one

containing glucose or sucrose.

The drinks that should be preferred for fast

absorption of water are isotonic drinks - that is

to say, drinks with a concentration of substances

similar to that of blood - or, according to some,

hypotonic drinks - that is to say, with a lower

concentration.

Though limited, the presence of carbohydrates,

is nonetheless useful because when passing

through the intestine's walls, the monosacchari-

des already present in the drink (glucose and

fructose) or those formed after the digestion of

carbohydrates formed by two or more monosac-

charides "drag" along with them some molecu-

les of water. Sodium ions, too, bind, with water

and hence favor its absorption. Put otherwise,

pure water is absorbed more slowly compared to

some saline-energy drinks, even though a

person who has sweated intensely should drink

mineral water sold in bottles or tap water rather

than not drinking at all.

Drinks to be taken after exercise

Finally, the main purpose of the drink to be

ingested after a competition or training is that

of replenishing the body not only with water, but

also with the minerals lost during exercise and

of providing a certain quantity of carbohydrates.

Unless an athlete is in a condition of severe

dehydration, drinking water immediately is not

urgent. While, on the one hand, an intake of

carbohydrates, even in large quantities, slows

down the passage of fluids through the stomach,

on the other, together with carbohydrates in

food, it helps to re-synthesize the glycogen con-

sumed by muscles.

This is especially useful when there are training

sessions or competitions almost every day.

DRINK TEMPERATURE

Drinks ingested right before the competition or

training or during exercise should be cool, espe-

cially if the temperature and humidity are high.

Those drinks with a temperature below 15°C

spend less time in the stomach compared to

those that are warmer. If drinks are between

2.5°C and 9°C, the mucosa of the mouth, larynx,

esophagus and, above all, of the stomach can be

cooled even by several degrees. Gastric motility

increases, and the time spent by fluids in the

stomach is reduced. Moreover, heat is dissipated

from the body by conduction. All these are defi-

nitely advantageous effects. When the drink is

too cold, though, there is the risk of suffering

gastric or abdominal cramps and other even

more serious consequences.

MINERALS IN DRINKS

The lack of one - or more - of the minerals lost

through sweat gives rise to problems in the body.

If the absorption of ions is blocked, even the

absorption of water stops - save for situations of

dehydration (Curran et al., 1962). Therefore,

sports drinks should contain the main minerals

that are found in sweat, namely sodium, chlorine,

potassium and magnesium.

Sodium is definitely the most important from

34

this point of view, both because it is the positi-

vely charged ion that is most lost in sweat during

physical exercise and because hyponatremia is a

serious risk in athletes. If the drink contains

sodium, among other things, rehydration is

faster because sodium favors the absorption of

water in the intestine. It should be noted that, if

it is true that with the same amount of sweat

produced, as illustrated in Table 2, a well-trai-

ned athlete loses less sodium compared to

someone who exercises occasionally, it is also

true that - due to the very fact of being well-trai-

ned - an athlete can perform workloads that are

much greater than those of someone who is less

trained and hence risks a substantial depletion

of this ion. Among other things, it is not true

that, in an individual with no heart, circulation or

kidney problems an intake of sodium leads to a

rise in fluid retention. If this occurs, it is only a

temporary phenomenon. Still, rehydration velo-

city is fastest with isotonic drinks containing - in

addition to about 5% of carbohydrates - about 50

mmol/L of sodium (Murray, 2002).

Potassium plays a synergistic role with sodium;

these two electrolytes, taken together, accelerate

rehydration. After drinking water with sodium

and potassium, diuresis is lower compared to

water without these minerals. The assessment

of their concentration in plasma, however, provi-

des limited information only because the values

that really matter are the intracellular ones.

Replenishment of magnesium is also essential.

Even though sweat does not contain very much

magnesium (see Table 2), a lack of it is much

more frequent that one would expect.

35

36

REFERENCES

Arcelli E.: La maratona: allenamento e alimentazione. EdizioniCorrere. Milan, 1989.

Arcelli E.: Calcio: alimentazione e integrazioni. Edizioni Correre,Milano, 1996.

Arcelli E. e Molteni G.: Il bilancio termico del maratoneta. LaMedicina del Lavoro, 67, 2: 183-195, 1989.

Åstrand P.O. and Rodahl K.: Textbook of Work Physiology, McGraw-HillBook Compani, New York, 1970.

Curran P.F., Macintosh J.R.: A model system for biological watertransport. Nature, Jan 27; 193:347-8, 1962.

Horta L.: Alimentaçao no deporto. Xistarca, Lisboa, 1986, 1986.

Kleiner, S.M.: Workouts worth their salt: replacing what you sweataway. Physician Sportsmed. 21: 25-26, 1993.

Liu, L., Borowski, G. and Rose L.I.: Hypomagnesemia in a tennis player.Physician Sportsmed. 11: 79-80, 1983.

McArdle W.D., Katch F.I. and Katch V.L.: Fisiologia applicata allo sport.Casa Editrice Ambrosiana, 1998.

Murray B.: Preventing dehydration: sport drinks or water. GSSIProceedings-2002.

Noakes T.: Lore of running. Human Kinetics, Champaign, 2003.

O’Toole M.L., Douglas P.S., Laird R.H. and Hiller W.D.B.: Fluid andelec- trolyte status in athletes receiving medical care at an ultradi-stance triathlon. Clin. J. Sport Med. 5: 116-122, 1995.

O’Toole M.L., Douglas P.S., Lebrun C.M., Laird R.H., Miller T.K.,Miller G.C. and Hiller W.D.B.: Magnesium in the treatment of exertionalmuscle cramps (abstract). Med. Sci. Sports Exerc. 25: S19, 1993.

37

- 4 -

fatigue in football

According to Rampinini (2008), among the defi-

nitions of "fatigue" given by various researchers

who have dealt with the issue, the most appro-

priate to illustrate what happens to a football

player during a match is the one given by Enoka

and Duchateau (2008), who stated that fatigue is

“...the impossibility to produce force or power or

to support a given task due to an exercise

carried out before.” It can be said that these

four are the main types of fatigue that a football

player can experience during a match:

• temporary fatigue: it occurs after a player

has carried out a certain quantity of high-

intensity work (for instance, sprints at short

intervals); it is temporary, i.e., it goes away

after a certain period of time;

• fatigue at the beginning of the second half:

right after half-time, in the early phase of the

second half, players are not able to give their

maximum;

• fatigue in the last phase of the match: in the

last 15 minutes of a match players in any

position, even when the final score is still

uncertain, run less and especially with less

intensity;

• fatigue due to dehydration: it typically occurs

when the match is played in the presence of

high air temperatures and high levels of

humidity and irradiation, when you have an

intense production of sweat.

It is important here to understand what are the

causes of these types of fatigue and determine

whether it is possible to prevent them through a

correct diet and supplements, but also through

physical activity.

TEMPORARY FATIGUE

“Temporary fatigue" is the fatigue that leads to a

drop in the physical efficiency of a player. It can

occur both in the first and second half and it is

marked by the fact that it is temporary and short,

that is to say from a few to several minutes.

Mohr et al. (2003) have proven that a period of 5

min of high-intensity work (for instance, running

at a fast speed) is always followed by a phase

during which a player's intensity is below the

average of the entire match.

Krustrup et al. (2006) have carried out a study,

which focused, among other things, on under-

standing which factors during a match, after

intense phases of play, cause “temporary fatigue”

and thus a drop in a football player's performan-

ce. The research study saw the participation of 31

Danish semi-professional players in a number of

friendly matches. Besides monitoring their heart

rate, blood samples were collected and muscle

biopsies were performed not only before matches,

during half time and at the end, but also during

the matches.

Players also performed another test several

times: it consisted in covering a distance of 30

m, as fast as they could, 5 times, with an interval

of 25 s during which they had to jog back to the

starting point. Even during the tests carried out

on the players before the match, the time obtai-

ned over 30 m continued to worsen (it is normal

for this to happen, considering the short break

between one sprint and another) between the

first run and the fifth of each test. In the tests

carried out during the match, right after the

high-intensity phases of play, time worsened by

1.6% - compared to those before the match -

when the test was carried out during the first

half and 3.6% when it was done during the

second half. A "crisis" was documented, but it

was followed by a return to normal after a few

minutes.

The causes of this temporary fatigue have not

been entirely cleared up, though. According to

Mohr et al. (2003), they are not linked to the

drop in muscle glycogen, but to a disorder in the

homeostatis of ions in muscle fibers. According

to Krustrup el al. (2006), it is likely that this

temporary drop in efficiency is not determined

by a single factor, but by a set of factors, such as

a rise in the concentration of lactate, ammonia

or potassium, or a drop in the pH of muscle

fibers.

38

It is unlikely that diet can affect this type of fati-

gue in a positive manner, while types of training

consisting of intense loads for a short period of

time are definitely useful, those that football

physical trainers call “lactacid loads” and during

which the level of "perturbation" inside muscle

fibers is even greater than during the match.

FATIGUE AT THE BEGINNING

OF THE SECOND HALF

According to Mohr et al. (2005), at the beginning

of the second half, the ability of players to give

their maximum level of performance is inhibi-

ted. Probably, this occurs as a consequence of

the fact that during the interval between one

half and the other, there is a drop in the tempe-

rature of the players' muscles compared to the

temperature at the end of the first half.

These are some tips that players can use to

avoid this type of fatigue:

• do light exercises while in the locker room; if

a player does static stretching, he should stop

a few minutes before returning to the pitch

according to Alberti's recommendations

(Arcelli, 2008);

• once out of the locker room, players should

jog along the way to their position on the pitch

and, if possible add a few hundred meters of

running especially if the outside temperature

is very low.

FATIGUE IN THE LAST PHASE OF THE MATCH

Bangsbo et al. (1994) observed that in the

Danish first and second division championships,

players - regardless of the role on the pitch and

the progress of the match - run less at a high

intensity during the last 15 min of the match

especially if compared to the first 15 min. At the

same time, players who came on in place of

other players (and hence were less tired) ran

25% more than players who had been on the

pitch from the beginning.

Ferretti (2008) determined that there is a drop in

efficiency at the end of the match even in Italy's

Serie A championship. With regard to Serie A,

Arcelli et al. (2010) observed that there tends to

be an increase in the number of goals scored

that are almost double those of the first 15

minutes of the match and that players who

came on in the second half scored more than

those on the pitch from the beginning. It is very

likely that this happens because fatigue has a

greater impact on the ability of defenders to

39

prevent shots on goal by attackers rather than

the ability of the latter to score.

According to Reilly (1997), the cause of this type

of fatigue is the lack of glycogen in muscles.

Already over 40 years ago, Karlsson (1969) had

observed in muscle biopsies that players with

lower glycogen concentrations in muscles

during half-time were those who in the second

half ran less at a lower average speed. Saltin

(1973) then observed that those players who at

the start of the match already had little glycogen

in their muscles ran much less than the others.

According to Krustrup et al. (2006), glycogen

deficiency in muscles especially affects type-1

fibers. Training for aerobic strength (for instan-

ce, 4 series of 4 min each at 90% of maximum

heart rate, according to the recommendations of

Hel gerud et al., 2001) increa-

ses the content of glycogen in

muscles, but does not enti-

rely solve the problem becau-

se it also leads to an increase

in the velocity of the anaero-

bic threshold and hence the

tendency to run more during

the match with an increase in

glycogen consumption.

The nutritional aspects can

be very important. Saltin (1973), as mentioned

above, had proven that it is beneficial to try star-

ting the match with the greatest possible con-

centration of glycogen in muscles. Foster et al.

(1986) had observed that the intake of maltodex-

trins during half-time allowed players to run

more and faster during the second half compa-

red to the placebo group. Shephard and Leatt

(1987), in turn, administered 28 g of maltodex-

trins in 400 mL of water before the match and

during half-time; during the first half there were

no beneficial effects, while in the second half

the distance covered increased by 25% and the

Fig. 1 - Muscle glycogen concentration before, during half-timeand at the end of the match in 6 players. In all players the con-centration of glycogen after the match is very low. FromKarlsson (1986), modified.

40

speed by 40%. No effect was registered in the

placebo group. Leatt and Jacobs (1989) had

given players a placebo or 35 g of glucose poly-

mers in 500 mL of water both 10 min before the

start of the match and during half-time; the

drop of glycogen was greater in the placebo

group compared to the players replenished with

carbohydrates.

Based on the statements of the last three

papers (Foster et al., 1986; Shephard and Leatt,

1987; Leatt and Jacobs, 1989), the intake of car-

bohydrates before the match and during half-

time does give a certain boost to performance in

football players. Why don't the habits of football

players include the regular intake of carbohy-

drates at these two moments?

If they do so, why in minimum quantities? And

why so few players?

There are several reasons. If you play having

taken 400 or 500 mL of fluids just a few minutes

before, you have an unpleasant feeling of stoma-

ch fullness that is bothersome when running. On

the other hands, problems do not decrease if you

wish to obtain the same quantity of carbohydrates

in a smaller volume of a drink, because the

greater concentration determines, at least, a

longer dwell time in the stomach and a longer

intestinal absorption time (Maughan, 1991).

Putting off the moment of the drink intake is not

possible during half-time (which lasts about 15

min). Before the start of the match, though, an

earlier intake by 10-20 minutes can lead to a

condition of reactive hypoglycemia and also an

inhibition to use fats, which, as is quite likely,

contribute during the second half, to supplying

energy to muscles, though to a limited extent

(Bangsbo, 1994; Krustrup et al., 2006).

Recently, a solid gelatin (a new category of

energy supplements, not to be mistaken with

gel) made of carbohydrates such as fructose

and isomaltulose has become available, and it

has a minimal dwell time in the stomach

matched by slow absorption. It can be taken up

to a short time before the start of the match (in

some cases even 15 min before the start and at

the beginning of half-time) without any inconve-

nience. Slow assimilation, on the other hand,

allows these carbohydrates to be a sort of

energy supply that passes slowly into blood

during the match. Since, according to Stolen et

al. (2005), a player of 75 kg burns between 1500

and 1770 kcal to complete a match, each gelatin

41

- which supplies 26 g of fructose and isomaltu-

lose (equal to slightly over 100 kcal) - guaran-

tees, in theory, an extra 5-6 min of autonomy

during the match.

FATIGUE DUE TO DEHYDRATION

When a football match is played in environmen-

tal conditions (high levels of temperature, humi-

dity and irradiation) which lead to copious swea-

ting, there is a risk that the players experience

another type of fatigue, i.e., the one due to dehy-

dration and the rise in body temperature

(hyperthermia). During a football match, the

drop in the body weight of football players is

frequently 1-2 kg and can even reach 4-5 kg in

extremely hot environments (Shephard and

Leatt, 1987). According to Åstrand and Rodahl

(1970), already when water loss amounts to

2-3% of body weight (equal to about 1.5-2 L), the

body's efficiency worsens, while greater losses

can even cause very serious disorders; in these

cases, it is useful to drink in the run-up to the

match (see article on drinks, pg 20-36), imme-

diately after warm-up and during half-time as

well as to supply players with solutions of water

and minerals also during the match, during any

pause. It is also possible to assess the opportu-

nity of resorting to pre-hydration (Arcelli, 1996),

immediately after warm-up, so that the entire

intake of water (at least 0.4 L) is not eliminated

through urine before the start of the match due

Fig. 2 - During Italian Serie A footballmatches, if the 90 min are divided into 6spans of 15 min each, the percentage ofgoals scored rises from one span toanother, up to 23.9% of the total in thelast 15 minutes of the match. FromArcelli et al. (2010).

42

to a drop in blood levels of adiuretin. In extreme

climate conditions, you can also consider

drinking 1.5 L of water with glycerol (0.7-1 g per

kg of body weight) starting 90 min before the

match (Lyons et al., 1990).

At any rate, being used to physical activities in

environments that lead to the production of great

quantities of sweat allows the body to resist a

greater loss of sweat before witnessing a drop in

efficiency (Åstrand and Rodahl, 1970).

43

Even in sports with easily measurable perfor-

mance (for instance, running or swimming), it is

very difficult to assess fatigue, simply due to the

fact that motivation plays an important role.

Things become even more complicated in sports

like football in which the performance also

depends on skill and tactics.

It would be useful to be able to assess also other

parameters in football players during various

moments of the match, such as the number of

errors (passes, shots, position…). However,

relying on a parameter such as the mobility of an

athlete is anyhow correct because it is assumed

that when the athlete moves less, it is because of

tiredness.

It should be borne in mind that a football player,

especially at the start of the match, works at

around the intensity of the anaerobic threshold

with periods in which the effort is even greater

(thus accumulating an oxygen deficit), alternated

with others in which it is lower and the athlete

can partly recover and be more ready to perform

actions in which the correct movement can be

matched by the high intensity of the effort.

FATIGUE AND ITS ASSESSMENT

REFERENCES

Arcelli E.: La reidratazione, in “Calcio: alimentazione e integrazio-ne”. Edizioni Correre, Milan, pg. 89-92, 1996.

Arcelli E.: Stretching e dintorni. Intervista a Giampiero Alberti.Scienza&Sport, n. 0, pg. 56-58, 2008.

Arcelli E., Pugliese L., Borri D. and Alberti G.: L’importanza dei gio-catori entrati nel secondo tempo. I gol segnati nel finale di partita inserie A. Scienza & Sport, n. 6, pg. 46-50, 2010.

Åstrand P.-O. and Rodahl K.: Textbook of Work Physiology, McGraw-Hill Book Company, New York, 1970.

Bangsbo, J.: The physiology of soccer with special reference to inten-se intermittent exercise. Acta Physiol Scand Suppl, 619, 1-155, 1994.

Ekblom, B.: Applied physiology of soccer. Sports Medicine, 3 (1), pg.50-60, 1986.

Enoka R.M., Duchateau J.: Muscle fatigue: what, why and how itinfluence muscle function. J. Physiol., 586 (1): pg. 11-23, 2008.

Ferretti, F.: Calcio: allenamento aerobico di qualità e di quantità. Attidel XVI Congresso Isokinetic, Milano, Calzetti e Mariucci Editori, pg.149-156, 2008.

Foster C., Thompson N.N., Dean J. and Kirkendall D.T.:Carbohydrate supplementation and performance in soccer players.Medicine & Science in Sports & Exercise. 18, S12, 1986.

Helgerud J., Høydal K., Wang E., Karlsen T., Berg P., Bjerkaas M.,Simonsen T., Helgesen C., Hjorth N., Bach R. and Hoff J.: Aerobichigh-intensity intervals improve VO2max more than moderate trai-ning. Medicine & Science in Sports & Exercise, 39 (4), pg. 665-671,2007.

Karlsson, H.G.: Kohlhydratomsattning under footballsmatch. ReportDepartment of Physiology III, reference 6, Karolinska Institute,Stokholm, 1969. Cited by Ekblom, 1986.

Leatt P. and Jacobs I.: Effects of glucose polymer ingestion on glyco-gen depletion during a soccer match. Canadian Journal of SportsSciences, 14, pg. 112-116, 1989.

Krustrup P., Mohr M., Steensberg A., Bencke J., Kjaer M., BangsboJ.: Muscle and blood metabolites during a soccer game: implicationfor sprint performance. Med. Sci. Sports Exerc., 38 (6): pg.1165-1174, 2006.

Lyons T.P., Riedesel M.L., Meuli L.E. and Chick T.W.: Effects of glyce-rol-induced hyperhydration prior to exercise in the heat on sweatingand core temperature. Medicine & Science in Sports & Exercise, 22(4), pg. 477-483, 1990.

Maughan R.J.: Fluid and electrolyte loss and replacement in exercise.Journal of Sports Sciences. 9: pg. 117-142, 1991.

Mohr M., Krustrup P., Bangsbo J.: Match performance of high-stan-dard soccer players with special reference to development of fati-gue. J. Sport Science, 21 (7): pg. 519-528, 2003.

Mohr M., Krustrup P., Bangsbo J.: Fatigue in soccer: a brief review.J. Sport Science, 23 (6): pg. 593-599, 2005.

Railly T.: Energetics of high-intensity execise (soccer) with particularreference to fatigue. J. Sports Scie., 15, pagg. 257-263, 1997.

Rampinini E.: Il ruolo della fatica nel gioco del calcio.Scienza&Sport, n. 0, July, pg. 60-63, 2008.

Saltin B.: Metabolic fundamentals in exercise. Medicine & Sciencesin Sports & Exercise, 5, pg. 137-146, 1973.

Shephard R.J. and Leatt P.: Carbohydrate and fluid needs of thesoccer players. Sports Medicine, 4, pg. 164-176, 1987.

Stolen T., Chamari K., Castagna C. and Wisloff U.: Physiology ofsoccer. An update. Sports Medicine, 35 (5), pg. 501-536, 2005.

44

- 5 -

gastrointestinal disorders

in long-distance runners

Athletes of some endurance sports and particu-

larly runners often report gastrointestinal

disorders, which can particularly affect the

esophagus (retrosternal pain, gastroesophageal

reflux), stomach (heartburn, nausea, vomiting)

and intestine (abdominal pain and cramps, need

to urgently evacuate, diarrhea, blood in stools).

These (generally temporary) disorders lead ath-

letes at times to reduce the intensity of their

effort, to temporarily interrupt activity and, in

the worst cases, to quit a competition (Sullivan,

1984; Peters et al., 1995; Peters et al., 1999).

In endurance competitions, gastrointestinal

disorders are among the most frequent causes

for withdrawal from the race or lower perfor-

mance (Pfeiffer et al., 2009).

WHO IS MOST LIKELY TO SUFFER

GASTROINTESTINAL DISORDERS

The first studies on the prevalence of gastroin-

testinal (GI) disorders in athletes date back to

40 years ago. Sullivan (1981) studied 57 mem-

bers of a running club (of whom only one-third

ran in competitions) and observed that 30% of

them had to evacuate urgently after the compe-

tition, 25% suffered abdominal cramps, 10%

heartburn and 6% intense nausea or vomiting

during the competition. Keeffe et al. (1984) stu-

died 707 athletes who participated in the Oregon

marathon and observed that they had more fre-

quent bowel movements or diarrhea after the

competition in 36% of the cases, they had to

interrupt the competition to move their bowels

in 20% of cases, suffered abdominal cramps in

14% of cases and had blood in stools in 2.4 % of

cases. More or less similar data were recorded

45

by Riddoch and Trinic (1988) in 536 runners of

the Belfast marathon and by Halvorsen et al.

(1990) in 279 runners in a local marathon.

This and other studies have shown that GI

disorders

• are present both in competitive runners and in

amateur runners (Eichner, 1988)

• are more frequent in women than in men (Keeffe

et al., 1984; Riddoch e Trinick, 1988; Peters et

al., 1999)

• are more frequent in runners who abruptly

increase the quantity of training (Eichner,

1988), are younger (Moses, 1990; Riddoch and

Trinick, 1988), are rather new to the sport and

are less trained (Moses, 1990)

• are more frequent in those who have already had

(Riddoch and Trinick, 1988) and in those who

normally have (Eichner, 1988) issues of gastritis

or colitis

• are more frequent in competitions than in trai-

ning and in more challenging competitions com-

pared to easier ones (Eichner, 1988; Riddoch and

Trinick, 1988).

According to Brouns and Beckers (1993), in

sports in which the body remains in a more sta-

ble position (cycling, swimming, ice-skating or

cross-country skiing) the frequency of GI disor-

ders, at the same intensity of effort and same

intake of substances before or during the compe-

tition, is lower compared to running. Rehrer and

Meijer (1991) measured accelerations and dece-

lerations in the GI region both in runners and

cyclists and observed that in the former they

were double compared to the latter. At every step

while running, you have vertical oscillations of the

trunk, and when you land on the ground there is a

sudden deceleration of the body, while you have

an acceleration at the moment of the thrust.

In runners, endoabdominal organs experience a

sort of continuous shaking.

THE CAUSES OF GASTROINTESTINAL

DISORDERS

Many researchers have sought to understand

which factors cause GI disorders. Riddoch and

Trinick (1988) stated that usually the causes of

these problems are unknown. According to

Dawson et al. (1985), hypertrophy of the psoas

muscle, with its movement during running, pres-

ses a section of the intestine, leading it to eva-

cuate; this could be a first cause of runner's

diarrhea. Eichner (1988) stated that some GI

disorders are the result of the use of anti-inflam-

46

matory drugs that runners frequently use to fight

disorders of the locomotor system. Rehrer et al.

(1990) stated that dehydration (especially when

water loss is greater than 4% of body weight)

favors GI disorders. Moses (1990) suggested that,

if you drink pure water, there are fewer disorders

compared to when you drink solutions rich in

carbohydrates and that nausea and vomiting are

often a sign of dehydration and hyperthermia.

Among the causes for the onset of GI disorders,

Brouns and Beckers (1993) also included:

• level of training: whoever starts to run - or resu-

mes running after a pause - will more likely have

GI disorders

• intensity of exercise: whoever gives his/her

maximum has more problems

• what is eaten before the competition: most pro-

blems result from the intake before physical

activity of too much food rich in fats, proteins or

fibers

• food or drinks during the competition: disor-

ders can arise, for instance, due to the intake of

caffeine, proteins and drinks that are too rich in

carbohydrates.

As for runner's diarrhea, Brouns and Beckers

(1993) stated that it can also be caused by diffi-

culties in absorbing sugars; for instance, if a few

dozen grams of fructose (a sugar that is absorbed

slowly) are taken together, once they are in the

small bowel they draw water from the gut walls

and the presence in the bowels of a consistent

amount of water and fructose acts as a mechani-

cal stimulus that causes diarrhea. The tolerance

of athletes to large doses of drinks containing

carbohydrates and the likelihood of developing GI

disorders seem to vary greatly from one indivi-

dual to another.

As for blood in stools, there are two hypotheses:

• traumatic: the shaking of abdominal organs

typical of running leads to the so-called “cae-

cal slap syndrome” (Porter, 1982), i.e., the

continuous knocking of intestinal walls

against one another, especially in the cecum,

thereby causing lesions in the mucosa; this

could explain why blood is frequently found in

the stools of runners (whose endoabdominal

organs, as already stated, experience intense

vertical accelerations and decelerations), but

not in cyclists or swimmers whose efforts are

of the same duration and intensity of running;

• ischemic: during intense physical exercise -

as demonstrated by Rowell et al. (1964),

Clausen (1977) and Qamar and Reed (1987) -

47

intestinal blood flow greatly decreases since

the blood is diverted to muscles and skin to

favor thermal balance. This could explain why

GI disorders are more frequent when running

at a high temperature (and even more so

when even humidity is also high). Since a lot

of blood needs to be channeled to the skin to

favor the dispersion of heat, much less blood

reaches the bowels.

PREVENTION OF GASTROINTESTINAL

DISORDERS

Here are some tips on how to avoid the onset of GI

disorders during exercise or right after.

Pre-competition diet

If you suffer from diarrhea, abdominal pain or

cramps or you often feel the need to urgently

move your bowels during a competition or right

after, you should limit the intake of foods with a

high fiber content (e.g., legumes and whole

grains) during the two days before the competi-

tion and large amounts of fruit in the 24 hours

before the competition. You should also avoid

consuming milk, cream and ice-cream (even in

small quantities that normally do not cause any

problems) in the previous 24 hours if you suffer

from lactose intolerance. In the hours right

before the competition, limit the amount of cof-

fee. If you usually suffer from nausea, vomiting

or a heavy stomach while you are running, the

last meal should be eaten at least three hours

before in case of slow digestion. The total fats

should be few; avoid fried fats or fats that have

been cooked at length. Coffee with milk is espe-

cially slow to digest.

Drinks during the competition

If during the last part of previous competitions

you have suffered from nausea and vomiting or if

you have had the feeling of not being able to eat

or drink, try to avoid dehydration and hyperther-

mia by regularly drinking beverages with a low

concentration of carbohydrates, especially if the

climate makes you sweat a lot.

Training

When training at competition intensity, try the

drinks you plan on drinking during the competi-

tion. Usually, every runner tends to more easily

tolerate drinks with a certain maximum concen-

tration of carbohydrates and maximum volumes

of fluids in the stomach; each athlete should

precisely determine both of these before the

competition especially if he or she wishes to

48

prepare customized refreshment. A glucidic

drink that passes rapidly through the stomach

must contain at least 5% of carbohydrates; fruc-

tose and maltodextrins, at the same concentra-

tion, pass through the stomach faster than

sucrose and glucose in the same concentration.

If the temperature is low and there is little swea-

ting and a reduced need for water intake,

the drink can be more concentrated.

Medical drugs

In order to reduce the risk of both gastric and

abdominal pains and of blood loss, be careful

when using anti-inflammatory drugs. Heartburn

(i.e., burning in the stomach) can be prevented

using antacids. Priebe and Priebe (1984) obser-

ved that diarrhea can be prevented with specific

drugs, while according to Eichner (1988) drugs

can be used even in the presence of blood in

stools; however, medical supervision is absolu-

tely necessary in these cases.

ESOPHAGUS

STOMACH

COLON AND RECTUM

SYMPTOMS FREQUENCY PREVENTION

HeartburnRetrosternal painBelching

● Be careful when using anti-inflammatory drugs● Take antacids (under medical supervision)

10%18%23%

NauseaVomit

● Eat the last meal 3 hours before the competition● Do not eat fried or elaborate food● Limit the content of fats in the previous meal● Regularly drink fluids with a low concentration of carbohydrates during the competition

● Limit foods with a high fiber content● Limit coffee consumption● Avoid food containing lactose in case of intolerance● Be careful when using anti-inflammatory drugs

10%9%

Abdominal crampsUrgent need to move bowelsDiarrheaBlood in stools

31%38%21%

7%

49

Table 1 - Main symptoms (in the esophagus, stomach and colon/rectum) felt by runners; approximate frequency in athletes (valuesobtained from various surveys) and prevention criteria.

REFERENCES

Brouns F., Beckers E.: Is the gut an athletic organ? Digestion,absorption and exercise. Sports Med., 15(4): 242-257, 199 Rowell etal. (1964), 3.

Clausen J.P.: Effect of physical training on cardiovascular adjust-ments to exercise in man. Physiol Rev, 57 (4):779-815, 1977. Cited byMoses F., 1990.

Dawson D.J., Khan A.N., Shreeve D.R.: Psoas muscle hypertrophy:medical cause for “jogger’s trot”? British Medical Journal, 391: 787-788, 1985. Cited by Eichner, 1988.

Eichner E.R.: Other medical consideration in prolonged exercise. In“Prolonged Exercise”, Lamb D.R. and Murray R., Benchmark PressInc., Indianapolis, Indiana (USA), 1988.

Halvorsen F.A., Lyng J., Glomsaker T., Ritland S.: Gastrointestinaldisturbances in marathon runners. British Journal of SportsMedicine, 24(4): pg. 266-268, 1990.

Keeffe EB, Lowe DK, Goss JR, Wayne R.: Gastrointestinal symptomsof marathon runners. West J Med., 141 (4): 481-484, 1984. Cited byMoses M., 1990.

Moses FM.: The effect of exercise on the gastrointestinal tract.Sports medicine 9(3): pg. 159-172, 1990.

Peters H.P., Bos M., Seebregts L., Akkermans L.M., van BergeHenegouwen G.P., Bol E., Mosterd W.L., de Vries W.R.:Gastrointestinal symptoms in long-distance runners, cyclists, andtriathletes: prevalence, medication, and etiology. Am JGastroenterol., 94 (6): pg. 1570-1581,1999.

Peters H.P., van Schelven F.W., Verstappen P.A., de Boer R.W., vander Togt C.R., de Vries W.R.: Gastrointestinal problems as a functionof carbohydrate supplements and mode of exercise. Med Sci SportsExerc., 25 (11): pg. 1211-1224, 1993.

Peters H.P., van Schelven W.F., Verstappen P.A., de Boer R.W., Bol E.,Erich W.B., van der Togt C.R., de Vries W.R.: Exercise performanceas a function of semi-solid and liquid carbohydrate feedings duringprolonged exercise. Int J Sports Med., 16 (2): pg. 105-113, 1995.

Pfeiffer B., Cotterill A., Grathwohl D., Stellingwerff T., JeukendrupA.E.: The effect of carbohydrate gels on gastrointestinal toleranceduring a 16-km run. Int J Sport Nutr Exerc Metab., 19 (5): pg. 485-503, 2009.

Priebe W.M., Priebe J.A.: Runners diarrhea: prevalence and clinicalsyntomatology American Journal of Gastroenterology., 79: pg. 827-828, 1984.

Qamar M.I., Read A.E.: Effects of exercise on mesenteric blood flowin man. Gut, 28 (5): pg. 583-587, 1987.

Porter A.M.: Marathon running and the caecal slap syndrome. Br JSports Med, 16 (3): pg. 178, 1982.

Rehrer N.J., Beckers E.J., Brouns F., ten Hoor F., Saris W.H.: Effectsof dehydration on gastric emptying and gastrointestinal distresswhile running. Med Sci Sports Exerc., 22 (6): pg. 790-795, 1990.

Rehrer NJ, Meijer GA.: Biomechanical vibration of the abdominalregion during running and bicycling. J Sports Med Phys Fitness,31(2): pg. 231-234, 1991.

Riddoch C, Trinick T.: Gastrointestinal disturbances in marathonrunners. Br J Sports Med., 22(2): pg. 71-74, 1988.

Rowell L.B., Blackmon J.R., Kenny M.A., Escourrou P.: Splanchnicvasomotor and metabolic adjustments to hypoxia and exercise inhumans. American Journal of Physiology, 247: H251-H258, 1964.Cited by Brouns and Beckers, 1993.

Sullivan S.N.: The gastointestinal symptoms of running (letter). NewEngland Journal of Medicine, pag. pg. 304: 915, 1981. Cited by MosesM., 1990.

Sullivan S.N.: The effect of running on the gastrointestinal tract. JClin Gastroenterol, 6 (5): pg. 461-465, 1984.

50

- 6 -

sports anemia

Sports anemia affects, above all, athletes who

train frequently and very intensely, starting with

those who do endurance sports such as

marathon, triathlon, cross-country skiing,

cycling and racewalking; but it also often affects

athletes who play individual or team sports.

Women athletes are affected more frequently

than men.

This article will discuss the most likely causes of

this disorder and the most effective treatments,

especially in light of recent discoveries (hepci-

din), which have shed new light on sports ane-

mia and, above all, have identified ways to cor-

rect it more easily.

SPORTS ANEMIA AND PSEUDOANEMIA

Hemoglobin is an iron-containing molecule that

is found in red blood cells; its task is to carry

oxygen. You have anemia when blood contains

scarce hemoglobin and/or when there are few

red blood cells and/or when the hematocrit is

low. Sports anemia is the result of iron defi-

ciency and is hence called sideropenic.

In sports that require a lot of oxigen in muscles

(typically aerobic continuous sports and those

with a substantial aerobic component, but also

intermittent sports - especially games - in which

fast recovery is needed between one intense

exercise and the next), performance is significan-

tly worse in athletes who become anemic. Often

times, there are even major problems to sustain

training sessions that were easily tolerated up to

a short time before.

It is often said that the ideal hemoglobin concen-

tration levels in blood should amount to at least

51

14.5 g/dL in men athletes and at least 13.5 g/dL in

women athletes. There have been though athletes

who have achieved extraordinary results (even

Olympic gold medals in the marathon) with levels

of hemoglobin much lower than these. Some

argue that you have anemia proper with levels

below 13 g/mL or, in women, below 11 g/L of

hemoglobin. In actual fact, an athlete can be con-

sidered anemic even if values fall within the nor-

mal range for the general population; the doubt

of an impending development of anemia must

arise when the values of an athlete’s last blood

exam are much lower than the values of the

exams when the athlete was in good condition.

Often times, though, low values of hemoglobin,

red blood cells and hematocrit in athletes are due

to pseudoanemia (i.e., false anemia). This can be

a consequence of training (e.g., of the sudden

rise in workloads, or work done at altitudes or in

conditions that cause copious sweating) and

involves a dilution of blood; there is no reduction

- rather an increase - in the total quantity of

hemoglobin or red blood cells in circulation, but

there is a significant increase in the volume of the

liquid portion. Therefore, the increase in plasma

volume is greater than the increase of the volume

of the red blood cells. In these cases, an athlete's

performance is not at risk.

In anemia proper - due to iron deficiency in bone

marrow (the organ that "makes" red blood cells) -

there is a drop in the total quantity of hemoglo-

bin in the blood, in the ability to carry oxygen and

in the availability of energy for muscles at every

second. The ability of muscles to work also

decreases because some very important mole-

cules for the use of oxygen (myoglobin, cytoch-

romes and various other enzymes involved in

producing energy through aerobic mechanisms)

contain iron and their production decreases

when there is an iron deficit.

Each time you have an anemic athlete, it is very

important to exclude the existence of other

pathologies that may have caused this condition.

It should also be borne in mind that celiac disea-

se too (which occurs in 1 out of every 150

Italians) can also cause anemia.

THE CAUSES OF SPORTS ANEMIA

Up to a few years ago, it was believed that the

only cause of sports anemia was that lost iron

amounted to more than the iron absorbed and

that the main reason for this imbalance consi-

sted solely in a low intake of iron with food or in

52

an increased loss of it especially through urine,

stools, sweat and, in women athletes, through

menstruation. Even today - although the role of

hepcidin has quite changed our view of things -

these aspects are nonetheless important and

should be known.

LOW IRON INTAKE

In Western countries an adult usually ingests a

few milligrams of iron through food. However, it

should be considered that only a small part of

this iron (often less than 10%) is usually absor-

bed. Heme iron, the one found in meat (inclu-

ding offal, cold cuts and fresh or frozen fish pro-

ducts), is more easily absorbed than non-heme

iron, i.e., that form of iron found in foods of plant

origin such as legumes, nuts (walnuts, hazel-

nuts, almonds, pineseeds, etc.), brewer's yeast,

parsley, spinach and so on.

Many of the athletes who tend to develop anemia

have a very low consumption of iron-rich food,

sometimes because they have totally eliminated

foods of animal origin from their diet without

having adopted, at the same time, those adjust-

ments that usually allow vegetarian athletes

with a good knowledge of dietetics to avoid

problems of iron deficiency.

INCREASE IN IRON LOSS

All individuals have a daily "physiological" loss

of iron through sweat, desquamation of the skin

and intestinal epithelium and so on. Some have

greater losses, for instance, due to blood losses

through the digestive tract (gastritis, duodenitis,

colitis, ulcers in various sites, hemorrhoidal

disorders, etc.), due to other hemorrhages (pro-

bably of minor extent yet continuous) and, in

women, gynecological disorders. The first goal

for anyone who has sideropenic anemia must be

to exclude these causes.

In athletes who train intensely and frequently,

there can be an increased loss of iron through

the following routes: stools, urine and sweat.

LOSS OF IRON THROUGH STOOLS

In runners' stools there are often traces of blood

especially after long training sessions or after

races over long distances (Stewart et al., 1984).

This can be due to various causes, such as “cae-

cal slap syndrome”, namely the shaking of the

cecum during running (Porter, 1982), or to inte-

stinal ischemia, i.e., a reduced supply of oxygen,

above all in the colon, with subsequent vasodila-

tion and the passage of red blood cells into the

53

intestine (Heer et al., 1987). In some cases blood

losses are due to lesions in the mucosa of the

bowels, stomach or esophagus or to full-blown

ulcers (Choi et al., 2001). These blood losses are

at times accompanied by GI disorders during

exercise and are often caused by the use of anti-

inflammatory drugs to treat problems in tendons

or joints, which are frequent in athletes (Baska et

al., 1990). See also the article on gastrointestinal

disorders, pg. 45-50.

LOSS OF IRON THROUGH URINE

The first researcher who spoke of “athletic

pseudonephritis” was Gardner over 50 years ago

(Gardner, 1956). He observed that after a match

the urine of American football players would

contain proteins and red blood cells, as if the

individuals had nephritis; but the urine would

return to normal after about ten hours of rest.

It is this very return to normal of urine that is

still considered today an important fact in deter-

mining whether it is a form of nephritis or a

condition linked to physical exercise. Hematuria

is caused by increased glomerular permeability

(in turn, favored by renal ischemia, which is

more likely if the hot climate draws blood to the

skin). The longer the duration and intensity of

physical exercise, the more common it is.

An important role is definitely played by catecho-

lamines and the increased production of free

radicals (Bellingheri et al., 2008).

In a runner's urine, blood can be found even in

large amounts due to lesions in the bladder cau-

sed by the continuous knocking between the

walls of the bladder (Blacklock, 1979). In cyclists

and in particular those riding mountain bikes,

hematuria can be caused by traumas to the peri-

neum (Albersen et al., 2006).

In urine, there can be hemoglobin when many

red blood cells break inside blood vessels; in

runners, this happens, above all, because of the

impact of feet on the ground, more specifically in

the tissue crushed between the ground and the

bones of the heel and forefoot (Telford et al.,

2003). Haptoglobin usually binds free hemoglo-

bin, which is released in blood and carried to the

spleen where iron is recovered. However, if trai-

ning is extended in time and if - due to the oxida-

tion of membranes as a result of the free radicals

formed during exercise - red blood cells tend to

break more easily, this molecule is no longer

available and a certain quantity of hemoglobin is

not “captured” eventually ending up in urine.

54

LOSS OF IRON THROUGH SWEAT

The sweat of an individual doing physical exerci-

se contains iron concentrations that tend to

decrease with the duration of the effort and the

degree of training in conditions that favor swea-

ting (DeRuisseau, 2002; Chinevere, 2008). Those

who train every day (or even twice a day) with

high temperatures, humidity and irradiation pro-

duce several liters of sweat every day. They can,

as a consequence, experience significant iron

losses. While in the past it was believed that

women athletes would lose more iron through

sweat compared to male athletes (Lamanca et

al., 1988), nowadays the tendency is to believe

that there is no significant difference between

genders especially in runners covering the same

number of kilometers (DeRuisseau, 2002).

EFFECTS OF A NEGATIVE IRON BALANCE

When the iron balance is negative (iron loss

greater than iron absorption), first there is just a

drop in total iron reserves in the body with the

blood level of ferritin dropping below normal

levels; this is a condition called pre-latent iron

deficiency and usually athletes do not feel any

symptoms (Fig. 1, pg. 57). Latent iron deficiency

occurs when even the values of transferrin are

also out of range (in this case high), while the

values of hemoglobin, red blood cells and hema-

tocrit are still or almost normal; the athlete

already feels much more tired than usual.

In manifest iron deficiency all values are alte-

red: ferritin, serum iron, hemoglobin, red blood

cells and hematocrit are low; transferrin is high;

the mean volume of red blood cells is small.

Besides generalized weakness, an athlete has

muscular pain and difficulty recovering between

one session and another and between one exer-

cise and another during training; the intensity

he/she can maintain (in running, cycling, swim-

ming, racewalking, etc.) is lower than usual.

HEPCIDIN AND THE ROLE OF INFLAMMATION

In recent years, the role that hepcidin plays in

the onset of sports anemia is becoming increa-

singly clearer. It is a hormone that is essential in

the regulation of iron in the body. Hepcidin grea-

tly influences the absorption of iron contained in

food: the greater its concentration in blood, the

less iron is absorbed in the duodenum.

Moreover, hepcidin regulates the release of iron

contained in reserves, especially in the liver and

spleen, in that the high levels of hepcidin

55

substantially reduces iron (Ganz, 2003; Leong

and Lönnerdal, 2004; Robson, 2004). As a conse-

quence of hepcidin’s double effect (inhibition of

both absorption of iron in the bowels and its

release from reserves), blood has a lower con-

centration of iron and bone marrow lacks enough

raw material, namely iron, which is absolutely

necessary for the synthesis of hemoglobin.

The rise in hepdicin levels is caused by the

increase in proinflammatory substances in the

body (Ganz and Nemeth, 2009), triggered by

some cytokines, in particular, interleukin-6 (or

IL-6); said increase is activated, in turn, by

intense and frequent training (Ostrowski et al.,

1998; Pedersen and Toft, 2000), although there

are significant differences between one indivi-

dual and another from this point of view.

RULES TO PREVENT SPORTS ANEMIA

The use of fish oil, thanks to its content of long-

chain omega-3 fatty acids and in particular EPA

and DHA, definitely makes it possible to reduce

the body's state of inflammation. In cell mem-

branes, these fatty acids replace in part arachi-

donic acid. This favors the production of both a

smaller quantity of pro-inflammatory cytokines

(starting from IL-6) and a greater quantity of

antiinflammatory series-1 prostaglandins (Bagga,

2003; Burns et al., 2007; Grimble, 1998).

Still, besides fish oil, supplements containing iron

can be taken in the case of anemia, but only until

blood levels indicating that the disorder is still in

progress normalize.

Anyone who has suffered sideropenic anemia in

the past tends to redevelop anemia.

Therefore, besides taking fish oil, an individual

should also follow some rules (Arcelli et al.,

1995):

• include a source of heme iron in main meals,

such as various types of meat at lunch and

dinner (white meat is better than red meat

because the latter is rich in arachidonic acid),

and a slice of trimmed ham or two slices of

bresaola at breakfast; iron absorption is favo-

red by the presence of vitamin C and other

organic acids, while it is hindered by tannins

found in tea, coffee and wine. Instead of these

beverages you should drink water or orange

juice at meals

• regularly follow an anti-inflammatory diet,

i.e., low in arachidonic acid (besides replacing

red meat with white meat, as mantioned

56

above, also reduce the intake of egg yolks to a

minimum). Limited amounts of plant seed oils

rich in omega-6 fatty acids should be consu-

med and very few foods containing them, such

as snacks, cookies and other packaged

products whose labels indicate the presence

of “vegetable fats”

• have regular blood tests, for instance, in win-

ter every 60 training sessions (every month

Fig. 1 - Situation of reserve iron, hemoglobin iron, blood tests and individual symptoms in normal conditions and conditions of pre-latent, latent and manifest iron deficiency.

57

and a half, if training 10 times a week and

every three months if training 5 times) and in

summer every 40 sessions

• keep a chart in a notebook or PC that summa-

rizes both the data of the main blood tests of

recent years (number of red blood cells,

concentration of hemoglobin, hematocrit,

ferritin, transferrin, MCV, and MCH) as well as

subjective feelings and objective results of

training and competitions at the time of the

blood tests.

Hepcidin is a peptide consisting of 25 amino acids, which, among other things, is also a regulator

of iron in the body. Individuals who do not have this hormone as a result of a genetic mutation accu-

mulate iron in the body and experience hemochromatosis. An abundance of hepcidin due to an

inflammation reduces the absorption of iron in the small bowel and makes macrophages (that build

iron reserves) release iron with difficulty. The name hepcidin was coined by Park et al. (2001) when

they discovered this peptide produced by the liver (hence the prefix hep-) in human urine and

realized that, in vitro, it had the power to kill bacteria (hence the suffix -cidin). Only some years later

was its role in iron metabolism fully understood.

HEPCIDIN

58

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