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Revista Brasileira de Medicina do Esporte

Print version ISSN 1517-8692

Rev Bras Med Esporte vol.9 no.2 Niterói Mar./Apr. 2003

http://dx.doi.org/10.1590/S1517-86922003000200002 

GUIDELINES

 

Guidelines of the Brazilian Society of Sports Medicine

Dietary changes, fluid replacement, food supplements and drugs: demonstration of ergogenic action and potential health risks

 

 

Editor: Tales de Carvalho
Co-editors: Tânia Rodrigues, Flávia Meyer, Antonio Herbert Lancha Jr. and Eduardo Henrique De Rose
Participants: Antonio Claudio Lucas da Nóbrega, Arthur Haddad Herdy, Carlos Alberto Werutski, Eney de Oliveira Fernandes, Félix Albuquerque Drummond, Glaycon Michels, Ileana Kazapi, Kharla Medeiros, José Kawazoe Lazzolli, Luis Fernando Funchal, Luiz Aragon, Magnus Benetti, Marcelo Bichels Leitão, Marcelo Salazar, Marcos Aurélio de Oliveira Brazão, Michel Dacar, Rafael de Souza Trindade, Ricardo Nahas and Turíbio Leite de Barros Neto

Realization: Brazilian Society of Sports Medicine
Supported by: Gatorade Sports Science Institute (GSSI)

 

 


 

INTRODUCTION

In Brazil, the indiscriminate use of different drugs, for both ergogenic and aesthetic purposes, has attracted attention and caused concern. Such use is being increasingly spread in environments where physical exercises are practiced, especially gym academies and sports associations.

Most of the times, it comes from an illegal trade, with no control from sanitary surveillance departments, carried out in the physical exercise practice facilities, and with direct or indirect involvement of the professional in charge of the physical exercise sessions. Typically, under these circumstances, there is no prescription from a specialist physician and/or guidance from a sports science-trained dietitian, who are the qualified professionals to act in such context. What should be considered only for specific circumstances, and always under control of qualified professionals, tends to be used by individuals, with no indication whatsoever. The financial interest prevails on the well-being and health of the population. And even when there is the involvement of physicians and dietitians, many a time the recommendation for use of products is made empirically, with no specific knowledge nor scientific grounds to support it.

This is due, in part, because of the lack of knowledge that a balanced, quality meal, except for special circumstances, meets the nutritional needs of a physical exercise practitioner, even a competition athlete, making unnecessary the use of food supplements.

When one deals with the use of some drugs and hormones of proven ergonogenic effect, but that poses health hazards and are considered doping substances, he faces not only an anti-ethical, but even a criminal situation. If it is proven the prescription was deliberate, professional who did it can be legally punished by a court of law.

Another aspect that justifies this consensus document is the existence of cases in which there are flaws in meals and fluid replacement schemes that restrain sports performance and place the health of physical exercise practitioners at risk, even of death. Such is the case of dehydration, often seen in long-course athletic contests.

This consensus document had the input of eminent professionals and researchers of sports medicine and other sports sciences in Brazil, and its main purpose is to add to an education process, by conveying information that may be used as guidelines for professionals who work in the field of sports and act on physical exercises program for the overall population. This information is intended to reach the main stakeholders, who are the physical exercise practitioners, whether they are competitive athletes or anonymous members of gym academies or other places where sports are practiced, to preserve their health by making them less vulnerable to nefarious actions from unqualified and/or ill-will individuals. Ultimately, its purpose is to demystify improper attitudes that, in spite of lack of scientific grounds and with potential health risk, are quite common in the physical exercise practice environment. It aims to disseminate the use of proven healthy practices, to allow for the best sports performance.

Prof. Dr. Tales de Carvalho
Editor of the Guidelines
President, Brazilian Society of Sports Medicine

 


 

 

For the stands taken by this document, the adopted criteria were suggested by the Evidence-Based Cardiology Committee of the Brazilian Cardiology Society and Brazilian Medical Association (tables 1 e 2). The stands were classified according to the status of recommendation and the level of scientific evidence. To determine the status of the recommendation, in addition to the degree of scientific evidence, the recommendation's applicability, cost-benefit and cost-effectiveness ratios, among other aspects, were taken into consideration.

 

 

 

 

I. DIETARY CHANGES

Scientific studies have proved that performance and health of athletes may benefit from dietary changes. There are few controversies on this issue, due to documentation that demonstrates beneficial effects to health, favorable changes of body composition and enhanced athletic performance from dietary management. Studies have been according in reaching the conclusion that, in general, dietary management alone is enough to reach the above mentioned outcomes. Food supplement should therefore be left for special cases only, and its use should derive from prescription of qualified professionals, dietitians and specialist physicians.

The food and nutritional supplies industry has developed modified food, aiming performance improvement. Typically, they use only nutrients whose sources are in the food from an ordinary meal. One can state that the athlete who wishes to optimize his/her performance, before any nutritional manipulation should follow a diet that is appropriate to his/her endured effort in terms of quantity and variety, taking into consideration what has been established as a healthy food.

The guidelines in this section target healthy athletes, adults and adolescents at the end stage of sexual maturation. They do not focus individuals who practice physical exercises with no further concern about performance, for whom a balanced diet according to the recommendations given to the overall population is enough to maintain health and enable a good physical performance. (Recommendation status A and evidence degree 2).

Nutritional assessment

Nutritional assessment is an important factor for diet design and compliance. A careful dietary anamnesis allows the definition of strategies for the introduction of eventual dietary changes that may be needed. Athletes should not be deprived of their favorite food, or start a diet with rules and impositions divorced from their reality. Prescriptions should be flexible, so they can become a regular eating habit. Nutritional needs can be calculated through appropriate protocols, being determined by specific tables. One should consider the modality of sports being practiced, the training stage, the calendar of competitions and the purposes of the technical team concerning performance, data related to basal metabolism, energetic requirements for training, needs for body composition changes, and the presence of clinical factors such as chewing, digestion and absorption conditions. Energetic requirements are calculated by the sum of basal energetic need (protocol of free choice), mean energetic expenditure in training, and extra or reduced intake to control body composition.

To determine the needs of macronutrients (carbohydrate, proteines and lipids), one should take into consideration the caloric needs and the necessary digestion time for muscle utilization. Macronutrients are essential for muscular recovery, maintenance of immunologic system, balance of the endocrine system, and maintenance and/or enhancement of performance.

Overall, micronutrients (vitamins, minerals and oligoelements) present in balanced and diversified diets, with enough caloric intake to meet energetic demand, are enough for the needs of a sportsperson. The use of food supplement is recommended in some special cases. One is the use of folic acid by pregnant women, the use of calcium in case of osteopenia and osteoporosis, and iron for anemia. Micronutrients play an important role in energy production, hemoglobine synthesis, bone health maintenance, immunologic function, and protection of body tissues from oxidative damages. They are necessary to build and maintain muscular tissues after the exercises. The training can increase or change the needs of vitamins and minerals. The stress from the exercises may result in a biochemical muscular adjustment that increase nutritional needs, with higher use and/or loss of micronutrients. Dietary adjustment, in terms of macronutrients, to higher caloric need derived from sports activities, provides, at the same time, adjustment in the intake of micronutrients. Thus, it is suggested that nutritional recommendations for the overall population be used, calculated for the intake of 1,000 Kcalories. Therefore, the increment in the supply of micronutrients is proportional to the caloric increase of the diet, and nutritional balance is kept at appropriate levels. (Recommendation status A and evidence degree 2).

Recommendations:

a) Total food caloric rate

A number of studies have shown low caloric intake and nutritional unbalance in professional and/or amateur athletes. In spite of the proven effectiveness of carbohydrates to recover muscular glucogen, elite athletes still resist in taking this nutrient. An adequate meal in terms of carbohydrate supply helps maintaining body weight and composition, maximizing results from training and contributing to health maintenance. A negative caloric balance, from a lower intake of micronutrients, may cause loss of muscular mass, hormonal dysfunction, osteopenia, and higher incidence of chronic fatigue, musculoskeletal lesions, and infectious disease, which are some of the main features of overtraining.

When one wishes to change body composition by reducing the mass of fat, one typically suggests reducing caloric intake by selecting low-energetic density, low-fat foods. However, in athletes, a 10% to 20% reduction in total caloric intake leads to changes in body composition by reducing body fat, and not inducing to hunger or fatigue, as diets of very low-calorie intake and low fat. A dramatic reduction in fat from diet may not ensure reduction in body fat, and cause significant muscular losses due to lack of important nutrients for post-exercise recovery, such as liposoluble vitamins and proteins.

In accordance with population nutritional recommendations (RDI National Research Council 98), one should intake, in Kilocalories (Kcal), from 1.5 to 1.7 times the produced energy, or from 37 to 41 Kcal/weight (Kg)/day. This variation is influenced by genetics, gender, age, body weight, body composition, physical fitness, and training stage. One should take into consideration the frequency, intensity and duration of physical exercise sessions. Depending on the purpose, the caloric rate can present broader variations, with diets ranging from 30 to 50 Kcal/ weight (Kg)/day. (Recommendation status A and evidence degree 2).

b) Carbohydrates

Ergogenic effect of carbohydrate intake during exercises has been consistently demonstrated in a number of experiments, many of which carried out at stages lasting for hours.It has been shown that prolonged exercises significantly decreases the level of muscular glycogen, and one should be constantly concerned on replacing it. Nevertheless, a low carbohydrate intake by athletes has been observed.

The energy used during training and competitions depends on the intensity and duration of exercises, gender of athletes and initial nutritional status. The higher the intensity of exercises, the higher the role of carbohydrates as energy suppliers. The role of fat can be important for the time the exercise lasts, becoming even more significant while the activity lasts and remains an open aerobic activity. However, the proportion of energy from fat tends to decrease when the intensity of the exercise is enhanced, requiring a higher role from carbohydrates. With the exercise lasting longer, the role of protein is enhanced, which helps serum glucose levels to be maintained, mainly through liver gluconeogenesis.

Selection of food to be source of carbohydrates and the preparation of the meal immediately before the sports event should be according to individual gastrointestinal features of each athlete. The recommendation to fraction diet in three to five meals a day should take into consideration the necessary digestion time for the pre-training or pre-competition meal. The size of the meal and its components as to amounts of proteins and fibers may require over three hours for gastric emptying. If it is impossible for one to wait for over three hours for digestion, gastric discomfort may be prevented by intake of food poor in fibers and rich in carbohydrates. It is suggested food of light or liquid consistency, with an adequate amount of carbohydrates. Thus, the last meal before training should have enough fluid to keep hydration, poor in fat and fibers to facilitate gastric emptying, rich in carbohydrates to keep serum glucose levels and maximize glucogen supplies, with moderate amounts of proteins, and should be part of the athletes nutritional habit.

It is estimated that carbohydrate intake corresponding to 60% to 70% of the daily calorie intake meets the demands of a sports training session. To optimize muscular recovery it is necessary carbohydrate intake of 5 to 8g/weight (kg)/day. In long-duration activities and/or intense training, there is the need of up to 10g/weight (kg)/day for proper muscular glucogen recovery and/or increase of muscular mass (Recommendation status A and evidence degree 2).

The amount of used glucogen depends on the duration of the exercise. For long contests, athletes should intake approximately 0.7 to 0.8 g/weight (kg) or between 30 and 60 g of carbohydrate at each hour of exercise, to prevent hypoglycemia, glucogen depletion and fatigue. Often the carbohydrates are part of beverages especially developed for athletes. After an exhaustive exercise, it is recommended intake of simple carbohydrate, in the amount ranging from 0.7 to 1.5 g/weight (kg) within a four-hour period, which is enough for a full muscular glucogen re-synthesis. (Recommendation status A and evidence degree 2).

c) Proteins

For sedentary individuals, it is recommended a daily intake (RDI) of proteins between 0.8 and 1.2 g/weight (kg)/day. Individuals who practice physical exercises require a higher amount, as proteins contribute to energy supply in endurance exercises, and are necessary in post-exercise muscular protein synthesis. For endurance athletes, proteins play an ancillary role in supplying energy to the activity, and one estimates its daily need to be between 1.2 and 1.6 g/weight (kg). For power athletes, protein has an important role in supplying "raw material" for tissue synthesis, being its daily need between 1.4 and 1.8 g/weight (kg). (Recommendation status A and evidence degree 2).

d) Lipids

An adult requires about 1 g of fat per kg of body weight daily, which is about 25% to 30% of the total amount of calories (TAC). Essential fatty acids intake should be of 8 to 10 g/day. For athletes, it goes the same nutritional recommendations for the population in general as to the proportion of essential fatty acids, which is 10% for the saturated, polyunsaturated and mono-unsaturated. (Recommendation status A and evidence degree 2).

Athletes should be oriented not to have a poor-fat diet for a long time. When hypolipidic diet is necessary, there should be quotas as to total calorie intake, being of less than 8% for saturated, more than 8% for mono-insaturated, and from 7 to 10% for polyunsaturated. It has been reported that, in general, athletes intake more then 30% of TAC in form of lipids, with deficit in the intake of carbohydrates, which are consumed in less than advisable proportions.

Some studies have suggested a positive effect of diets somewhat rich in fat for athletic performance. Average- and long-chain lipid supplements have been suggested for intake a few hours before or during exercise. Thus, muscular glucogen would be spared. However, in face of evidence available today, in this document we recommend it should never be used. (Recommendation status E and evidence degree 7).

e) Vitamins

There is disagreement as to greater needs by athletes. For athletes, it has been suggested the intake of C vitamin between 500 and 1,500 mg/day, which would allow better immunologic response and important antioxidant action. It has also been suggested the use of vitamin E by athletes undergoing intense training, to enhance antioxidant action. Scientific evidence allows physicians and nutritionists to prescribe C and E vitamins, even with a low-degree evidence (Recommendation status C and evidence degree 7).

f) Minerals

Zinc plays a role in the cell respiratory process, and its shortage in athletes may cause anorexia, significant weight loss, fatigue, lower performance in endurance competitions, and risk of osteoporosis, which explains why it has been given as a supplement. However, due to lack of quality scientific evidence on its systematic use as a nutritional supplement, this document recommends it should not be used other than in regular meals. (Recommendation status E and evidence degree 7).

Female athletes under low calorie diet may lack minerals, particularly those involved in bone formation and maintenance, such as calcium. Any diet should include, at least, 1,000 mg/day of calcium. The low level of iron seen in about 15% of the world population is cause of fatigue and anemia. Iron deficiency affects performance and the immunologic system. Special attention should be paid to the intake of high bioavailability food with iron, being recommended for the female population the amount of 15 mg/day, and 10 mg/day for males. For pregnant women, RDI is of 30 mg. These needs may be achieved by manipulating diet, not being supplementation necessary. For dietary manipulation, in the specified cases, this document confers a high recommendation status. (Recommendation status A and evidence degree 2).

 

II. FLUID REPLACEMENT

The stress of the exercise is accentuated by dehydration, which increases body temperature, impairs physiological responses and physical performance, and causes health hazards. These effects may take place even if dehydration is light or moderate, with up to 2% of loss, and worsens as it increases. With 1 to 2% dehydration, body temperature starts raising in up to 0.4oC for each subsequent dehydration proportion. At about 3% there is a significant performance weakening; between 4 to 6%, thermal fatigue may occur; from 6% on, there is the risk of thermal shock, coma and death.

As sweat is hypotonic in relation to blood, dehydration from exercise may lead to an increase in serum osmolarity. Both hypovolemia and hyperosmolarity increase internal temperature and reduce heat dissipation from evaporation and convection. Serum hyperosmolarity may increase internal temperature, affecting the hypothalamus and/or sweat glands, delaying the starting of sweat and peripheral vasodilation during exercise.

Dehydration affects aerobic performance, decreases cardiac output due to reduction in the volume of blood, and increases heart rate. These changes are more accentuated in warm and humid climates, as higher skin vasodilatation transfers a good portion of blood flow to peripheral, rather than musculoskeletal vessels, leading to significant reduction of blood pressure, venous return, and cardiac output. Fluid replacement in a volume equal to loss of water through sweat may prevent a decrease in ventricular output, and is beneficial for thermal regulation as it enhances peripheral blood flow, facilitating internal heat to be transferred to the periphery.

It is important for dehydration signs and symptoms to be recognized. Mild to moderate dehydration is evidenced by fatigue, loss of appetite and thirst, red skin, heat intolerance, dizziness, oliguria and enhanced urinary concentration. Severe dehydration causes difficulties to swallow, loss of balance, dry and withered skin, sunken eyes and blurred vision, dysuria, numbness, delusions, and muscle spasms. It has been shown that fluid intake, regardless of the presence of carbohydrate, enhances performance during one hour of high-intensity aerobic exercise. As exercise-related dehydration may occur not only from intense sweating, but also from insufficient intake and/or deficient absorption of fluids, it is important to recognize the elements that influence hydration quality.

Water

Water can be a good rehydration option, as it is readily available, inexpensive and allows a somewhat swift gastric emptying. However, for prolonged activities, that last for more than one hour, or for highly intense activities, such as football (soccer), basketball and tennis, it has the disadvantage of not containing sodium or carbohydrates, and because it is tasteless, it favors involuntary dehydration and makes hydroelectrolyte balance process difficult. Voluntary dehydration is seen when one compares hydration with water versus hydration with flavored beverages.

Sodium

As we lose sodium through sweat, in some circumstances it should be taken during exercise. Sodium concentration in the sweat varies from one individual to another, in accordance to a number of factors such as age, the degree of fitness and being used to a warm climate. Mean sodium concentration in the sweat for an adult in around 40 mEq/L. Assuming that a person of 70 kg runs for three hours and loses two liters of sweat per hour, total loss of sodium is 240 mEq, i.e., 10% of the total extracellular space Na+. Such loss would be irrelevant, were it not for the risk of hyponatremia, a concentration of serum sodium less than 130 mEq·l-1, due to a fluid replacement with sodium-free or low-sodium fluids, particularly in lengthy events. Reduction of serum osmolarity produces an osmotic gradient between blood and brain, causing apathy, nausea, vomiting, altered perception, seizures, which are some of the neurological signs of hyponatremia. Including sodium in rehydrating beverages allows higher intestinal absorption of water and carbohydrates during and after exercise. This happens because glucose transportation at the enterocyte mucosa is coupled with sodium transportation, leading to a higher absorption of water.

In lengthy exercises, which take longer than one hour, it is recommended the drinking of fluids with 0.5 to 0.7 g/l (20 to 30 mEq·l-1) of sodium, which corresponds to a similar or even lower concentration as in the sweat of an adult. (Recommendation status A and evidence degree 2).

Carbohydrate

The intake of carbohydrates during a lengthy exercise enhances performance and may delay fatigue in those sports that involve intermittent, high-intensity exercises. Carbohydrate intake prevents glucose levels to fall after two hours of exercise. The necessary carbohydrate replacement to maintain serum glucose levels and delay fatigue is of 30 to 60 g/hour, with concentration ranging from de 4 to 8 g/deciliter. It is to be stressed that there are publications showing that a beverage with 8% carbohydrate is not absorbed nor allow a swift gastric emptying as water or beverages with 6% carbohydrate. It is preferred that a mixture of glucose, fructose and sacarose be used. The single use of fructose may cause gastrointestinal disorder. (Recommendation status A and evidence degree 2).

Other elements that affect effectiveness of a sports beverage

Gastric emptying is facilitated by intake of low-calories fluids, and intestinal absorption is optimized with isosmotic fluids between 200 and 260 mosmol/kg. Intake of hypertonic fluids could cause body water to be secreted to the intestinal lumen. A number of other factors related to the taste of the fluid affect spontaneous intake, such as temperature, sweetness, intensity of flavor and acidity, in addition to sensation of thirst and personal preferences.

Recommendations concerning fluid replacement

One should intake fluids before, during and after practicing exercise. To ensure a good hydration at the beginning of the exercise, it is recommended the drinking of about 250 to 500 ml of water two hours before the exercise. During the exercise, fluid intake should begin within the first 15 minutes, and kept on at every 15 to 20 minutes. The volume to be taken ranges according to sweat rates, from 500 to 2,000 ml/hour. If the activity lasts for more than one hour, or if it is intense, of intermittent type, even lasting less than one hour, one should replace carbohydrate in the amount of 30 to 60 g·h-1 and Na+ in the amount of 0.5 to 0.7 g·l-1. The temperature of the beverage should range from 15 to 22oC, and flavored according to individual preference. The beverage should be easy to reach, in bottles that make drinking easy, interrupting the exercise as little as possible. After the exercise, one should keep on drinking fluids to make up for additional losses of water through urine and sweat. One should take the opportunity to ingest carbohydrates, about 50 g of glucose on average within the first two hours after the exercise, for re-synthesis of muscular glucogen to take place, along with a swift storage of muscular and hepatic glucogen. (Recommendation status A and evidence degree 2).

Even if a good hydration during lengthy exercises under heat favors thermoregulatory response and performance, one cannot ensure that, in extreme thermal stress it is enough to prevent fatigue or thermal shock. Specific recommendations have been made by the American Academy of Pediatrics Sports Medicine and Fitness Committee (see Table below). The degree of thermal stress follows the Wet Bulb and Globe Temperature (WBGT) index, which combines measurements for air temperature (Tdb), humidity (Twb), and solar radiation (Tg), under the equation WBGT = 0.7 Twb + 0.2 Tg + 0.1 Tdb.

 

 

III. FOOD SUPPLEMENTS

Proteins

The benefits of a proper intake of proteins for those who practice regular physical activity are well documented in the international literature. For the proper amount of protein intake to be established, before anything else it is necessary to establish, in addition to individual features (gender, age, anthropometric profile, health status, etc.), basic parameters on the physical activity practiced, such as intensity, duration and frequency. It is recommended for sedentary individuals the intake of 0.8 g of protein per kg/day. For active individuals, 1.2 to 1.4 g/kg/day meet their needs. Athletes and individuals aiming muscular hypertrophy have their needs met with the maximum intake of 1.8 g/kg/day. These needs may be fulfilled by a balanced meal, unless there is a special situation. (Recommendation status A and evidence degree 2).

Studies recommend that the use of protein supplements, such as milk serum protein or egg-white albumin, should be in accordance with total intake of protein. Additional intake of such protein supplements over the daily needs (1.8 g/kg/day) does not determine gain in muscular mass nor promotes performance enhancement.

The intake of proteins after physical exercise for hypertrophy favors the increase of muscular mass when combined with intake of carbohydrates, reducing protein degradation. Such intake should be in accordance with total intake of proteins and calories. The increase of muscular is consequence of training, like protein demand, but the reverse is not true.

Amino acids

The intake of amino acids as a food supplement has been suggested as a strategy to meet specific metabolic requirements for the practice of exercises. According to some studies, the intake of essential amino acids after intense training, associated to carbohydrate solutions, allows for a better recovery from the effort, followed by augment of muscular mass. Only essential amino acids have their use supported by the literature as beneficial. The effects of supplementation with branch-chained amino acids (BCAA) in sports performance are discordant, and most studies show it provides no benefits in performance. There is a lack of scientific studies with consistent information on the ergonogenic advantages of such supplementation and on occurrence of side effects.

Special considerations

Branch-chained amino acids leucine, isoleucine and valine being potent modulators of tryptophane reuptake by the central nervous system, would foster tolerance to prolonged physical strain. However, these data, which have been reported by some studies, are difficult to be duplicated, and the use of these amino acids for ergogenic purposes is not justified. Another aspect to be considered in branch-chained amino acids is their use to enhance the immune system after intense physical activity, but for this, more significant scientific evidence is also lacking. (Recommendation status E and evidence degree 7).

Glutamine is an amino acid that acts as nutrient for fast dividing cells, such as intestinal and immune system cells. Its high use by intestinal cells does not make it available to other body areas when it is orally administered. Thus its use to favor immune response after intense physical activity is not justified. (Recommendation status E and evidence degree 7).

Ornitine and arginine are amino acids that, taken intravenously, promote higher secretion of growth hormone, but are ineffective if orally administered. (Recommendation status E and evidence degree 7).

Creatine

Lately, in the sports area, the use of creatine supplement is being related to potential ergogenic effects that would reflect in increased resistance to strain in short-duration, high intensity activities, and muscular mass augmentation. The use of creatine as an ergogenic resource in prolonged lengthy physical activities has no support in scientific literature.

Even though with controversial results, a number of studies have suggested that creatine would have ergogenic effects for those individuals whose intake of creatine from food is little, such as vegetarians and elders, and only for these specific cases its use is recommended, upon assessment of a specialized professional, either physician or dietitian, though yet with a low recommendation status.

It is permitted the usage, always as an exception, only for competitive athletes participating in high-intensity and short lasting events, i.e., activities involving predominantly phosphagens. Therefore, even in these cases, creatine should not be widely used, but accepted in rare occasions (Recommendation status D and evidence degree 4). For the other athletes, the recommendation is not to use creatine (Recommendation status E).

b-hydroxy-b-methylbutirate

The use of b-hydroxy-b-methylbutirate (HMB) is being considered a potential agent to enhance strength and lean body mass. Its action would be anti-catabolic, but it lacks scientific studies that prove, without a doubt, the effectiveness of this supplement for such ergogenic action other than in some specific cases, such as elders who take part in physical exercise programs. For the overall population, even for competition athletes, its use is not recommended; on the contrary, recommendation is for it not to be used. (Recommendation status D and evidence degree 7).

 

IV. LICIT AND ILLICIT DRUGS

Illicit drugs are those whose use breaks ethical and disciplinary codes, according to the World Anti-doping Agency and the International Olympic Committee (IOC), and may lead to punishments to athletes, coaches, physicians and officials. A list of forbidden drugs and methods, approved on September 1st, 2001, is in the Appendix A of the Olympic Movement Anti-doping Code.

I. Classes of forbidden drugs:

A. Stimulants;
B. Narcotics;
C. Anabolic agents:
   1. Androgen anabolic steroids;
   2. Beta-2 agonists;
D. Diuretics;
E. Peptide, mimetic hormones and analogues:
   1. Chorionic gonadotrophic hormone (hCG) (only for male athletes);
   2. Pituitary and synthetic gonadotropins (LH) (only for male athletes);
   3. Corticotrophines (ACTH, tetracosactide);
   4. Growth hormone (hGH);
   5. Insulin-type growth factor-1 (IGF-1)
Precursors and analogues to these hormones are also forbidden:
   6. Erythropoietin (EPO);
   7. Insulin (except for insulin-dependent athletes)

The presence of an abnormal concentration of an endogenous hormone (listed above, in class E) or its diagnostic markers in an athlet's urine is a transgression, unless due to a condition peculiar to the individual.

II. Forbidden methods:

1. Blood doping: it is the intravenous infusion of blood, red cells and/or similar blood products. It may be preceded by withdrawing blood from an athlete, who goes on training with blood deficiency;
2. Dispensation of artificial oxygen transporters or plasma expanders;
3. Pharmacological, chemical or physical manipulation of urine.

III. Classes of drugs forbidden in some circumstances:

1. Alcohol;
2. Cannabinoids;
3. Local anesthetics;
4. Glucocorticoids;
5.Beta-blockers.

It is to be mentioned that some drugs may be licit at some circumstances and illicit at others. Such is the case of stimulants, analgesic narcotics and corticosteroids, which may be used in some medical situations during training period, but cannot be used before a competition. The use of some illicit drugs may lead to legal prosecution, for infringement of the Penal Code. The Brazilian Olympics Committee regularly publishes a bulletin listing the brand name of licit drugs according to symptoms, and illicit pharmacological classes of drugs, in accordance with IOC regulations.

Some results are positive when drugs are present in the urine over a specified level, such as caffeine, catine, ephedrine, methylephedrine, phenylpropenilamine (phenilpropanolamine), morphine and pseudoephedrine. To these, one adds nandrolone precursory substances. There is also a ceiling concentration for THC, to protect passive smoking. Salbutamol is considered to be stimulant over a specific concentration, and anabolic agent over another, ten-fold higher. And last, testosterone/epitestosterone ratio will be considered doping if higher than 6.

Androgen anabolic steroids, peptide hormones and diuretics cannot be used unless specific authorization from a relevant medical official for a particular sport or competition. In case of proven medical indication, the specialized physician can prescribe any drug, even if theoretically illicit, and a relevant medical officer should expressly authorize it. Even though the most important reasons for a sports physician not to prescribe doping drugs are of ethical and moral nature, it is also important to understand the medical problems related to the use of such drugs. Athletes are entitled to know the relative risks of an eventual inadequate choice of drug, and discussing this issue is also a task of a team's physician. The activity of the specialized sports physician is regulated by ethics codes of the World Medical Association, International Federation of Sports Medicine and the IOC.

Problems related to the use of food supplements

Due to an increase in the number of positive cases for nandrolone on high performance sports from 1997 on, the Sports Council of the United Kingdom appointed a committee of experts to analyze the reasons for this problem, and concluded that there is no endogenous production of this hormone in humans, at least not in amounts above the established by the IOC for its accredited labs to consider the amount positive for doping.

The presence of steroids in food supplements and vegetable preparations, such as vitamins, creatines, and amino acids has been detected, but it was not stated in their labels. IOC Medical Committee, due to flaws in legislation of many countries on quality control for manufacturing, decided to warn on the risks of such products to be used. A study financed by IOC (available in its web page) shows that of 634 supplements analyzed by the Cologne Anti-doping Laboratory from 215 suppliers of 13 countries, 94 of those (14.8%) contained hormone precursors not stated in their labels and that could be positive for doping. Among those, 24.5% had testosterone precursors, and 24.5% nandrolone precursors. For this reason, echoing IOC recommendations, we advise Sports Medicine professionals to take extreme caution when prescribing such substances.

 

Ergogenic benefits and potential health hazards

 

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9. Garlick PJ, McNurlan MA, Ballmer PE. Influence of dietary protein intake on whole-body protein turnover in humans. Diabetes Care 1991; 14:1189-98.         [ Links ]

10. Ginsburg GS, O'Toole M, Rimm E, Douglas PS, Rifai N. Gender differences in exercise-induced changes in Sex hormone levels and lipid peroxidation in athletes participation in the Hawaii Ironman triathlon. Ginsburg-gender and exercise induced lipid peroxidation. Clin Chim Acta 2001;305:131-9.         [ Links ]

11. Glesson M, Bishop NC. Elite athlete immunology: importance of nutrition. Inter J Sports Med 2000;21:S44-50.         [ Links ]

12. Hassapidou MN, Manstrantoni A. Dietary intakes of elite female athletes in Greece. J Hum Nutr Diet 2001;14:391-6.         [ Links ]

13. Jeukendrup AE, Saris WHM, Wagenmakers AJM. Fat metabolism during exercise: a review. Int J Sport Med 1998;19:371-9.         [ Links ]

14. Kiens B. Diet and training in the week before competition. Can J Appl Physiol 2001;26:S56-63.         [ Links ]

15. Lemon PW. Effects of exercise on dietary protein requirements. Int J Sport Nutr 1998;8:426-47.         [ Links ]

16. Manore MM. Effect of physical activity on thiamine, riboflavin, and vitamin B-6 requirements. Am J Clin Nut 2000;72:598S-606S.         [ Links ]

17. Maughan RJ. Role of micronutrients in sport and physical activity. Br Med Bull 1999;55:683-90.         [ Links ]

18. Maughan R. The athlete's diet: nutritional goals and dietary strategies. Proc Nutr Soc 2002;61:87-96.         [ Links ]

19. McConell G, Snow RJ, Projetto J, Hargreaves M. Muscle metabolism during prolonged exercise in humans: influence of carbohydrate availability. J Appl Physiol 1999;87:1083-6.         [ Links ]

20. Micheletti A, Rossi A, Rufini S. Zinc status in athletes: relation to diet and exercise. Eur J Physiol 2002;443:791-7.         [ Links ]

21. Nakamura M, Brown J, Miller WC. Glycogen depletion patterns in trained rats adapted to a high-fat or high carbohydrate diet. Int J Sports Med 1998;19:419-24.         [ Links ]

22. Nieman DC, Pedersen BK. Exercise and immune function recent developments. Sports Med 1999;27:73-80.         [ Links ]

23. Nutrition and athletic performance. Med Sci Sports Exerc 2000;32:2130-45.         [ Links ]

24. Pendergast DR, Leddy JJ, Venkatraman JT. A perspective of fat intake in athletes. J Am Coll Nutr 2000;19:345-50.         [ Links ]

25. Poortmans R, Dellalieux O. Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sports Med 2000;20:28-38.         [ Links ]

26. Sacheck JM, Decker EA, Clarkson PM. The effect of diet on vitamin E intake and oxidative stress in response to acute exercise in female athletes. Eur J Appl Physiol 2000;83:40-6.         [ Links ]

27. Schroder H, Navarro E, Mora J, Seco J, Torregrosa JM, Tramullas A. The type, amount, frequency and timing of dietary supplement use by elite players in the First Spanish Basketball League. J Sports Sci 2002; 20:353-8.         [ Links ]

28. Sen CK. Antioxidants in exercise nutrition. Sports Med 2001;31:891-908.         [ Links ]

29. Spivak JL. Erythropoietin use and abuse: when physiology and pharmacology collide. Adv Exp Med Biol 2001;502:207-24.         [ Links ]

30. Stannard SR, Constantini NW, Miller JC. The effect of glycemic index on plasma glucose and lactate levels during incremental exercise. Int J Sport Nutr Exerc Metab 2000;10:51-61.         [ Links ]

31. Tauler P, Aguilo A, Fuentespina E, Tur JA, Pons A. Diet supplementation with vitamin E, vitamin C and beta-carotene cocktail enhances basal neutrophil antioxidant enzymes in athletes. Eur J Physiol 2002;443: 791-7.         [ Links ]

32. Thompson JL. Energy balance in young athletes. Int J Sport Nutr 1998; 8:160-74.         [ Links ]

33. Van Erp-Baart AM, Saris WH, Binkhorst RA, Vos JA, Elvers JW. Nationwide survey on nutritional habits in elite athletes. Part 1. Energy, carbohydrate, protein and fat intake. Int J Sports Med 1989;10:S3-10.         [ Links ]

34. Vasankari T, Kujala U, Sarnas S, Ahotupa M. Effects of ascorbic acid and carbohydrate ingestion on exercise induced oxidative stress. J Sports Med Phys Fitness 1998;38:281-5.         [ Links ]

35. Wigernaes I, Hostmark AT, Stromme SB, Kierulf P, Birkeland K. Active recovery counteracts the post-exercise rise in plasm-free fatty acids. Int J Sport Nutr Exerc Metab 2000;10:404-14.         [ Links ]

36. Xia G, Chin MK, Girandola RN, Liu RY. The effect of diet and supplements on a male world champion lightweight rower. J Sports Med Phys Fitness 2001;41:223-8.         [ Links ]

37. Zachwieja JJ, Ezell DM, Cline AD, Ricketts JC, Vicknair PC, Schorle SM, et al. Short-term dietary energy restrition reduces lean body mass but not performance in physically active men and women. Int J Sports Med 2001;22:310-16.         [ Links ]

II. Fluid replacement

1. American Academy of Pediatrics. Climatic Heat Stress and the Exercise Child and Adolescent. Pediatrics 2000;106:158-9.         [ Links ]

2. American College of Sports Medicine. ACSM Position Stand on Exercise and Fluid Replacement. Med Sci Sports Exerc 1996;28:i-vii.         [ Links ]

3. American College of Sports Medicine. Position Stand: Heat and cold illnesses during distance running. Med Sci Sports Exerc 1996;28:i-x.         [ Links ]

4. Below PR, Mora-Rodriguez R, Gonzalez-Alonso J. Fluid and carbohydrate ingestion independently improve performance during 1 h of intense exercise. Med Sci Sports Exerc 1995;27:200-10.         [ Links ]

5. Berry PL, Belsha CW. Hyponatremia. Pediatr Clin North Am 1990;37: 351-163.         [ Links ]

6. Clowes GHA, O'Donnel TF Jr. Heat stroke. N Engl J Med 1974;291: 564-7.         [ Links ]

7. Coggan AR, Coyle EF. Carbohydrate ingestion during prolonged exercise: effects on metabolism and performance. Exerc Sport Sci Rev 1991; 19:1-40.         [ Links ]

8. Coyle EF, Montain SJ. Benefits of fluid replacement with carbohydrate during exercise. Med Sci Sports Exerc 1992;24:S324-30.         [ Links ]

9. Coyle EF, Coggan AR, Hemmert MK, Ivy JL. Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrates. J Appl Physiol 1986;61:165-72.         [ Links ]

10. Coyle EF. Cardiovascular drift during prolonged exercise and the effects of dehydration. Int J Sports Med 1998;19:S121-4.         [ Links ]

11. Crane RK. The gradient hypothesis and other models of carrier-mediated active transport. Rev Physiol Biochem Pharmacol 1977;78:100-59.         [ Links ]

12. Davies MJ, Lamb DL, Pate RR, Slentz CA, Burgess WA, Bartoli WP. Carbohydrate-electrolyte drinks: effects on endurance cycling in the heat. Am J Clin Nutr 1988;48:1023-30.         [ Links ]

13. Fortney SM, Wenger CB, Bove JR, Nadel ER. Effect of blood volume on forearm venous and cardiac stroke volumes during exercise. J Appl Physiol 1981;55:884-90.         [ Links ]

14. Gisolfi CV, Copping JR. Thermal effects of prolonged treadmill exercise in the heat. Med Sci Sports Exerc 1974;6:108-13.         [ Links ]

15. Gisolfi CV, Summers RW, Schedl HP, Bleiler TL, Opplinger RA. Human intestinal water absorption: direct vs indirect measurements. Am J Physiol 1990;258:G216-22.         [ Links ]

16. Greenleaf JE, Sargent R. Voluntary dehydration in man. J Appl Physiol 1965;20:719-24.         [ Links ]

17. Gruskin AB, Baluarte HJ, Prebis JW, Polinski MS, Morgenstern BZ, Perlmen SA. Serum sodium abnormalities in children. Pediatr Clin North Am 1982;29:907-32.         [ Links ]

18. Hamilton MT, Gonzalez-Alonso J, Montain SJ, Coyle EF. Fluid replacement and glucose infusion during exercise prevents cardiovascular drift. J Appl Physiol 1991;71:871-7.         [ Links ]

19. Horswill CA. Effective fluid replacement. Int J Sport Nutr 1998;8:175-95.         [ Links ]

20. Hubbard RW, Sandick BL, Matthew WT, Francesconi RP, Sampson JB, Durkot MJ, et al. Voluntary dehydration and alliesthesia for water. J Appl Physiol (Respirat Environ Exercise Physiol) 1984;57:868-75.         [ Links ]

21. Ivy JL, Lee MC, Brozinick JT, Reed MJ. Muscle glycogen storage after different amounts of carbohydrate ingestion. J Appl Physiol 1988;65: 2018-23.         [ Links ]

22. Leiper JB, Maughan RJ. Absorption of water and electrolytes from hypotonic, isotonic, and hypertonic solutions. J Physiol 1986;373:90.         [ Links ]

23. Leiper JB. Gastric emptying and intestinal absorption of fluids, carbohydrates, and electrolytes. In: Sports Drinks: Basic and Practical Aspects, 2001;89-128.         [ Links ]

24. Maughan RJ, Leiper JB, Shirreffs SM. Factors influencing the restoration of fluid and electrolyte balance after exercise in the heat. Br J Sports Med 1997;31:175-82.         [ Links ]

25. Meyer F, Bar-Or O. Fluid and electrolyte loss durante exercise: the pediatric angle. "Leading article". Sports Med 1994;18:4-9.         [ Links ]

26. Meyer F, Bar-Or O, MacDougall D, Heigenhauser G. Sweat electrolyte loss during exercise in the heat: effects of gender and level of maturity. Med Sci Sports Exerc 1992;24:776-81.         [ Links ]

27. Montain SJ, Coyle EF. Fluid ingestion during exercise increases skin blood flow independent of increases in blood volume. J Appl Physiol 1992;73:903-10.         [ Links ]

28. Nadel ER, Fortney SM, Wenger CB. Effect of hydration state on circulatory and thermal regulations. J Appl Physiol 1980;49:715-21.         [ Links ]

29. Noakes TD, Goodwin N, Rayner BL, Branken T, Taylor RKN. Water intoxication: a possible complication during endurance exercise. Med Sci Sports Exerc 1985;17:370-5.         [ Links ]

30. Passe HD. Physiological and psychological determinants of fluid intake. In: Sports Drinks: Basic and Practical Aspects, 2001;45-87.         [ Links ]

31. Pitts GC, Johnson RE, Consolazio FC. Work in the heat as affected by intake of water, salt, and glucose. Am J Physiol 1944;142:253-9.         [ Links ]

32. Rivera-Brown AM, Gutiérrez R, Gutiérrez JC, Frontera WR, Bar-Or O. Drink composition, voluntary drinking, and fluid balance in exercising, trained, heat-acclimatized boys. J Appl Physiol 1999;86:78-84.         [ Links ]

33. Rothstein A, Adolph EF, Wills JH. Voluntary dehydration. New York: Interscience, 1947.         [ Links ]

34. Saltin B. Circulatory response to submaximal and maximal exercise after thermal dehydration. J Appl Physiol 1964;19:1125-32.         [ Links ]

35. Sawka MN, Gonzalez RR, Young AJ, Dennis RC, Valeri CR, Pandolf KB. Control of thermoregulatory sweating during exercise in the heat. Am J Physiol 1989;257:R311-6.         [ Links ]

36. Sawka MN, Young AJ, Francesconi RP, Muza SR, Pandolf KB. Thermoregulatory and blood responses during exercise and graded hypohydration levels. J Appl Physiol 1985;25:149-52.         [ Links ]

37. Sawka MN, Pandolf KB. Effect of body water loss on physiological function and exercise performance. In: Gisolfi CV, Lamb DR, eds. Perspectives in Exercise and Sport Medicine. Fluid Homeostasis during Exercise. Indianapolis: Benchmark Press Inc, 1990;1-30.         [ Links ]

38. Sawka MN, Young AJ, Latzka WA, Neufer PD, Quigley MD, Pandolf KB. Human tolerance to heat strain during exercise: influence of hydration. J Appl Physiol 1992;73:368-75.         [ Links ]

39. Sawka MN. Physiological consequences of hypohydration: exercise, performance, and thermoregulation. Med Sci Sports Exerc 1992;24:657-70.         [ Links ]

40. Senay L. Temperature regulation and hypohydration: a singular view. J Appl Physiol 1979;47:1-7.         [ Links ]

41. Shapiro Y, Moran D, Epstein Y. Acclimatization strategies — Preparing for exercise in the heat. Int J Sports Med 1998;19:S161-3.         [ Links ]

42. Shi X, Gisolfi CV. Fluid and carbohydrate replacement during intermittent exercise. Sports Med 1998;25:157-72.         [ Links ]

43. Shirreffs SM, Maughan RJ. Volume repletion following exercise-induced volume depletion in man: replacement of water and sodium losses. Am J Physiol 1998;43:F868-75.         [ Links ]

44. Szlyk PC, Sils IV, Francesconi RP, Hubbard RW, Armstrong LE. Effects of water temperature and flavoring on voluntary dehydration in men. Physiol Behav 1989;45:639-47.         [ Links ]

45. Wilk B, Bar-Or O. Effect of drink flavor and NaCl on voluntary drinking and hydration in boys exercising in the heat. J Appl Physiol 1996; 80:1112-17.         [ Links ]

III. Food supplements

1. Butterfield G. Amino acids and high protein diets. In: Perspectives in exercise science and sports medicine: Ergogenics-enhancement of performance in exercise and sport. Lamb DR, Williams MH, eds. Miami: Cooper Publishing, 2001.         [ Links ]

2. Casey A, Greenhaff PL. Does dietary creatine supplementation play a role in skeletal muscle metabolism and performance? Am J Clin Nutr 2000;72:S607-17.         [ Links ]

3. Chrusch MJ, Chilibeck PD, Chad KE, Davison KS, Burke DG. Creatine supplementation combined with resistance training in older men. Med Sci Sports Exerc 2001;33:2111-17.         [ Links ]

4. David JM, Alderson NL, Welsh RS. Serotonin and central nervous system fatigue: nutritional considerations. Am J Clin Nutr 2000;72:573-8.         [ Links ]

5. Hargreaves MH, Snow R. Amino acids and endurance exercise. Int J Sport Nutr Exerc Metab 2001;11:133-45.         [ Links ]

6. Harris, RC, Soderlund K, Hultman E. Elevation of creatine in resting and exercise muscle of normal subjects by creatine supplementation. Clin Sci 1992;83:367-74.         [ Links ]

7. Hultman E, Soderlund K, Timmons A, Cederblad G, Greenhaff PL. Muscle creatine loading in men. J Appl Physiol 1996;81:232-7.         [ Links ]

8. Paul GL, Gautsch TA, Layman DK. Amino acid and protein metabolism during exercise and recovery. In: Wolinsky I, ed. Nutrition in Exercise and Sport. Florida: CRC Press, 1998.         [ Links ]

9. Persky AM, Brazeau GA. Clinical pharmacology of the dietary supplement creatine monohydrate. Pharmacol Rev 2001;53:161-76.         [ Links ]

10. Poortmans JR, Francaux M. Adverse effects of creatine supplementation. Sports Med 2000;30:155-70.         [ Links ]

11. Rasmussen BB, Tipton KD, Miller SL, Wolf SE, Wolfe RR. An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. J Appl Physiol 2000;88:386-92.         [ Links ]

12. Slater GJ, Jenkins D. b-hydroxy-b-metilbutyrate (HMB) supplementation and the promotion of muscle growth and strength. Sports Med 2000; 30:105-16.         [ Links ]

13. Tarnopolsky MA. Protein and physical performance. Curr Opin Clin Nutr Metab Care 1999;2:533-7.         [ Links ]

14. Terjung RL, Clarkson P, Eichner ER, Greenhaff PL, Hespel PJ, Israel RG, et al. American College of Sports Medicine roundtable. The physiological and health effects of oral creatine supplementation. Med Sci Sports Exerc 2000;32:706-17.         [ Links ]

15. Tipton KD, Wolfe RR. Exercise, protein metabolism, and muscle growth. Int J Sport Nutr Exerc Metab 2001;11:109-32.         [ Links ]

16. Wagenmakers AJM. Amino acid supplements to improve athletic performance. Curr Opin Clin Nutr Metab Care 1999;2:539-44.         [ Links ]

IV. Licit and illicit drugs

1. American College of Sports Medicine Position Stand on the Use of Blood Doping as an Ergogenic Aid. Med Sci Sports Exerc 1996;28.         [ Links ]

2. American College of Sports Medicine. Use of anabolic androgenic steroids in sport. Med Science Sport Exer 1987;19:534-9.         [ Links ]

3. Comitê Olímpico Brasileiro. Http://www.cob.org.br        [ Links ]

4. De Rose EH, Nóbrega ACL. Drogas Lícitas e Ilícitas. In: Ghorayeb N, Barros T. O Exercício. São Paulo: Atheneu, 1999.         [ Links ]

5. Eichner ER. Ergogenic Aids: What athletes are using — and why. Phys Sports Med 1997;25:97.         [ Links ]

6. Feder MG, De Rose EH. O uso de medicamentos no esporte. Rev Bras Med Esporte 1996;2.         [ Links ]

7. Gruber AJ, Pope HG Jr. Psychiatric and medical effects of anabolic-androgenic steroid use in women. Psychoter Psychosom 2000;69:19-26.         [ Links ]

8. International Olympic Committee Antidoping code. Http://www.olympic.org?uk/organisation/comissions/medical/antidopinguk.asp        [ Links ]

9. International Olympic Committee. www.olympic.org/uk/news/publications/pressuk.asp?release=113        [ Links ]

10. International Olympic Committee. www.olympic.org/uk/news/publications/pressuk.asp?release=173        [ Links ]

11. International Olympic Committee. Http://www.olympic.org/uk/news/publications/press.uk.asp?rel        [ Links ]

12. International Olympic Committee. Http://multimedia.olympic.org/pdf/enreport21.pdf        [ Links ]

13. International Olympic Committee. Http://multimedia.olympic.org/pdf/enreport22.pdf        [ Links ]

14. Pardos CL, Gallego VP, Rio-Mayor MJ, Martin AV. Dopaje sanguineo y Eritropoietina. Archivos de Medicina Del Deporte 1998;64:145-8.         [ Links ]

15. Stephen MB, Olsen C. Ergogenic supplements and health risk behaviors. J Fam Pract 2001;50:696-9.         [ Links ]