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Nutrition and Athletic Performance

Joint Position Statement: American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine

ABSTRACT

It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance.

This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of the sports dietitian.

Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins and to contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged.

Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise,maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia.

Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution and only after careful product evaluation for safety, efficacy, potency, and legality.

A qualified sports dietitian and, in particular, the Board Certified Specialist in Sports Dietetics in the United States, should provide individualized nutrition direction and advice after a comprehensive nutrition assessment.

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Alcohol and Athletic Performance

ACSM current comment

The effects of alcohol can depend on the amount consumed, the environmental context, and on the individual. Daily consumption of up to four drinks may have a protective effect on the cardiovascular system. Nonetheless, people most commonly drink for alcohol’s anxiolytic (stress-reducing) property. Conversely, alcohol has a wide spectrum of negative effects, from societal to physiological, accounting for approximately 100,000 deaths yearly in the United States. From a physiological perspective, two situations draw special attention for the fitness-oriented individual who consumes alcohol. Acutely, alcohol can cause negative effects on motor skills and physical performance. Chronically, alcohol abuse may eventually impede physical performance; individuals diagnosed with alcohol dependence have displayed varying degrees of muscle damage and weakness. Furthermore, alcohol abuse is at least as prevalent in the athletic community as it is in the general population; the vast majority of athletes have begun drinking by the end of high school.

ALCOHOL USE IN ATHLETICS 

Alcohol use by athletes often starts at the junior high school level and can start even earlier. Among high school students, male athletes are more likely to not only use alcohol regularly but also to abuse alcohol. This relationship does not seem to exist at the college level. Nonetheless, alcohol consumption is high enough for alcohol to have been named the most abused drug in collegiate sport by the NCAA and in professional and Olympic sports by the NFL, NBA, and USOC.

ALCOHOL AS A NUTRIENT 

Each gram of alcohol (ethanol) provides seven kilocalories compared to nine for fat and four each for carbohydrate and protein. Other nutrients may be present, depending on the type of beverage. Beer, for example, has been seen as a good source of many nutrients and has sometimes been used in preparation for endurance events or to replenish nutrients following competition. Actually, orange juice supplies four times the potassium plus almost three times the carbohydrates, and it would take 11 beers, for example, to obtain the B-vitamin recommended daily allowance (RDA).

PERFORMANCE WHILE BLOOD ALCOHOL IS PRESENT (ACUTE EFFECT) 

Motor Performance – Low amounts of alcohol (0.02-0.05g/dL) can result in decreased hand tremors, improved balance and throwing accuracy, and a clearer release in archery, but in slower reaction time and decreased eye-hand coordination. A moderate (0.06-0.10 g/dL) amount of alcohol negatively affects such skills.

Strength/Power and Short-term Performances – The effect of alcohol, in low to moderate doses, is equivocal. It can have a deleterious effect on grip strength, jump height, 200- and 400-meter run performance, and can result in faster fatigue during high-intensity exercise. Conversely, alcohol has been shown to lack an effect on strength in various muscle groups, on muscular endurance, and on 100-meter run time.

Aerobic Performance – Low or moderate amounts of alcohol can impair 800- and 1500-meter run times. Because of its diuretic property, it can also result in dehydration, being especially detrimental in both performance and health during prolonged exercise in hot environments.

PERFORMANCE DURING HANGOVER 

Any lingering effect of alcohol would especially hinder physical conditioning progress. According to current research, the effect during a hangover seems to be undecided, with no effect on several performance variables, but a decline in total work output during high-intensity cycling. Furthermore, handgrip muscular endurance has been shown to suffer a delayed decline on the second morning following intoxication.

PERFORMANCE WITH CHRONIC ALCOHOL USE 

Chronic alcohol abuse may be detrimental to athletic performance secondarily to many of the sequelae that can develop. Alcohol affects the body’s every system, linking it to several pathologies, including liver cirrhosis, ulcers, heart disease, diabetes, myopathy, bone disorders, and mental disorders. The following implications may especially interest the athletic individual. Alcohol can result in nutritional deficiencies from alterations in nutrient intake, digestion, absorption, metabolism, physiological effects, turnover, and excretion of nutrients. Myopathy (muscle damage, wasting, and weakness) can occur in various muscles, including the heart, often compounded by alcohol-caused neuropathies. Also, the hormonal environment can change, making it less conducive to increasing muscle mass and strength.

PRACTICAL APPLICATIONS 

There are various methods to screen for alcohol abuse. Standardized questionnaires are available, but taking a more subtle approach by adding questions in medical history forms may be more effective. A team physician may also look for certain signs in the athlete’s appearance, but this has limited usefulness; it is good only for extreme cases of alcoholism. Athletes should be informed of all of alcohol’s detrimental aspects. Team rules and guidelines such as the following can be used:

* Pre-event: Avoid alcohol beyond low-amount social drinking for 48 hours.

* Post-exercise: Rehydrate first and consume food to retard any alcohol absorption.

To address any underlying causes of alcohol abuse, professional counseling should be available to athletes either directly or by referring athletes to community resources.

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blog | A propósito de “LANCE”

 

Más allá de la evidencia sobre el uso o abuso de sustancias prohibidas, el caso de Lance Armstrong, sin duda el mejor ciclista de ruta de todos los tiempos, ilustra la complejidad del deporte competitivo.

En muchos casos se juzga con severidad al atleta, quien frecuentemente es el eslabón final de una cadena de presiones económicas, sociales y políticas por alcanzar el triunfo a cualquier costo.

A diferencia de muchas decisiones importantes en salud, la mayoría de los deportistas no tiene la información completa y objetiva sobre las ventajas y riesgos de cada una de las recomendaciones médicas , técnicas y nutricionales que recibe de sus superiores. Más aún, la subordinación a dirigentes deportivos y patrocinadores los obliga con frecuencia a seguir rigurosamente las órdenes de sus entrenadores, médicos y directivos, quienes tienen como misión fundamental garantizar el triunfo y la figuración del atleta, de su equipo, marca, gremio, región o país.

Este entorno poco tiene de ético o de preocupación genuina y honesta por respetar el juego limpio o la salud del ser humano y pone a los grandes atletas en situaciones de poca libertad a la hora de tomar una decisión informada sobre las numerosas opciones técnicas, médicas y nutricionales que hacen parte del mundo competitivo.

La frustrante lucha contra el dopaje es un reflejo más de la incoherencia de una sociedad que aplaude únicamente el triunfo, la medalla o el título, que solo pueden alcanzar unos pocos entre miles de atletas de condiciones admirables y desconoce casi por completo la lucha heroica de niños y adolescentes por buscar un futuro mejor para ellos y sus familias. Que “lance” la primera piedra quien haya respetado todas las normas éticas y morales ante la promesa del éxito o la amenaza del fracaso…

Como en otros fenómenos preocupantes de nuestra sociedad moderna, si realmente queremos un cambio, debemos cuestionarnos a cerca de las raíces y responsables reales del problema y no pretender solucionarlo exclusivamente por medio de reglamentos, normas y sanciones, que aunque necesarias, son claramente insuficientes.

- JD