Nutritional Recommendations for Athletes

NUTRITIONAL RECOMMENDATIONS FOR ATHLETES

By: Matt Eshelman, B.S. Exercise Science

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INTRODUCTION

Proper nutrition is an important consideration for athletes who seek to maximize their performance. There is no diet that directly increases strength, power, or aerobic endurance, but an adequate diet allows an athlete to train and compete to the best of their ability. The ideal diet for an athlete depends on many factors such as age, body size, genetics, and environmental training conditions, as well as on duration, frequency, and intensity of training sessions.

To support the demands of training and competition an athlete must consume a balanced diet that provides all the essential nutrients: carbohydrate, protein, fat, water, vitamins, and minerals. The two most fundamental components of a diet are appropriate calorie levels and appropriate nutrient levels to prevent nutrient deficiency or toxicity. A simple tool to establish the adequacy of an athlete’s diet is MyPyramid ( This website was developed by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services in 2005. MyPyramid combines the outdated “Food Guide Pyramid” with inclusion ofphysical activity and the latest nutritional science. This tool displays the types and amounts of food to eat on a daily basis from each of the five major food groups: grains, vegetables, fruits, milk, and meat and beans. Although the basic guidelines in the pyramid are universal, athletes have different needs from those of the general population. In the following pages I will provide general recommendations for consumption of macronutrients (protein, carbs, fat), micronutrients (vitamins and minerals), as well as fluid and electrolytes for athletes.

ENERGY REQUIREMENTS

Energy is commonly measured in calories (kcal). The number of calories an athlete needs is based on body size, physical demands of the sport, length of training, training environment, and age. Energy requirement is defined as enery intake equal to expenditure, resulting in constant body weight. Consuming more calories then you burn results in weight gain, and consuming less calories then you burn results in weight loss. The energy requirement is determined by three factors:

1. Resting Metabolic Rate: calories required to maintain normal body function. (breathing, cardiac funtion, thermoregulation).
2. Thermic Effect of Food: increase in energy expenditure above the resting metabolic rate that can be measured for several hours after a meal (digestion, absorption, metabolism, storage).
3. Physcial Activity: calories required expended through physical actity. Dependant on frequency, duration, and intensity.

All of these factores are affected directly or indirectly by age, genectics, body size, body composition, environmental temperature, and training conditions. Table 1.1 provides an estimated daily caloric need based on gender and activity level. Most of you reading this will be classified in the moderate or heavy activity level due to the demands of your sport.

Table 1.1:Estimated Caloric Needs Based on Activity Levels of Athletes

*Adopted from Esssentials of Strength Training and Conditioning by the National Strength and Conditioning Association. (2005).

For example: The energy requirement of a 200lb male athlete with a heavy activity level is 4,600 kcal. 200 x 23 = 4,600 kcal.

My Daily Caloric Estimate: ______

*Please note that this is merely an estimate. Monitoring of body weight will provide information if more or less calories are needed.

MACRONUTRIENTS

Macronutrients are nutrients that are required in significant amounts in the diet. Three important classes of macronutrients are protein, carbohydrates, and fat.

Note: All recommendations are expressed in grams per kilogram of body weight.

1 kg = 2.2 pounds. For example: A 200lb athlete weighs 90.72kg. 200/2.2 = 90.72kg

My Body Weight: ______kg

Protein

Amino acids are the building blocks of protein and when combined together they form the thousands of various proteins occurring in nature. Proteins in the human body (muscle, bone, & organs) are composed of 20 amino acids. More than half of these amino acids are produced in the human body and are commonly known as “non-essential” amino acids because they do not need to be consumed in the diet. Nine of the amino acids are termed “essential” because they are not produced by the human body and therefore must be consumed through the diet (Table 1.2).

Table 1.2: Essential and Nonessential Amino Aids

*Adopted from Esssentials of Strength Training and Conditioning by the National Strength and Conditioning Association. (2005).

The amino acid content of a dietary protein affects its value in supporting growth and tissue maintenance. Whether the protein supplies amino acids in amounts proportionate to the body’s needs determines the protein quality. A high quality protein refers to a protein with an amino acid pattern similar to that needed by the body; high quality proteins include eggs, meat, fish, and dairy products. Proteins that are deficient in one or more of the essential amino acids (grains, vegetables, beans) are referred to as low quality proteins. This presents a problem for vegetarians that only consume plant proteins. When relying on low quality proteins it is important to consume a variety of plant foods so that all essential amino acids are consumed on a daily basis. For example: beans and rice, corn and beans, and peanut butter and bread.

Protein Requirement

Both aerobic endurance training and resistance training increase the body’s need for protein. This increased demand for protein is the result of tissue damage and using protein as a fuel source.

Research suggests that the protein requirement for an aerobic endurance athlete is 0.8 to 1.4g/kg of body weight. Heavy resistance training can increase protein requirements to as high as 1.7g/kg of body weight. Because most athletes do not fall neatly into one category, a general recommendation of 1.5 to 2.0g/kg of body weight ensures adequate protein intake. Expressed as a percent of daily caloric intake, a common protein intake recommendation is 10 to 15%.

For example:The protein requirement of a 90kg strength athlete is 135-180g of protein/day.

My Daily Protein Requirement: ______g/day

Carbohydrates

The primary role of carbohydrate in human physiology is to serve as an energy source. The importance of carbohydrates to an athlete’s diet has been shown in numerous studies which have documented an increase in aerobic endurance, work output, and high-intensity exercise performance. Breads, cereals, pasta, fruits, and starchy vegetables are promoted to athletes as ideal sources of carbohydrates. All types or dietary carbohydrate are effective with the fuel they need to perform. Consumption of carbohydrate low on the glycemic index (GI) is desirable except for immediately after exercise when consumption of high GI carbohydrates combined with quick digesting whey protein promotes recovery. Use the internet to examine the GI of various foods.

Carbohydrate Requirement

Aerobic endurance athletes who train for long durations (over 90 or more daily) should replenish glycogen (stored carbohydrates) levels by consuming maximal levels of carbohydrates, approximately 8-10g/kg of body weight. This level has been shown to adequately restore skeletal glycogen (stored carbohydrates) within 24 hours. Athletes who would benefit from this level of carbohydrate intake are endurance athletes (rowers, distance runners, cyclists, triathletes, soccer). Carbohydrate intake of 5 to 6g/kg of body weight appears adequate to support performance of strength, sprint, and skill athletes (basketball, football, volleyball, sprinters).

For example: The carbohydrate requirement for a 68kg lightweight rower is 544-680g/day.
The carbohydrate requirement for a 90.9kg football player is 455-546g/day.

My Daily Carbohydrate Requirement: ______g/day

Fiber

A diet low in fiber is associated with several disorders such as constipation, heart disease, color cancer, and diabetes. The recommended intake of dietary fiber is 25 to 38g/day. Foods rich in fiber include oatmeal, whole wheat bread, popcorn, raspberries, and pears.

My Daily Fiber Recommendation: ______g/day

Fats (Lipids)

Fats include triglycerides (oils) as well as related fatty compounds that are important to the structure and function of cells. Fat in food is often perceived negatively by athletes, but avoidance can lead to nutrient deficiencies which can harm performance. Body fat is necessary for insulation and protection of organs and for hormonal regulation. Fat also serves as a carrier for the fat-soluble vitamins and essential fatty acids. Food sources of dietary fat are red meats, nuts, and oils.

Fat Requirement

The recommendation for the general public is that fat intake should constitute 20-35% of total daily calories consumed, with less than 10% coming from saturated fats. This recommendation is generally given to reduced reduce the risk of heart disease. Fat guidelines for athletes may be higher than the standard “heart healthy” guidelines. Research shows that during periods of heavy aerobic endurance training increases in fat up to 50% of total calories have been reported without negatively effecting body fat. A fat intake over 30% is common among elite athletes. Diets extremely low in fat (15% of daily calories or less) have been shown to decrease testosterone production, thus decreasing metabolism and muscle development.

For example: The fat requirement for a 68.2kg lightweight rower who consumes 3400kcal/day would be 680 to 1700g/day.

My Fat Requirement: ______g/day

MICRONUTRIENTS

A micronutrient is a nutrient that is required in small amounts in the diet. The two primary types of micronutrients are vitamins and minerals.

Vitamins

Vitamins are organic substances that are not made by the human body, so they must be obtained from food sources or supplementation. Vitamins A, B, C, D, E, and K are vital for health and athletic performance.

Minerals

The human body requires various minerals for a wide variety of metabolic functions. Calcium, phosphorus, magnesium, iron, and the electrolytes sodium, potassium, and chloride are called the major minerals. The importance of minerals for bone health, oxygen-carrying capacity, and fluid and electrolyte balance is well recognized; with iron and calcium receiving special attention by athletic populations. Athletes who do not consume enough dietary iron risk iron depletion and impaired performance. Inadequate dietary calcium can contribute to low bone density and risk for fracture.

Iron

Iron makes up part of hemoglobin and myoglobin in the blood which play a role in oxygen transport and utilization of energy. Iron deficiency reduces athletic performance. Spinach, clams, cereal, oysters, meat, and soybeans are rich in iron.

Calcium

Athletes who consume a low-calcium diet may be at risk for osteoporosis, a deterioration of the bone tissue that leads to an increased risk of fracture. Milk, cheese, and yogurt are high in calcium.

FLUID AND ELECTROLYTES

Water and electrolytes play a critical role in keeping your body from overheating during exercise. Dehydration not only affects performance, but in serious cases causes heat related illness (heat stroke) or even death.

Water

Water is the largest component of the body, representing 45 to 75% of a person’s body weight. Water affects athletic performance more than any other nutrient. Consuming fluids in sufficient amounts is essential for normal cellular function and, of particular importance to athletes, heat dissipation. The recommended intake for water is 3.0L/day (100 oz., 13 cups) for men and 2.7L/day (74 oz., 9 cups) for women. Athletes sweating profusely for several hours per day may need to consume an extra 3 to 4 gallons (11-15 L) of fluid to replace losses.

Fluid loss equal to as little as 1% of body weight can be associated with an elevation in core temperature during exercise. Fluid loss of 3% to 5% of body weight results in cardiovascular strain and impaired ability to dissipate heat. At 7% loss, collapse is likely.

In order to monitor hydration status an athlete should take his/her weight before and after a workout. Each pound lost during the workout represents 1 pint (0.5L) of fluid loss that needs to be replaced before the next training session. Water weight loss is not healthy weight loss!

Electrolytes

Electrolytes play an important role in the regulation of water distribution in the body. Sodium plays a major role in fluid regulation while potassium, chloride, and magnesium are essential to muscular contraction and nerve conduction. Deficiencies in electrolytes hinder athletic performance. Recommended daily sodium intake is 4 to 6g/day. This level is normally sufficient to replace sodium lost through sweat, although athletes who sweat profusely or exercise in hot environments may need higher levels of sodium. Daily potassium intake of 2 to 6g/day is sufficient to replace levels lost in sweat.

Fluid Replacement

Fluid replacement occurs in three general times: before activity, during activity, and after activity. The goal is to begin exercise in a hydrated state, avoid dehydration during exercise, and rehydrate before the next training session. See table 1.3 for general fluid replacement guidelines.

Table 1.3: Fluid Replacement Guidelines

• Must be properly hydrated before prolonged exercise in a hot environment.
• Intake should be approximately 16 ounces (0.5 L) 2 hours before a workout.

• Have cool fluids readily available (water or sports drink)
• Sports drink or 50/50 mix of sports drink and water is recommended for exercise in hot conditions to ensure adequate electrolyte levels
• Athletes should drink frequently – 6 to 8 ounces of fluid every 15 minutes.

• Athletes should replenish fluids with at least 1 pint (0.5 L) for every pound of body weight loss
• The ideal replacement beverage is dependent on the duration and intensity of exercise, environmental temperature, and the athlete.
• Sports drink or 50/50 mix of sports drink and water is recommended after profuse sweating or exercise in extreme heat to ensure proper replacement of electrolytes.

*Adopted from Esssentials of Strength Training and Conditioning by the National Strength and Conditioning Association. (2005).

REFERENCE

Information and charts in this article are adopted from Esssentials of Strength Training and Conditioning by Thomas Baechle and Roger Earle.