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Sports Nutrition

Introduction

Carbohydrates, fats, proteins, and water are the four components essential to nutrition. In performance, the ratio of these four substances in the diet is imperative for success and safety. In sports nutrition, diets come in all types of ratios and are packed with different supplements. These diets will very according to each individual sport. Before you prescribe or look for a diet, you must first learn the description and function of the components and consult a sports nutritionist. There are various diets on the market for athletes. For instance, a triathlete may ingest a high amount of carbohydrates whereas a body builder may ingest high percentages of protein. Therefore, the type of exercise done by the athlete will dictate the diet in which that athlete should ingest. Also the time of day in relation to rest and exercise will have an affect on the outcome of a diet. For instance, some research states that muscles uptake protein and carbohydrates more effectively immediately after exercise. Thus, there are various parameters that an athlete must weigh when choosing the proper diet. A proper diet can be prescribed by a sports nutritionist. A sports nutritionist may be worth the money if you are serious about quality performance and safety.

When athletes undergo the stresses of exercise their bodies break down. Rest and nutrition help build their bodies back up and make them stronger. An improper diet can cause athletes harm; it can delay or cause an inadequate repair process. It can also make an athlete prone to thermal and mechanical injury. For instance, during exercise muscles are stressed. Proteins are needed to repair the muscles and help them grow. If the diet is inadequate with protein, then the muscles cannot repair. When the athlete stresses the muscles again, it will result in further damage. This will cause injury to the athlete. When athletes exert themselves, they often break down their immune system. During rest the body uses certain substances from the diet to help rebuild the immune system and make it stronger. Therefore, the proper athletic diet is crucial for safety in sports.

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Water

Water is the essential nutrient of life. Without it nothing could survive. Water accounts for about 60% of body weight in most species, and it is the primary component of blood, cells, urine, and sweat. Water can be divided into two components once it enters the body. Once in the body, water either becomes intracellular fluid (ICF, water in the cell) or it will become extracellular fluid (ECF, water outside the cell). The intracellular water is the major component comprising two thirds of the total body water. The extracellular fluid can be further divided into interstitial fluid (water between the cells of the body) or plasma. Plasma accounts for approximately 25% of the extracellular fluid.

Water has many functions in the body. It acts as lubrication, such as the synovial fluid that surrounds joints and allows bones to move freely. The water in muscle holds all the constitutes that are necessary for contraction. Water also acts as a transporter. Blood plasma serves as a transporter of nutrients to cells and uptakes metabolic waste.

Water also functions to regulate electrical and chemical gradients which insures cell function and allows electrical communication throughout the body. This is made possible by the regulation of electrolytes within the water content of the body. Electrolytes are sodium, potassium, calcium, chloride, and magnesium. They posses electrical charges that are vital to the electrochemical functioning of the body. Sodium is the major electrolyte present in the extracellular fluid and potassium is in a much lower concentration. In the intracellular fluid the situation is reversed and potassium is in a high concentration, whereas sodium is in a low concentration. It is essential for the body to maintain this distribution of electrolytes. This allows for efficient electrical and chemical gradients to be established, which provides the optimal environment for cell function and electrical communication.

Water consumption comes in two forms and water loss comes in three forms. One form of water consumption is when one drinks, whereas the other form is when one ingest foods. Foods such as fruits are high in water content and thus account for the daily consumption of water. The three forms of water loss are respiratory water loss (~2-3 cups per day are expired), sweat loss, and urinary and feces water loss.

When the body becomes dehydrated, cells within the body become smaller and chemical reactions within the body become impaired. With dehydration blood volume decreases and less blood is available to transfer oxygen and nutrients throughout the body. At this point the muscles become weak and fatigued. In addition, thermoregulatory (heat regulation) mechanisms greatly depend on the availability of water. Dehydration will cause a decrease in performance and safety.

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Carbohydrates

What are carbohydrates?
Carbohydrates are composed of carbon, oxygen, and hydrogen. A carbohydrate is formed when one or more sugar molecules bind together. Depending on the size of the molecule, depends on the name given to the molecule. Individual sugar molecules are monosaccharides; pairs of sugar molecules are disaccharides and in chains of three or more are polysaccharides. All sugars are reduced to simple sugars through digestion. A simple sugar is glucose. Therefore, the larger the sugar molecule, the longer it takes to break down, and the longer it takes to be utilized as energy. This is important to remember when searching for the right source of carbohydrate to consume during athletics. Artificial sweeteners such as saccharin or aspartame are not true sugars. They do posses the sweetness qualities of sugars without having as many calories, but they obtain little nutritional value.

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What is the function of carbohydrates?
Once the sugar has been broken down in the digestive system, it travels to the cells to be broken down to yield energy. In performance, athletes are concerned with glucose entering the muscles. In muscles, glucose is stored as glycogen. Muscles break down glycogen and glucose to yield energy. Athletes want as much glycogen available to the muscles as possible. However, the muscles can only uptake a certain amount of glycogen. Without antiquate stores of muscle glycogen, muscles will fatigue faster and athletes may “hit the wall” (run low on energy).

If an athlete has an imbalance of carbohydrates in the diet, two things may happen. First, if there is too many carbohydrates in the diet, then the excess carbohydrates will be stored as fat. If there are not enough carbohydrates in the diet, then the body may mobilize fat to a greater extent than what it can use. This will produce an abundance of ketone bodies which will lead to ketosis, and it will affect the body’s acid base balance. In addition, if glucose levels are not balanced, an athlete may experience hyperglycemia or hypoglycemia. Hyperglycemia is when blood glucose levels are extremely high, and an athlete may have difficulty breathing and may become confused at that point. Hypoglycemia is when blood glucose levels are too low. In this instance an athlete may feel dizzy and weak. Both extremes of glucose levels can be fatal. A well balanced diet in carbohydrates is important for an athlete’s success and safety. Athletes who suffer from diabetes mellitus should consult their physician and seek counseling from a sports nutritionist.

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How are carbohydrates digested?
Carbohydrate digestion starts when they enter the mouth and are partially broken down by salivary amylase. There is limited digestion of carbohydrates in the stomach. The majority of breakdown occurs in the intestines. The enzymes pancreatic amylase, intestinal amylase, maltase, sucrase, and lactase all act to break down carbohydrates into simple sugars. The simple sugars are absorbed by the intestinal mucosa and pass into the blood stream. The simple sugars are now glucose and are routed to where ever they are needed in the body. Carbohydrates that are not absorbed into the blood stream are usually dietary fiber and are excreted in the feces.

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Proteins

What are proteins?
Proteins are made up of oxygen, nitrogen, hydrogen, and carbon. Proteins are comprised of amino acids. There are 9 essential amino acids and 12 non-essential amino acids. Non essential amino acids can be manufactured by the body to carry out their function once they have been formed. Essential amino acids must be ingested in the diet because the body cannot manufacture them at a rate sufficient to meet the needs for growth and maintenance. Therefore, the body’s protein requirements are not only quantitative but they are qualitative as well.

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What is the function of proteins?
Protein is the primary structural material of cells and tissues. Proteins are required for maintenance and repair of body tissues (e.g. muscle), formation of antibodies (help fight off infection), blood clotting factors, production of enzymes, hormones that regulate body processes, fluid and electrolyte regulation, acid-base regulation, and manufacturing of hemoglobin (carries oxygen to cells). Protein also provides a small amount of energy and heat when necessary.

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How are proteins digested?
Proteins begin to be digested when they enter the stomach. The enzyme pepsin, which performs optimally in the acidic environment of the stomach, initiates breakdown of the proteins. Once the proteins are broken down into fragments, they are further broken down by trypsin in the duodenum. At this point the fragments are further degraded to amino acids which are absorbed by the small intestines and delivered to the circulatory system. Amino acids which are not needed are deaminated in the liver. The deaminated amino group is converted to urea and excreted in the urine. The amount of urea excreted will depend on the individual athlete’s protein intake.

There is an on going controversy in athletics as to how much protein should an athlete ingest. Another debate argues wether or not one sport or body type require more or less protein than another. This question is still being researched and one day hopefully scientist will meet a conclusion.

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Fats

What are fats?
Fats are substances that cannot desolve in water and are sometimes referred to as lipids and/or oils. They are made up of carbon, hydrogen, and oxygen. Fats provide essential fatty acids and carry vitamins (A, D, E, and K). They are comprised of fatty acids and glycerides (monoglycerides, diglycerides, and triglycerides). The most common lipids are triglycerides. Fatty acids can be short, medium, and long chain (containing 2 to 12 or more carbons). In addition, fatty acids can be saturated or unsaturated. They can also be monounsaturated fatty acids (found in peanut, olive, and canola oils) and polyunsaturated fatty acids (found in soybean, corn, and sunflower oils). The type of fatty acid will determine its action within the body.

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What is the function of fats?
Fat has many functions in the body from hormone synthesis to padding of the organs. Fats are a primary source of muscle energy at rest, and fats can provide energy for endurance events. When digested fats are broken down to component parts, they become fatty acids, monoglycerides, and glycerols. Cells in the body can use fat as energy however, just like carbs and proteins unused fats get stored in the body as adipose tissue. Since glycogen stores are limited and fat stores are abundant, endurance athletes often tap into fat stores during long duration endurance activities. However, fat is a less efficient source of energy because it requires a larger amount of oxygen to use it. In fact one pound of body fat yields 3,500 calories, but glycogen must be present in order to convert it.

When fat is stored in the body it has three main functions. First stored fat is used for energy. Stored fat is also used as an insulator from cold temperatures (helps conserve body heat). Lastly, fat is used as a shock absorber. It is packed in between organs and strategically placed throughout the body to absorb shock from external and internal forces.

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How are fats digested?
There is little digestion of fats by lipase in the mouth and by gastric lipase in the stomach. Bile must be present to digest fats. Bile is synthesized from cholesterol. The primary digestion of fats is initiated by intestinal and pancreatic lipases. Most fats are absorbed as glycerol, fatty acids, and monoglycerides. Glycerol and short to medium chain fatty acids are water soluble and enter directly into the circulatory system. Long chain fatty acids and monoglycerides are transformed into triglycerides and are transported by the lymphatic system to the circulatory system. Cholesterol found in the body may come from foods of animal origin or it may be synthesized by the body. The more cholesterol ingested in the diet, the less cholesterol synthesized by the body. Once fats enter the blood stream they can be used for energy or stored as fat.

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Vitamins

What are vitamins?
Vitamins are naturally occurring substances that have nutrient qualities and are found in food. They come in two forms which are fat soluble and water soluble. Fat soluble vitamins are the vitamins A, D, E, and K. Water soluble vitamins are the B vitamins and vitamin C. Vitamins are needed in small amounts for normal functioning, health, growth, recovery, and athletic performance. They cannot be synthesized by the body in amounts adequate enough for optimal functioning. Therefore, they must be consumed in the daily diet. In fact, if athletes are vitamin deficient, their metabolism may become altered and they may develop symptoms of vitamin deficiency. On the other hand athletes who ingest too much of a vitamin, may develop a toxic level of a particular vitamin. In sports nutrition, more is not always better.

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What are the functions of vitamins?
There are too many functions of vitamins to mention and the biochemistry of the vitamins is too complex to mention on this website. Therefore, the following is a list of the major vitamins and their related functions.

  • Vitamin A is an antioxidant and plays a role in vision, growth, and immunity.
  • B Vitamins are thiamin, riboflavin, niacin, B6, folic acid, B12, pantothenic acid, and biotin. The functions of the B vitamins are very complex and numerous, therefore, the functions will not be mentioned.
  • Vitamin C is an antioxidant and may aid in immune function.
  • Vitamin D aids in skin cell development, usage of calcium, and is associated with immune function.
  • Vitamin E is an antioxidant.
  • Vitamin K is involved in blood clotting.

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Minerals

What are minerals?
Minerals are inorganic elements. Minerals are found throughout the body and are considered to be minerals, trace minerals, and electrolytes. They make up approximately 4-6% of the body however, they are important for their many structural and metabolic functions. For example, calcium is a structural component of bone. They are also found in parts of organic molecules such as iron is part of hemoglobin. Minerals in their ionic form are found in blood and cellular fluid. Minerals provide many important complex functions in the body. Athletes have to have adequate amounts in order to safely compete and to maintain performance. Athletes who do not receive enough structure minerals such as calcium can experience weakened musculoskeletal tissues which can make an athlete prone to injury. Consult a sports nutritionist to figure out the proper amount of minerals you or your athlete should be ingesting. The following is a list of the minerals, trace minerals, and electrolytes.

  • Minerals: calcium, magnesium, and phosphorus.
  • Trace Minerals: boron, chromium, copper, fluoride, germanium, iron, iodine, manganese, molybdenum, selenium, vanadium, and zinc.
  • Electrolytes: sodium, potassium, and chloride.

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