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Nutritional Considerations

Nutritional Considerations. Introduction… . Research shows that, regardless of the sport, an athlete’s diet plays a critical, if not essential, role in performance. Yet misinformation and misconceptions persist among coaches and athletes regarding what constitutes an adequate diet.

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Nutritional Considerations

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  1. Nutritional Considerations

  2. Introduction… • Research shows that, regardless of the sport, an athlete’s diet plays a critical, if not essential, role in performance. • Yet misinformation and misconceptions persist among coaches and athletes regarding what constitutes an adequate diet. • We will first examine available evidence concerning the dietary knowledge and practices of coaches and athletes. • Then we will examine dietary recommendations for healthy eating, including the roles of carbohydrates, proteins, fats, vitamins and minerals.

  3. Introduction… • Next, we will look at evidence pertaining to protein supplementation and other ergogenic aids. • Special attention will be given to the sport of wrestling, which has been plagued with the problem of athletes attempting to lose body weight rapidly by dehydration, and a simple method is provided to assess an athlete’s ability to rehydrate adequately. • We will discuss the relationship between nutrition and recovery from injury. • Finally, we will use our 3 day calorie tracker to incorporate into our fitness program in the computer lab

  4. A brief history of sports nutrition… • Specific text on the diet of ancient athletes are rare. • Human muscle energy metabolism began to be studied in the late 19th century

  5. Milo of Croton – 6th century BC • Was the first Olympian • Would consume 20 pounds of bread and meat a day • = 16,000 calories/day • Nathan Zuntz – 1911 • Was a psychologist who discovered you need to combine carbohydrates and fat together to help increase energy

  6. Boston Marathon Studies – 1923 • A group of scientist we called in to test marathon runners after their race. • Their conclusions found that the majority of marathon runners had low blood sugar levels after the race. • Low blood sugar levels = hypoglycemia • In the next Boston Marathon, a few runners were encouraged to consume high-carbohydrate food. • Conclusion = consuming high carbohydrate prevented lower glucose level and improved running time to complete the race

  7. Harvard Dog Studies – 1932 • Scientist took 2 sled dogs • Increased the sled dogs food for 4 hours, 6 hours, 17 hours, 23 hours • Provided more carbohydrates after the rest period

  8. Dr. Robert Cade – 1965 • An ephrologist (kidney specialist) who studied physiology of exercise • Came to University of Florida College of Medicine • Put together a team who began to work on answering the famous question asked about the football team • “Why don’t football players urinate after a game?”  • At the time, basic exercise wisdom  discouraged athletes from replenishing liquids lost due to sweating during the game • The team lost so much fluid, that they had none left to form urine • Dr. Robert Cade began to develop a hydration drink (combined with sugar and salt) that could be absorbed more quickly. • Thus, this became the basis of Gatorade

  9. He first used Gatorade on guinea pigs(who were the JV squad) • Noticed that in the scrimmage during practice the Varsity would over power the JV team • After consuming the Gatorade beverage, in the second half, JV overpowered V

  10. Introduction… • Proper nutritional knowledge is imperative for all individuals, but especially for those involved in athletic competitions (Jacobson, Sobonya, & Ransone, 2001). • An athlete’s diet has a direct impact on performance, recovery from training and competition, resistance to environmental extremes, recovery from injury, and, to some extent, likelihood of injury. • In essence, diet influences virtually all aspects of sports participation.

  11. Most athletes (68%) were familiar with the food groups and 71% reported incorporating them into their diet, but Parr et al. (1984) also demonstrated that athletes largely relied on parents for information about nutrition – followed by TV commercials and magazines. • Although the knowledge of most parents concerning nutrition cannot be measured, it is probably safe to assume that both parents and the media represent, at best, marginal sources of current nutritional advice always or often during their college carriers.

  12. Nutrients: An Overview • According to the American Dietetic Association (2009), eating correctly for sports performance will • Help the athlete train longer and at a higher intensity • Delay the onset of fatigue • Promote recovery • Help the athlete’s body adapt to workouts • Improve body composition and strength • Enhance concentration • Help maintain healthy immune function • Reduce the chance of injury • Reduce the risk of heat cramps and stomachaches

  13. Although a comprehensive investigation of both macronutrients (required in large amounts) and micronutrients (required in small, or trace, amounts) is beyond the scope of this text, a brief review of the six classes of nutrients is presented. • Carbohydrates, fats, and proteins are the macronutrients, and each is important in the diet. • The mix of these may change based on fitness levels, exercise goals, and personal food preferences. • Vitamins and minerals are micronutrients that contribute to metabolic reactions and tissue structure. • And finally, water is essential for substrate transport, waste removal, and joint health (McArdle, Katch & Katch, 2009).

  14. Carbohydrates… • Carbohydrates (CHO) are molecules that, by way of their metabolic breakdown, provide energy for high-intensity exercise. • The specific forms of CHO used within the body are glucose and glycogen (the storage form of glucose) found in the blood, liver, and skeletal muscle.

  15. Carbohydrates… • Carbohydrates consist of carbon, hydrogen, and oxygen atoms, with the number of carbon atoms ranging from three to seven. • They fall into three general categories, based on the complexity of the molecule. • the simplest forms of CHO are the monosaccharides (a single molecule), which include sugars such as fructose, glucose (blood sugar), and galactose.

  16. Carbohydrates • The next group is the disaccharides (two monosaccharide molecules combined), which include commonly known sugars such as lactose (milk sugar), sucrose (the most common form of sugar in the diet), and maltose. • The complex carbohydrates are known as polysaccharides (10 to thousands of monosaccharides linked together) and include compounds such as glycogen, starch, and cellulose (dietary fiber).

  17. Carbohydrates… • The majority of dietary CHO is derived from plant sources, primarily grains, seeds, fruits, and vegetables. • In a practical context, carbohydrates are classified as either simple (monosaccharides) or complex. • In general, complex CHO contain more nutrients and fiber than simple CHO do. • The most common form of dietary CHO intake is from simple sugars, primarily foods high in sucrose • Soft drinks, candies, and cereals (high in sugar).

  18. Carbohydrates… • Although high in caloric content, these foods stimulate insulin release , cause fluctuations in blood glucose levels, and provide little in any way of other nutrients; therefore, they are often referred to as “empty calorie” foods.

  19. Carbohydrates… • A superior form of dietary CHO is derived form eating more complex CHO or whole-grain cereals and breads, vegetables, and fruits. • The CHO in these foods is in the form of starch found in the cereals and breads or cellulose found in leaves, stems, roots, seeds, and coverings of plants. • An added benefit of consuming complex CHO is that they typically contain dietary fiber (indigestible CHO), which may lower cholesterol absorption and is also beneficial to the digestive tract. • Daily fiber intake should be between 21 g and 38 g depending on gender and age (McArdle et al., 2009).

  20. Carbohydrates… • Another excellent source of CHO is fruits, which can provide a significant amount of CHO in the form of fructose. • Fructose, a monosaccharide, is much sweeter than surcose; however, the benefit of fructose is that it “does not stimulate pancreatic insulin secretion” and, as a result, “helps to stabilize blood-glucose and insulin levels” (McArdle et al., 2009).

  21. Carbohydrates… • An added benefit of whole-grain breads, cereals, fruits, and vegetables is that they typically contain a wide variety of other nutrients and, as such, help to provide a balanced diet.

  22. Carbohydrates… • Although the classifications of simple and complex CHO often are suitable to describe foods containing CHO, these classifications do not represent the way both simple and complex CHO are hydrolyzed and absorbed by the body (Manore, Meyer, & Thompson, 2009) • Foods are now also classified as producing either high, moderate, or low glycemic responses. • Foods classified as having a high glycemic response typically result in a large and rapid rise in blood glucose and insulin, followed by a rapid decrease in blood glucose.

  23. Carbohydrates… • Those foods with a lower glycemic response cause a steadier rise and decline in blood glucose and insulin. • Low glycemic index CHO improve diabetes management, reduce the risk of heart disease, reduce hunger and keep a person fuller for longer, and prolong physical endurance, whereas high glycemic CHO help refuel carbohydrate stores after exercise.

  24. Carbohydrate & Muscle • Muscles require CHO as a fuel source during exercise. • The recommended percentage proportion of CHO in the diet should range between 60% and 70% of the total calories consumed daily, depending on the exercise frequency and intensity. • Regardless of the type of CHO consumed, they all provide approximately 4 kal/g CHO. • The average person stores approximately 1500 to 2000 kcal of CHO, the majority of which is in the form of muscle and liver glycogen, with a small portion available and blood glucose (McArdle et al., 2009).

  25. Carbohydrates… • All individuals need to consume carbohydrates to maintain body functions or support exercise; however, athlete engaging in different activities need to consume carbohydrates at greater levels than sedentary individuals do.

  26. Carbohydrate (Glycogen) Loading… • As stated earlier, the majority of CHO in the body is stored in the skeletal muscles and liver in the form of glycogen. • Physiologically, it is to the athlete’s advantage if the total amount of stored glycogen can be increased prior to a competition. • Athletes involved in aerobic sports, especially those with durations in excess of 60 minutes, benefit the most from an increased level of stored glycogen.

  27. Carbohydrate (Glycogen) Loading… • Essentially, the process of CHO loading involves the systematic decrease of dietary CHO intake in conjunction with a significant increase n exercise intensity. • Early procedures for CHO loading were particularly Spartan in nature, requiring multiple days of intense exercise (depletion phase) combined with dietary restriction of CHO intake.

  28. Carbohydrate (Glycogen) Loading… • Ironically, although such protocols often did result in an increase in stored glycogen, the negative impacts often outweighed the benefits in performance. • These included severe physical fatigue associated with the depletion phase, along with negative emotional changes such as hyperirritability. • In addition, another problem related to CHO loading is that for ever gram of CHO stored, an additional 2.7 g of water is also stored. • As such, the process of CHO loading results in an overall increase in body weight that, in sports such as distance running, may represent a performance detriment.

  29. Carbohydrate (Glycogen) Loading… • Research verified that a properly executed regimen of CHO loading can boost the level of stored glycogen from the normal 1.7 g of glycogen/100 g of muscle tissue to 4 to 5 g of glycogen/100 g of muscle tissue. • A typical modified regimen begins approximately one week prior to competition and includes a gradual tapering of physical activity accompanied with a slight increase in CHO ingestion. • Exercise (75% maximal O2 consumption over the first 3 days follows a steady decline in total time 1.5 hrs/day to 50 mins) while CHO consumption is maintained at 50% of total caloric intake.

  30. Carbohydrate (Glycogen) Loading… • Over the next 3 days, exercise time is decreased to about 10-15 minutes while CHO consumption is increased to 75% of total caloric intake. • A normal protein and fat intake is maintained. • A high-CHO meal is then consumed on the day of the competition (McArdle et al., 2009) • http://www.youtube.com/watch?v=heQ5eukh8t8

  31. Carbohydrate and Exercise • CHO stored in muscle and liver as glycogen • -350 grams in muscle; - 90 grams in liver • -1800 calories in all • Trained muscle can carry more glycogen • Small amount circulating as blood glucose • Excess CHO stored as fat when glycogen stores are full (Jon Vredenburg, MBA, RD, CSSD, LD/N, HFS)

  32. Carbohydrate and Exercise • High intensity makes CHO the preferred substrate. • 50-60% of energy over 1-4 hours of continuous (70% capacity) exercise comes from CHO. • Since CHO is a primary fuel source – low levels lead to fatigue. • Fatigue = when exercise continues to the point that compromises liver and muscle glycogen supply. • 2 hour strenuous workout can deplete liver and muscle glycogen. • (Jon Vredenburg, MBA, RD, CSSD, LD/N, HFS)

  33. Carbohydrate and Exercise • Rate of ingested carbohydrate oxidation is limited to -60 grams per hour (240 calories). • Intestinal transports become saturated. • CHO combinations (i.e. glucose +fructose) have greater oxidation rates. • Overall carbohydrate oxidation rates usually well above 500 calories/hour. • In moderate to higher intensity activities. • Clarifies the need for adequate fueling throughout training cycles (between sessions) • Jeukendrup. A (ED) (2010). Sports Nutrition from lab to kitchen, Meyer & Meyer Sport

  34. Where the fuel could be used… *Brain storage has 20% at rest

  35. Fat (Lipids) • Fats serve a variety of functions in the body, including: • Providing energy for muscle contraction • Insulation • Primarily in the form of subcutaneous fat • Protection of vital organs such as the kidneys and heart • Dietary fats are either simple or complex, depending on their specific molecular structure. • Fats, like CHO, consist of carbon, hydrogen and oxygen atoms; however, the ration of hydrogen to oxygen is far greater in fats than in carbohydrates.

  36. Fat (Lipids) • Depending on their molecular structure, fats can exist either in liquid (oils) or solid form. • Simple fats consist of two compounds: • Glycerol • Fatty acid • Can be either saturated or unsaturated

  37. Fat (Lipids) • The term saturated describes the fact that in this form of fat all of the available bonding sites on the fatty acid molecule are occupied by a hydrogen atom. • Most dietary sources of saturated fats are derived from animal sources (i.e. beef, pork, poultry, and dairy products) and are generally solid at room temperature.

  38. Fat (Lipids) • Unsaturated fats, as the term implies, are structured in such a way as to prevent all of the available bonding sites from being occupied by a hydrogen atom. • The majority of unsaturated fats exist in two forms, monounsaturated and polyunsaturated.

  39. Fats (Lipids) • Monounsaturated fat • Include a single site on the carbon chain where a double bond exists, thus preventing hydrogen atoms from bonding at the site. • Polyunsaturated fats • Have two or more double bonds and, as such, have at least two sites that cannot be occupied by hydrogen atoms

  40. Fat (Lipids) • The recommended percentage proportion of fats in the diet should be 30% or less of the total calories consumed daily (McArdle et al., 2009). • It is recommended that saturated fats make up only 10% of total fats (20-25g based on 2000 – 2500 kcal/day); therefore, the majority of fats consumed should be unsaturated. • This helps avoid the problems attributed to excessive consumption of saturated fats, including high cholesterol and cardiovascular disease.

  41. Fat (Lipids) • Dietary sources of fats, as stated earlier, are animal products such as beef, poultry, and pork. • Other sources include dairy products, such as milk, butter, and cheese. • In addition, plant sources of fats include nuts and plant oils such as corn oil, olive oil, and soybean oil.

  42. Fat (Lipids) • In addition to CHO, fat is an important source of energy during rest and exercise. • Both CHO and fats are oxidized for energy at the same time. • The proportion of energy that comes from CHO and fats is dependent on the duration, intensity, and type of exercise as well as the athlete's fitness level and meal eaten prior to exercise (Manore et al., 2009). • Regardless of the type of fat consumed, all forms provide approximately 9 kcal/g; therefore, fats are calorie dense.

  43. Fat (Lipids) • One tablespoon of butter has the same kilocalories as 4 cups of chopped broccoli (100 kcal). • The available amount of energy in the form of stored body fat is significantly greater than what is available from CHO. • For example, the available energy in a 70-kg person who has 18% body fat is calculated to be around 113,400 kcal.

  44. Fat and Exercise • Potentially unlimited source of fuel during aerobic exercise. • 150 pound (68 kg) runner in a marathon at a 8 min/mile pace burns 3245 kcal. • One pound of fat = 3500 kcal. • Improving fatty acid oxidation during exercise preserves muscle glycogen. • Result of training adaptations.

  45. Fat burning, simplified… • Fatty acids broken down in the mitochondria generate Acetyl CoA entry in the Kreb’s (TCA) cycle. • Accumulation of Acetyl CoA occurs in absence of carbohydrate. • Physical activity becomes compromised • Carbohydrate substrates needed to sustain Kreb’s Cycle • Fat burns in a carbohydrate flame

  46. Protein… • As with both carbohydrates and fats, proteins also contain carbon, hydrogen, and oxygen atoms in their molecules. • However, proteins also include nitrogen and, as such, they are unique molecules compared to the other nutrients. • Protein molecules are assembled by combining amino acids using peptide bonds to form large, complex molecules. • The majority of the body’s protein is found in muscle and connective tissues. • Proteins are also found in the body fluids and in the blood from thousands of different enzymes and structures related to blood clotting such as fibrin and fibrinogen

  47. Protein… • In addition, muscle protein is used as an energy source during prolonged exercise, producing as much as 10% to 15% of the energy requirements for long duration activity. • Research suggests that a regimen of regular aerobic exercise enhances the body’s ability to generate energy from the metabolism of proteins (Sumida & Donovan, 1995).

  48. Protein… • The body builds proteins from the amino acids that are available from the protein that is consumed in the diet. • Of the 20 amino acids required to construct the body’s proteins, 8 cannot be synthesized by the body and must, therefore, be ingested in the diet.

  49. Protein… • These eight amino acids are known as “essential,” implying that they must be present in the diet. • They are isolucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. • The best dietary sources of the essential amino acids are eggs, meats, and dairy products, all known as complete proteins. • Incomplete proteins are those that lack one or more or contain insufficient amounts of one or more of the essential amino acids.

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