Главная > Реферат >Остальные работы
Sports Nutrition Essay, Research Paper
I play water-polo. It is a physically demanding sport. Sometimes during games I am exhausted and then there are times in other games when I m energized. I began to wonder why this happens. Could it possibly be because I live on bread? I have always thought what I ate didn t really matter. Could it be what you are is what you eat? I decided to do a little research on nutrition and the endurance athlete.
By far the most popular diet for athletes during the past fifteen years has been the high carbohydrate diet, otherwise known as carbo-load to the athletic community. The foremost authority on athlete nutrition and a big promoter of the high carbohydrate diet is Nancy Clark, a nationally recognized nutritionist and author of The Athletes Kitchen..
The main focus of the high carbohydrate low-fat diet is on calorie consumption. According to these nutritionists, the calories consumed need to be primarily in the form of carbohydrates. They state that the best fuels for your muscles are carbohydrates, either simple sugars (such as the naturally occurring sugars in fruits and juices) or complex carbohydrates (the unrefined grains and starches in whole bread, brown rice, bran cereal, oatmeal,etc.). According to Clark et al you store only carbohydrates, not protein or fats, in your muscles in the form of glycogen (muscle sugar). During hard exercise, you burn this glycogen for energy and if it becomes totally depleted you hit the wall and you feel overwhelmingly exhausted. These nutritionists preach that eating a high carbohydrate diet can help prevent early exhaustion.(1)
It is generally known that eating lots of sweets and sugary foods before exercise can hurt your performance. When you eat concentrated sugar, your body secretes insulin. Insulin is a hormone that carries the sugar away from your blood into the muscles. Therefore, the combined effect of the insulin with the exercise causes the sugar in your blood to drop abnormally low and you may feel light headed, shaky, tired and uncoordinated, a condition known as hypoglycemia.(2)
If you need an energy boost, these nutritionists recommend a snack of crackers or bread to perk you up. But the best thing to do is to avoid needing an energy boost. It is more important to eat properly earlier so your body has time to digest the foods. You ll be less likely to crave sweets because you ll already have adequate energy.
This group of nutritionists maintain that for health and performance reasons, you should try to choose wholesome carbohydrate rich foods for both daily training diet and for pre competition meals. A high carbohydrate diet eaten everyday should prevent chronic glycogen completion and ensure adequate glycogen replacement.
Theses nutritionists believe that carbohydrates such as cereal, bread, bagel, crackers, potatoes, pasta, etc., are the best choices because they digest quickly and are readily available for fuel. They say that protein rich foods (eggs, tuna, steak) take longer to digest and increase need to urinate. Fats (fried foods, peanut butter, burgers) stay longest in the stomach and may feel heavy and uncomfortable.(3)
The suggested diet from this group of nutritionists consists of 70% carbohydrates, 15-20% fat and 10-15% protein. The theory is that the endurance athlete wants to maximize glycogen storage in the muscles but needs to use stored fat along with the stored glycogen for fuel in order to have enough energy during the performance period to avoid hitting the wall. The athlete, by following the 70-20-10 ratio is supposed to create a constant training condition that will allow the body to access the optimum ratio of energy sources during exercise.
In recent years, a new diet theory has been promoted by other nutrition consultants such as Dr. Barry Sears. It is their belief that athletic performance and weight gain are not dependent on calories at all but on hormone levels. They believe that it is necessary to have the right balance of hormones.
The theory is that the food you eat is probably the most powerful drug you will ever encounter and that we must learn how to administer food at the right time, and in the correct dosage to keep the hormone insulin at the right level, not too high, not too low. One of the suspected side effects of the popularity of the carbo load mentality has been the huge increase in the incidence of diabetes among Americans. Many physicians fault the high carbohydrate diet adopted by many Americans.(4)
It is necessary to maintain a steady range of insulin in the blood stream. Dr. Sears maintains that previous diets have ignored the importance of protein and fat. Ten thousand years ago there were no grains on the face of the earth. During mankind s evolution, our ancestors had only two food groups from which to choose: Low fat protein and low density carbohydrates (fruits and vegetables). As a result, this is what we are genetically designed to eat. When grains were first introduced into the human diet 10,00 years ago, the archeological record clearly reflects three immediate and dramatic changes in grain eating societies:
A.) Mankind shrank in height from lack of adequate protein.
B.) Disease of modern civilization, such as heart attacks , first appeared.
C.) Obesity first became apparent.(5)
Dr. Sears believes that the reason ancient Egyptians were six inches shorter than Neo-
Paleolithic man was probably because the Egyptians protein consumption had dropped dramatically. Ancient Egyptian medical books, as long as 3500 years ago, describe heart disease in extreme detail. Ancient Egyptian mummies have also been found to have excessive skin folds around the mid sections, indicating obesity among ancient Egyptians. The diet of the ancient Egyptians closely approximated today s diet recommendation by the U.S. government.
It is Dr. Sear s contention that there is very little biochemical difference between the carbohydrates in a spoon of table sugar and the carbohydrates in a bowl of pasta as far as the body is concerned. The body has to bring them all down into simple sugars so they can be absorbed. What both the sugar and the pasta lack is the balance of low fat protein to be eaten at the same time. It is Dr. Sears theory that it is the ratio of protein to carbohydrates that determines how your body will function athletically.
Eating adequate protein is essential to health. The body loses protein everyday through normal metabolism. If there isn t an equal amount of protein coming into the body to balance the amount that is being lost, protein malnutrition develops. This leads to a decrease in the ability of the immune system to fight infection. Muscle mass is also lost as the body consumes existing muscles in a losing effort to keep up with the demand for new protein to support the immune system and new enzyme formation. Thus the theory is that performance will increase if the body receives adequate amounts for protein consistently throughout the day. Not excessive amounts but adequate amount for a persons individual needs. Low fat protein is preferred such as chicken, fish, turkey, egg whites, low fat cottage cheese, tofu and isolated protein powders as opposed to bacon, steaks, and sausage.
In addition to the reasons above, protein also plays another critical role. It stimulates the release of the hormone called glucagon, which is the hormone that allows the body to use stored energy as an energy source. Glucagon also is important for controlling insulin output.(6)
Also necessary to the diet, according to Dr. Sears, is fat. Although fat has no direct effect on insulin or glucagon, it does slow down the absorption rate of any carbohydrate in to the blood stream thereby decreasing insulin production. Monounsaturated fat, the kind that is liquid at room temperature but solid in the freezer, is preferred. Good sources for these kind of fats are olive oil, slivered almonds, macadamia nuts, and guacamole.
This new diet promotes primarily eating low density carbohydrates such as fruits and vegetables, as opposed to high density carbohydrates, such as sugar and bagels. This way a natural control system is set up that controls the total amount of carbohydrates being consumed at one meal. Also, the fiber and low density carbohydrates help slow down the rate of entry of carbohydrates into the blood stream thus lowering insulin secretion.
To summarize this diet,one should 1) Eat small meals throughout the day.
2.) Should have some protein at every meal but balance it with carbohydrates. 3) Eat fruits and vegetables- the preferred source of carbohydrate, and 4) Eat some form of fat, a monounsaturated fat is best.
The next area of importance for the endurance athlete is hydration. This is a nutrient that is easy to overlook in the middle of intense competition but is generally agreed to be the most important nutrient. Dehydration can affect performances in many ways. The reason hydration is so critical is because it keeps the body temperature below 104 degrees Fahrenheit. Sweat accounts for the loss of most body water and this comes mostly from blood plasma. A loss of five percent body water means a loss of ten percent water from blood plasma, leading to reduced oxygenation of brain and muscle-crucial function in athletic performance. (7)
The next area of investigation is that of performance enhancing substances. Popular supplements right now are Creatine and Androstendione. My research has indicated that these supplements essentially benefit for strength training athletes and not endurance athletes. Additionally, there are thought to be long term health risks associated with the use of these substances and thus I decided against considering them as a part of my diet as an endurance athlete. One supplement that appears to have some benefit for the endurance athlete is caffeine. Caffeine, when taken properly, appears to have a beneficial affect on some athletes.
The effect of caffeine on endurance activities, such as long distance running and cycling, has been well documented. It has been shown to decrease marathon run times as well as time trials in cycling.(5) Caffeine has been shown to increase endurance in these activities and activities like them. It does this by increasing lipolytic activity (fat breakdown) in the adipolyte (fat cell), thereby, increasing free fatty acid (FFA) oxidation in the plasma. A simplified explanation of this is that FFA s are readily oxidized (burned enabling energy production) in place of muscle glycogen. This benefits to anyone attempting to lose weight, or more specifically, fat mass because caffeine will enable you to run swim or bike for a long period of time. This equates to more calories being burned plus increased energy expenditure and hormonal and other benefits.
It has been noted that the use of caffeine on a regular basis will reduce its beneficial effects due to the body s tendency develop a tolerance to it. The recommended dosage is 2-3 cups of coffee; more is not beneficial, and is potentially dangerous due to its powerful diuretic and vasoconsrticting ability (which increases water loss and blood pressure, respectively). These effects in themselves can be harmful and disadvantageous to athletic performance.
In addition, the use of caffeine in conjunction with substances such as ephedrine (found in Mau-Hung and Gin-Singh) is potentially dangerous due to their ability to over excite the Central Nervous System and cause vasoconstriction, which can lead to cardiac arrest.(8)
After reviewing all of the relevant data concerning these diets, my goal is to adopt the diet that I feel will be most effective in improving my athletic performance. Since I have been following the high carbohydrate diet and have not been satisfied with the results, my plan is to adopt a diet with higher percentage of fat and protein. During competition, I plan to keep myself hydrated with water and sports beverages. Prior to competition, in addition to proper nutrition, I will add caffeine to my diet to see if it helps prevent fatigue. I intend to chronicle all of this to see if diet really does matter, or to see if I can eat just anything with the same results.
- Sports Medicine Essay, Research Paper Participation in athletics is both ... abroad.( Edelson 19) Nutrition Nutrition is very important in sports medicine. For an ... Cross stated, ?Most games, sports and play activities either create or take ...
- Nutrition Essay, Research Paper ?Nutrition 101: Back to ... some key tips on nutritional timing, metabolic enhancement and ... supported and accepted by many sports nutritionists and bodybuilding experts, ... some essential fatty acids, which play a role in growth, ...
- Nutrition Essay, Research Paper Most people know that good nutrition is important for ... carbohydrates is helpful. Most sports nutritionists recommend a meal ... , but will prevent nutritional deficiency diseases like scurvy ... go into a single pill. Water You won’t ...
- Strategic Plan Gnc Essay, Research Paper Company Background General Nutrition Companies Inc., was founded 65 ... emphasizing vitamin and mineral supplements, sports nutrition and herbal products. The Company ... is that they want the ?pill? or supplement to take the ...
- ... Essay, Research Paper Bodybuilding Essay Bodybuilding is one of the fastest growing sports in ... So nutritional supplements take on a role of a practical necessity.Minerals play a ... bodybuilder must meet all the nutrition requirements to be a successful ...