What is Fitness Science?
The principles involved in human performance nutrition, also known as sports nutrition, are built upon the principles of general nutrition and fitness science with special emphasis on optimizing human performance. Optimal nutrition is an essential part of every athlete’s training program, and the information contained separately in the Textbook of Nutrition is essential to understanding the proper application of nutrition in athletics.
The primary areas of concern are:
1) consuming enough calories to support performance;
2) consuming the correct balance of macronutrients before, during and after exercise; and
3) proper hydration.
There are other concerns for certain population groups as well, such as vegetarian or vegan athletes, or female athletes – particularly those who compete in sports that focus on weight or body build, such as figure skating and gymnastics.
Nutrition before, during and after exercise has significant effects on human performance. A pre-event meal keeps the athlete from feeling hungry before and during the event, and it maintains optimal blood glucose levels for working muscles. Carbohydrate feedings just prior to exercise can help restore suboptimal liver glycogen stores, which could result, for example, after an overnight fast. Allowing for personal preferences and habits, the pre-event meal should be high in carbohydrate, low in fat and fiber and easily digested.
Hydration and nutrition during an event has revolutionized human performance. During exercise, athletes should consume 30 to 60 grams of carbohydrate each hour (120 to 240 calories from carbohydrate per hour). Since both carbohydrates and fluids are necessary during events, sports drinks can go a long way in providing adequate carbohydrates and fluids. Typical foods that are used during long events include sports drinks, carbohydrate gels, energy bars and bananas. During vigorous activity, heat that is produced is dissipated through the process of sweating. However, long-term, extensive sweating can pose significant challenges for athletes with regard to fluid and electrolyte balance.
Without effective management, athletes will fatigue prematurely and, as dehydration progresses, heat exhaustion, heat cramps and heat stroke can result. Finally, recovery from intense activity requires nutrients that will replenish muscle glycogen stores, body water, electrolytes and triglyceride stores in skeletal muscle. Proper nutrition during the recovery period is essential for rapid and effective recovery and for optimal performance at the next event or workout.
Over the long term, athletes must pay attention to general nutrition and conditioning, while, during an event, adequate hydration and electrolytes become critical to maintaining optimum performance.
What you should know about Vitamins and Minerals.
Vitamins and Minerals
Vitamin and mineral deficiency diseases, even in industrialized nations, such as the United States, were relatively common prior to World War II. Today, with the fortification of the food supply and the widespread use of multivitamins, classical vitamin deficiency diseases, such as scurvy and rickets, are rare except in the case of:
* Specific disease states.
* Drug effects on vitamins.
* Extreme malnutrition due to poverty.
On a global basis, vitamin deficiencies still occur in many large countries, such as India and China, in both rural and urban populations. What can be classified as suboptimal intake of some vitamins, such as vitamin D in areas of low-sun exposure, is a more recently discovered and important area of vitamin deficiency, where supplementation is being recommended by authorities in the field.
Establishing RDA Levels
The recommended dietary allowance (RDA) is normally issued every 10 years by the National Academy of Sciences Food and Nutrition Board to help guide healthy individuals and to help in planning various national nutrition programs for infant feeding and school nutrition. The RDA levels are normally set above the threshold needed to prevent deficiency diseases, but in some cases the levels are below those some experts would like to see for the prevention of disease. In fact, in 1980, the guidelines were not issued due to a philosophical difference of opinion among the expert members of the group as to whether the RDA should be raised to encourage intake of Vitamin A-rich (carotenoid) and Vitamin C-rich foods, such as fruits and vegetables. The controversy was finally settled with the issuance of the 1989 guidelines that reverted to the original aim of averting nutritional deficiency states through public policy recommendations.
Fat-Soluble Vitamin Deficiencies
The fat-soluble Vitamins A, D, E and K have separate functions. Vitamins A and D are closely related to steroid hormones and act to induce the synthesis of specific proteins and to maintain normal cellular function. Rare deficiencies of Vitamin A cause night blindness and susceptibility to mumps infection. Deficiencies of Vitamin D cause a bony disease called rickets, and suboptimal intakes of Vitamin D have been related to various forms of cancer. Vitamin E includes a family of eight compounds found in plant cell walls where they act as antioxidants. Vitamin E deficiency does not occur in humans, but this family has interesting functions in the body beyond antioxidation. Vitamin K is a fat-soluble vitamin. The “K” is derived from the German word “koagulation.” Coagulation refers to blood clotting, because Vitamin K is essential for the functioning of several proteins involved in blood clotting.
Unlike fat-soluble vitamins, which can be stored after a single administration for long periods of time, water-soluble vitamins need to be supplied in foods and supplements on a regular basis to avoid deficiency. Industrialized societies have few cases of water-soluble vitamin deficiency, except in homeless or alcoholic individuals. The recent increase in obesity surgeries, which lead to malabsorption of Vitamin B12 by bypassing the stomach, have led to a new group of individuals at risk of vitamin deficiencies. Strict vegans, individuals with food intolerances, and raw food enthusiasts can also develop vitamin deficiencies if their choices of foods are narrowed significantly.
Smoothies Make Weight Loss Easy
The Importance of Protein
The word protein originates from the idea that proteins are central to life and the first nutrient. Vitamins – vita meaning life and amin meaning protein – got their name from the misconception that amino acids, the building blocks of protein, were the essential components for maintaining life.
Proteins are found in animals and plants, but the mixture of amino acids – the building blocks of the protein found from different sources – varies. As a result, there are 21 common amino acids consisting of 12 nonessential and nine essential amino acids. Essential amino acids are those that cannot be synthesized from other amino acids, but must be consumed in the diet. The usual way that nonessential amino acids are formed is by metabolism of other amino acids. All amino acids have a basic structure of an alpha-amino nitrogen and carboxylic acid.
Maintaining the amounts of protein in muscles and organs is essential to life and is the main objective of the adaptation to starvation. In fact, loss of more than 50 percent of body protein is incompatible with life. The protein is stored in organs and there is no labile compartment.
The Importance of Protein
There is evidence that modestly increasing the proportion of protein in the diet, while controlling total calorie intake, may:
* Improve body composition.
* Facilitate fat loss.
* Improve body weight maintenance after weight loss.
Mankind is very well adapted to malnutrition and starvation, and this adaptation is reflected both in the way the body stores energy and how it uses these stores of energy when food intake is reduced or eliminated altogether. In the average 70 kg (154 lbs) man:
* The largest store of calories is in the form of fat in adipose tissue with approximately 135,000 calories* stored in 13.5 kg (30 lbs) of adipose tissue.
*A dietary calorie is 1,000 calories or a kcal, but for simplicity will simply be noted as calories. You may also see dietary calories capitalized as “Calories.”
This storage compartment can be greatly expanded with long-term overnutrition in obese individuals.
There are approximately 54,000 calories stored as protein both in muscle and organs, such as the heart and liver. Only half of these calories can be mobilized for energy, since depletion below 50 percent of total protein stores is incompatible with life. In addition to being an energy source, protein plays a functional role in many organs, including the liver, and depletion is associated with impaired immunity to infection. In fact, the most common cause of death in an epidemic of starvation is typically simple bacterial pneumonia. Conservation of protein is an adaptation tightly linked to survival during acute starvation.
Meal Replacement Shakes and Weight Maintenance
Studies show that meal replacement shakes are a viable way to maintain weight, as recognized by the European Food Safety Authority, and that increasing the protein to about 30 percent of resting metabolic rate, as estimated by bioelectrical impedance, leads to greater loss of fat with retention of lean body mass.
What about Antioxidants?
Mankind evolved on Earth when it was already filled with plant life, and plants influenced human evolution. Plants interact with the atmosphere differently than humans. While humans consume oxygen and produce carbon dioxide, plants take in carbon dioxide from the air and produce oxygen. This oxygen produced by plants is a chemically reactive compound that would damage and kill the plant, so plants evolved the ability to make antioxidants such as Vitamin C, Vitamin E and colorful chemicals to protect their cells from the damaging effects of oxygen. This system sometimes breaks down and the damage from oxygen can be seen when a houseplant gets too little light or water and its leaves turn brown.
The oxygen we breathe can also damage human tissues, as illustrated by the damaging effects of 100 percent oxygen in intensive care units, where the lung tissue can be destroyed without proper protection. Like plants, humans evolved defense systems that are based on circulating substances and proteins. These systems are reinforced with the intake of antioxidants in the diet from colorful fruits and vegetables. There is overwhelming data showing that populations that consume a diet rich in colorful fruits and vegetables have lower risks of many common chronic diseases.
It takes very little to avoid vitamin and mineral deficiencies, but the optimal levels of intake of antioxidants are likely greater than the amounts needed to avoid deficiency.
For example, humans, unlike many species of animals, have lost the gene for making Vitamin C, because it was part of ancient mankind’s diet, which was rich in Vitamin C from fruits and vegetables. Eating a single orange provides twice the recommended amount of Vitamin C needed to prevent Vitamin C deficiency. In the 1750s, sailors in the British navy developed the disease called scurvy, characterized by bleeding gums, corkscrew hairs and ultimately death, from a lack of Vitamin C. It was customary for sailors to eat no plants at sea. However, once it was discovered that eating limes or other citrus prevented scurvy, citrus became part of the sailors’ diets (which is why British sailors were called limeys).
Today, inadequate intake of antioxidants is not as noticeable as the deficiency disease of scurvy, but the inadequate intake of plants, including colorful fruits and vegetables, is thought to be associated with many chronic diseases of aging.