Sports Nutrition
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SPORTS NUTRITION Do dietary habits of student athletes affect their performance? One of the most important ways of improving athletic performance and maintaining a healthy life style is achieved through following sound nutritional practices. Sound nutrition is based on the wise selection of foods and beverages according to the stage of the life cycle of the individual and individual nutritional needs (Anderson and McMurray, 1997). What are some factors that prevent student athletes from achieving a high level of nutritional health? Many factors prevent student athletes from achieving a high level of nutritional health. According to Burke (1995), a student athlete may not be adequately nourished for the following reasons: 1. Poor understanding of sports nutrition principles. 2. Belief in misconceptions and myths. 3. Failure to recognize individual nutritional requirements related to a personal training program, and personal characteristics such as age, sex and type of physique. 4. Conflict between achieving good nutrition while trying to diet to lose body fat. 5. Lack of practical nutrition knowledge and skills. 6. Inadequate time and opportunities to obtain or consume appropriate foods due to a busy schedule. 7. Poor money management that leads to inadequate food supplies. 8. Frequent travel, eating "on the road." SOUND NUTRITIONAL HABITS = IMPROVED ATHLETIC PERFORMANCE INFORMATION CONTAINED IN THIS PACKET Pages Pages Hydration 2 – 5 Recovery and Regeneration Charbohydrate Intake 5 – 9 Food 28 Protein Intake 9 Post-Training 29 – 30 Fat Intake 10 Types of fatigue 30 – 31 Vitamin/Minerals Intake 10 – 11 Sleep 31 – 34 Food Pyramis guidelines 12 – 15 Sample Menus 16 Dining Out 17 – 22 How many calories do you need? 23 Breakfast is for Champions 24 Calorie content of alcoholic beverages 25 Supplements 26 - 28 HYDRATION How much liquid does a student athlete need? Water makes up to 70% of total body weight. An average 75kg human contains about 60% or 45 liters of water (Sawka and Pandolf, 1990). Student athletes with lean body and low fat mass have higher water content. The fluid losses of student athletes depend upon the the intensity at which the student athlete is exercising, an individual genetic predisposition for sweating, his or her level of fitness, the environmental and climatic conditions, and the amount and type of clothing and headgear worn by the student athlete (Sawaka and Wenger, 1988). During low intensity exercise in cool and dry settings sweat loss can be less than 500 ml/h. In hot and humid conditions during intense exercise sweat loss may exceed 3 litres/hour (Sawka and Pandolf, 1990). Therefore, fluid intake should be carefully monitored to ensure that fluid needs during these conditions are met by adequate intake. What are the effects of dehydration on performance? Under normal conditions the water content of the body is constant. An imbalance between fluid intake and fluid losses results in dehydration (Brouns, 1993). The volume of fluid varies widely among athletes but in general the amount of fluid needed to compensate for the fluid lost is about 50% of the sweat loss (Noakes et. al., 1988). Even slight dehydration can have noticeable and negative effects on performance during high intensity exercise. Dehydration causes fluid imbalances in the body that can lead to impaired mental focus, impaired energy metabolism, and important changes in electrolyte concentration levels. Plasma fluid volume plays an important role in maintaining a normal blood flow through the tissues. Dehydration causes a decrease in plasma volume, and as a result leads to decreased blood flow. This will lead to reduced transport of substrates and oxygen to the muscles needed for energy production. This will result in decreased energy and a marked, rapid onset of fatigue (Brouns, 1993). The American College of Sports Medicine (ACSM) recommends that athletes regardless of sport should ensure that they are well hydrated before training or competition. Athletes should drink at least 500 ml (about 16 oz) of fluid (water, juice, sports drink) 2 hours before exercise. When the urine is darkly colored, and the urine volume is low the student athlete is in a dehydrated physical state and should consume more fluid until the urine returns to a normal, clear or very light amber color. To assure adequate hydration prior to training and competition athletes should consider ingesting an additional 250 -500 ml of fluid 30 minutes before exercise. Athletes should stay well hydrated before and during exercise, and make sure that cool fluid is available at all times, because cool fluid leaves the stomach more quickly. Drinks can be flavored and sweetened sufficiently to encourage student athletes to drink. One teaspoon of salt per liter helps to ensure complete hydration and normalize the body's sodium levels. Some commercially available sports beverages are available and can be used to sustain normal electrolyte levels (ACSM, 1996; Broad, 1996; Burke, 1995). Team sports: Athletes who are involved in team sports such as soccer have tended in the past to limit fluid intake to the half-time break. This is not adequate for maintaining optimal fluid levels in the body. Student athletes should drink fluids freely on an as needed basis. Coaches and team 2 trainers should encourage student athletes to drink at all times, and attention should be given to student athletes with above average sweat rates to make sure they are drinking appropriately (Broad, 1996; Burke, 1995). Short duration and high intensity sports: Athletes involved in high intensity sports can experience rapid and significant dehydration. Depending on the level of competition, efforts of less than 30 seconds do not involve significant dehydration (Horswill, 1991). However, participation involving extreme efforts of greater than 30 seconds in duration can cause rapid weight loss from fluid depletion (Horswill, 1994). Long duration moderate intensity sports: Athletes who compete in long distance running, cycling, and skiing events that last longer than 30 minutes generally have access to fluids at regular intervals. Sometimes runners restrict fluid intake when experiencing gastrointestinal problems that are already due to dehydration, and increase the effects of dehydration. Student athletes need to practice in training drinking habits that will be effective in maintaining adequate body fluid levels during competition. After competiton athletes should consume 16 oz of fluid for every pound lost, and avoid diuretics (caffeine, alcohol). Fluids during training: • Drink enough fluids everyday so you should urinate every 2-4 hours, and urine should be light in color and significant in quantity • Weigh yourself before and after a workout. Each pound lost represents one pound (16oz) of sweat; you should replace this amount adequately and shouldn’t lose 2% or more of your weight • Fluids include water, juice, sports drinks, soft drinks, and watery foods such as yogurt, many types of fruit, and soup • Alcoholic beverages contribute to dehydration; avoid them or be sure to first quench your thirst with plenty of other fluids and eat carbohydrates to fuel muscles Fluids before hard endurance exercise: • Drink extra water and other fluids the day before • The morning of, drink at least 16oz of fluids up to 2 hours prior to exercise • 5-10min before start of exercise drink another 8-16oz of water or sports drink Fluids during hard exercise: • Drink 8-10oz of water, sports drink, or diluted juice every 20min, but stop drinking if your stomach is “sloshing” • Prevent dehydration by drinking some early in the event before you get thirsty (by the time your brain signals thirst you’ve lost 1% of your body weight, and by 2% dehydration you reduce your work capacity by 10-15% Fluid after exercise: • Drink more fluid than it takes to quench your thirst because thirst is a bad indicator of hydration. Instead, monitor your urine; if you go several hours without having to urinate you’re still dehydrated • Juices replace fluid and carbs (often more than most sports drinks) so drinking 16-24oz within an hour after exercise can help muscle recover Water vs. sports drinks: • For casual exercise, water is usually sufficient. However, for intense exercise that lasts an hour or more, and for endurance athletes who expend large amounts of energy for 3 more than an hour, sports drinks during exercise will optimize fluid absorption and retention along with enhancing stamina. The drink should have 50-80 calories per 8oz and include a little sodium Sodium replacement: • Sweat contains sodium and other electrolytes, so if you’re losing large amounts of sweat during exercise you should replace the lost sodium. This can be done through food such as pretzels, soup, etc. Note that the sodium in sports drinks typically is added to enhance fluid absorption, not replace sweat losses Nancy Clark, MS, RD www.nancyclarkrd.com WATER TIPS As another year goes by, the tradition of making New Year’s resolutions always comes up. The most common resolution that people make is to “LOSE WEIGHT”. In this month’s tip we’ll discuss an inexpensive, readily available, safe, and natural drink that can help you reduce body- fat. What is this supplement you ask…it’s a micronutrient that many of us have forgotten about in this new day and age….WATER! Here are the key benefits of drinking plenty of water each day: • Lubricates Joints - Water is what our body uses to lubricate these joints. When our water levels are reduced there is increased friction between the cartilage surfaces resulting in swelling, stiffness and pain. • Aids in removal of waste products/Excretes excess sodium • Allows the kidneys to function optimally. This then allows the liver to become more efficient at mobilizing fat. The result is an increased fat burning capacity in the liver. • Acts as a natural appetite suppressant. Drinking plenty of water tends to make you feel less hungry.