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Eating for sports Unit 6
- 1. Eating for Sports Lesson 6 Aw eso me .2 Cen t s!
- 2. In this lesson, we will cover: Types of Exercise The Benefits of Exercise Energy sources Carbohydrate loading Fluid Needs During Exercise Physical Inactivity in the U.S. Physical Activity Recommendations Pennington Biomedical Research Center
- 3. To Clarify Some Terms... Physical Activity Exercise Physical Fitness Pennington Biomedical Research Center
- 4. Types of Exercise Aerobic or Anaerobic? Aerobic Anaerobic Requires oxygen. Anaerobic means Aerobic simply 'without air'. means 'with air'. Pennington Biomedical Research Center
- 5. Types of Exercise Aerobic or Anaerobic? Aerobic Anaerobic Brisk walking Bowling Dancing Racquetball Jogging Tennis Bicycling Sprinting Skating Hiking Swimming Weightlifting Treadmill, bike, elliptical machine Curl-ups Roller skating Push ups Rowing Sit ups Racket sports Pennington Biomedical Research circles Arm Center
- 6. The Benefits of Aerobic Exercise Aerobic exercise can: Reduce health risks Help you manage chronic conditions Keep excess pounds at bay Ward off viral illnesses Keep your arteries clear Strengthen your heart Boost your mood Increase your stamina Help you stay active and independent as you get older Pennington Biomedical Research Center
- 7. The Benefits of Anaerobic Exercise Anaerobic exercise can: Increase muscle tone Keep excess pounds at bay Boost your mood Increase your stamina Help you stay active and independent as you get older Improve balance Increase strength and endurance Pennington Biomedical Research Center
- 8. Energy sources for physical activity
- 9. Energy sources Phosphagens – immediate energy pool, first 10- 15 seconds Anaerobic/Aerobic Glycolysis – carbohydrate breakdown, quick source of energy Oxidative phosphorylation – fat breakdown, energy for endurance sports Pennington Biomedical Research Center
- 10. Energy sources Phosphagens The first burst of energy: phosphagens Adenosine tri-phosphate (ATP) and phosphocreatine (PC) These are reserves of high energy phosphates Phosphagens provide the first 15 to 30 seconds of energy Pennington Biomedical Research Center
- 11. Energy sources Carbohydrate With sustained demand glycogen kicks in Glycogen is a stored carbohydrate in the muscle (about 1500KC), and in the liver (about 400KC) and in the blood as glucose (about 80KC). Glycogen can be burned in the muscle in two ways: aerobically or anaerobically Burning glycogen/glucose anaerobically produces lactic acid. Soreness Pennington Biomedical Research Center
- 12. Energy sources Carbohydrate Stored glycogen - mobilized in ~ 10 - 20 seconds. Highly trained sprinters can produce twice the energy from stores compared to an untrained person. Muscle and liver store glucose for the brain. “Hit the wall” means that all body carbohydrate/glycogen has been used up. Pennington Biomedical Research Center
- 13. Energy sources Fat Fat burning is always aerobic. During sustained exercise fat is mobilized from the adipose tissues. Takes ~ 20 minutes. A well trained marathoner can burn fat twice the rate of an untrained individual. Pennington Biomedical Research Center
- 14. Energy sources Fuel use Pennington Biomedical Research Center
- 15. Energy Sources: Fuel use Source/System When in Use Examples of an Exercise Phosphagens Immediate source of energy Short bursts of activity (anaerobic) Carbohydrate High-intensity exercise, especially lasting 30 200-yard (20 meter) (anaerobic) seconds to 2 minutes sprint Carbohydrate Exercise lasting 2 minutes to 4-5 hours. Basketball, swimming, (aerobic) The higher the intensity, the greater the use. jogging Fat Exercise lasting more than a few minutes. Long-distance running, (aerobic) Greater amounts are used at lower exercise long-distance cycling. intensities when the body is more efficiently Much of the fuel used using oxygen. in a brisk walk is fat. Protein Low quantity during all exercise. Moderate Long-distance running (aerobic) quantity in endurance exercises when carbohydrate fuel is lacking. Pennington Biomedical Research Center
- 16. Endurance Athletes How can performance be improved? Training helps improve the muscles’ use of glycogen. With training, glycogen stores become larger. Trained muscles become more tolerant of lactic acid. As training proceeds, the lungs are able to carry oxygen more efficiently. The whole cardiovascular system improves with aerobic exercise and becomes more efficient. Pennington Biomedical Research Center
- 17. Carbohydrate and endurance Muscles normally store only small amounts of glycogen. Continuous exercise might deplete muscle glycogen. In turn, stamina and performance may suffer. This can be an issue during activities such as long-distance running, swimming, cycling, soccer, and triathlons. Mayo Clinic, 2007 Pennington Biomedical Research Center
- 18. Carbohydrate Loading Storing extra energy for greater endurance Traditionally, carbohydrate loading is done in two steps the week before a high-endurance activity: Step 1. Deplete: About a week before the event, reduce carbohydrate intake to about 40 percent to 50 percent of total calories. Increase protein and fat intake to compensate for the decrease in carbohydrates. Continue training at normal level. Step 2. Replete: Three to four days before the event, increase carbohydrate intake to 60 percent to 70 percent of daily calories — or about 4 to 4.5 grams of carbohydrates per pound of body weight. Also scale back training to avoid depleting glycogen stores. Rest completely for a day or two before the event. Mayo Clinic, 2007 Pennington Biomedical Research Center
- 19. Carbohydrate Loading Storing extra energy for greater endurance With carbohydrate loading, there is still a need to replenish carbohydrates during the event to maintain blood sugar levels — especially if the event lasts more than 60 minutes. Meet your goals Carbohydrate loading may be an effective way to get that extra edge you need to compete. If you're uncertain about your specific carbohydrate needs, consult your doctor or a registered dietitian. Mayo Clinic, 2007 Pennington Biomedical Research Center
- 20. Carbohydrate Loading Consider possible drawbacks Carbohydrate loading isn't right for every endurance athlete. Side effects may include: Weight gain. Expect to gain 2 to 4 pounds during the week you're carbohydrate loading. Much of this weight is extra water. Digestive discomfort. You may need to avoid or limit some high-fiber foods one or two days before your event. Blood sugar changes. Carbohydrate loading can affect your blood sugar levels. It's a good idea to consult your doctor or a registered dietitian before you start carbohydrate loading, especially if you have diabetes. Mayo Clinic, 2007 Pennington Biomedical Research Center
- 21. How much protein does an athlete need? Engaging in endurance exercise can result in breakdown of body proteins. endurance athletes need up to 50% more protein than sedentary adults. To find out how much you need, multiply your weight in pounds by 0.6 to calculate the number of grams of protein you should consume per day. Pennington Biomedical Research Center
- 22. Vitamins/Minerals Can athletes meet their needs for vitamins and minerals? There may be a need for extra iron, magnesium, vitamin C, and vitamin E by endurance athletes. However, these can easily be obtained from a standard over the counter vitamin and mineral supplements. Do they need any special supplements? Normal nutrient needs can be met by eating a healthy diet. Pennington Biomedical Research Center
- 23. The Critical Need for Fluids The consumption of adequate amounts of fluids may be the most critical aspect to sports nutrition. There is a rapid loss in performance due to water loss. Learn to recognize the symptoms of dehydration. Pennington Biomedical Research Center
- 24. The Symptoms of Dehydration Symptoms of dehydration include: Headache Dizziness Nausea Dry Skin Dehydration can also cause Shivering increases in body Confusion temperature and heart rate. Athletes need to be particularly cautious when exercising in hot, humid weather. Pennington Biomedical Research Center
- 25. Avoiding dehydration Weigh before and after a training event to find out how much your body loses water during an extended training session. 1 kg weight loss = 1 liter of water Follow a regimen to replace fluids. Pennington Biomedical Research Center
- 26. Tips to Stay Hydrated You should consume: 2 hours before 3 cups of water To avoid dehydration, the event... (750 ml) athletes should consume water before, during, before during 10-15 minutes 1-2 cups of water and after an event. before the (250-500 ml) event... At 10-15 minute ½ -1 cup of water intervals during (125- 250 ml) the event... After the event... 2 cups of water (500 ml) for every pound of body weight lost Pennington Biomedical Research Center
- 27. What Types of Beverages and When? Beverage 15 to 30 Minutes During Event After Event Reason Before Event Water Yes Yes Yes Best fluid for your system; (cool to regulates body temperature cold) Special Maybe Maybe Yes Depends on content; may be sports high in sugar, which slows drinks fluids in emptying from the stomach; salt content may be too high Carbonated No No Yes Carbonation may cause soft drinks problems during an event and sugar may prevent fluids from emptying in the stomach Pennington Biomedical Research Center
- 28. What Types of Beverages and When? Beverage 15 to 30 Minutes During Event After Event Reason Before Event Fruit juices No No Yes Sugar content is high; can be used to replace carbohydrates after an event Coffee/tea No No No Caffeine is a diuretic and increases urination; increases heart rate Milk No No No High protein content delays digestion Alcohol No No No Undesirable, does not help performance, dehydrates cells and decreases muscle efficiency Pennington Biomedical Research Center
- 29. As an Athlete Time Your Eating Correctly 1. Eat a full breakfast 2. Time your meals, 3-4 hours before an exercise session 3. Eat snacks during long training sessions 4. Don’t skip meals 5. Eat after your workout Pennington Biomedical Research Center
- 30. Energy Needs of an Athlete An athlete burns more calories than a non-athlete. Therefore, he or she needs to consume more calories to maintain their body size. But how many calories will he or she need? Calculate needs: Use Harris Benedict Formula Pennington Biomedical Research Center
- 31. Harris Benedict Formula Calculate your BMR (basal metabolic rate): Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years) Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years) Multiply your BMR by the appropriate activity factor, as follows: Sedentary (little or no exercise): BMR x 1.2 Lightly active (light exercise/sports 1-3 days/week): BMR x 1.375 Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55 Very active (hard exercise/sports 6-7 days a week): BMR x 1.725 Extra active (very hard exercise/sports & physical job or 2x training): BMR x 1.9 Calculate your BMR and the approximate number of calories you need each day! Pennington Biomedical Research Center
- 32. An Athlete’s Diet What about the Macronutrient Content? Approximately 50 to 60% of calories from carbohydrates No more than 30% of calories from fat Approximately 10 to15% of calories from protein Can you find out how many grams of protein you need? Pennington Biomedical Research Center
- 33. What if you are not an athlete? Do you need to be active?
- 34. Physical Activity Recommendations The latest physical activity recommendations from CDC and American College of Sports Medicine: Accumulate at least 60 minutes of moderate activity on most, if not all, days of the week Can involve more than one type of activity Combine lifestyle activities to accumulate the recommended amount of physical activity. Pennington Biomedical Research Center
- 35. Physical Inactivity National health concern in the U.S. Major reason that many people lack physical fitness Overweight is on the rise. Pennington Biomedical Research Center
- 36. Physical Inactivity vs. Physical Activity Physical Inactivity Being Physically Active Loss of muscle Improved muscle tone, Promotes obesity strength, and endurance Reduced functional ability Better balance Low physical fitness and Sleep better increased chronic disease risk Reduced likelihood of overweight or obesity Fact: 37.2% of high school students spend three or more hours a day watching TV. Pennington Biomedical Research Center
- 37. Everyone benefits from physical activity Here are some things you need to know: 1) Improves self image 2) Reduces depression 3) Improves over all well being Pennington Biomedical Research Center
- 38. How do I Stick with my Exercise Program? Choose something that you like to do Get a partner Vary your routine Choose a comfortable time of day Don’t get discouraged Forget “no pain, no gain” Make exercise fun Pennington Biomedical Research Center
- 39. Intensity of Exercise Intensity of exercise reflects oxygen use & the calories you burn Moderate-intensity is best in producing results. Telltale signs of moderate-intensity exercise: • You’re breathing faster • You’re developing a light sweat • You’re feeling some strain on your muscles Pennington Biomedical Research Center
- 40. Making Exercise a Habit Tips for Success Choose activities that are fun, not exhausting. Wear comfortable footwear and clothing that is appropriate. Find a convenient time and place to do activities. Use music to keep you entertained. Surround yourself with supportive people. Don’t overdo it. Keep a record of your activities. Pennington Biomedical Research Center
- 41. Pennington Biomedical Research Center Heli J. Roy, PhD, MBA, RD Associate Professor Reviewed by: Dr. Marc Hamilton
- 42. The Pennington Biomedical Research Center is a world-renowned nutrition research center. Mission: To promote healthier lives through research and education in nutrition and preventive medicine. The Pennington Center has several research areas, including: Clinical Obesity Research Experimental Obesity Functional Foods Health and Performance Enhancement Nutrition and Chronic Diseases Nutrition and the Brain Dementia, Alzheimer’s and healthy aging Diet, exercise, weight loss and weight loss maintenance The research fostered in these areas can have a profound impact on healthy living and on the prevention of common chronic diseases, such as heart disease, cancer, diabetes, hypertension and osteoporosis. The Division of Education provides education and information to the scientific community and the public about research findings, training programs and research areas, and coordinates educational events for the public on various health issues. We invite people of all ages and backgrounds to participate in the exciting research studies being conducted at the Pennington Center in Baton Rouge, Louisiana. If you would like to take part, visit the clinical trials web page at www.pbrc.edu or call (225) 763-3000. Pennington Biomedical Research Center
- 43. References The Mayo Clinic. http://www.mayoclinic.com/ Brown, Judith. Nutrition Now, 4th Edition, Thompson and Wadsworth, 2005. West, Dorothy. Nutrition Food and Fitness. The Goodheart Wilcox Company, 2006. American College of Sports Medicine Myplate.gov Pennington Biomedical Research Center
Notas do Editor
- Physical activity is any kind of body movement. Any form of exercise or movement. Physical activity may include planned activity such as walking, running, basketball, or other sports. Physical activity may also include other daily activities such as household chores, yard work, walking the dog, etc. Exercise is a planned activity for a length of time. The activity of exerting your muscles in various ways to keep fit. Usually it includes aerobic and strength training aspects. Physical fitness: a measure of functional ability in an individual. Physical fitness is a set of attributes a person has in regards to a person's ability to perform physical activities that require aerobic fitness, endurance, strength, or flexibility and is determined by a combination of regular activity and genetically inherited ability. Clarifying Some Terms... Physical activity is defined as “ any bodily movement produced by skeletal muscles that results in an expenditure or usage of energy .” Physical activity may include planned activity such as walking, running, basketball, or other sports. Physical activity may also include other daily activities such as household chores, yard work, walking the dog, etc Exercise is defined as a subset of physical activity that is planned, structured, repetitive, and purposeful . The activity of exerting your muscles in various ways to keep fit. Usually it includes aerobic and strength training aspects. Examples of exercise could include: jogging around the LSU lakes 5 afternoons a week, doing a set routine of weight-lifting at the gym three days a week, or using your elliptical machine at home for 30 minutes a day on 4 days out of the week. It’s easy now to see the difference, right? So, what now is physical fitness ? Physical fitness is defined as a measure of one’s ability to perform physical activities that require endurance, strength or flexibility. Physical fitness is a set of attributes a person has in regards to a person's ability to perform physical activities that require aerobic fitness, endurance, strength, or flexibility and is determined by a combination of regular activity and genetically inherited ability. With time and patience, active individuals increasingly get more and more fit. Of course views on what “physically fit” looks like differ from one person to the next. But, one thing is certain, and that is that everyone can benefit from physical activity in some way and that being physically activity is a must!
- Say: Any activity which strengthens the heart generally will provide the most health benefit. Because the heart is a muscle, it, too, can be made stronger with regular physical activity or exercise. There are two types of exercise: aerobic and anaerobic. Aerobic activities use the arm and leg muscles and give the heart (and lungs) a continuous workout. Aerobic activities require oxygen. Aerobic simply means 'with air'. When an exercise or activity is described as aerobic, it means the conditions allow your body to replenish the needed oxygen (air) to the muscles being exercised. Anaerobic activities build and tone muscles but are not as beneficial to the heart and lungs as aerobic activities. Anaerobic means 'without air'. When we say an exercise is anaerobic, it means the exercise is so strenuous it uses oxygen faster than your body can replenish it. Here are some examples of activities which fall under each category. Aerobic activities include: brisk walking, dancing, jogging, bicycling, skating, swimming, snow shoveling, lawn mowing, leaf raking, and vacuuming, for example. Anaerobic activities include: baseball, sprinting, tennis, weightlifting, leg lifts, arm circles, curl-ups, dusting, doing laundry, and washing windows. By a show of hands, I’d like to see who believes that they do more aerobic activities in the week. Do: Encourage students to participate. Note about how many students raise their hands. Say: Now, by a show of hands, I’d like to see who believes that they do more anaerobic activities in a given week. Do: Encourage students to participate. Not how many students raise their hands.
- Forms of Aerobic Exercises The key to successful weight control and improved overall health is making physical activity a part of your daily routine. Any type of physical activity you choose to do--strenuous activities such as running or aerobic dancing or moderate-intensity activities such as walking or household work--will increase the number of calories your body uses. It's easier than one thinks to perform numerous aerobic activities throughout the day. Examples of mild to moderate aerobic activities: Take a short walk around the block Rake leaves Play actively with the kids Walk up the stairs instead of taking the elevator Mow the lawn Take an activity break--get up and stretch or walk around Park your car a little farther away from your destination Examples of higher intensity aerobic activities: Brisk walking Jogging Bicycling Swimming Aerobic dancing Racket sports Rowing Ice or roller-skating Cross-country or downhill skiing Using aerobic equipment (i.e., treadmill, Anaerobic Exercise: Anaerobic exercise is any exercise that is very strenuous, lifting heavy weights, being the most popular. Other anaerobic exercises include sprinting, climbing, long jump, push-ups, pull-ups, sit-ups, leg lifts, squat thrusts, etc. Anaerobic Exercise Equipment: There are many types of anaerobic exercise equipment on the market at all price ranges. Some examples of exercise equipment are dumb bells, free weights, home gyms, Bow Flex, thigh and abdominal workout equipment. If you're on a really tight budget, you can buy bungee cords or medical tubing and make your own anaerobic exercise equipment. Anaerobic Activity: Almost all labor activity is anaerobic, including landscaping, carpentry, concrete work, plumbing, electrical, roofing, floor covering, loading trucks, etc. Some recreational activities are also anaerobic, including gardening, steep hiking/climbing, some downhill skiing and snowboarding, bowling, archery, etc.
- The Benefits if Aerobic Exercise Say: We’ll now turn back to the type of activity which provides the most health benefits – aerobic activities. It is important to know that regardless of your age, weight, or athletic ability, aerobic exercise is good for you. Your body only gets stronger and more efficient as it adapts to regular aerobic exercise. Consider some of the benefits of engaging in regular aerobic activities. 1. Aerobic exercise can help to reduce health risks, such as obesity, heart disease, high blood pressure, type 2 diabetes, stroke, and certain types of cancer. From engaging in weight-bearing aerobic activities such as walking, you can also reduce your risk for developing osteoporosis. 2. Aerobic exercise can also help individuals to manage chronic conditions that they may already have. Examples include: lowering high blood pressure, controlling blood sugar levels in individuals with diabetes, and relieving chronic muscle pain through exercise. Regular aerobic exercise can also prevent subsequent attacks in individuals who have previously had a heart attack. 3. Aerobic exercise can keep excess pounds at bay, particularly when it is combined with a healthy diet. Remember the energy balance equation? Eating fewer calories or burning more calories through exercise creates an energy deficit, which over time, results in weight loss. When you combine calories burned from exercise with fewer calories consumed from eating a healthy diet (versus the typical American diet that many of us eat), you will likely achieve your ideal weight or maintain your current weight much easier. 4. Regular aerobic exercise also helps to ward off viral illnesses. This is because it activates your immune system, leaving you less susceptible to minor viral illnesses, like colds and the flu. 5. Aerobic exercise is also important in that it helps to keep your arteries clear. How does it do that? The answer involves two types of cholesterol, both of which we have previously discussed. By increasing the concentration of high-density lipoprotein (HDL, or “good”) cholesterol and decreasing the amount of low-density lipoprotein (LDL, or “bad”) cholesterol in our blood through aerobic activities, the result is less buildup of plaques in the arteries. Even though heart attack and stroke are rare in young people, there is evidence linking the onset of heart disease to childhood. So, why not start protecting yourself now, through aerobic exercise? 6. As we’ve already said, aerobic exercise strengthens the heart, and a stronger heart is much more efficient. This, in turn, improves blood flow to all parts of the body. So, we would expect a person who is more physically fit to have a lower heart rate when doing the same exercise as a person who is less physically fit, correct? We would expect a higher heart rate in a person who is jogging as opposed to a person who is walking, correct? 7. Aerobic exercise can also help to boost your mood. Ever heard of the phrase “walk it off?” This is a phrase that is often told to someone who is upset or angry about something. Aerobic exercise has been shown to ease depression and reduce the tension associated with anxiety. 8. Aerobic exercise will also increase your stamina. True, in the short-term when you are just starting out, you may feel tired. Over the long-term, you’ll enjoy increased stamina and reduced fatigue. It definitely gets easier with time. It’ll pay off! 9. Lastly- aerobic exercise helps you to stay active and independent as you get older. It not only keeps your muscles strong, allowing for you to maintain mobility as you get older, but it also keeps your mind sharp. Researchers say that as little as 30 minutes of aerobic exercise three times per week can reduce cognitive (brain functional capacity) decline in older adults. So, go for a short walk with your grandma if she is healthy and able to. It’s a great way to catch up and beneficial for the both of you
- The Benefits of Anaerobic Exercise Anaerobic exercise can: Increase muscle tone. Anaerobic activities tend to strain muscles and therefore increase muscle strength. Keep excess pounds at bay. Since anaerobic activities increase muscle mass, muscle tissue is an active tissue that uses more energy than fat tissue. Boost your mood. Physical activity releases endorphins which can improve mood. Increase your stamina. With increased muscle mass there is an improvement in stamina due to larger glycogen stores. Help you stay active and independent as you get older. With increased muscle mass, there is an improvement in strength and balance which can improve independence and activity level. Improve balance. Increased muscle mass helps improve balance. Increase strength and endurance. Increased muscle mass improves strength.
- Let’s talk about the different energy sources in our body.
- Phosphagens – immediate energy pool in the body. These are energy molecules that are used immediately when activity begins, in the first 10-15 seconds Anaerobic/Aerobic Glycolysis – This is carbohydrate breakdown, quick source of energy. Energy is available within 20 seconds of the beginning of activity. Oxidative phosphorylation – fat breakdown is the slowest source of energy. This is used for endurance sports in particular.
- The first burst of energy supplied to muscles comes from high-energy compounds, called phosphagens. These are Adenosine tri-phosphate (ATP) and phosphocreatine (PC). The phosphagens, or high energy phosphate compounds, are energy storage compounds in the muscle tissue. Phosphagens provide the first 15 to 30 seconds of energy needed for jumping or starting a race. As muscle tissues can have sudden demands for lots of energy, these compounds can maintain a reserve of high energy phosphates that can kick in as needed, providing the energy that could not be immediately supplied by glycolysis or oxidative phosphorylation.
- When the sustained demand for energy increases above about 3KC/minute another fuel called glycogen kicks in to provide the balance of the required demand that fat alone cannot satisfy. Glycogen is a stored carbohydrate. It is stored in the muscle (about 1500KC), the liver (about 400KC), and in the blood as glucose (about 80KC). Glycogen can be burned in the muscle in two ways: with or without oxygen (aerobically or anaerobically). Burning glycogen/glucose anaerobically produces lactic acid. This results in muscle soreness after the activity. The result of incomplete breakdown of glucose is a buildup of a product known as lactic acid in the muscles. This is the very substance responsible for the burning sensation and fatigue in the muscles that you begin to feel when you run for long distances. Once the muscles are given a moment to rest, they are able to move some of this lactic acid out. Once they have enough oxygen again, and the cramps subside, energy can be produced more efficiently again. Burning glycogen aerobically releases more total energy than anaerobic glycogen burning but aerobic burning releases energy slowly.
- G lucose is the chief source of energy for the body. We get from the diet and in addition, the liver can make glucose from other sugars and starches in the diet. The storage form of glucose in our bodies is referred to as glycogen , and it can be found in both the liver and the muscle. As the body breaks down glucose, the following components are released : carbon dioxide, water, and energy . This energy produced from the breakdown of glucose is the energy which enables us to perform a sport. This process where energy is made from glucose can continue to work so long as the breakdown of glucose continues to occur efficiently. One thing that is important to remember is that in order for the body to continue utilizing energy from glucose, oxygen is needed. After about 20 minutes of aerobic activity, fats from the body also begin to be metabolized (or broken down) for energy. Because the body can stockpile much more fat than carbohydrate, fats serve as an almost unlimited energy source. However, fat can not be converted to energy without the presence of oxygen , which means that fat is not burned for energy in anaerobic activities . Stored glycogen has to be mobilized from the muscle and liver depots. This takes about 10 - 20 seconds. The maximum rate depends on the athlete. Highly trained sprinters can produce up to about 45Kilocalories/minute from glycogen compared to 25Kilocalories for an untrained person. Energy production is dependent on the athlete's ability to deliver oxygen to the muscle. Normally, the muscle and liver stores are primarily to maintain the blood glucose level for the brain, which can only burn glucose . When an athlete ‘hits the wall’ that means that all body carbohydrate/glycogen has been used up. The stores need to be repleted before further activity can take place.
- Fat burning is always aerobic. We have fat in the bloodstream at all times, and it is used first. During sustained exercise fat is mobilized from the adipose tissues into the blood stream, a process that takes about 20 minutes to reach the maximum level. A well trained marathoner can burn fat at a rate of 18Kilocalories/minute; while in an untrained individual it is about half of that.
- This graph shows the different energy sources and when they are used. As you can see, the phosphagens (ATP and phsophocreatine) are used immediately and decline very rapidly, then anaerobic glycolysis (using glucose), then aerobic glycolysis kick in to burn glucose for fuel. Fat burning is a much slower process but is significant in long runs.
- This table shows the same information as before. Phosphagens (anaerobic) are the immediate energy source, followed by anaerobic carbohydrate and then aerobic carbohydrate. Fat is used after a longer period of time and continues through the exercise, those lasting for hours such as marathons and other endurance events. Protein is used in low quantity, unless someone is not consuming adequate carbs.
- Say: As you know, some sports require athletes to be active for long periods of time- sometimes even several hours. Examples of some of these sports include: marathon bicycling, foot races, or distance swimming. So how is it that these athletes are able to keep performing without having to stop because of incomplete glucose breakdown? The answer is: training . Training helps to improve the muscles’ use of glucose. Trained muscles also become more tolerant of lactic acid. And, as training continues, the lungs are better able to carry oxygen. So, this is why it is important to stick with an exercise program. Because although it may be difficult at first, with time, it gets easier, and your endurance can greatly increase with time.
- Say: Muscles normally store only small amounts of glycogen — enough to support activities such as recreational biking or swimming, weightlifting, and five- or 10-kilometer runs. But depending on the individuals level of fitness, muscles may run out of glycogen if exercising intensely for more than 90 to 120 minutes. In turn, stamina and performance may suffer. This can be an issue during activities such as long-distance running, swimming, cycling, soccer, and triathlons. Carbohydrate loading can improve the length of time an athlete is able to be active. Carbohydrate storage can be improved with certain techniques.
- Traditionally, carbohydrate loading is done in two steps the week before a high-endurance activity: Step 1. About a week before the event, reduce your carbohydrate intake to about 40 percent to 50 percent of your total calories. Increase protein and fat intake to compensate for the decrease in carbohydrates. Continue training at your normal level. This will help deplete your carbohydrate stores and make room for the loading that comes next. Step 2. Three to four days before the event, increase your carbohydrate intake to 60 percent to 70 percent of your daily calories — or about 4 to 4.5 grams of carbohydrates per pound of body weight. Cut back on foods higher in fat to compensate for the extra carbohydrate-rich foods. Also, scale back your training to avoid depleting your glycogen stores. Rest completely for a day or two before the event. Various studies suggest that simply resting and increasing carbohydrate intake two to three days before a high-endurance activity is effective too, but there are a few caveats.
- Carbohydrate loading works best when the athlete has consumed a carbohydrate-rich diet throughout the training — and it may be more effective for men, perhaps because endocrine differences between the genders cause men to utilize carbohydrates to a greater extent during endurance exercise. With carbohydrate loading, there is still a need to replenish carbohydrates during the event to maintain blood sugar levels — especially if the event lasts more than 60 minutes. Try a piece of fruit or a sports drink. Meet your goals Carbohydrate loading may be an effective way to get that extra edge you need to compete. If you're uncertain about your specific carbohydrate needs, consult your doctor or a registered dietitian.
- Carbohydrate loading isn't right for every endurance athlete. Side effects may include: Weight gain. Expect to gain 2 to 4 pounds during the week you're carbohydrate loading. Much of this weight is extra water — but if it hampers your performance, you're probably better off skipping the extra carbs. Digestive discomfort. You may need to avoid or limit some high-fiber foods one or two days before your event. Beans, bran, and broccoli can cause gassy cramps, bloating, and loose stools when you're loading up on carbohydrates. Blood sugar changes. Carbohydrate loading can affect your blood sugar levels. It's a good idea to consult your doctor or a registered dietitian before you start carbohydrate loading, especially if you have diabetes.
- Protein Why is protein important? Protein is needed for muscle growth and repair. Regular physical training tends to reduce muscle protein breakdown and protein loss from the body. While some protein breakdown may occur during exercise, protein build-up is enhanced during the recovery and the effectiveness of protein synthesis is increased. When muscle glycogen stores are high, protein contributes no more than 5% of the energy needed. However, when muscle glycogen stores are low, due to inadequate calorie and carbohydrate intake, protein is used for energy rather than for muscle growth and repair and may contribute as much as 10% of the energy needed for exercise. Such use of protein for fuel is expensive and inefficient. How much protein do I need to eat? Engaging in endurance exercise can result in breakdown of body proteins and damage due to continuous pounding action. Due to this increased muscle breakdown and repair, endurance athletes need up to 50% more protein than sedentary adults. Protein should contribute 12-15% of total calories per day. To figure out the amount for you, multiply your weight in kilograms by 1.3, or multiply your weight in pounds by 0.6 to calculate the number of grams of protein you should consume per day.
- Can athletes meet their needs for vitamins and minerals? There may be a need for extra iron, magnesium, vitamin C, and vitamin E by endurance athletes. However, these can easily be obtained from a standard over the counter vitamin and mineral supplement. Do they need any special supplements? Normal nutrient needs are met by eating a healthy diet and special supplements have not proven to enhance endurance athletes’ performance. Supplements such as creatine monohydrate, branched chain amino acids, and L carnitine have not been found to improve performance. Caffeine is the only substance that has proven to improve performance in athletes.
- You lose water when you sweat. If you do vigorous activity and don't replace fluids as you go along, you can become dehydrated. Hot, humid weather increases the amount you sweat and the amount of fluid you lose. But you can also become dehydrated in winter if you don't replace lost fluids. Preteens and teens who participate in sports may be especially susceptible, both because of their body weight, which is generally lower than that of adults, and because they may not be experienced enough to know the warning signs of dehydration (Mayo Clinic). But athletes who train for and participate in ultramarathons, triathlons, mountain climbing expeditions and cycling tournaments are at particularly high risk. That's because the longer you exercise, the more difficult it is to stay hydrated. During exercise, your body may lose more water than it can absorb. With every hour you exercise, your fluid debt increases. Dehydration is also cumulative over a period of days, which means you can become dehydrated with even a moderate exercise routine if you don't drink enough to replace what you lose on a daily basis. If you don't drink enough fluids when you're exercising vigorously and perspiring heavily, you may end up with a heat injury, ranging in severity from mild heat cramps to heat exhaustion to potentially life-threatening heatstroke. Dehydration can occur without any initial symptoms. Dehydration symptoms generally become noticeable after 2% of one's normal water volume has been lost. Athletes may suffer a loss of performance of up to 30% and experience flushing, low endurance, rapid heart rates, elevated body temperatures, and rapid onset of fatigue. At around 5% to 6% water loss, one may become groggy or sleepy, experience headaches or nausea, and may feel tingling in one's limbs (paresthesia).
- Say: Symptoms of dehydration include: headache, dizziness, nausea, dry skin, shivering, and confusion. Dehydration can also cause increases in body temperature and heart rate. Dehydration can set in before the sense of thirst tells us to drink. Performance athletes may not feel thirsty until they have lost a significant amount of fluids. Even in comfortable environments where the air temperature is cool, athletes are losing water during exercise. This is why it is important for athletes to drink regardless of if they feel thirsty. Athletes need to be particularly careful when exercising in hot and humid weather as water losses are greatest in this type of environment. Anyone exercising in the summer months in Louisiana needs to know this as this type of environment increases the risk for heat cramps and heat exhaustion making water fluid replacement even more critical.
- So what can I do to prevent dehydration? In order to avoid dehydration, athletes need to drink water before, during, and after an event. In fact, the American Dietetic Association recommends a specific plan for fluid intake So how will you know how much body weight was lost during the event so that you can consume enough water to replenish losses after the event? Easy, just remember to weigh yourself (and record that weight) both before and after the event.
- Say: Eating too much before working out can be a bad thing, what about not eating before working out? Can that be bad? The answer is yes . Not eating before you exercise (or eating too little) can be just as bad as eating too much because it can lead to low blood sugar levels and can make you feel weak, faint, or tired; slowing your mental abilities which help you react to situations.. To get the most from your workout, it is recommended that you: Eat a full breakfast- to replenish the energy that you have used during the night. However, if you plan to exercise within an hour after breakfast, you may want to eat a smaller breakfast, or drink something to help raise your blood sugar, such as a sports drink. Time your meals – As we previously mentioned, you don’t want to eat large meals right before exercising. It’s important to wait at least three to four hours after consuming a large meal to exercise. And, if you are having a small meal, eat about two to three hours before exercising. Don’t skip meals – Skipping meals can make you feel weak or light headed due to decreases in blood sugar. If you are pressed for time, grab something quick to eat, like a banana or some yogurt. If healthful choices like these aren’t available to you, it’s better to eat something rather than nothing, but remember that options like candy aren’t as nutritious as fruit or low-fat dairy choices. Eat after you workout – Eating after you work out is important to help your muscles recover and to replace their glycogen stores that were used during exercise. [Glycogen is the storage form of glucose found in the body.] Try to eat a meal that contains both protein and carbohydrates within two hours of your exercise session.
- Energy needs of an athlete Say: The typical athlete burns many calories through exercise. And , the number of calories burned are, of course, dependent on the type of activity that the athlete is doing, the duration of the activity , and also the athlete’s body weight . As some of us probably already know, The more vigorous the activity, the more calories are burned The longer the activity, the more calories are burned And the heavier the person exercising, the more calories are burned as more energy is required to move a heavier body mass. So, how many calories will athletes need? It depends on the type and length of training, body type, gender, and body size . It depends on how active the athlete is. Remember that if a person burns more calories through exercise than what they consume through food, that person will lose weight. So, an athlete needs to be careful to consume enough calories, from a wide range of foods, if they do not want to lose any weight. Use the Harris Benedict Formula from lesson 1 to determine calorie needs
- An Athlete’s Diet Say: So what does the typical athlete’s diet look like? One thing that is important to note is that in an athlete’s diet, the majority of fuel or energy is coming from carbohydrates. In fact, approximately 50 to 60% of calories (or energy) in an athlete’s diet come from carbohydrate food sources. Great nutritious sources of carbohydrates, as you may recall, come from the grains group, the fruit and vegetable groups, and the milk group. In an athlete’s diet, a significant portion of energy comes from fat, but this should be primarily from healthy fat sources, like mono- and polyunsaturated fats as opposed to saturated and trans fats, often found in high fat meats and high fat dairy products; baked goods, like pies, cookies, and cakes; and fried foods, like doughnuts and other commercially prepared fried items, such as French fries. Protein is also important in an athlete’s diet. Approximately 10 to 15% of the calories in an athlete’s diet should come from protein. Remember, there are some choices of protein-rich foods that are better than others: such as low- or non-fat milk and milk products over whole-milk and milk products and lean cuts of meat over high-fat and non-trimmed cuts of meat. Although athletes’ protein needs may be slightly higher than a non-athlete, it is important to remember that Americans generally exceed their protein needs . For example, teen females following the MyPyramid system consume about 91 grams of protein, while teen males consume about 116 grams of protein, which is more than enough for even the most active teens. So, typically athletes do not require any additional protein supplemental bars or powders that we often hear about.
- Physical Activity Recommendations Say: The Dietary Guidelines for Americans recommend children and adolescents should engage in at least 60 minutes of physical activity on most, preferably all, days of the week . The good news is that this 60 minutes worth of activity doesn’t have to be from one activity. Instead, it can be accumulated throughout the day from a variety of different activities. For example, if riding your bike to school takes 15 minutes, then there is 30 minutes of physical activity accumulated just from going to and from school each day. Taking your dog for a 15-minute walk followed by 15 minutes of shooting hoops in the driveway with friends will help you to accumulate the rest of your recommended amount of physical activity in no time. So, you may have thought that taking the stairs over the elevator wasn’t really helpful in any way, but on the contrary, that little bit of extra physical activity, combined with other small increases in physical activity throughout the day, does add up.
- Say: Physical inactivity can lead to a loss of muscle. Since muscle is a lot more physiologically active than is fat, having less muscle translates to lower energy (or calorie) requirements, which makes it easier to gain weight. As you may have guessed, physical inactivity has the potential of leading to obesity among all ages and to reduced functional capacity (or a measure of what an individuals heart will allow them to do), which is particularly a problem among older adults. Low physical fitness, caused by physical inactivity, can actually increase one’s risk for diseases like, cardiovascular disease, diabetes, and even some forms of cancer. Although we don’t generally think of these conditions as things that occur in youth, evidence does show that the process leading to conditions like stroke and heart attack begin early on in childhood. We also know that physically fit individuals can do more things, have better endurance for activities and tasks, and are healthier than individuals who are not physically fit. The plus is that even small increases in physical activity can make a big difference to an individual’s health. These small changes, over time, will gradually improve your fitness, leading to a better you! Did you know that 37.2 percent of high school students spend three or more hours a day watching TV? Think about how much time you may spend on weekday afternoons or weekends watching TV. Now think about other activities that you could be engaging in to fill some of that time.
- Say: The first topic that we will discuss today is physical inactivity since it is a national health concern for both youth and adults in the United States. According to a 2005 study, approximately 9.6% of youth do not engage in either moderate or vigorous physical activity. Physical inactivity is a major reason of why many people lack physical fitness. In fact, recent estimates [from the national health and nutrition examination survey (NHANES)] illustrate that 17.9% of American males and 16.0% of American females between the ages of 12 -19 are overweight . This is actually an increase of about 179% from 1971 to 2004.
- Say: Everyone can benefit from regular physical activity. Regular physical activity not only provides immediate benefit by helping you now, but also in the future by improving quality of life and helping you to have lower risks for the development of several chronic diseases. Know that no one should ever start out at a high exercise intensity; especially if they have been sedentary for some time. In fact, you should probably check with your doctor before starting an exercise program if: You have been sedentary for a long time You are overweight Or if you have a high risk of coronary heart disease or some other chronic health problem Physical activity can improve self image, it can reduce depression and improve overall well being.
- Say: Exercise has benefits and incorporating more physical activity into a daily routine is important. It can be small changes as long as they are consistent. Even little changes can have big results. Here are some tips to help you stick with the exercise program you choose: Choose something that you actually like to do , whether it is walking, jogging, tennis, or swimming – whatever the case. This way, instead of dreading the activity, it can be something that you look forward to. Get a partner – exercising with someone not only makes it more fun but gives you someone to help keep you motivated. Vary your routine – If you change up your routine, you will be less likely to get bored or injured. For example, walk one day. Bicycle the next. And, even consider activities like racquet sports or kickboxing. Choose a comfortable time of day. For example, don’t works out right after you eat, during the time of day when it’s too cold or too hot or when you are too tired or groggy. Don’t get discouraged – it can take time to notice significant changes from exercise, weeks and even sometimes months. Keep with it. Forget “no pain, no gain”. While a little soreness is normal after you first start exercising, pain is not. Stop if you hurt! Make exercise fun. For example, if exercising alone, listen to music. Or, if exercising at a gym on a stationary bike or elliptical machine, watch TV or read a book. Look for ways to exercise that are fun to you, like taking a walk through the zoo, signing up for a dance class, or learning to play something you previously didn’t know how—tennis, basketball, football, etc.
- Say: The intensity at which you exercise reflects the amount of oxygen that your body uses to do an exercise and the number of calories you burn while doing it. For aerobic exercises , like walking, swimming, or cycling, the intensity translates into how hard the exercise feels to you. As a general rule, moderate-intensity exercise is best because with light-intensity exercises, you may not be meeting your fitness or weight loss goals. And, with vigorous-intensity exercises, you may be pushing yourself too hard, increasing the risk for injuries, soreness, or getting burned out. Here are some telltale signs that you are engaging in a moderate-intensity exercise: You’re breathing faster; You’re developing a light sweat; You’re feeling some strain on your muscles. There is also the talk test . If you can carry on a conversation of brief sentences but you can’t sing a song, then you are probably exercising at the recommended moderate-intensity range.
- Say: One of the hardest things about being physically active is remaining physically active. Putting things off until tomorrow is something that we all do from time to time. Even convincing ourselves that something isn’t that important or all that beneficial, but know that being physically active most definitely is beneficial, and although you may not see immediate changes in whatever it is that you are looking to do; whether it be toning up or having more energy, sticking with a physically active lifestyle is key. Here are some additional tips for exercise success: 1. Choose activities that are fun, not exhausting. Make sure to vary things, so that you don’t get bored with your exercises. 2. You need to be sure to wear comfortable, properly fitted footwear and comfortable, loose-fitting clothing that is appropriate for the weather and the activity. For example, don’t wear shoes that you know easily give you blisters if you are going for a walk, and don’t wear too many layers of clothing if you are exercising in a hot, humid environment. 3. Find a convenient time and place to do activities, this way you’ll be more likely to stick with it. But, don’t sweat it if you can’t get to exercise one day, just make it up another time. 4. Surround yourself with supportive people – people that know how important your activities are to you. Ask a family member or friend to exercise with you. Go for walks with your mom or play basketball with friends. It’s a great time to catch up and spend time together. 5. Don’t overdo it. Always start out with low- to moderate-level activities and then gradually increase your duration and intensity as you become more fit. Over time, and only when you feel comfortable enough to, work up to exercising on most days of the week for 30-60 minutes. 6. And, finally keep a record of your activities. This way you can note your progress and reward yourself when you reach special milestones that you have set for yourself.