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Nutrition . . . |
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| Training and Nutrition Triathletes often train or compete in the morning without eating. The overnight fast lowers your liver glycogen stores (the source of blood glucose) and can lead to fatigue during exercise. Eating a high-carbohydrate power breakfast before morning exercise will maintain blood glucose levels so that you can perform at your best. During exercise, you rely primarily on your pre-existing glycogen and fat stores. Although breakfast doesn't contribute immediate energy, it can provide energy when you exercise for longer than an hour. The carbohydrate in the meal elevates your blood glucose to provide energy for the exercising muscles. It can also keep you from feeling hungry, which may impair performance. You should consume your breakfast one to four hours before training or competition to allow adequate time for the food to empty from your stomach. Exercising with a nearly full stomach can cause indigestion, nausea, and vomiting, as blood is diverted from the stomach to the muscles. The amount and kind of food you should consume depends on the timing of the meal. To avoid potential gastrointestinal distress, the carbohydrate and calorie content of the meal should be lesser the closer to exercise the meal is consumed. For example, you can consume a large meal of 700 to 800 calories four hours before exercise, while a smaller meal of 300 to 400 calories is better an hour before exercise. Consuming carbohydrate several hours prior to morning exercise helps to restore your liver glycogen stores, which will aid in endurance events that rely heavily on blood glucose. If your muscle glycogen levels are also low, consuming carbohydrate several hours before exercise can help to increase them as well. If stomach emptying is a concern, you can use liquid meals. Good examples of high-carbohydrate foods for pre-exercise consumption include bread products such as toast, bagels, pancakes or muffins (adding jam or jelly increases the carbohydrate content), cooked or dry cereal, fruit, sports bars, nonfat or 1 percent fat yogurt, and liquid meals. Fruit juices, nonfat or 1 percent fat milk, and sports drinks are good high carbohydrate beverages. Drinking fluids with breakfast and just before exercise helps to ensure proper hydration. Fatty foods should be limited because fat slows the process of stomach emptying and may make you feel sluggish and heavy. Many popular high-protein breakfast foods (bacon, sausage and cheese) are high in fat. In contrast, carbohydrates provide the quickest and most efficient source of energy, and unlike fats, are rapidly digested. You may need to watch your fiber intake (especially bran) in your morning meal to avoid a bathroom stop during exercise. This kind of interruption is merely annoying during training, but can be disastrous during competition. Also, it is a good idea to minimize intake of gas-forming foods such as beans and onions. Extremely salty foods (bacon and sausage) can cause fluid retention and a bloated feeling. Above all, you should choose palatable, familiar, and well-tolerated foods. Experimenting with a variety of power breakfasts in training helps you determine what foods you're most likely to handle well before competition. Many people are tense before competing, which slows digestion. Even familiar, well-tolerated foods may take longer to digest. Liquid meals have the advantage of leaving your stomach sooner than regular meals and thus help to keep you from becoming nauseated before competition. The fluid and carbohydrate content of most liquid meals makes them a desirable food choice before exercise. They can satisfy hunger and supply energy without giving an uncomfortable feeling of fullness. Many people value a feeling of "lightness," especially prior to a major triathlon competition. Because of their low residue, liquid meals are also less likely to necessitate a bathroom break during exercise. Home-made liquid meals can be concocted by mixing milk, non-fat milk powder, and fruit in a blender. If you are lactose intolerant, you can substitute soymilk or Lact-Aid milk and soy powder. For added variety, cereal, yogurt and flavoring (e.g., vanilla or chocolate) can be added. Sugar or honey may be added for additional sweetness and carbohydrate. Some athletes have "lucky" foods that they associate with peak performance. As long as these foods don't hinder your performance, you can eat them for breakfast, even if they're not typical breakfast foods (e.g., pizza). Sample breakfasts One hour before: 2 slices whole wheat toast with strawberry preserves 8 ounces 1 percent fat milk Two to three hours before: One Healthnut English muffin with blueberry preserves 8 ounces 1-percent-fat flavored yogurt mixed with 1/2 cup Grapenuts Four hours before: 1 and 1/2 cups cooked oatmeal with brown sugar 1 banana 8 ounces 1-percent-fat milk 8 ounces orange juice 1 bagel (sliced in half) with blackberry preserves Liquid breakfast two hours before: 8 ounces 1-percent-fat milk or soymilk 1/2 cup non-fat dry milk powder or soy powder 4 ounces plain yogurt Chocolate syrup and malted milk powder to taste Many runners still believe that all fats are taboo. Yes, some can wreak havoc on our bodies, but others are not only essential, but they also can boost your performance and lower your times. When it comes to enhancing performance, perhaps the best quality about fats is that they are used to produce our body's anti-inflammatory chemicals, which are crucial in the recovery process from competing and training. The aerobic system relies on fats to fuel the aerobic muscles, and fat produces energy and prevents an overdependency on sugar. Fats provide more than twice as much potential energy as carbohydrates (9 kilocalories from good fats, as opposed to 4 kilocalories from carbs). Not only do fats provide us with a great energy potential, they are also important for physical protection of our bones and organs (especially the kidneys and heart). They help insulate us in hot and cold environments, keep us from being hungry, improve digestion and, as an added benefit, add taste to the foods we eat. Dr. Phillip Maffetone, a world-renowned expert on sports nutrition and human performance, outlines three basic types of fats to be aware of when shopping, preparing and eating your food: Good fats: These are the natural fats and oils, which contain important nutrients the body cannot make on its own. They are called "essential fatty acids." These include the omega-6 and omega-3 oils found in nature. Here are some foods high in these good fats. Omega-6: Foods: squash, peas, carrots, broccoli, asparagus, cabbage, beets, etc. Most food oils: safflower, peanut, soy, sesame Best supplement if you can't get from food: black currant seed oil Animal fats, such as meat, dairy, egg yolks, butter and shellfish, are also the omega-6 type. Omega-3: Foods: beans, fish (salmon and sardines), most nuts and seeds, leafy vegetables (kale, Swiss char, spinach, leaf lettuce) Food oils: linseed (flax), walnut, pumpkin Best nutrition supplement if you can't get from food: EPA (fish oil), linseed What's most important about these fats is that you consume equal amounts of them. Many people eat too many omega-6 fats and too few omega-3 fats, and the inbalance translates into a "bad" fat. Oils from vegetables also are called "polyunsaturated," and those from animal fats are "saturated." Maffetone says the best oil to use regularly is extra-virgin olive oil. It is used in abundance in the Mediterranean diet, a regime acclaimed to be one of the healthiest in the world. Olive oil is mostly a "monounsaturated" fat, and helps protect against heart disease, cancer and other problems. Maffetone says extra-virgin olive oil is the highest grade (first pressed) and contains all the key nutrients, including antioxidants. On the other hand, oils marked "pure" and "light" contain unwanted chemical solvents and are less nutritious. Bad fats These are natural fats that are, according to Maffetone, "not inherently bad, but if we don't balance them (with omega-3 fats), they can turn bad." He says if there's too many omega-6 fats in our diet, some of them can be converted to excess amounts of saturated fat, turning them into bad fats. This occurs more often if there's too much sugar in the diet. Bad fats cause too much inflammation in the body, and increase your risk of heart disease, among other conditions. Really bad fats Watch out for these! These are the artificially and chemically processed fats and are, by far, the most deadly. Fortunately, they are listed on the labels of foods, and consequently, are pretty easy to spot. The problem with these fats is that they last for weeks once inside the body. They can elevate the bad LDL cholesterol, while the good HDL cholesterol is reduced. This increases your risk for heart disease. The really bad fats include: Trans fats: These are found in hydrogenated and partially hydrogenated oils. Margarine is the most popular hydrogenated product. Heated oils: Most dangerous are the polyunsaturated oils when heated. They are changed into chemicals called free radicals and are very unhealthy. Tropical oils: The most popular are palm and palm kernel oil. Fractionated oils: These are chemically processed fats. Through this chemical process, all the good omega oil is extracted, leaving only the saturated fat. Whether it's a meal or an energy bar, check the ingredients in what you're eating. When eating out, ask if your food contains margarine, if it's fried, or what kind of oil they use. You are most likely compromising your running potential if you cut too much fat from your diet. The good fats are essential. Sure, you can run without them, but you most likely won't go down the road as far or as fast if they're missing from your diet. Maffetone's book, "In Fitness and In Health," contains a lot of additional information about fats. For more information, call (877) 264-2200. Recipe: Baked salmon over spinach (This is simple to make, and the salmon contains great essential fats) Ingredients: One box frozen spinach (thawed and drained in colander) Four salmon steaks Spices (black pepper and red pepper) Jalapenos (optional) 1 tablespoon butter Lemon juice Directions: Spread the spinach in the bottom of a glass baking pan. Place salmon steaks on top of spinach. Sprinkle spices and jalapenos (according to personal preference) over salmon steaks. Dot with butter and sprinkle with lemon juice. Cook at 350 degrees about 25 minutes or until salmon is done all the way through. (Serves four.) Laurie Parton Corbin is a marathon runner who lives in northern New Jersey. She has qualified for the 2000 Olympic Marathon Trials. Laurie has won three marathons, including the Mardi Gras Marathon in January '99, and enjoys competing in all distances, from 5K to the marathon. Laurie is a freelance writer with a specialty in nutrition, and works full-time for the M.A.F. Group, based in Boonton, N.J. |
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VITAMIN FOOD SOURCES HEALTH BENEFIT DEFICIENCY
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| Four questions for rebuilding your diet . . . |
By Adam Bean |
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| Hamish Blair/Allsport 'Front loading' at breakfast and lunch is the healthiest way to go You know what your nutritional goals should be. But how do you get there? Chances are that you could make big gains with incremental changes in your diet. Call them adjustments. To do this, study your food record and ask yourself the following four questions. 1. When am I eating during the day? Nutritionists agree that you'll eat healthiest if you spread your calorie intake evenly throughout the day. If anything, you should "front-load." In other words, eat a solid breakfast and lunch. 2. How big are my portions? If your food record shows that you eat 8 ounces or more of meat at a sitting, you need to cut down on your portions. How? It may sound nutty, but using smaller-sized dishes has been shown to work. Another portion cutting method: Skip the second helping. Once you've eaten what's on your plate, consider yourself done. 3. How fast am I eating? When you eat too fast, you probably don't consume the right kinds of foods. If all your breakfasts and lunches are over in 10 minutes, slow down, you eat too fast. 4. Am I consuming too much fat? Can't keep track? Buy one of those little fat-calorie pamphlets, available at many grocery stores and bookstores. The pamphlets list the fat content (in grams) of most common foods, and often will give you instructions on determining what your daily percent of fat should be. Breaking old food habits doesn't come easy. But the payoff, in terms of feeling better and living healthier, is worth the effort. |
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| Creatine: Fuel for endurance? | By Tim Mickleborough |
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| During the past few years, we athletes have been barraged with media hype about the use of creatine supplementation
in sport. We've heard about its reported ability to enhance exercise performance and, as a result, we've been left
with questions about its application to endurance sports, proper dosage, side effects, and ethical issues. In fact,
there's been so much speculation tossed around that we've been left with little more than misinformation. Fear
not, multisport enthusiasts, we have the scientific skinny on the most critical questions surrounding creatine.
Creatine defined Creatine is a physiologically active substance indispensable to muscle contraction. In addition to being present in the diet, creatine is synthesized by the liver, kidneys and pancreas in humans. However, because 95 percent of the body's creatine pool is found in skeletal muscle, creatine must be transported from its site of synthesis to skeletal muscle. Oral ingestion of creatine depresses its biosynthesis, a response that is reversible when supplementation ceases. Despite several decades of research devoted to creatine metabolism, little information, other than anecdotal reports, has been reported about the influence of dietary supplementation on exercise performance. In addition to creatine synthesis in the body, a normal daily diet of meat and fish can supply approximately 1g of creatine. The daily creatine turnover is approximately 2 g in a 70-kg man. Clearly, creatine ingestion adds to the whole-body creatine pool. One kilogram of raw steak contains approximately 4 g of creatine, but some degradation of creatine occurs during cooking. Athletes living on a vegetarian diet consume very little in their meals. Hence, they depend on their own creatine synthesis. The introduction of muscle biopsy in 1968 allowed quantifiable data to be obtained on the creatine muscle content. In humans, there is a pool of 120-140 g of creatine, of which most is stored in skeletal muscle. No greater than 30 percent of muscle creatine is free, with the majority being bound in the creatine phosphate (CP) store. Fast-twitch muscle fibers (predominantly used in sprinting) have a higher total creatine content than slow-twitch muscle fibers (predominantly used in endurance events). The creatine used in muscle contraction is replaced via the bloodstream. It appears that speed training increases the CP content in muscle. Sprinters have a higher adenosine triphosphate (ATP) and total creatine content in muscle than long-distance runners, and track speed cyclists show higher levels than road cyclists. Creatine is needed for the formation of CP in the mitochondria (which are found within the skeletal muscle cell and function to produce the energy needed to power muscle contraction) and for the resynthesis of adenosine diphosphate (ADP) to produce ATP (the energy currency of the body). A reversible equilibrium exists between creatine and CP and, at rest, approximately 60 percent of the creatine content of muscle is in the form of CP. The availability of CP is one of the most likely limitations to muscle performance during brief, high-power exercise, because the depletion of CP results in an inability to resynthesize ATP at the rate required. Human studies involving maximal contraction and studies on laboratory animals are in agreement that creatine/CP availability is essential to muscle function during short-duration maximal exercise. Who's to gain? It is important to point out that human muscle appears to have an upper limit of creatine storage of 150-160 mmol/kg dm, which, once achieved with or without supplementation, cannot be exceeded. Thus, feeding creatine to an athlete with an already high muscle creatine content or ingesting high doses of creatine for a prolonged period will be of little additional benefit. Second, individuals with the lowest levels of creatine in their muscles appear to achieve the most pronounced increases following creatine ingestion. The normal creatine content of muscle is 125 mmol/kg dm, and individuals whose muscles contain less than 120 mmol/kg dm can expect to have a greater than 25 percent increase after dietary supplementation. Since vegetarians are likely to have a reduced body creatine pool; therefore, vegetarian athletes represent a population that presumably could gain significant benefits from creatine ingestion. Aside from diet, what determines whether athletes have a high or low content of creatine in their muscles is not yet clear and needs to be investigated. Interestingly, females, for reasons as yet unknown, appear to have a slightly higher creatine content than do males. Proper dosage At present, the recommended dosage of creatine supplementation is 20 g daily over a five- day period. Studies have shown that muscle creatine stores remain elevated when higher dose supplementation (20g/day for 5 days) is followed by lower dose supplementation (2g/day) used for maintenance. It appears that once creatine is absorbed, it remains "trapped" in the skeletal muscle. It appears that low-dose supplementation (3g/day) for 30 days is less effective at raising muscle creatine stores, at least during the initial loading (1-2 weeks) phase of ingestion, compared with a higher (20g/day) for 5 days. It should be stressed that not all studies investigating the ergogenic benefit of creatine supplementation have been positive. Such conflicting results may be attributed to subject differences and study design. One study investigated creatine supplementation in 20 competitive swimmers during 25-, 50-, and 100-m performance and observed no significant difference between the effects of creatine ingestion and placebo on swim times. Another study investigated the effect of creatine supplementation on muscle (CP) and short-term maximal power output during 30-seconds maximal cycling. Creatine was ingested as creatine monohydrate. Biopsies were conducted on these nine cyclists and no differences were noted between ingestion of creatine monohydrate and placebo for conditions of peak, mean 10-secs, and mean 30-secs power output, percent fatigue, post-exercise blood lactate concentrations, and intra-muscular ATP and CP stores. Endurance power? The question still remains: Does creatine supplementation aid endurance athletes? The answer: Although endurance athletes are required to use anaerobic metabolism only occasionally, it may still play an important role in a race, such as intermediate and finishing spurts. A recent study investigated the effect of creatine supplementation versus no supplementation in athletes undergoing repeated interval tests at a top power to within a 3 mmol.L-1 lactate concentration during a 60-minute cycling session. The results indicated that creatine supplementation had no influence on the cardiovascular system, oxygen uptake and blood lactate concentration. A fall in blood glucose was significantly reduced after consumption of creatine. And although interval power performance was significantly increased, by 18 percent, endurance performance was not. Researchers concluded that creatine supplementation has positive effects on short-term anaerobic bursts within aerobic (submaximal) endurance exercise. Although it is now clear that creatine supplementation can have a positive effect on brief, maximal exercise, some individuals will probably benefit more than others from creatine ingestion. Studies have shown that five days of creatine ingestion at a rate of 20g/day will markedly increase (25 percent) the muscle creatine concentration of those athletes whose pre-supplement creatine concentrations are not very high (i.e., less than 120 mold/kg dm). Interestingly, however, only these naturally less creatine-abundant athletes showed an accelerated rate of CP resynthesis during recovery from intense muscular contraction. As might be expected, subjects who experienced little or no uptake of creatine into muscle during creatine supplementation showed no change in CP resynthesis during recovery following creatine ingestion. Possible side effects In addition to interest in possible ergogenic benefit, there is a growing concern regarding side effects from creatine ingestion. Most of the side effects have been reported from athletes mega-dosing (consuming large doses of creatine above the recommended dosage rates of 20g/day for the first week) and range from weight gain to dehydration and cramping. Studies have demonstrated that creatine facilitates the uptake of glucose and, hence, electrolytes (e.g., sodium) from the blood into the skeletal muscle cell. Therefore, mega-dosing could exacerbate this situation and lead to an electrolyte imbalance in the plasma and cause dehydration and cramping. This area requires further study, but it should be noted that anecdotal reports of cramping are not in short supply from athletes using creatine. A troubling side-issue is the increasing use of creatine supplementation among junior high school and high school athletes. It appears that these young athletes are consuming creatine as an ergogenic aid (e.g., wrestlers, football players, sprinters, and track and field athletes). Unfortunately, as these athletes age it may well lead to them taking banned substances to stay ahead. The last word In closing, there is research that supports the claim that creatine supplementation can increase peak power muscle contraction and prolong time to fatigue in short-term (10-20 seconds), maximal exercise. For endurance athletes, creatine ingestion may have benefits when undergoing a weight training program (explosive exercise sessions) and during intermediate and finishing spurts, which are anaerobic in nature. However, creatine supplementation appears to have no direct ergogenic benefit for athletes engaging in endurance events conducted at a submaximal intensity. As stated previously, many studies have found no ergogenic benefit from creatine ingestion during anaerobic short-term exercise and, therefore, the subject still remains controversial. |
