Complete Guides: The Complete Guide to Functional Training by Allan Collins (2012, Paperback)
However, to have a performance-boosting effect, creatine has to be taken in large doses. This is higher than you could reasonably expect to get from food. You would need to eat at least 2 kg of raw steak a day to load your muscles with creatine. The average-sized person stores about g creatine, almost all in skeletal muscles higher levels in fast-twitch muscle fibres, see p.
How does the anaerobic glycolytic system work? This system is activated as soon as you begin high-intensity activity. It dominates in events lasting up to 90 seconds, such as a weight training set in the gym or a m sprint. In order to meet sudden, large demands for energy, glucose bypasses the energy pro ducing pathways that would normally use oxygen, and follows a different route that does not use oxygen. This saves a good deal of time. The anaerobic glycolytic system uses carbohydrate in the form of muscle glycogen or glucose as fuel. Glycogen is broken down to glucose, which rapidly breaks down in the absence of oxygen to form ATP and lactic acid see Fig.
Each glucose molecule produces only two ATP molecules under anaerobic conditions, making it a very inefficient system. The bodys glycogen stores dwindle quickly, proving that the benefits of a fast delivery service come at a price. The gradual build-up of lactic acid will eventually cause fatigue and prevent further muscle contrac tions.
Contrary to popular belief, it is not lactic acid, but the build up of hydrogen ions and acidity that causes the burning feeling during or immediately after maximal exercise see p. How does the aerobic system work? The aerobic system can generate ATP from the breakdown of carbohydrates by glycolysis and fat by lipolysis in the presence of oxygen see Fig. Although the aerobic system cannot produce ATP as rapidly as can the other two anaerobic systems, it can produce larger amounts.
Lactic acid produced by the muscles is not a wasted by-product. It constitutes a valuable fuel. When the exercise intensity is reduced or you stop exercising, lactic acid has two possible fates. Some may be converted into another substance called pyruvic acid, which can then be broken down in the presence of oxygen into ATP. In other words, lactic acid produces ATP and constitutes a valuable fuel for aerobic exercise. Alternatively, lactic acid may be carried away from the muscle in the bloodstream to the liver where it can be converted back into glucose, released back into the bloodstream or stored as glycogen in the liver a process called gluconeo - genesis.
This mechanism for removing lactic acid from the muscles is called the lactic acid shuttle. This explains why the muscle soreness and stiffness experienced after hard training is not due to lactic acid accumulation. In fact, the lactic acid is usually cleared within 15 minutes of exercise. Most of the carbohydrate which fuels aerobic glycolysis comes from muscle glycogen. Additional glucose from the bloodstream becomes more important as exercise continues for longer than 1 hour and muscle glycogen concentration dwindles. Glucose delivered from the bloodstream is then used to fuel your muscles, along with increasing amounts of fat lipolytic glycolysis.
Glucose from the bloodstream may be derived from the breakdown of liver glycogen or from carbohydrate consumed during exercise. In aerobic exercise, the demand for energy is slower and smaller than in an anaerobic activity, so there is more time to transport sufficient oxygen from the lungs to the muscles and for glucose to generate ATP with the help of the oxygen. Under these circumstances, one molecule of glucose can create up to 38 molecules of ATP. Thus, aerobic energy production is about 20 times more efficient than anaerobic energy production. Anaerobic exercise uses only glycogen, whereas aerobic exercise uses both glycogen and fat, so it can be kept up for longer.
The disadvantage, though, is that it produces energy more slowly. Fats can also be used to produce energy in the aerobic system. One fatty acid can produce between 80 and ATP molecules, depending on its type see Fig. Fats are therefore an even more efficient energy source than carbohydrates. However, they can only be broken down into ATP under aerobic conditions when energy demands are relatively low, and so energy production is slower.
Muscle fibre types and energy production The body has several different muscle fibre types, which can be broadly classified into fast-twitch FT or type II, and slow-twitch ST or type I endurance fibres. Everyone is born with a specific distribution of muscle fibre types; the pro portion of FT fibres to ST fibres can vary quite considerably between individuals. The pro portions of each muscle fibre type you have has implications for sport. For example, top sprinters have a greater proportion of FT fibres than average and thus can generate explosive power and speed.
Distance runners, on the other hand, have proportionally more ST fibres and are better able to develop aerobic power and endurance. During aerobic exercise the use of carbo hydrate relative to fat varies according to a number of factors. The most important are: 1 the intensity of exercise 2 the duration of exercise 3 your fitness level 4 your pre-exercise diet.
Intensity The higher the intensity of your exercise, the greater the reliance on muscle glycogen see Fig. So, for example, during sprints, heavy weight training and inter mittent maximal bursts during sports like football and rugby, muscle glycogen, rather than fat, is the major fuel. During aerobic exercise you will use a mixture of muscle glycogen and fat for energy.
As you increase your exercise intensity, for example, as you increase your running speed, you will use a higher proportion of glycogen than fat. Duration Muscle glycogen is unable to provide energy indefinitely as it is stored in relatively small quantities. As you continue exercising, your muscle glycogen stores become progressively lower see Fig.
Thus, as muscle glycogen concentration drops, the contribution that blood glucose makes to your energy needs increases. The proportion of fat used for energy also increases but it can never be burned without the presence of carbohydrate. On average, you have enough muscle glycogen to fuel minutes of endurance activity; the higher the intensity, the faster your muscle glycogen stores will be depleted. During interval training, i. Figure 2. During mainly anaerobic activities, muscle glycogen will deplete within minutes.
Once muscle glycogen stores are depleted, protein makes an increasing contribution to energy needs. Muscle proteins break down to provide amino acids for energy production and to maintain normal blood glucose levels. Fitness level As a result of aerobic training, your muscles make a number of adaptations to improve your performance, and your bodys ability to use fat as a fuel improves.
Aerobic training increases the numbers of key fat-oxidising enzymes, such as hormone-sensitive lipase, which means your body becomes more efficient in breaking down fat into fatty acids. The number of blood capillaries serving the muscle increases so you can transport the fatty acids to the muscle cells. The number of mitochondria the sites of fatty acid oxidation also increases which means you have a greater capacity to burn fatty acids in each muscle cell. Thus, improved aerobic fitness enables you to break down fat at a faster rate at any given intensity, thus allowing you to spare glycogen see Fig.
This is important because glycogen is in much shorter supply than fat. By using proportion ally more fat, you will be able to exercise for longer before muscle glycogen is depleted and fatigue sets in. Pre-exercise diet A low-carbohydrate diet will result in low muscle and liver glycogen stores. It also affects your ability to perform during shorter periods of maximal power output. When your muscle glycogen stores are low, your body will rely heavily on fat and protein. However, this is not a recommended strategy for fat loss, as you will lose lean tissue. See Chapter 9 for appropriate ways of reducing body fat.
Virtually every activity uses all three energy systems to a greater or lesser extent. No single energy system is used exclusively and at any given time energy is being derived from each of the three systems see Fig. Anaerobic glycolysis and aerobic energy pro - duction depend on exercise intensity. For example, during explosive strength and power activities lasting up to 5 seconds, such as a sprint start, the existing store of ATP is the primary energy source. During power endurance activities such as m events, muscle glycogen is the primary energy source and produces ATP via both anaerobic and aerobic glycolysis.
In aerobic power activities, such as running km, muscle glycogen is the primary energy source producing ATP via aerobic glycolysis. During aerobic events lasting 2 hours or more, such as half- and full marathons, muscle glycogen, liver glycogen, intra-muscular fat and fat from adipose tissue are the main fuels used. The energy systems and fuels used for various types of activities are summarised in Table 2. What happens in my body when I start exercising? When you begin to exercise, energy is produced without oxygen for at least the first few seconds, before your breathing rate and heart can catch up with energy demands.
Therefore, a build-up of lactic acid takes place. If you are exercising fairly gently i. If you continue to exercise aerobically, more oxygen is delivered around the body and more fat starts to be broken down into fatty acids. They are taken to muscle cells via the bloodstream and then broken down with oxygen to produce energy. In effect, the anaerobic system buys time in the first few minutes of an exercise, before the bodys slower aerobic system can start to function. For the first minutes of exercise depending on your aerobic fitness level the main fuel is carbohydrate glycogen.
As time goes on, however, more oxygen is delivered to the muscles, and you will use proportionally less carbohydrate and more fat. On the other hand, if you begin exercising very strenuously e. The delivery of oxygen cannot keep pace with the huge energy demand, so lactic acid continues to accumulate and very soon you will feel fatigue. You must then either slow down and run more slowly, or stop.
Nobody can main tain a fast run for very long. If you start a distance race or training run too fast, you will suffer from fatigue early on and be forced to reduce your pace consider ably. A head start will not necessarily give any benefit at all. Warm up before the start of a race by walking, slow jogging, or performing gentle mobility exercises , so that the heart and lungs can start to work a little harder, and oxygen delivery to the muscles can increase.
Start the race at a moderate pace, gradually building up to an optimal speed. This will prevent a large oxygen debt and avoid an early depletion of glycogen.
In this way, your optimal pace can be sustained for longer. The anaerobic system can also cut in to help energy production, for instance when the demand for energy temporarily exceeds the bodys oxygen supply. If you run uphill at the same pace as on the flat, your energy demand increases. However, this can only be kept up for a short period of time, because there will be a gradual build-up of lactic acid. The lactic acid can be removed aerobically afterwards, by running back down the hill, for example. The same principle applies during fast bursts of activity in interval training, when energy is produced anaerobically.
Lactic acid accumulates and is then removed during the rest interval. In scientific terms, fatigue is an inability to sustain a given power output or speed. It is a mismatch between the demand for energy by the exercising muscles and the supply of energy in the form of ATP. Runners experience fatigue when they are no longer able to maintain their speed; footballers are slower to sprint for the ball and their technical ability falters; in the gym, you can no longer lift the weight; in an aerobics class, you will be unable to maintain the pace and intensity.
Subjectively, you will find that exercise feels much harder to perform, your legs may feel hollow and it becomes increasingly hard to push yourself. Why does fatigue develop during anaerobic exercise? In other words, the demand for ATP exceeds the readily available supply. During activities lasting between 30 seconds and 30 minutes, fatigue is caused by a different mechanism.
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The rate of lactic acid removal in the bloodstream cannot keep pace with the rate of lactic acid production. So during high- intensity exercise lasting up to half an hour there is a gradual increase in muscle acidity, which reduces the ability of the muscles to maintain intense contractions. It is not possible to continue high-intensity exercise indefinitely because the acute acid environment in your muscles would inhibit further contractions and cause cell death.
The burning feeling you experience when a high concentration of lactic acid develops is a kind of safety mechanism, preventing the muscle cells from destruction. Reducing your exercise intensity will lower the rate of lactic acid production, reduce the build-up, and enable the muscles to switch to the aerobic energy system, thus enabling you to continue exercising.
Why does fatigue develop during aerobic exercise? Fatigue during moderate and high-intensity aerobic exercise lasting longer than 1 hour occurs when muscle glycogen stores are depleted. Its like running out of petrol in your car. Muscle glycogen is in short supply compared with the bodys fat stores. Liver glycogen can help maintain blood glucose levels and a supply of carbohydrate to the exercising muscles, however stores are also very limited and eventually fatigue will develop as a result of both muscle and liver glycogen depletion and hypoglycaemia see Fig.
During low to moderate-intensity exercise lasting more than three hours, fatigue is caused by additional factors. Once glycogen stores have been exhausted, the body switches to the aerobic lipolytic system where fat is able to supply most not all of the fuel for low-intensity exercise. However, despite having relatively large fat reserves, you will not be able to continue exercise indefinitely as fat cannot be converted to energy fast enough to keep up with the demand by exercising muscles.
Even if you slowed your pace to enable the energy supplied by fat to meet the energy demand, other factors will cause you to fatigue. These include a rise in the concen tration of the brain chemical serotonin, which results in an overall feeling of tiredness, acute muscle damage, and fatigue due to lack of sleep.
Glycogen is used during virtually every type of activity. Therefore the amount of glycogen stored in your muscles and, in certain events, your liver, before you begin exercise will have a direct affect on your performance. The greater your pre-exercise muscle glycogen store the longer you will be able to maintain your exercise intensity, and delay the onset of fatigue. Conversely, sub-optimal muscle glycogen stores can cause earlier fatigue, reduce your endurance, reduce your intensity level and result in smaller training gains.
You may also delay fatigue by reducing the rate at which you use up muscle glycogen. You can do this by pacing yourself, gradually building up to your optimal intensity. Anaerobic glycolysis provides energy for short-duration high-intensity exercise lasting from 30 seconds to several minutes. Muscle glycogen is the main fuel. The lactic acid produced during anaerobic glycolysis is a valuable fuel for further energy production when exercise intensity is reduced. The aerobic system provides energy from the breakdown of carbohydrate and fat for sub-maximal intensity, prolonged exercise.
Factors that influence the type of energy system and fuel usage are exercise intensity and duration, your fitness level and your pre- exercise diet. The proportion of muscle glycogen used for energy increases with exercise intensity and decreases with exercise duration.
For most activities lasting longer than 30 seconds, all three energy systems are used to a greater or lesser extent; however, one system usually dominates. The main cause of fatigue during anaerobic activities lasting less than 6 seconds is ATP and PC depletion; during activities lasting between 30 seconds and 30 minutes it is lactic acid accumulation and muscle cell acidity. Fatigue during moderate and high-intensity exercise lasting longer than 1 hour is usually due to muscle glycogen depletion. For events lasting longer than 2 hours fatigue is associated with low liver glycogen and low blood sugar levels.
For most activities, performance is limited by the amount of glycogen in the muscles. Low pre-exercise glycogen stores lead to early fatigue, reduced exercise intensity and reduced training gains. A high muscle-glycogen concentration will allow you to train at your optimal intensity and achieve a greater training effect. A low muscle-glycogen concentration, on the other hand, will lead to early fatigue, reduced training intensity and sub- optimal performance.
Clearly, then, glycogen is the most important and most valuable fuel for any type of exercise. This chapter explains what happens if you fail to eat enough carbo hydrate and glycogen levels become depleted. It shows you how to calculate your precise carbohydrate requirements and considers the latest research on the timing of carbohydrate intake in relation to training.
Each different carbohydrate produces a different response in the body, so this chapter gives advice on which types of carbohydrate foods to eat. It presents comprehensive information on the glycaemic index GI , a key part of every athletes nutritional tool box. Finally, it considers the current thinking on carbohydrate loading before a competition.
The relationship between muscle glycogen and performance The importance of carbohydrates in relation to exercise performance was first demonstrated in Christensen and Hansen, found that a high-carbohydrate diet significantly increased endurance. However, it wasnt until the s that scientists discovered that the capacity for endurance exercise is related to pre-exercise glycogen stores and that a high-carbohydrate diet increases glycogen stores. In a pioneering study, three groups of athletes were given a low-carbohydrate diet, a high- carbohydrate diet or moderate-carbohydrate diet Bergstrom et al.
Researchers measured the concentration of glycogen in their leg muscles and found that those athletes eating the high-carbohydrate diet stored twice as much glycogen as those on the moderate-carbohydrate diet and 7 times as much as those eating the low- carbohydrate diet. Those on the high- carbohydrate diet managed to cycle for minutes, considerably longer than those on the moderate-carbohydrate diet minutes or the low-carbohydrate diet 60 minutes see Fig 3.
There is plentiful evidence that such a diet enhances endurance and performance for exercise lasting longer than one hour. This recommendation is based on the fact that carbohydrate is very important for endurance exercise since carbohydrate stores as muscle and liver glycogen are limited.
Depletion of these stores results in fatigue and reduced performance. This can easily happen if your pre-exercise glycogen stores are low. In order to get the most out of your training session, you should ensure your pre-exercise glycogen stores are high. However, this method is not very user- friendly and can be misleading as it assumes an optimal energy calorie intake. It does not provide optimal carbohydrate for those with very high or low energy intakes. Scientists recommend calculating your carbohydrate requirement from your body weight and also your training volume IAAF, ; Burke et al.
While most of the research on diet and endurance has focused on the role of carbohydrate, a number of studies have considered whether a high fat diet might enhance the muscles ability to burn fat. The thinking behind this research is that since fat is a major fuel during prolonged endurance exercise, a high fat diet may be able to train the muscles to burn more fat during exercise, conserving precious glycogen and giving muscles greater access to a more plentiful supply of energy in the body.
Indeed, it appears that increasing fat intake enhances the storage and burning of intramuscular fat as well as improving the ability of the muscles to take up fat from the blood stream Muoio et al. However, these effects are observed only in elite or well- conditioned athletes and the performance advantage only applies at relatively low exercise intensities. US researchers analysed 20 studies that looked at the high fat diets and performance Erlenbusch et al.
They concluded that high fat diets have no performance advantage for non-elite athletes but all athletes especially non-elite benefited from a high carbohydrate diet. Schokman, , since your glycogen storage capacity is roughly proportional to your muscle mass and body weight, i. The greater your training volume, the more carbohydrate you need to fuel your muscles.
It is more flexible as it takes account of different training requirements and can be calculated independent of calorie intake.
Table 3. In practice, eating a high carbohydrate diet can be difficult, particularly for those athletes with high energy needs. Many complex carbohyd rate foods, such as bread, potatoes and pasta are quite bulky and the diet quickly becomes very filling, particularly if whole grain and high fibre foods make up most of your carbohydrate intake. This may be partly due to the large number of calories needed and therefore the bulk of their diet, and partly due to lack of awareness of the benefits of a higher carbohydrate intake. It is interesting that most of the studies upon which the carbohydrate recommendations were made, used liquid carbo - hydrates i.
Tour de France cyclists and triathletes consume up to one third of their carbohydrate in liquid form. If you are finding a high carbo hydrate diet impractical, try eating smaller more frequent meals and supplementing your food with liquid forrns of carbohydrate such as meal replacement shakes see p. Carbohydrates are traditionally classified according to their chemical structure. The most simplistic method divides them into two categories: simple sugars and complex starches and fibres. These terms simply refer to the number of sugar units in the molecule.
Simple carbohydrates are very small molecules consisting of one or two sugar units. They comprise the monosaccharides 1-sugar units : glucose dextrose , fructose fruit sugar and galactose; and the disaccharides 2-sugar units : sucrose table sugar, which comprises a glucose and fructose molecule joined together and lactose milk sugar, which comprises a glucose and galactose molecule joined together. Complex carbohydrates are much larger molecules, consisting of between and several thousand-sugar units mostly glucose joined together. They include the starches, amylose and amylopectin, and the non-starch polysaccharides dietary fibre , such as cellulose, pectin and hemicellulose.
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In between simple and complex carbo - hydrates are glucose polymers and malto dextrin, which comprise between 3- and sugar units. They are made from the partial breakdown of corn starch in food processing, and are widely used as bulking and thickening agents in processed foods, such as sauces, dairy desserts, baby food, puddings and soft drinks. They are popular ingredients in sports drinks and engineered meal-replacement products, owing to their low sweetness and high energy density relative to sucrose. In practice, many foods contain a mixture of both simple and complex carbohydrates, making the traditional classification of foods into simple and complex very confusing.
For example, biscuits and cakes contain flour complex and sugar simple , and bananas contain a mixture of sugars and starches depending on their degree of ripeness. Not all carbohydrates are equal Its tempting to think that simple carbo hydrates, due to their smaller molecular size, are absorbed more quickly than complex carbohydrates, and produce a large and rapid rise in blood sugar. Unfortunately, its not that straightforward. For example, apples containing simple carbo - hydrates produce a small and prolonged rise in blood sugar, despite being high in simple carbo - hydrates.
Many starchy foods complex carbohydrates , such as potatoes and bread, are digested and absorbed very quickly and give a rapid rise in blood sugar. So the old notion about simple carbohydrates giving fast-released energy and complex carbo hydrates giving slow-released energy is incorrect and misleading.
What is more important as far as sports performance is concerned is how rapidly the carbohydrate is absorbed from the small intestine into your bloodstream. The faster this transfer, the more rapidly the carbo hydrate can be taken up by muscle cells or other cells of the body and make a difference to your training and recovery.
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While the GI concept was originally developed to help diabetics control their blood sugar levels, it can benefit regular exercisers and athletes too. It is a ranking of foods from 0 to based on their immediate effect on blood sugar levels, a measure of the speed at which you digest food and convert it into glucose. The faster the rise in blood glucose the higher the rating on the index. The GI of foods is very useful to know because it tells you how the body responds to them. If you need to get carbohydrates into your bloodstream and muscle cells rapidly, for example immediately after exercise to kick-start glycogen replen ishment, you would choose high GI foods.
How is the GI worked out? The GI value of food is measured by feeding 10 or more healthy people a portion of food containing 50 g carbo hydrate. For example, to test baked potatoes, you would eat g potatoes, which contain 50 g of carbohydrate. Over the next two hours, a sample of blood is taken every 15 minutes and the blood sugar level measured. The blood sugar level is plotted on a graph and the area under the curve calculated using a computer programme see Fig. On another occasion, the same 10 people consume a 50 g portion of glucose the reference food.
Their response to the test food e. The GI is given as a percentage which is calculated by dividing the area under the curve after youve eaten potatoes by the area under the curve after youve eaten the glucose. The final GI value for the test food is the average GI value for the 10 people. Appendix 1 The glycaemic index and carbohydrate content of foods gives the GI content of many popular foods. Most values lie somewhere between 20 and This simply makes it easier to select the appropriate food before, during and after exercise.
In a nutshell, the higher the GI, the higher the blood sugar levels after eating that food. In general, refined starchy foods, including potatoes, white rice and white bread, as well as sugary foods, such as soft drinks and biscuits are high on the glycaemic index. For example, baked potatoes GI 85 and white rice GI 87 produce a rise in blood sugar almost the same as eating pure glucose yes, you read correctly!
Less refined starchy foods porridge, beans, lentils, muesli as well as fruit and dairy products are lower on the glycaemic index. They produce a much smaller rise in blood sugar compared with glucose. Only a few centres around the world provide a legitimate GI testing service.
The smaller the crispies have a higher GI particle size i. Degree of starch The more gelatinised swollen Cooked potatoes high GI ; gelatinisation with water the starch, the greater biscuits lower GI. Amylose to amylopectin There are two types of starch: Beans, lentils, peas and ratio amylose long straight molecule, basmati rice have high difficult access by enzymes and amylose content, i. The containing it have high more amylose a food contains the amylopectin content, i.
Fat Fat slows down rate of stomach Potato crisps have a lower emptying, slowing down digestion GI than plain boiled and lowering GI. Sugar sucrose Sucrose is broken down into Sweet biscuits, cakes, 1 molecule of fructose and 1 molecule sweet breakfast cereals, of glucose. Fructose is converted honey. Soluble fibre Soluble fibre increases viscosity of Beans, lentils, peas, oats, food in digestive tract and slows porridge, barley, fruit. Protein Protein slows stomach emptying Beans, lentils, peas, pasta and therefore carbohydrate all contain protein as well digestion, producing a smaller blood as carbohydrate.
Eating sugar rise, i. But new and revised data are constantly being added to the list as commercial foods are reformulated and these are available on the website www. Factors that influence the GI of a food include the size of the food particle, the biochemical make-up of the carbohydrate the ratio of amylose to amylopectin , the degree of cooking which affects starch gelatinisation , and the presence of fat, sugar, protein and fibre. How these factors influence the GI of a food is summarised in Table 3. How can you calculate the GI of a meal? To date, only the GIs of single foods have been directly measured.
In reality, it is more useful to know the GI of a meal, as we are more likely to eat combinations of foods. It is possible to estimate the GI of a meal by working out its total carbohydrate content, and then the contribution of each food to the total carbohydrate content. For a quick estimate of a simple meal, such as beans on toast, you may assume that half the carbohydrate is coming from the bread and half from the beans. What are the drawbacks of the GI? Pasta has a low GI because of the physical entrapment of ungelatinised starch granules in a sponge-like network of protein gluten molecules in the pasta dough.
Pasta cooked al dente has a slighter lower GI than pasta that has been cooked longer until it is very soft. Pasta is unique in this regard, and as a result, pastas of any shape and size have a fairly low GI 30 to When glucose levels are high for example, after consuming high GI foods , large amounts of insulin are produced, which shunts the excess glucose into fat cells.
However, it is the combined effect of a large amount of carbohydrate as well a foods GI value that really matters. The biggest drawback of the GI is that it doesnt take account of the portion size you are eating. For example, watermelon has a GI of 72 and is therefore classified as a high GI food which puts it off the menu on a low GI diet. However, an average slice g gives you only 6 g carb ohydrate, not enough to raise your blood glucose level significantly. You would need to eat at least 6 slices g to obtain 50 g carbohydrate the amount used in the GI test.
Similarly, many vegetables appear to have a high GI, which means they may be excluded on low GI diet. However, their carbohydrate content is low and therefore their effect on blood glucose levels would be small. So despite having a high GI the glycaemic load GI x g carbohydrate per portion divided by is low. Another drawback is that some high fat foods have a low GI, which gives a falsely favourable impression of the food.
For example, the GI of crisps or chips is lower than that of baked potatoes. Apples, pears, oranges, grapefruit, peaches, nectarines, plums and apricots have the lowest GI values while tropical fruits such as pineapple, papaya and watermelon have higher values. However, as average portion size is small, the GL would be low. Fresh vegetables most vegetables have a very low carbohydrate content and dont have a GI value you would need to eat enormous amounts to get a significant rise in blood glucose. The exception is potatoes, which have a high GI.
All Bran Low GI grains these include bulgar wheat, noodles, oats, pasta, basmati not ordinary brown or white rice Beans and lentils chick peas, red kidney beans, baked beans, cannellini beans, mung beans, black-eyed beans, butter beans, split peas and lentils Nuts and seeds almonds, brazils, cashews, hazelnuts, pine nuts, pistachios, peanuts; sunflower, sesame, flax and pumpkin seeds Fish, lean meat, poultry and eggs these contain no carbohydrate so have no GI value Low fat dairy products milk, cheese and yoghurt are important for their calcium and protein content.
Opt for lower fat versions where possible. Its important you dont select foods only by their GI check the type of fat i. What is the glycaemic load? You can gain a more accurate measure of the rise in your blood glucose and insulin level by using the glycaemic load GL. It is calculated simply by multiplying the GI of a food by the amount of carbohydrate per portion and dividing by One unit of GL is roughly equivalent to the glycaemic effect of 1 g of glucose.
This results in a large surge in blood glucose and insulin. Conversely, eating smaller amounts of a low- carbohydrate high GI food e. This results in a smaller and more sustained rise in blood glucose. To optimise glycogen storage and minimise fat storage, aim to achieve a small or moderate glycaemic load eat little and often, avoid overloading on carbohydrates, and stick to balanced combinations of carbo hydrate, protein and healthy fat. Theres no need to cut out high glycaemic foods. This will evoke lower insulin levels and less potential fat storage. For example, have a baked potato high GI food with a little margarine and baked beans or tuna both low GI foods.
Both protein and fat put a brake on the digestive process, slowing down the release of glucose. GI remains the best-researched and one of the most reliable indicators of health risk. Thats because exercise modifies the glycaemic response. Studies at the University of Sydney in Australia have found that when athletes are fed high GI foods, they produce much less insulin than would be predicted from GI tables. In other words, they dont show the same peaks and troughs in insulin as sedentary people do. Use the GI index only as a rough guide to how various foods are likely to behave in your body.
So if you have a low GI diet the chances are you have a high good cholesterol level and a lower risk of heart disease. However, the risk of disease is also predicted by the GL of the overall diet. In other words, GL simply strengthens the relationship, which suggests that the more frequently people eat high GI foods, the greater their health risk. Sell it yourself. Get an immediate offer. Get the item you ordered or your money back.
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Processed by PayPal Get more time to pay. International postage paid to Pitney Bowes Inc. Click on the cover image above to read some pages of this book! Functional training is the hottest concept in fitness and strength and conditioning, and also the most poorly understood.. This book, part of the Complete Guide series, explains functional training as any exercise routine that can benefit nearly any user, improving your ability to perform tasks required in your daily life, job, or chosen sport.
It then explains how each movement included as part of your workout should mimic the range of motion and engage the muscles that are necessary to impact performance, whether on the basketball court or in day-to-day life, such as the ability to lift children out of their car seats. Help Centre. My Wishlist Sign In Join. Be the first to write a review. Add to Wishlist. Ships in 15 business days.
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