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Nutrition for Runners Long distance endurance events are performed at moderate to high intensities. These energy demands are met by the breakdown of carbohydrate and fat sources in the body. Internal carbohydrate stores in the body - mostly in the form of muscle and liver glycogen, but these are limited so if the muscles can be fed more carbohydrate, athletes can perform better. BUT - carbohydrate availability to the muscles is limited by how fast it can pass through the intestine and into the bloodstream - the transporters only work as fast it takes to get you the sugar you need. In the past it was believed that glucose was pretty much the only type of carbohydrate that should be ingested during endurance events and that the maximum rate of glucose absorption in the gut was 1gram per minute. New research now shows that fructose can also be ingested at the same time to increase the total carbohydrate absorption. Studies suggest that muscles can absorb a combination of fructose and glucose almost 40% faster than glucose alone. This combined consumption of glucose and fructose at an approximate 2:1 ratio can increase the total carbohydrate absorption and oxidation rate - resulting in better performance. Since this new research has come into light it has shown that carbohydrate absorption can be increased to at least 1.5g/min (possibly as high as 2.1g/min) to increase the overall metabolic rate. Researchers have determined that a 2:1 ratio of carbohydrates, glucose:fructose may be optimal. There are several sports nutrition products on the market that have this ratio. Getting this ratio correct can help your race performance. What is the difference between glucose and fructose and why these are important? Both are classified as simple carbohydrates, but glucose is the only one that your cells (including muscle cells) use to produce energy directly. For fructose to be used for energy, it must first be absorbed in your gut, up-taken by your liver and then converted into glucose. So by having a 2:1 balance of both glucose and fructose in your race diet you can get more overall carbohydrate into your muscle cells for high energy production, and improved performance. Does my body weight matter in terms of intake of fuel during a race? No. It is the gut itself that is the limiter to how fast you get carbohydrate into your bloodstream. A 90 kg person doesn't have that much of a larger gut than a 60 kg person, therefore it doesn't make sense to overload the 90 kg person with more carbohydrate. The recommendation remains the same for everyone, irrespective of their body weight. How to calculate: Optimum: 1.5g carbohydrate per minute of exercise High Five energy gel = 23g of carbohydrate Exercise time: 1hr 40mins (100mins) 100mins 23(g) x 1.5(g) = 6 gels This is optimum intake. Nutrition for Runners What about fluids? Should I use caffeine? You’ll notice that we are not giving you a dedicated fluid intake recommendation. This is because we now know that fluids should be consumed, not at a set rate, but in accordance with your own body’s needs. Caffeine has both positive and negative effects on the body. It acts as a central nervous system stimulant which causes changes in muscle contraction and has effects on cardiac muscles. Caffeine may also help with carbohydrate absorption and oxidation however the performance improvement often shown with caffeine use is probably related to a decreased perception of fatigue as well as its direct effect on muscle (ie a placebo effect). The key is for fluids to be available during the race and for you to be able to drink according to your thirst. Your body’s own inbuilt thirst centre is the best gauge of your own body’s fluid needs, just listen to it’s advice ;o) You’ll also note that there is no recommendation for electrolyte consumption, that is because recent studies have shown there is no influence of low versus high sodium (salt) on glucose absorption and no effect of sodium supplementation in the prevention of cramping. The only principle you need to follow is to ensure there is some level of sodium in your diet during the day. By consuming a normal endurance race diet (i.e. gels) there will be enough sodium for your body. Everyone has different responses to caffeine; some athletes will experience a positive effect while others may have no effect or negative effects from the same dose. Trialling caffeine in different doses is the best way to find out if it works for you and at what level of intake. We recommend that you start with a caffeine dose of 3mg/kg as this does typically work well for most athletes. You should consume this amount approximately 45mins prior to race start. Nutrition for Runners How does your body get energy? The carbohydrate in food and drink is what fuels your body. It it transformed into blood sugar or blood glucose (BG). BG is essential to DRIVE the body’s power and endurance metabolic systems. BG is essential to keeping the whole system firing. If BG levels drop, the system cannot function efficiently and the body cannot perform at it’s best. For strength and power sports, the fuel of choice for muscles is carbohydrate, even more so than for endurance sports. So it is very important to have this readily available to facilitate training. Forget about low-carb diets! Protein functions in a structural (repair) and transport capacity (facilitates transport of sugar back into cells for recovery) and is therefore an important part of the nutritional equation also. However, too much protein is hard on your kidneys. Maintaining energy by understanding Glycaemic Index (GI) GI is the measure of how long carbohydrate takes to turn to blood sugar (BG) Low GI foods, like pasta, rice and whole grains take a longer time to turn to BG and therefore provide sustained energy. High GI foods, like sports drinks, glucose and processed grains, alongside a source of protein are good foods to have after training to maximise recovery. High GI foods work by stimulating blood glucose and an insulin response to help prevent muscle degradation. This optimises uptake and replacement of glycogen, or stored glucose, and prepares the body for subsequent training sessions. Index of Low GI Foods: http://www.the-gi-diet.org/lowgifoods/ What to do when you are exercising Pre-exercise fuelling 1-2 hours before a workout have a low GI carbohydrate snack. Aim for around 50-100 grams of carbohydrate depending on your energy needs. Drink your caffeine drink 3mg/kg 45mins before the start. During Exercise 1.5g/min of glucose and fructose in an approximate 2:1 ratio. Fluid needs: Remember thirst is your gauge. Start your session by being “topped up” with water then replenish throughout the race. After exercise WITHIN 30 mins. 1.2g carbohydrate/kg + 10-20g protein within 30mins after training. Choose high GI sources of carbohydrate to speed uptake of glucose into cells. Repeat every hour for 3 hours after, or a pasta/ rice based meal with a source of protein, whichever is more practical. The greater the intensity and duration of the workout, the more important it is to follow this protocol closely. If the workout was light and easy then you won’t need as much food as suggested. Example: Protein smoothie with banana, honey, low fat yoghurt. (80g carb, 28g protein) Don’t forget to re-hydrate. Carbo Loading Tips for the Carbo loading Start 1 1/2 days before race day. Have high carbohydrate meals with low GI. Your reduction in exercise will help your carbo loading. Eat foods that you know won’t make you sick. On race morning have a low GI breakfast 1-2 hours before the race. Some food facts: Benefits of healthy eating: Obtain energy for fuelling the body. Obtain essential nutrients needed for the body’s functions. Maintain a healthy weight and feeling of wellbeing. Prevent nutrition-related diseases (obesity, diabetes, cancer, heart disease). Healthy immune system. Live longer ;o) Energy you need Carbohydrate = 50-60% of total energy. Fat = 25-30% of total energy. Protein = 10-15% of total energy. There are 2 types of Carbohydrates; Complex (starches) and Simple (natural and refined sugars). Natural sugars, such as fruit, vegetables, milk and yoghurt are low GI and high fibre (dairy foods do not have fibre). Low GI foods take a longer time to turn to blood sugar so they are good for providing sustained energy and keep hunger levels at bay. Wholesome grains such as rolled oats, multigrain bread, muesli and beans/pulses are also low GI and high fibre. Refined sugars should be limited but are ok in small amounts and in moderation. Nutrition labels give a breakdown of total carbohydrates and sugars which can be confusing if the sugars are natural. It is more important to evaluate the GI than the sugar content. Protein and Fat Eating 2-3 small servings of lean meat or meat alternatives each day will provide the body’s protein requirement. Protein is also found in whole grains, dairy products, nuts, seeds, vegetables and soy foods. A low-fat diet is important to keep cholesterol levels down. Heart healthy fats, such as olive oil, seed oils, avocado, fish fat, nuts, seeds, dark chocolate and coconut are excellent for cardiovascular health and should be consumed in small amounts too.