Friday, 22 April 2011

22nd April 2011

                        Nutrition and the endurance athlete.
          Nutrition is one of the most important factors for any athlete as it forms the fuel which makes the muscles work. In the early stages of exercise and sport, carbohydrates provide about 50% of the energy requirement. Carbohydrates yield more energy per unit of oxygen consumed than any other form of dietary fuel, and as oxygen is often the limiting factor in endurance events, it is beneficial to use the energy source requiring the least amount of oxygen per kilocalorie produced.
         Complex carbohydrates come from foods such as pasta, potatoes, cereals and other grain products. Simple carbohydrates are found in fruits, milk, honey and sugar. When you eat, the body breaks down these carbohydrates and stores it in the muscles and liver as glycogen.
         During exercise and sport, the stored glycogen is converted back to glucose and it used for energy. The ability to sustain energy levels for long periods in endurance events such as the parish is directly related to the initial levels of these stored glycogen deposits. If an event lasts for 90 minutes or less, the glycogen stored in the muscles is usually enough to supply the energy needed. Extra carbs will not help, just as adding fuel to a half full tank in a car will not make it go faster.
         For events lasting more than 90 minutes though, a high carbohydrate diet eaten for at least three days before the event allows the glycogen storage to be at it’s maximum. This is usually referred to by athletes as “carbing up”, something which I’d heard of but didn’t really understand why until I heard the above explanation. In studies, it was found that extreme endurance athletes reported benefits from a pre-competition diet consisting of 70% carbs. High carb foods taken little and often during the day, and a largish carb meal before bedtime which the body absorbs into glycogen while sleeping. Training is considered to be done by this time, so little exercise should be done to avoid using the stored glycogen. This time is also beneficial to repair muscles after all training for the event is over.  It isn’t recommended to keep to a diet like this all the time though, as you will be missing out on essential nutrients and fatty acids essential for a healthy diet, and a high carb diet will eventually lead to weight gain.
        If this pre diet is done correctly then there should be energy enough for three to four hours. After this, carbohydrates should be taken regularly to top up energy levels. Simple sugars are absorbed and used almost immediately and can give a lift, although this is often in the form of a sugar rush and can be over quickly leading to a drop in energy levels. Simple sugars contain mainly glucose, fructose and sucrose which is absorbed easily by the gut, although sufficient water levels are necessary to help absorption. This was thought to be sufficient for long endurance races, but recent research shows that a more mixed diet is necessary, with a simple and complex carbs/protein/fat mix so that constant energy levels are achieved. There are powders and gels available on the market but these are expensive and a much easier option is a mix of, for example, fruit and vegetables, pasta and chicken. The body can absorb liquids better than solids, so make a chicken soup, blended into a fine liquid, and take little and often. I got a good tip last year of very thin porridge with honey, I got a 2 litre flask with thin porridge and poured in a full jar of honey, easily digestible, it has simple carbs in the honey, complex carbs in the oats and fat in the (full fat) milk. It can be quite refreshing. Mixed with another 2 litre flask of chicken soup, alternating between the two, with protein shakes and fruit, pretty much all you need. After four or five hours, the body reacts differently to food, and if possible different foods should be tested on a long distance training walk. Everyone is different, some can eat burgers and sandwiches some can’t eat anything. Remember, if the weather is warm, you will be fighting de-hydration, and a dry mouth is not good for eating dry foods. Also pack in some treats, Michael Bonney got me onto Jaffa cakes, which have simple carbs and complex carbs in the sponge, milk chocolate and the smashing orangy bit in the middle. Sweets, cold fruit such as pieces of apple, orange, water melon and fresh pineapple. Cut up, put into small pots and keep in a chiller box in the boot of your back up car.
       In endurance athletes, fat consumption may grow to 75% of the aerobic energy consumed, training for longer periods can teach the body to burn fat more efficiently, at the same time, athletes with minimal amounts of fat can suffer in longer events. It has been said in the past that caffeine helps burn fat during exercise, although this is frowned upon now as it is a diuretic, taking water from the muscles and expelling it, so avoid coffee. I like a cup of tea later on, it’s refreshing, and I know it has caffeine, but I’m weighing up the psychological benefits against the physical benefits, and a grand cuppa when you’re parched just can’t be beaten. The lovely ladies at Maughold have filled my flask in recent years with one of the finest cuppas I have ever tasted.
       Carbs can be taken with water, you can get mixes and powders that carb up the water, but this has also proved to be not as good as previously thought. Any carb mix in water up to 6% to max 8% can be okay, but tests have proved that the water is absorbed more slowly when taken like this. A simple drink made from a fruit juice high in vitamins, such as barley water or Ribena with a pinch of sea salt for sodium electrolyte replacement is as good, if not better than expensive sports drinks. Also, make them weak, as later on during the parish the taste buds are affected to such a degree that what at the beginning of the race was a tasty drink, will later on taste rich and sickly. Chilled drinks are better as they are absorbed by the body faster and can also help lower body core temperature. A couple of bottles of ginger tea, chop fresh ginger into a saucepan, add water, bring to the boil then simmer for ten minutes, add lemon and honey to taste, then bottle and chill, can help stomach upset, and can also clean muscle waste away as well as reducing swelling.
       Protein is necessary although in small amounts, to prevent sports anemia, a reduction of red blood cells caused by endurance exercise. The muscles take about 10% of it's nutrition from protein, and, later on in the race as protein levels drop, the body starts taking it's protein from an easy source, your own muscles! This is called lean muscle tissue catabolism and can affect performance. Protein taken during endurance events can also help post event recovery. I take an occasional weak protein shake in milk, the cold milk makes it palatable, especially the banana flavour…
       Vitamins and minerals. There is no evidence that extra vitamins and minerals are necessary, especially if you are taking a proper varied diet with the simple and complex carbs, fat and protein, although some minerals can run low, sodium, potassium, iron and calcium, these can be replaced with fruit and vegetables which contain them. Bananas for potassium, green vegetables for iron, milk for calcium, and a pinch of sea salt which, unlike table or refined salt, is 50% minerals including those listed above. So, mixed diet again.
The pre race meal.
     This is something I’ve been interested in for a while, I’ve long been the advocate of a large bowl of porridge with fruit and honey, but with me this tends to sit in the stomach like a heavy lump as it settles without being digested, eventually solidifying and causing problems later on. The meal should be high in starch with complex carbohydrates such as pasta vegetables, potatoes and cold cereals. These are digested at a constant rate to provide energy and can be emptied from the stomach in two to three hours. Avoid fats, simple sugars and fibre. Fats and fibre take much longer to consume and can sit heavy in the stomach. Simple sugars, sweets and sugars such as honey lead to an early rise in blood sugars and can lead to premature exhaustion of muscle glycogen stores. If possible, blend the pre race meal to a liquid so it can be easily digested.
     This blog isn’t exhaustive, research is still going on, and everyone is different so, although I’ve tried to explain the reasons why we take different methods of nutrition into a race, if you try out your own and it works for you, or, indeed, if I’m proved wrong, please feel free to let me know. 
     Google can give you a list of simple and complex carbs as well as lists of food high in carbs as well as recipes and suggestions for high carb meals for pre race preparation. Personally, in the days before the race I eat pretty much the same as during the race and as often so that the stomach can get used to what it’s going to have to put up with, so the diet changes only a little from pre race to race diet.
Now, I'm off to a high protein/carb meal with an iron rich drink. Steak in ale pie and chips, with a pint of guinness!


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