Sabine Spiesser BSc Grad Dip Dietetics

Every sport has it's own nutritional and hydration requirements, which allows athletes to perform at their best. This is no different in gliding. Fitness and optimal health are a year round concern. This section deals with the nutritional requirements of cross-country flights in a hot climate. The main concerns are optimal hydration over the entire day, and enough energy to be able to concentrate over a prolonged period of time. We want to feel comfortable, not hungry, bloated or nauseous. We do not want to have to cut our flight short due to indigestion or diarrhea, nor do we want to lose our concentration due to lack of energy and fluids. In Australia's hot climate, especially when unaccustomed to the heat, we can easily lose several litres of fluid though perspiration and evaporation, even before we launch.

Our muscles need fuel for everyday activity. Gliding, while in the air, is a mainly sedentary sport and thus the quantitative energy intake does not need to exceed our normal daily intake. However, the peak performance required for an ongoing high concentration level calls for consistent energy availability. The type and timing of meals and snacks is therefore critical to success. The stress in long-distance flying clearly lies in the constant level of concentration required over long hours, as well as the extreme temperatures experienced in Benalla during a typical Australian summer.

The brain needs fuel too. Our brain relies totally on glucose for fuel. Our bodies store limited amounts of glucose as glycogen in muscles and the liver for emergency purposes. Glucose must be provided to the brain on an ongoing basis for optimal cognitive function. Glucose from carbohydrate-containing foods must be provided at regular intervals to keep us alert and focused on whatever we choose to do. A constant blood glucose level will therefore provide a constant supply of nourishment to the brain.

When blood glucose levels drop, usually 1 1/2 -3 hours after a meal, the brain needs to send a signal to the body to draw on its stored glucose reserves. While some people may feel hungry, others may feel fatigued or irritable, losing concentration and coordination skills. The symptoms will depend on every person's unique way of handling blood glucose levels. If you are familiar with these symptoms then you will realise that you need to refuel regularly. It is vital that glucose stores are topped up well before this stage is reached, as digestion and absorption take time. Don't wait until fatigue sets in.

Added protein may keep us satiated longer, and keeps the blood glucose levels more even by slowing down stomach emptying. Easily digested carbohydrate-containing foods, eaten frequently, are the best choice, when it comes to refuelling. We do not want to overly stimulate our digestive tract, when we are unable to heed the call of nature for long hours at a time. Fat, fructose (fruit sugar) and fibre stimulate gut motility, can cause bloating and flatulence, and their intake is therefore best kept relatively low on flying days. Tolerance is very individual. While glucose is an easily absorbed carbohydrate, all fruit and sugar also contain fructose. Fructose is only absorbed very slowly. High concentrations of fructose attract a lot of water to the digestive tract to dilute it. This can cause discomfort (bloating and wind) and ultimately diarrhoea. The higher the fructose content, the more likely we are to experience some discomfort. Some fresh fruit, such as apples, pears, bananas, cherries and plums, as well as dried fruit such as raisins, sultanas, figs, dates, prunes and cranberries and the respective fruit juices, when consumed in significant quantities, may cause digestive upsets and diarrhoea. We should aim at eating the bulk of our fruit intake after we have landed. (Other laxative sugars are xylitol, mannitol, sorbitol found in some sugarless sweets and cough medications) How we manage our digestive system on flying days, depends on our individual requirements. This chapter can only provide guidelines based on current nutritional knowledge.

Ideally, we are looking for a gradual release of glucose after carbohydrate digestion. Easily digestible carbohydrates in combination with some protein – in foods and/or fluids – make the best fuel before and during a flight. This can be achieved, by eating frequent small portions throughout the day, starting with a healthy breakfast.

The gliding season is not the time for weight loss or drastic dietary manipulation, we need to nourish ourselves optimally, for our own and others' safety.

Food choices

Practical choices for pre-flight breakfasts

  • Porridge or cereal of your choice with milk and/or
  • Toast with 1-2 eggs or cheese or lean ham (no bacon) or
  • Yoghurt.
  • Orange juice.
  • If this all sounds too much, try an ice cold glass of Sustagen.

Choosing low fibre, low fructose, low fat means less bloating, flatulence and a less likely urge for bowel motions during flight. (This is contrary to the normal everyday nutritional recommendations of high fibre, high fruit intake, you need to be the judge of your own tolerance levels. You can easily catch up with a fruit- and vegetable/salad-rich evening meal. If your digestive system is sluggish, you can be more liberal in your choices).
In-flight eating

Practical choices for in-flight nourishment should be foods, which require minimal handling, and are packed conveniently. Food should provide you with energy, but not leave you fatigued or sluggish. Given the high temperatures during the Australian summer they also need to be foods, which don't melt easily and which don't spoil in these high temperatures. We need to snack frequently, and in small quantities, or resort to fluid nourishment as part of our refuelling strategy. See hydration below. Choices are personal and depend on our preferences. Below are some examples.
Generally, it is not necessary to consume extra salt. Too much salt can contribute to dehydration, as extra fluid is required by the body to handle the load. Or bodies do not lose vast quantities of salt during perspiration, and these are easily obtained from the foods listed in the following table.

Foods & Beverages Comments

Sports drinks like Gatorade, Isostar & Isosport. 
* Contain easily absorbed sugars and salt in optimal concentration for best absorption.

White bread rolls or sandwiches cut to size. 
* Avoid seeds and crusty crumbly rolls, fillings, which melt or deteriorate.

Plain bagels. 
* Excellent to munch on.

Plain sweet biscuits. 
* Excellent, not messy.

Crispbreads like Salada, Thin Captain & Vita Wheat. 
* Could be eaten with cheese. Prepare in advance and keep cool.

Muffins, fruit buns. 
* Energy dense.

* Fiddly.
* High in fibre.
* High in salt and fat.

Low fat muesli bars or sports bars. 
* Too many can cause diarrhoea or bloating.

* 1-2 pieces, no more than you usually consume during this period of day.

The following foods may cause bloating, flatulence and diarrhoea when consumed in excess; know your limits! Eating too many of these high-sugar foods can lead to rapid fluctuations in blood sugar levels and may make you feel tired, and decrease performance.

Foods & Beverages Comments

Jelly beans, snakes & lollies. 
* Too many can cause diarrhoea.
* Stick to teeth and can cause dental enamel to break down.

Fruit juice. 
* Too much apple or pear juice can cause diarrhoea.
* Too much sugar, no salt.

Dried fruit. 
* Too much dried fruit can cause diarrhoea.
* Don't exceed your daily tolerance.
* It's easy to eat the equivalent of a large bunch of grapes in a handful of sultanas.
* Apricots have less fructose than pears, apples, prunes or sultanas.
* Stick to teeth and can cause dental enamel to break down.

Further reading on nutritional matters

* Dr Louise Bourke, The complete guide to food for sports performance, Allen & Unwin.
* Rosemary Stanton, Eating for Peak Performance, Allen & Unwin.
* Australian Institute of Sport online.
* Catherine Saxelby, Nutrition For Life.
* Foodwatch online.

Source: Gliding Club of Victoria

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