Nutrition & Hydration Basics, courtesy of GetBuzzing
The loss of fluid and a reduction in the body’s carbohydrate stores are the two major causes of fatigue in prolonged exercise. Therefore it is essential that you define your optimal nutrition and hydration strategies to ultimately help you to achieve your goals.
When you undertake a prolonged activity, your body needs energy. This energy comes from what you eat and what you drink. is carbohydrates that are stored in your muscles and liver as a fuel’ called glycogen.
The body’s glycogen stores are limited and fatigue occurs when glycogen stores are depleted resulting in a significant reduction in performance. Crossing the start line with already low glycogen stores is like taking a car out of a half empty fuel tank – you will run out of fuel more quickly and may suffer premature fatigue.
Carbohydrate feeding before and during prolonged activity has been shown to reduce the time to fatigue by delaying glycogen depletion, so ensure you eat plenty of carbohydrates to keep these stores topped up. When you are training, at least 60% of your daily calorie intake should come from carbohydrates (e.g. pasta, rice,
bread, cereals and potatoes).
However, you should not base your carbohydrate intake on percentage alone. This is a good indicator but it is best to also follow the below-suggested guidelines, which are based on grams per kilogram of body weight.
- Moderate duration/ low-intensity training: 5-7g per kg per day
- Moderate to heavy endurance training: 7-12g per kg per day
- Extreme exercise performance: 10-12g per kg per day
In the same way that varying your training and racing helps to promote fitness and prevent boredom, varying your diet will also mean that the essential energy, nutrients and fluid that support your activity are easier to obtain. While you can never prevent coughs and colds occurring, certain nutrients can help to maintain a healthy immune system.
Eat a balanced diet including plenty of carbohydrate from a range of sources including starchy foods such as bread, pasta, rice and potatoes, as well as simple carbs such as honey, jelly and marmalade.
Fat is also a source of fuel for your body. A trained athlete can tap into fat for fuel much more quickly than someone less trained. Physical training will improve your body’s ability to use fat as fuel and also extend your time to fatigue. Consuming fat during exercise is not advised because it takes a long time to digest but including it in your daily diet will enhance your performance. Fat is also essential in the diet for providing soluble vitamins. As an overall proportion, the percentage of fat in the diet should comprise no more than 25-30% of total energy intake, with less than 10% coming from saturated fat.
Protein is also important since it contains the essential amino acids that are the building blocks for muscle growth and repair. While meat and dairy products are good examples of protein-rich foods, it should be remembered that high doses of protein won’t develop strength any more than a sensible intake of around 1.5 grammes per kilo of body weight per day.
Vitamins and Minerals
A diet with plenty of fresh fruit and vegetables should provide the vitamins and minerals that are needed to keep the body healthy and sustain the immune system. While there is no evidence that supplementing the diet with extra vitamins will improve performance, anyone who thinks their diet might be deficient in certain nutrients may benefit from taking a daily multivitamin supplement or a boost of vitamin C or zinc, which can help to sustain the immune system.
In many cases, athletes begin training without being hydrated, which not only affects the quality of training in the short term but makes it even harder to hydrate in time for their next training session.
In an ideal world, drinking strategies are individually tailored, as some people are naturally heavy sweaters compared to others. However, given that not everyone has access to the help that they need; the following tips are widely recognised as guidelines for fluid intake before, during and after exercise:
- 5-7 ml/kg before training before training
- 300-580ml every 15-20 mins during training but no more than 500ml per hour
- 500ml (approx) after exercise depending on your sweat loss during exercise (note the advice on weight loss below)
You can be much more accurate about how much to drink after training by weighing yourself before and after. For every kilogram lost this should be replaced with 1.5L of fluid. Weigh yourself wearing the least amount of clothes possible to improve the accuracy of the results.
The easiest way to tell if you are hydrated enough is to monitor the colour of your urine. It should be light-pale yellow, not a dark yellow or brown. Drink the higher recommendation for fluids if your urine is darker in colour.
Stay well hydrated throughout the day (a minimum of 2 litres of fluid per day) drinking little and often and in the periods before, during and after exercise. An excellent way to ensure a high fluid intake is to carry a water bottle around with you at home and at work to help promote regular drinking.
Remember that you will need to drink more in hot and humid conditions as well as in air conditioned environments!
Hydration – the facts
- A 2% reduction in body weight can significantly decrease performance
- Fluid loss is related to exercise intensity and duration, environmental conditions and individual characteristics such as fitness level
- Fluid lost through sweat conditions key electrolytes such as sodium and potassium which must also be replaced
- Sports drinks have been shown to negate the negative impact of not being properly hydrated on prolonged performance
The effect of body water loss on performance
2% Impaired Performance
4% Capacity for muscular work declines
6% Heat Exhaustion
10% Circulatory collapse and heat strokes
Drink fluids that contain sodium
To maintain healthy levels of sodium in the blood, it is advisable to consume fluids during training that contain sodium (i.e. fitness drinks or sports drinks). Drinks containing sodium also have the added benefit in that they are designed to rehydrate you quicker and more effectively than plain water.
As soon as you have crossed the finish line, it is critical that you provide the body with the nutrients
that it needs, in a quick and practical manner, so that the refuelling, replacing lost fluids and recovery processes are optimised.
By consuming a high carbohydrate meal or snack that also includes a small amount of protein, such as chocolate milk or a Clif Bar within 30 minutes of finishing you will ensure that the carbohydrate is absorbed quickly and efficiently.
Replace lost fluids
Replacing fluid and electrolytes that you have lost through sweat is also equally important in recovery. Do not drink more than 500ml of fluids immediately after the race. You can be more accurate about how much to drink after racing by weighing yourself before and afterwards. For every kilogram lost in body weight, you should aim to replace with 1.5 litres of fluid. Weigh yourself wearing the same amount of clothes to improve the accuracy of results.
Consume a high carbohydrate meal/snack within 30 minutes of completing the exercise. Aim for an intake of typically 1.0 – 1.2g of carbohydrate per kg body weight (50-150g) immediately after exercise and repeat after 2 hours until normal meals patterns are resumed. A daily carbohydrate intake of 7-10g/kg body weight is required to optimise carbohydrate stores for those completing heavy training.
Increase protein in your immediate ‘post race’ nutritional strategy to aid the regeneration process.Share the GBIBR on:
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