The Importance Of Hydration While Exercising
Hydration during exercise is important to replace fluids lost during training. If fluids are not replenished, a runner will become dehydrated and this will impair their performance.
To keep hydrated, it’s important to keep fluids up during training and to match fluid intake with what is being lost through sweat. According to Nutrition Australia there is a small rise in body temperature for each small increment of fluid loss. This means it’s important to drink during, as well as before and after exercise.
Dehydration affects performance by causing an increased heart rate, impaired heat regulation, increased perceived exertion, reduces skill level, reduced mental function, and makes exercise harder than usual by making you feel more fatigued.
Symptoms of heat stress include headaches, dizziness, nausea and muscle cramps. Depending on the exercise you are doing, you should be able to take breaks and replenish your fluids, especially in hot weather.
What to drink
Water is important for rehydration. Sports drinks¹ may also be useful for keeping up glucose levels during activities that last for an hour or more. Sports drinks include carbohydrates and electrolytes, are easily absorbed by the body and can help to replace minerals lost through sweat and also provide a source of fuel with some added simple carbs in sugars. Other options include cordial, fruit juice, soft drink or a liquid meal supplement.
When to drink
Ideally you should drink enough fluid to match what is being lost, this means replacing fluids throughout your training session. While this isn’t always practical for some sports, during a run you can take a water bottle with you and replenish throughout the run. You should drink around 500ml of fluid a couple of hours before exercise, and the same again afterwards. During physical activities you should take in about 200ml of fluid every 15-20 minutes.
Avoiding heat stress
Heat stress occurs when sweat can’t evaporate from the skin fast enough to cool the body down. During exercise, the body’s temperature rises, but it is important for the core temperature to be cooled down to 37⁰C. Heat stress reduces performance and can cause nausea and headaches and is mainly caused through loss of excess fluids.²
To avoid heat stress occurring, don’t exercise in hot weather, keep hydrated, take rests in the shade, and sponge your body lightly with slightly warm (not super-cold) water. If symptoms of heat stress continue you should seek medical assistance.