How to stay hydrated during exercise - pre, during & post exercise guidelines

As we start to move in to the warmer months of the year hydration during exercise becomes even more important. If the fluid lost during exercise is not replaced dehydration will occur. Dehydration causes dramatic decreases in training and sports performance and if untreated can result in overheating, loss of consciousness and death. The large variability between individuals makes it impossible to prescribe a 'one size fits all' hydration plan but I have put some pre, during and post exercise guidelines together that should work for most of us. Check them out!

We lose water during exercise by sweating - this is the body's cooling mechanism. As sweat evaporates off the skin heat is lost from the body, and the body is cooled down. A number of factors influence the amount of sweat lost during exercise, these include:

• The intensity of exercise - sweating increases as exercise intensity increases.
• Ambient temperature and humidity - sweating increases as temperature and humidity increase.
• Body size - sweating typically increases as body size increases.
• Level of fitness - fitter people tend to start sweating earlier in exercise.
• Gender - men tend to sweat more then women.
• Genetics - some people just tend to sweat more then others.

Pre-Exercise Hydration Goal: Aim to start exercise well hydrated.

• Drink fluids frequently throughout the day and drink approximately 400-600ml of fluid in the 2-3 hours leading up to the start of exercise.
• Drink pproximately 200-300ml of fluid in the 15-30min immediately before exercise.
• There is no performance benefit of being over hydrated before exercise. Being over-hydrated may decrease performance by causing bloating, gastrointestinal discomfort and toilet breaks.
• Urine that is pale yellow in colour is a good indicator of being well hydrated. Weighing yourself before exercise will give you a good indicator of what your weight should return to following exercise.

During Exercise Hydration Goal: Aim to replace as much lost fluid as possible during exercise.

• Drink approximately 200-300ml of fluid every 15mins during exercise, most people can tolerate this however you need to find a rate that is comfortable for you. This will differ for everyone and for the type of exercise being performed. 
• Drinking too much too quickly during exercise may decrease performance by causing bloating, gastrointestinal discomfort and toilet breaks.
• Begin replacing fluids early in exercise. Thirst is not a good indicator of hydration, a significant amount of fluid will have already been lost by the time you start feeling thirsty.
• Take every opportunity to drink during exercise,

Post-Exercise Hydration Goal: Aim to replace all fluid lost during exercise.

• Continue to drink approximately 200-300ml of fluid every 15mins following exercise until you are well hydrated. Rehydration can take 2-6 hours depending on the intensity and duration of exercise performed.
• Sweating continues after exercise has ceased so this needs to be accounted for by ongoing rehydration post exercise.
• Urine that is pale yellow in colour is a good indicator of being well re-hydrated. Returning to pre-exercise weight is also a good indicator.

Related Reading

• Sports drinks VS water: what's recommended

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