A Guide to Staying Hydrated During your Triathlon

A Guide to Staying Hydrated During your Triathlon

The idea that the more water we drink, the more hydrated we are is a common misconception. Many athletes will end up drinking more than their usual amount of water just before a big event. However, is this necessary or beneficial to the body? It’s easy to think we’re underdoing our water intake during the day, but the dangers of over-drinking are more common than you’d think.

To achieve ideal hydration, a hydration strategy should be devised. This involves understanding your body’s capabilities and ensuring that you do not deny your body of what it needs. ‘Pre-loading’ is one way of ensuring that your body has an adequate fluid and electrolyte level before the event. It minimises the negative aspects of dehydration, which in turn then increases performance and decreases the risk of illness.

What is hydration?

Hydration, by definition, is the process of water absorption. The human body is made up of 50-70% water (dependant on body fat and muscle weight), and every cell, tissue and organ in the body relies on adequate hydration to function properly.

Water helps our body to not only maintain temperature, remove waste and lubricate joints but also helps us to reach peak performance levels during exercise. A third of the body’s water is found in extracellular fluids such as blood, and one of the most important electrolytes in these fluids is sodium. Sodium is responsible for fluid and water regulation, where the normal levels are between 134 and 145mg/l. Sodium levels can be controlled through diet, with the daily recommended dosage of sodium being 2,300mg, this is the equivalent to 1 tablespoon of salt. Substantially, the more sodium in the body equals more fluid. The less sodium, the less fluid there is.

All athletes will know that with exercise, comes sweat. Also, with sweat, comes dehydration. When exercising, the importance of staying adequately hydrated increases due to the body losing significant amounts of electrolytes through sweat. Many triathletes will find themselves struggling with exercise if they have not been properly hydrating, ultimately their sodium levels will be at a low causing their performance to be at a low. Below is a handy guide with step by step instructions on how to make sure you’re adequately hydrated before, during and after a triathlon:


  • Calculate your individual sweat/sodium loss. Each person sweats different amounts and therefore loses different amounts of sodium. You can use this handy tool to help you calculate.
  • It is crucially important to remember that drinking too much fluid can have a devastating impact on not only performance but also health. Not only can it cause headaches and uncomfortable stomach bloat but drinking too much liquid can cause a condition called hyponatremia, which is when sodium dilution happens too quickly and at too high of a rate. 10% of tested ironman contestants were found to experience this, and this condition can be fatal.
  • Maintain a consistent level of hydration before an event, over a more extended period. It’s useless not keeping yourself hydrated regularly and then expecting yourself to perform well. Many athletes recommend drinking water throughout the day before the event, right up until you go to bed, to ensure you’re still hydrated the next day.
  • Before a race or a triathlon event, ensure that you consume a strong electrolyte loaded drink. This boosts endurance performance and reduces cardiovascular strain. Low sugar sports drinks, which often contain carbohydrates and electrolytes to increase energy levels can be highly useful during intensive training sessions, although it's then necessary to check those drinks aren’t containing higher sodium levels or excessive caffeine levels (200mg-300mg is the recommended caffeine dosage a day).


  • The body produces sweat to cool you down. 20-25% of muscle energy is movement; the remaining 75-80% of muscle energy is used in generating heat. If this heat isn’t combatted, body temperature will rise to the point of damage to performance and health of the athlete. Water intake helps to combat higher body temperatures.
  • During certain triathlon events, high fluid intake isn’t always necessary. Triathletes might find themselves not always needing to have a drink during or after swimming but might feel more of a need to have water while cycling or running. Although you shouldn’t deny your body water if you’re feeling thirsty, you won’t need to drink vast amounts during every event. During less intense periods of exertion, take small mouthfuls every so often.
  • During more intensive bouts of exercise, don’t always wait to feel thirsty before drinking. If you find yourself sweating a lot, take a swig of drink. Your body will cue you as to what you need.
  • Rule of thumb: the less intense the exercise is – water will suffice. If the exercise is more intense, drink an ISO+ type drink, to help restore the body’s natural electrolytes. Avoid drinking fluids unnecessarily, as this can cause gastrointestinal upset and stitches. Also, avoid sports drinks with too high of a concentration of sodium per litre. Around 1,380mg/l is fine.


  • After a triathlon or event, remember to not suddenly increase your fluid intake once you’ve finished physical exertion. Give your body time to adjust and acclimatise to the conditions.
  • Let your body recover by cooling yourself down but avoid ice cold drinks. These can cause stomach upsets and can also cause your body to go into shock if your body temperature hasn’t had a chance to decrease naturally.
  • Avoid excessive alcohol consumption after an event. Your body is least likely to absorb alcohol at its standard rate when you’re even a little bit dehydrated. If you do drink, do so moderately and with regular water consumption too.
  • Continue to maintain the same levels of hydration as you did in the days before the event. Your body will have become acclimatised to those levels of fluid intake, so it’s important not to cause it any unnecessary stress or loss.

Written by Catharyne Walton-Matthews