Hydration in sport

Hydration in Sport: Improving Athlete’s Health and Performance

Water is an essential constituent of the human body as it makes up approximately 60% of its whole composition. Hydration in sport is very important because dehydration will negatively impact an athlete’s performance. All cells, organs and tissues are primarily comprised of water making it vital for correct function of all physiological processes in the body. Water transports nutrients and oxygen into cells, regulates body temperature (thermoregulation), acts as a lubricant and shock absorber to protect joints, the brain and foetus during pregnancy, supports digestion & removal of waste products, and is also required to breakdown food so we can use it as energy.

Proper Hydration for Athletes

Proper hydration for athletes is linked to the correct amount of water and electrolytes they need to consume before, during and after exercise to prevent dehydration to maintain sports performance.

To satisfy the demand of water for bodily functions, fluids (typically drinking water) should be consumed regularly throughout the day. If you don’t drink enough water, then you are likely to become dehydrated. In this instance, the body cannot perform at its best and severe dehydration can cause serious health problems, even death. Everybody’s body shapes and sizes are different, but it’s typically recommended to consume 1.5 – 2 litres of water each day to stay hydrated.

There are many different factors that can influence hydration status and need to be considered to apply suitable hydration strategies to prevent dehydration. Athlete’s need to know what to drink during exercise to maintain hydration levels and promote performance. As previously mentioned, your body utilises body water to function and metabolise food for energy, but other additional stressors that may accelerate body water losses include physical activity/exercise, environmental temperatures, illness, and different dietary practises will also play a part, e.g., high/low carbohydrate intake.

Now that we’ve discussed the importance of proper hydration for athletes, we’ll now move our focus to how hydration is influenced by exercise.

Hydration in Sport – Role of Sweating

During exercise or any physical activity for that matter, which can include daily chores like gardening or hoovering, our core body temperature will rise. When this occurs our body will automatically respond by trying to maintain a level of homeostasis by cooling itself down (thermoregulation). By doing this, the body will start to sweat allowing water to be evaporated from the skin and release heat.

60% of the human body is made up of water which is why water for athletes is such an important area of sports nutrition to maximise their performance.

During prolonged periods of exercise sweat rates can increase and lead to dehydration if fluids are not consumed to alleviate this deficit. The effects of dehydration on sports performance are always negative and in severe conditions, dehydration can be hazardous to health. A loss of just 2% body mass of water can be detrimental to performance, so maintaining a good level of hydration by replacing fluids lost by sweating with appropriate fluids is advantageous to promote performance.

How to Stop Dehydration?

 The first point of call before doing any exercise, or more importantly competing if you’re an athlete, is ensuring that you begin in an optimally hydrated state. Deciding what to drink before exercise can make a big impact on performance by avoiding starting exercise in a dehydrated state.  So, how does dehydration affect sports performance? Turning up dehydrated puts added pressure on your body to supply muscles with nutrients and oxygen, meaning your heart needs to work much harder to meet that demand resulting in premature fatigue. 

There’s a very easy way to determine how hydrated you are by checking your urine. Colour, volume and smell are good indicators of hydration status – dark colour, small amounts and strong smells can all signal dehydration. Monitoring hydration status should be a key part of your training! See the urine colour chart to manage your hydration practises.

Hydration for athletes

During exercise, you should attempt to replace some of the water lost through sweat, but this should never be done at the expense of gastrointestinal (GI) discomfort. Therefore it’s very unlikely that you’ll be able to consume similar amounts to that lost during exercise, as this can be at rates of anything between 1-2.5 litres per hour!! (See below). You’re better off drinking to thirst during training, and with regular hydration monitoring strategies, you can estimate your body’s sweat rate during such exercise and transfer appropriate drinking habits into a competition.

How to rehydrate quickly during exercise?

This can depend on training duration, but water is still the first point of call. This will be sufficient for short (less than 60 minutes) training sessions, but as training increases, and also if you’re training multiple times per day, water alone may not be enough. Sweat contains electrolytes (such as sodium) as well as water, so simply drinking only water when sweat rates are high during prolonged training, you could be susceptible to hyponatremia; an imbalance between body water and sodium levels causing a diluted effect.

In this instance, drinking a solution that contains both water and electrolytes (sodium, potassium & magnesium) is important to correct that balance. Electrolytes aid absorption across the intestine, retain body water in cells and are also involved in muscle and nerve function.

Carbohydrates may also be required during high volume training, but without adequate hydration, it will not be absorbed properly. This is a likely cause of GI distress so before you start with the gels, make sure you’ve got enough fluids on board.

An ideal solution for hydrating before, during and after training is Hydra+ as it contains the required amount of electrolytes when mixed with 500ml water.

It also contains a small amount of carbohydrates that is sufficient to fuel your training and boost brain and muscle function without unwanted GI problems.

How to Rehydrate Quickly Post-Training?

Athlete’s should know what to drink after exercise to ensure they rehydrate sufficiently and are ready for their next training session, as poor rehydration can impair recovery and subsquent performance.

As you’re calculating your changes in body weight during training based on the amount of water is lost, you can use this data to rehydrate for optimal recovery. Drinking 1.5 times the total body weight loss is recommended and this should always contain sodium to promote fluid retention, otherwise, it will be passed out in the urine. 

Hydra+, along with sufficient water in the hours after training, is a good strategy to rehydrate.

But,  when considering other nutritional requirements after training, your body may also need protein and carbohydrates. Milk is a natural source of protein, carbohydrates and sodium, and has been shown to be more effective for hydration, protein synthesis and glycogen replenishment compared to commercialised sports drinks. So if you have milk to hand, then this could be your best choice.

Another factor to consider is the weather. When training in hot conditions, sweat rates will be greater in the body’s attempt to cool itself. Therefore, it would be prudent to include more fluids with added sodium, both during and after training.

What is The Best Recovery Drink?

Cow’s milk is the best recovery drink as it a natural combination of protein, carbohydrates and electrolytes to maximise recovery and rehydration after exercise.

Measuring Sweat Rates

Calculating your sweat rate is a very practical and important technique for getting the most from your nutrition to maximize performance. Weighing yourself before and after training and measuring how much you drink during that session is all you need to get a good estimate.

Sweat rate calculation:

Pre-training weight = 75kg

Post-training weight (before showering & dry off any excess sweat) = 73kg

Change in body weight = 2kg

Fluid intake during training = 1 litre

Training duration = 2 hours


  • Fluid loss (L) = pre-weight (75kg) – post-weight (73kg) = 2kg
  • Total sweat loss (L) = change in weight (2kg) + fluid intake (1L) = 3kg
  • Sweat rate (L/hr) = total sweat loss (3kg) ÷ training duration (2hrs) = 1.5 L/hr

Hydration for Athletes: Take Home Points

Hydration Plan

  • Hydration is vital for health as the body is 60% water.
  • It helps in nutrient & oxygen transport, energy metabolism, thermoregulation, joint & organ protection, digestion & renal function.
  • It is important to regularly drink fluids to maintain hydration, particularly during exercise and recommended to assess your own sweat rates if physically active.
  • Just a 2% reduction in body weight from dehydration can negatively impact performance.
  • Drinking sufficient fluids that combine water, electrolytes and in some cases carbohydrates before, during and after long training sessions is required to ensure adequate hydration for athletes to maintain their performance.
  • Consume 1.5 x total body weight loss after exercise to rehydrate properly.
  • Be aware of weather conditions and remember to drink more in the heat.



Do athletes need to care more about hydration than normal people?

Staying hydrated is vital for athletes who undertake larger than normal volumes of training, and therefore must drink a lot more fluids to match that loss through sweat. Dehydration impairs performance and therefore must be avoided to maintain training intensity. Normal people who go to the gym and exercise frequently also need to prioritize hydration.

How do you measure hydration status?

Athletes can measure their hydration status by analyzing their urine color and frequency of urination. Urine should be a clear, straw-like color to show good hydration levels, and going more frequently, whereas a darker yellow color, stronger smell, and going less often suggest dehydration. Athletes can also measure their sweat rates by weighing themselves before and after training, and factoring in fluids consumed to track how much they have sweat, and how much they need to drink during/after training

Which drinks can cause dehydration?

Drinks that are classed as diuretics, mainly alcohol and caffeinated drinks over ~350mg, may be linked to dehydration

How reliable is the urine color test to analyze the hydration status?

A urine color test is a very reliable and practical way of assessing hydration status. Some foods or supplements including B vitamin drinks/supplements and fresh beetroot can discolor urine so just be aware of this and think about the frequency and the volume of your urine as to whether you are hydrated or not.

Should every athlete measure sweat rates during exercise?

Monitoring sweat rates are a great way for athletes to determine the correct amount of fluid they need after exercise to rehydrate. Athletes will generally sweat more in hotter conditions and climates, therefore needing to drink more to rehydrate during and after training. Having a sweat patch test done during training helps to accurately analyze your total sweat and sodium losses so you know how much and what type of drinks you need to consume to stay fully hydrated to maximize performance.

Will drinking too much water affect sports performance?

Water is important for hydration but you can have too much of a good thing, meaning that drinking too much water can be detrimental to sports performance. Drinking too much water can create an imbalance between the amount of water and sodium in your body, which can lead to Hyponatremia. Athletes will be okay only drinking water for shorter training sessions, typically 1 hour or less. Beyond this, the addition of electrolytes could help maintain fluid/sodium balance in the body.

How does dehydration affect performance?

Dehydration causes:
1 ) Premature fatigue
2 ) increased heart rate
3 ) impaired thermoregulation
4 ) reduced concentration and cognitive function
5 ) greater reliance on muscle glycogen for energy
6 ) higher RPE
7 ) joint stiffness.

What are the best drinks for hydration besides water?

Sweat is made up of water but also contains vital electrolytes such as sodium, potassium, and chloride. Consuming drinks or supplements that contain these electrolytes helps to rehydrate better than water alone. Cow’s milk, orange juice, and rehydration solutions like Diuralyte better hydrated than water alone.

Should athletes replace water with sports drinks?

Water is irreplaceable. Sports drinks can be beneficial if you use them to complement water instead of using them to substitute water. The main ingredient of sports drinks is water, but the addition of electrolytes and carbohydrates make them a good energy drink during intense training sessions.

How much should I drink before training?

Drinking enough fluids to ensure your urine is a clear color and you are well hydrated before training is key. A good rule of thumb is to drink 400-600ml two hours before exercise.

How much should I drink during training?

So long as you are well hydrated before you start training, you can drink to thirst for sessions less than 2 hours long. On the other hand, some sports like cycling and triathlon that require strategic hydration strategies for their events will need to practice these during training to match their measured sweat rates.

How much should I drink after training?

Measuring the changes in your body weight during training will give you a good idea of how much to drink to rehydrate. Weighing yourself before and after training to calculate your weight loss (e.g. 1kg), you should aim to drink 150% of this (e.g. 1.5L) in the hours after training to replace lost fluids and allow for the additional sweat lost as your body continues to cool itself.

How much water should I drink a day?

This will be different for everyone based on their body weight and activity levels, but a good daily target is to consume 30ml per kg of body mass, plus an extra 500ml-1L per hour of exercise.

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