Hydration and Athletes

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Euhydration – State of Water Balance

Hyperhydration – Positive water balance

Hypohydration – Negative water balance

Dehydration – Excess loss of fluid

Rehydration – Fluid replacement

Hyponatremia – When there is low sodium concentration in the blood, detrimental to health.


We all know that the body is mainly compromised of water. Approximately 45% – 70% is water.  Water in our body isn’t just plain water, so the idea that we can drink gallons and all will be well is very incorrect. Our body water also contains a wide range of electrolytes. Electrolytes are salts that are dissolved into the body.  

This magic combo helps regulate the fluid balance in our bodies, keeps the acidity of the blood in check and also assists with muscle function. So it is a good idea to clock up the cups of water during the day.

Our body and water


This is can be a real problem to long distance runners, I am talking here ultra-runners but even shorter distance runners if they don’t hydrate adequately. This year with all the water problems that we experienced with races this one hit quite close to home.

Hyponatremia occurs when blood sodium concentration falls to an abnormally low level, prompting a rapid and dangerous swelling of the brain that can result in seizures, coma, and death. Although hyponatremia is often associated with prolonged exercise, it can also occur at rest when too much fluid is ingested too quickly. Excessive drinking is a key risk factor for hyponatremia, but it is possible for hyponatremia to occur—without excessive drinking—in dehydrated athletes during very prolonged exercise as a result of large sodium losses in sweat.


The risk of hyponatremia can be reduced by making certain that fluid intake does not exceed sweat loss and by ingesting sodium containing beverages or foods to help replace the sodium lost in sweat. For most athletes, dehydration remains the primary challenge to physiological homeostasis and performance, but hyponatremia should be recognized as a possible threat to those athletes who drink more fluid than they lose in sweat.


Now that we have look at worst case scenario, how do we actually loose water during exercise? When we are active, by running or other physical activities, our bodies create heat. When our bodies are hot we sweat, the evaporation of the sweat cools down our bodies. Failure to regulate our temperatures can be very bad for athletes, they lose up to 3 litres of water an hour during intense sessions.

Try this if you want to see how much water you can lose during a training session. Get your butt naked and weigh yourself before and after exercise. During this session do not hydrate to get a more or less indication of how much water you have lost. For every 1 kg you lose (or 2.2lbs) of weight you lose it means you have lost approximately 1 litre of fluid from your body.


We have all at one point in our lives experienced dehydration if various degrees. What is it actually? The most basic definition our bodies loose more fluid than what it takes in. This impairs some of our body functions, as you can remember we run on water, our blood volume decreases and places extra strain on our other organs. Dehydration as low as 2% can impair sports performance.


We know it’s important to hydrate but how much should we hydrate before we exercise? Here are some recommendations. 5 – 7 ml of body weight (2-3ml per lb) at least 4 hours before session.  I hear you when you say what if you fall out of bed and then go run. Hydrate when you wake up as much as possible without making you uncomfortable. For an average person it’s about 300ml of liquid.

During exercise replace losses from sweating. If you drink a sports drink and not just plain water it can be a source of energy during to help you push a little extra. Aim to replace 80% of losses whilst exercising.  

After exercise and hour or more will likely result in dehydration. This is so important to rehydrate after those long runs. What I like to do is drink something that will replace some of those electrolytes that we loosing during intense exercise. I use to get such headaches and since doing this it has helped so much.

Hydration needs for athletes

I would love to hear from Ultra runners and other long distance runner’s do you have a hydration plan when you run or do you just wing it and hope for the best. I have learned so much about what my body need hydration wise in the past couple of years. Let me know if I have missed something.

If you want you can join me on my Facebook page https://www.facebook.com/SpookyBooZoo/

A lot of information is from the Shaw Academy sports nutrition course.

Categories: HealthTags: , ,


  1. I just wing it. Usually depending how hot the day is and my body condition, I would drink more during the race. I sometimes carry my own bottle and definitely good to have one for ultras because an aid station could be miles away. I usually drink too much and have to use the rest room, and also by the end of the race, I feel too bloated to take in any more liquid. Yes, for ultras, we not only drink water but other stuffs like pickle juice to replenish the sodium lost. I’ve only done two ultras of 31 miles, so, I guess I should think more about water replenishing strategy for longer races.

    Liked by 1 person

    • We have been problems with water supply with our races, one 42km run the athletes didn’t have any water for the first 20km and no warning there won’t be. I was so surprised to see how aggressive some became because of dehydration. Thanks for the read and I also wing it most of the time 🌸

      Liked by 1 person

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