Does Dehydration Impair Exercise Performance

March 11, 2021

Does Hydration Impair Exercise Performance?

Do you pay attention to your fluid intake? Do you find you sometimes forget to drink? Have you ever thought about what impact your hydration levels may have on your running performance?

In this episode we explore all these questions and more. We delve into the scientific research to gain an understanding of the current thinking around hydration and exercise performance as well as consider the impact of poor hydration on exercise performance.

We also endeavour to help you understand WHY appropriate hydration (euhydration) is important for YOUR running performance and give you lots of hints and tips on how to ensure you are getting adequate fluids into your daily routine.

LISTEN HERE Episode 5: Does Hydration Impair Your Exercise Performance?


Does Hydration Impair Exercise Performance?


Outlining the current scientific thinking and research on hydration and exercise performance. Looking at study methodology and its limitations and how scientists are trying to overcome these difficulties.

Moving on to consider “Involuntary Dehydration” and how easy an athlete could become overtly dehydrated over a short period of time.


Giving you an understanding of normal fluid regulation within the body so you better understand how dehydration could occur so easily e.g. did you know that water is the most abundant molecule in the body making up between 45% and 70% body mass and is very tightly regulated.


Discussing some of the health outcomes from severe dehydration whilst also pointing out some key symptoms to observe for which may suggest underhydration e.g. thirst, dark urine, dry lips, mouth, and eyes, and dizziness.


Delving into the impact of hydration status on exercise performance and introducing the condition called hypertonic hypovolemia ie intracellular dehydration. Moving on to discuss the physiological impact of dehydration including: reduced muscle function, increased cardiovascular strain and increase of core body temperature.


Introducing a new debate in the Sports Nutrition world: drinking to thirst versus planned drinking, We give you our thoughts on this.


Introducing the Female Factors


Outlining some hints and tips to introduce to ensure you are appropriately hydrated on a daily basis AND for your running training. Some ideas include: Remembering to drink fluids before, during and after your run, use a camelback if you like to remain hands free, set a reminder on your phone to drink regularly.


Does Hydration Impair Exercise Performance?

  1. There are no differences in effects of dehydration between men and women.
  2. There no studies that I am aware of looking at women compared to men and the few female only studies carried out show similar results to men.
  3. In general, women have a lower body water percentage than men. This is thought to be due to the fact that women have more tissue than men.
  4. The ideal water percentage for adult women will fluctuate between 45 and 60%, while the ideal percentage for adult men will be between 50 and 65% of the total body.


Does Hydration Impair Exercise Performance?

1) Hydration is a limiting factor in exercise performance – so could make the difference between you winning or losing in reaching YOUR goals.

2) The current research on hydration status is conflicting regarding how dehydrated an individual needs to be for performance to be impaired

3) Our recommendation would be to remain EUHYDRATED – so appropriately hydrated on a day to day basis

4) Ensure you drink BEFORE, DURING and AFTER training so you do not go into your next training session already in a hypohydrated state.

5) Remember that although the degree of dehydration linked to performance effects is uncertain, it is known that more than 5% dehydration causes cognitive dysfunction and as much as 15% can lead to circulatory failure and death…..but this is extreme.

6) Be on the lookout for any symptoms that may suggest you are poorly hydrated including:

  • feeling thirsty.
  • dark yellow and strong-smelling urine.
  • feeling dizzy or lightheaded.
  • …………..But there are many others.

7) There are many factors that will determine how much fluid YOU require on a daily basis….a one size does not fit all.

8) Finally, PLAN your fluid intake for your training AND your everyday hydration using our tips as your guide to ensure that hydration does not become the limiting factor in your running performance.

Related Episodes:

Sports Nutrition Foundations for Female Runners

Hydration and Running Performance


The suggestions we make during this episode are for guidance and advice only, and are not a substitute for medical advice or treatment. If you have any concerns regarding your health, please contact your healthcare professional for advice as soon as possible.

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