Dehydration Makes You Work Harder and More Injury Prone
Staying hydrated is essential for optimal health and exercise performance, but then you probably already know that! But did you ever wonder how dehydration actually works?
Water accounts for almost 60-70% your total body weight and these are it’s main jobs:
Help to regulate body temperature
Protect and lubricate body tissues
Transport nutrients around the body
Remove waste products from the body
And it’s a vital component of blood plasma
You lose water when you go to the toilet (and a tiny bit when you cry or blow your nose of course), and of course by sweating. Losing more water than you consume leads to dehydration.
Dehydration lowers the volume of your blood.
Lower blood volume means your heart rate has to increase to achieve the same output to deliver the same amount of oxygen to your muscles
Dehydration makes you fatigue faster
It can affect concentration
Reduces quality of your movement
Which increases risk for injury
So the risk of dehydration is increased by exercise AND the impact of dehydration can then impair your performance.
Increased sweat rate during exercise can reach 3-4 litres/hour in some athletes, although 1-2 litres/hour is more typical. Exercise mode, duration, intensity, frequency and the type of environment it is being performed in are all factors.
Could dehydration be making you work harder in training without you realising it?
Research suggests that hypohydration (reduced body water stores) has a negative effect on exercise performance. Although it’s difficult to blind participants to how much they are drinking, and methods to induce dehydration are uncomfortable and unfamiliar, there are some more robust blinded studies being performed which support the view that dehydration of 2-3% body mass impairs exercise performance.
How do you know how much you need to drink?
The body has a tightly regulated homeostatic system, designed to maintain normal hydration levels. It makes us feel thirsty to encourage drinking and maintain the body’s water level within 1-2% of its ideal. But some athletes don’t have a particularly strong “thirst drive” and drinking enough is a bit of a battle. If you’re a heavy sweater, you might be losing more than you think. It’s also possible to underestimate how much we sweat in the winter when we wear more layers of clothing which soak up our sweat.
And there is no “one size fits all” recommendation; fluid needs are highly individual. The more training you do, the warmer the weather and your own individual physiology will govern how much you need to drink. The best approach is to measure sweat rates and have a personalised hydration plan. This would take into account how much you need to drink and exactly what you should drink as sweat contains more than just water.
Different fluids also have varying effects on hydration status. What do you guys choose to hydrate with during or after training?