Dangers of dehydration during exercise

by Graeme Hilditch

If you head out for a run in an already dehydrated state, there are several health risks you should be aware of.

Although over hydration (water toxicity) is also something that everyone who trains in the heat should be aware of, most people find themselves badly dehydrated when training in these warm conditions and it’s something that can easily be avoided.

So, what are the dangers and what effect does dehydration have on your body when you exercise?

  • Increased Heart rate - when dehydrated, your blood becomes thicker and your heart has to beat faster to pump the thicker blood around the body. This puts more strain on the heart which is not only dangerous but also makes you far more fatigued.

  • Muscle cramps - the muscles need water to function properly and when dehydrated, they are not able to contract as well as they should. Throw fatigue into the mix and you increase your chances of developing a severe cramp or even a pulled muscle.

  • Heat Stroke - Your internal fluids levels help to cool you down and prevent your body temperature from going to high. If you become severely dehydrated, you increase the risk of developing heat stroke, which can be very serious.

  • Performance drop - Although more damaging to your pride than your health, if you run or ride in a state of dehydration, then it will show in your performance. You’ll being to suffer greatly from fatigue and slow down significantly.

Tips for Running in the Heat

Once you are confident that you are well hydrated before you head out for your run, what are the best tips for training in the heat?

Ultimately, common sense has to play a big part in how you approach training or racing in the heat, but here are our top tips:

  • First thing or last thing - If you can, try and get your session done first thing in the morning or last thing at night. Your performance will be better, you won’t become as dehydrated - besides - it is a far more beautiful time of the day to train.

  • Forget about splits - There are times and places to put in hard sessions, and in the heat is not one of them. By all means, if you are well conditioned to the training in the heat, then be my guest, but for most runners and cyclists, steady and easy paced runs are far less dehydrating and far safer to do.

  • Wear a hat - Try to avoid the sun from heating your head and wear a cap (preferably white) to reflect the heat. This will help you to avoid getting sunstroke.

  • Wear white kit - White clothes help to reflect the sun and keep you cool(er)

  • Go the gym - If you have access to a gym, give your run / ride a miss and head to a lovely air conditioned gym and work on your conditioning instead.

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