Staying Hydrated in the Heat – What you Need to Know

Water is essential to life, and a lack of it will soon lead to serious health issues and ultimately to death. A lean person comprises around 70 – 75% water, losing just 1% of this will leave you dehydrated, losing 2% and things are getting serious.

Water carries heat away from the vital organs and transports it to the surface through your skin, where it is removed as sweat. The sweat evaporates from the surface of your skin and this cools you down.

If you do not replace this water you will quickly become dehydrated. Being dehydrated effects the efficiency of our muscles, and adversely effects concentration and decision making.

So how do we ensure we stay hydrated in hot weather? Here are our tips to staying hydrated in the heat.

1. In hot weather drink before you begin your hike, up to 500ml if possible and drink it slowly over a period of time, as you are driving to the start point for example.

2. Drinking plain water is good, but during intensive exercise or excessive heat you need to replace lost electrolytes, which are essential minerals and salts lost when you sweat and which are vital for the correct functioning of the body.

3. Make your own electrolyte solution by mixing water and fruit juice in a ratio of 1:1, add a few pinches of salt. This will also contain around 6% carbohydrate, the same as in expensive energy drinks, but with less sugar and zero caffeine.

4. Drink when you begin to feel thirsty, it is better to drink a little and often, rather than chugging down large amounts in one go. How much you need to drink depends on the level of exercise, the temperature, your own level of fitness, and your body mass.

5. Check the colour of your pee, it should be a light straw yellow colour, if it’s a lot darker than this then you are dehydrated and need to drink more.

6. Remember to drink after your hike too, skimmed milk is absorbed well by the body and has plenty of the essential electrolytes you need, as well as protein, which aids muscle recovery.

7. In some instances, drinking too much can lead to a rare condition called hyponatremia, where important salts such as sodium are flushed from the body. This can result in a serious brain swelling condition and is life threatening.

8. Try to keep your body as cool as possible. Cover exposed skin with light clothing, wear a hat to protect your head and try to wet it when you can in a stream, if possible wet a buff/neck tube and wear it around your neck to cool the blood going to your head.

Russ Mills runs Mountaintrails, a guided hiking and skills training business based in Dublin, Ireland.