Coping with Extreme Heat & Dehydration

Today I have the pleasure of posting a guest article by Mark Lyons, or on twitter as @runner786 

I have followed Mark on Twitter for a good while now and find his level of knowledge in so many disciplines very useful. A climber, kayaker, runner and a whole lot more than that his website is full of inspiration, comedy and useful articles.

See it by clicking HERE

Enjoy todays article on coping with EXTREME  hear and dehydration…

Coping with extreme heat and hydration

I do not write this article on the premise  that I am any kind of expert. I write as someone who over the past 20 years has survived in some of the world’s most inhospitable places and latterly raced/ran in extreme environment ultra-running events where my knowledge of surviving in the intense heat has again been tested, this time to achieve better performance rather than just staying alive.

As an expedition kayaker/climber I have had to be self-sufficient for long periods of time and have researched the effects heat has on the body for more years than I now care to admit. Some of the advice I have taken and the conclusions I have drawn have worked well for me and others have not. I have developed my own practices based on years of my own experience and what I write below is knowledge based on what “works” for me … my advice to anyone reading this is to utilise it as part of your own research and to try it out for yourself in advance of any situation/event that may hinge on your individual hydration plan.          

Heat and hydration: the facts

The human body, although able to survive comfortably for over a month without food, can last only a few days without water, as humans have no way of storing fluid for any longer. We are not camels; there is no hump on our back that we can fill with a month’s supply at any opportunity. Evolution has shaped us in our ability to find regular fresh water . This is to our advantage until we head to where heat is extreme and water is in short supply. In these environments hydration is essential for our bodies wellbeing; it can be the difference between life or death in extreme situations. Water helps regulate our temperature through sweat, which in turn evaporates to cool the blood flowing close to the skin, and when we exert ourselves in hot environments, we sweat a lot! This causes dehydration fast and without regular fluid replenishment our performance will suffer. Left unchecked the body will dehydrate and ultimately overheat. Symptoms can include dark urine, headaches, nausea, dizziness, hallucinations and bad diahorea . The loss of fluids also goes hand in hand with electrolyte loss and these vital salts must also be replenished.

And to make it even more complicated, as ultra runners we run over these hostile environments trying to eek our every last kilojoule of energy to get a good result in our chosen extreme race. At these times, hydration can be the deciding factor in the fine line of reaching peak performance or crashing into the abyss of fatigue and failure.

How to get the best out of your performance in extreme conditions

Dealing with extreme heat is all about the conservation and supply of water. This is the single most important factor to consider when out in the heat and my first piece of very simple advice is to cover up! Not just a hat, consider a long sleeve top and even tights. This one act will keep the skin cooler, hence your blood will cool faster and in turn reduce your need to sweat. A light wicking base layer is actually cooler than bare skin in the direct sun. Not only will it save you from sunburn, but the wicking layer spreads your sweat and gives you a larger cooling area. Some prefer a looser layer so try it and see what works best for you. Either way you will appreciate the difference. The use of a “soak” can help and these can be something as simple as a cotton neck chief regularly soaked in water or the new breed of water absorbing gel variety that retain the water and help to keep you cool for up to two hours.

In the extreme heat and dry climate of the desert a supply of water is required at all times and it needs to be easily accessible. One of the main causes of dehydration when we have adequate water available is a person’s own laziness and a hard to reach bottle can be the culprit. Even the most disciplined of us will find it all too easy to put off taking a drink if it’s difficult to reach, especially when suffering fatigue during a hard days running. So make sure water is easily accessible to avoid this.  Bottle belts, integrated bladder systems and shoulder bottles will keep water at hand, so try to use these. My advice in the desert is to drink small amounts regularly and to be aware of your own thirst. The body will signal in plenty of time when to drink, you just need to be aware of it and to react when it tells you . During my own desert runs I had permanent dry lips and throat so I had to constantly sip small amounts just to stop the dry cough and my lips cracking. This seemed to take care of my requirements, others set their watch on an interval alarm so they knew it was time to take a sip.  At all times remember to monitor your own intake against what is left in your supply and adjust your effort level accordingly. You need to make it to your goal and pacing yourself according to your fluid intake may be required.

Always remember  your electrolyte replacement when filling water bottles. Be it salt tabs taken separately from your water or a Nuun/High5 water dissolvable tablet , it’s very important. One of my very fit tent mates in the Marathon des Sable had a habit of forgetting his salt tablets and on day four I caught up with him while running across a long desert plain. As unusual as it was for me to catch a runner of his calibre, it wasn’t as crazy as the dance he appeared to be doing in front of me, hands in the air, shake them like you just don’t care! As I gained on him, I saw why he was repeatedly shaking them in the air, they were like huge fat pork sausages! He had left his salt tabs to late and had an electrolyte imbalance causing extremity fluid retention. 20 minutes later he recovered and left me for dust, literally.

The lure of high altitude races in the Himalaya and even hot alpine forays can bring other factors into the mix and dehydration at altitude can be caused simply by breathing. At only six-thousand feet you exhale and perspire moisture twice as fast as you do at sea level. The reduced air pressure allows increased evaporation from your skin and lungs, the higher you go the worse it becomes. Running, kayaking and even the slow progress of mountaineering is eating up the body’s water supply FAST ! At high altitude the body can delay in sending out the signal that it needs fluid, so careful attention to your hydration plan is required even when you’re not exerting yourself.

I personally suffered from bad dehydration while on an expedition in the Himalaya, sat in a kayak at 17,000 feet surrounded by water and yet I was unable to drink a drop due to the high silt concentration, think dark grey liquid mud. The particular section I was kayaking down was so full on that I was constantly fighting to stay upright and keep my lines. Stopping to drink fresh water was far from my mind and the headache that I thought was the cold water constantly engulfing me was actually the onset of dehydration. This happened in the space of an hour and gave me the shock of my life when I suffered a bout of dizziness as I swung into a must make eddy above a huge siphon. Dizzily swirling around trying to stay upright next to certain death is something to reinforce the need to hydrate, I’ll tell you.

My final piece of advice is that if you should suffer some kind of dehydration effects, be it the first signs of mild dehydration or the initial stages of heat stroke, then please sip the water slowly, no guzzling. Take slow regular sips until you feel yourself getting back to normal.

Have Fun.



About Mark Cooper

My name is Mark Cooper, I am an ultra runner, motivational speaker, expedition consultant and public relations rookie. I help people achieve greatness in their lives. For bookings or more information you can email
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