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Adventurous activities and the heat

Right, just let's start by saying I prefer cold than heat for adventurous activities, but this heatwave is a theme that grinds my gears. Specifically the way the media present the heat.


First, why do feel I can talk about this, well, I ran Marathon des Sables (MdS) (251km in the Sahara, with 9l of water a day, self supported with average day time temperatures in excess of 40c) and I'm pretty happy dealing with heat from a first aid and first aid training point of view in remote areas.


The human body is an amazing thing, in that it can adapt to very extreme conditions. This current heat wave is extreme in the UK and it is unusual - but some media reports are very Chicken Licken (or Chicken Little in some parts of the world) - but the sky is not going to fall in.


I'll start with an obvious statement - if you don't know what you're doing, or it doesn't feel ok. Stop. Be cautious with the young and old, they're less resilient.


However, enjoying the outdoors when it's warm is possible, and occasionally enjoyable.


For MdS I spent a lot of time in hot baths, stepping up on milk crates in Sauna's and wearing far too many clothes for the activities I was doing in the UK. This was an effort to force the body to adapt to what I was going to experience. Clearly, you can't do that in a day or two, but the principles apply.


As the body adapts to heat it becomes more efficient at taking water from our digestive system and keeping our blood well hydrated. De-hydration is a key thing to manage, but it is not the only thing. Heat stresses the body, a lot. And uncommonly hot periods will cause a number of things of happen to the body before you get poorly.


Because your body is being stressed, your heart will reach its maximum capacity faster. So, even if you're a well conditioned fit person, your heart rate will be faster for longer, and it won't recover as quickly. So, if you are wanting to do something outdoors when it is hot, expect to do it slower. Expect your recovery to take longer too.


Because your body's normal mechanism to cool you down is to sweat, you lose water from your system. With this sweat are salts and minerals. When you're exercising it is normal to replace the water, with water. But if you imagine you're doing this over a long period of time, what you are actually doing is reducing the proportion of salts in your system through dilution. Don't expect your body to immediately okay to be able cope with taking more nutrition or hydration on when you're stressing it through exercise. Remember, it takes time for your body to adapt, and be more efficient.


Speed and hydration/nutrition are key things in keeping an activity safe, factor it in when planning an activity. Some activities you can start earlier in the cool of the morning. Because you're stressed, your judgement can be altered, so make decisions early, and keep an eye on folk in your group. With short sharp changes in the weather, it is always better to adapt your activity than it is to expect your body to adapt.


Don't forget that sun (UV index of 3 or above) is damaging longer term, so always be sun safe - wear a hat, use sun screen, wear loose long sleeve and long leg clothes and stay in the shade. Melanoma is a killer, and the main reason I ran across the desert. Look after your skin.


Fixing a human that is too hot can be hard in a remote location. Sorting any kind of heat illness out early is key. Things don't get better on their own, usually. There are a lot of indicators and things to consider with this. If you play outdoors, get a minimum 16hr first aid ticket, get the knowledge.


Effectively we talk about two types of heat illness. Heat exhaustion and heat stroke. To keep it simple;


Heat exhaustion - the core body temperature is less than 40c, and behaviour is normal. Sweating is normal.


Heat stroke - the core body temperature is more than 40c, and behaviour is altered. Sweating will stop. Ultimately this person will become unconscious.


Heat exhaustion is relatively simple. Number one is get less heat stress on that person. If you are moving outdoors, stop, stop in the shade. Loosen clothing, use damp clothing to accelerate the cooling process, give sips of water.


Heat stroke is urgent, if they're still conscious we might keep using damp clothing, but we need to get that person out of that environment fast, we are going to evacuate. If available, managed cold water immersion is effective - deep water is not preferred for obvious reasons. We'll keep on with oral rehydration (sips of water) but we might start eyeing up the camelbak they have... I'll explain.


Untreated this person will become unconscious. In a remote environment you continue cooling and prepare to give CPR - the other option, highly recommended, is rectal rehydration - and for this, a camelbak is a brilliant piece of kit to use. Learn how to do it!


So what is the message here?

  1. Unless you are well prepared you are going to have change your activity (time of day, speed etc)

  2. Plan how you can make your activity safer (more water, more shade, easier evacuation)

  3. Be aware of the effect of sun, both now and long term and be sun safe

  4. Know how to spot heat illness, and when it becomes the more serious heat stroke

  5. Do something about heat illness early and be prepared

With heat you do not need to stop activity altogether, though you may consider it for some people.


Please be aware, that if you make a mistake at times like the forecasted heat wave, emergency service response will be slower, and put others at risk. Don't do that either.


As with all things outdoors and adventurous, if in doubt, don't.


This video shows me on an 80km leg in the Sahara after completing 130km over the previous 3 days. I had a total of 9l of water for all my needs in a 24hr period. You'll see the salt stains on my shoulders, I was on a strict regime of salt tablet. I have factor 50 sun screen on, I have a hat with a neck cover. I've got clothing that is designed for cooling. I'm moving slowly, to my comfort levels, and planning my strategy ahead.



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