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KEEPING THIRST AT BAY: HOW TO STAY HYDRATED ON THE TRAILS 

Run the Wild's Karin Voller explains what, where, when, why and how to stay hydrated when you're out running.


We all know the feeling. We head out for a run because the sun is gloriously high in the sky, and we want to feel the warmth on our face. Being from the UK, it feels like a rare enough commodity that any time the sun does have his hat on, we should make the very most of it. Not wanting to wear a pack because then our back would be uncomfortable and sweaty, we opt to carry nothing. 30 minutes in, now burning up, sweat pouring, we start to feel a little dizzy and our well-intentioned run has now turned into an unenjoyable slog to get home by the easiest route possible.

Why is it important to stay hydrated?

The body is comprised of approximately 50-65% water, so for continued everyday function we need to remain hydrated, making it a basic need far more urgently required than food. Water is used in the transportation of nutrients around the body, for waste removal, heat control, and aid for lubricating the joints. While this justifies why it is worth having a drink when we get back from a run, does it make any difference while we are running? In short, YES! As you sweat, your blood volume decreases, which means there is less blood being pumped to your muscles providing them energy to run. 

Further to this, an increased portion of your blood is sent to the skin, to reduce body temperature, so again there is less still blood going to the muscles. Your heart has to work harder for the same aerobic effort, which means a decrease in speed and increase in fatigue. There are some counter arguments to say that dehydration leading to a decrease in body mass means you have less weight and thus require less energy to run, but most research notes indicate that the negative impacts of dehydration outweigh this possibly advantage, and certainly at the more exaggerated ends of the spectrum (over 2% loss in body mass). 

How much should we drink?

Again, there is no one rule here, as we all vary, but generally speaking, using our own thirst as a guide is pretty helpful. How much you need to drink will depend on weather, your physical mass, how much you are exerting yourself and so on. If you are thirsty, drink enough during your run to quench the thirst, but don’t feel you need to finish the bottle. Due to the body’s limitations on processing water in the body, it is actually far more effective to maintain hydrated through drinking smaller amounts throughout the day, rather than finishing your run, downing 4 pints of water, and thinking that will suffice. One of the reasons the queues for the portaloos at the start of any race are so long is that many people understand hydration is important for running performance, and thus drink a huge amount just before the race. Any water the body can’t process is eliminated, so you may just find you need the toilet more frequently to the detriment of your running performance. I won’t pretend nerves don’t play a factor here also of course! 

The other advantage of regular drinking in smaller amounts is a reduction in the feeling of water sloshing around inside us, and feeling nauseous. Less blood flow goes to the stomach during intense exercise, and there is increased pressure within the core. These two factors can make running with a full stomach (which includes liquid), very uncomfortable. If you weigh yourself directly before and after a run, you can calculate your loss of fluid, so try and essentially recover that amount of fluid. This does not all need to be during the run, but before and after is sufficient. Loss of over 2% of body weight through dehydration is a more serious threat to performance and health, so running in the heat in particular requires more active monitoring of hydration.

Equipment

This is somewhat personal preference, but ways you can try include running holding a bottle (some are designed with a split in the bottle to allow for easy hand holding), using a running vest/backpack with hard bottles, with soft flasks, or with a bladder. Alternatively, if you are doing loops you can always keep some water in your car, or at your house, if you will pass by frequently enough. Depending where you live you may also find you have access to water fountains, or natural water sources. For these times it can be really useful to keep a speed cup in your pack, but be mindful of anything upstream. If you have visibility of 50 meters or more, and can see no reason to think the water source is contaminated, you should be ok. If you see a sheep standing 10 meters above you on the trail having a drink, you are probably best to steer clear. It is better to be safe than sorry!

Running with a bladder has the advantage that the extra weight is being carried in a place you are unlikely to notice it (1ltr of water weighs 1kg), and also has the advantage that you can easily sip smaller amounts while you run. The disadvantages include that you can’t see how much water you have left, bladders are notorious for leaking, they can be difficult to clean, the water can become warm if pressed up against your body, and filling the bladder up can logistically be challenging in a full backpack. Flasks held on the side of your pack can also be useful, but make sure they do not get in the way of your arm swing. Soft flasks carried in the front of your pack are a relatively new addition to the running scene and are surprisingly robust for their light weight. They can also squash down as you drink more from them. They can be slightly trickier to fill up at an aid station, than a bottle which can be placed down as you tighten the lid back on.

What to drink?

Once you have your means for hydrating decided, what should you be hydrating with? Generally speaking, for runs lasting an hour or less, water will suffice. Beyond an hour, and you may want to consider a drink with electrolytes. Electrolytes sodium and potassium play a critical role in regulating the body’s water balance during exercise, and preventing cramping as they are required to both facilitate muscle contractions and extensions. During exercise, we lose electrolytes via sweating (it is the sodium content of sweat that makes it taste salty). If we do not replace sodium we lose during exercise, and just continue to hydrate with water alone, over the period of a long run, we can actually suffer from hyponatremia, which is when sodium levels in the blood stream are too low. Hyponatremia can cause nausea, disorientation and muscle weakness. All this being said, if you tend to run for an hour or less at a time, the nutrition you take on before and after running means you are not required to take electrolytes during the run itself.

Once you’ve finished your run, ensure that you are staying on top of your hydration, flushing our toxins through the kidneys is an important part of your recovery and will help bring you back to peak performance for your next run.

Stay hydrated and you’ll not only be able to perform better during your run, you’ll enjoy it a lot more too!


RUN THE WILD

Karin Voller is a Lead Runner for Run the Wild - the UK’s first premier, dedicated trail running holiday adventure company. Operating in the UK and the Alps, they deliver holidays that combine the sense of 'team' from mountaineering, with the thrill of trail running in wild places. Karin is an experienced trail and ultra runner with a marathon PB of 3hrs 20mins. She is also a qualified Leader in Running Fitness.


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