Hydration is always a major issue when doing extended periods of exercise; dehydration can cause severe drops in physical and mental capabilities, slow you down and exacerbate the problem.
There are usually guidelines quoted telling you how much water you need based on activities and conditions but what most people tend to over-look is techniques that you can employ to improve your hydration efficiency and that allow you to consume and carry less water while maintaining a good level of hydration.
Here are my top tips for hydration efficiency;
Tip #1: Small sips often
This is the most important method to improve your hydration efficiency. I learned this during a 4 day trek through Malaysian jungle; I was trekking with two Sweedish guys, and as I had the water sterilisation pills I was aware of how much water each person consumed. It was during a very hot spell of weather (in an already hot and humid place) we were sweating so much that you could literally squeeze a puddle of sweat from your tee-shirt after taking it off.
Clearly this sort of activity requires a lot of water to stay hydrated and as there were plenty of small streams to re-fill we could drink as much as we needed. I noticed that between leaving after breakfast and arriving at the next camp I was only consuming a little over 2 litres of water whereas my friends were drinking well over double this amount and despite this I felt well hydrated.
The reason I could get away with comparably so little water was that I was using a hydration pack and was having a small sip of water every time my throat & mouth felt dry. It may have been as little as 10ml of fluid each time. My friends however were using a 2l plastic bottles and would stop every-so-often, sling their bags off and take a long drink, downing around 500ml or more, in order to quench their thirst.
The reality is your body (and by body I really mean cells – muscle cells – brain cells etc) can only absorb water at a certain rate – when people are severely dehydrated it can take many hours, or even days, for their body to be fully hydrated again. By taking on fluid in large quantities you are effectively creating a spike in the water in your body, of which some will get exchanged into your cells, but as your cells can only take water on slowly most of this water is extracted from your body by your kidneys and passed out as urine. This is highly inefficient.
By taking small sips of water every 5 minutes or so your are taking on water at a rate your body can accept it, creating a continuous input of water that will similarly match the gradual water loss. I would go as far to say that by taking sips regularly you can stay well hydrated using as little as 40% of water as someone downing large volumes of water every so often.
This means you need less water, you urinate less fluid and your mouth/throat is less dry therefore increasing your comfort.
Tip #2: Remove hydration barriers
To take sips of water every few minutes is not practical if you have to take a bottle out of your bag, open it, have a drink and return it each time. A hydration pack, like a platypus or camel-back with a hose, is essential to removing barriers to efficient hydration. Ideally you would be able reach the hose easily with your mouth hands-free.
When we (sort of) speed climbed Half Dome it took 21 hours of non-stop movement and being on lead for the majority of the route meant that a bottle of water is very impractical; I used this technique and 2 litres of water lasted neatly the entire duration of the climb to such an extent I was not thirsty even after our 4 hour bivi and a walk down to our bags where we had more water.
The downside of hoses is that they are not practical in cold conditions. The first time I walked of the Midi station in Chamonix, which happened to also the first time I used crampons, it was the 2nd of January and the one of the first of many things I learned was how pointless a hose is in cold conditions; within 10 minutes the hose was frozen solid. When doing long-routes in cold conditions you just need to try and be diligent and try and get in to a routine of drinking at each belay. Keeping your water in belay jacket in your bag will stop the inevitable freezing of your water.
Tip #3: Sweat less
When doing extended periods of exercise changes in body temperature is inevitable especially with changes to the weather throughout the day. By being diligent with your layers, taking them off/on or, at minimum unzipping, to reduce sweating reduces your water loss.
Sweat is wasted water – it is not being used to replenish cell-fluid levels or to remove toxins from your body (as urine) the less you sweat the better.
Tip #4: Drink Electrolyte solution
If your going to carry water you might as well make sure it is loaded with things that help to keep your body working. Electrolyte mixes are great – we will often just buy a few bottles – unload it into the platypus and top it up with water. This will improve your performance and reduce the likelihood of muscle cramping.
It is generally inexpensive and for extended periods of exercise absolutely makes sense.
Tip #5: Breathe through your nose
Not always possible of course, but breathing through your mouth increases moisture loss and will reduce the parched feeling a dry mouth can cause. Apparently desert dwellers suck on a pebble to help with this; although I have never tried this technique and I cannot imagine it being very good for your teeth.