I was so proud of myself for staying well hydrated during a recent hike in the 90 degree heat. Proud until I told my well informed friend about the extreme amount of water I'd consumed and she responded with a puzzled look, "And you felt ok after all that water? Did you add electrolytes to it? Or have any salt." Uh....nope.
That's when it struck me - I could have easily overdone it with the water intake. I had been so focused on not getting dehydrated, that I'd forgotten about the potential for over hydration or "hyponatremia". This risk is as potentially hazardous as dehydration. Excessive fluid intake can cause dangerously low levels of sodium in the blood, which is really not good.
I'd been so hell-bent on preparing for water lost through sweat on my hot hike that I'd packed 4 liters of water PLUS a water filter, just in case. I also brought a camel back so that I could take small sips throughout the hike...and was surprised at how much more water I drank that way. Here's what my supply looked like.
I did actually feel great during the hike (and did drink ALL of that water), but realized I should probably do my research before trying that again...or sharing hydration tips with other hikers. I went back to my WFA (Wilderness First Aid) guide and also did some searching online. Here is what you need to know about both under and over hydration.
Dehydration - This can happen easily in the summer months. Signs are thirst, dizziness, headache, fatigue, and dark yellow pee. The treatment is to reduce exercise/exertion, find shade and replace lost fluids with water. Guzzling large amounts of water halfway through a hike is not the best plan, since the body can't absorb more than 1 liter of water per hour, even in extreme heat/humidity. The recommendation from my WFA instructor was to drink 4-6 fluid ounces of water every 15 minutes throughout your hike. 4 ounces is equal to 1/2 cup.
Over-hydration - This is caused by having too much water in the body. Sometimes when athletes (or hikers) exert themselves on hot days, they lose both salt and water in their sweat, replacing these losses with mostly water. This combination can be dangerous because it dilutes the remaining sodium left in the body. This can lead to the following symptoms: muscle cramps/weakness, nausea, vomiting, lethargy, headache, confusion and seizures. These symptoms are similar to those of dehydration, so it can be confusing to know which is happening. To prevent hyponatremia, a helpful REI article I read suggested drinking no more than 10 fluid ounces of water every 20 minutes.
To further prevent hyponatremia, keep sodium levels in balance by adding an electrolyte powder to your water or eating salty snacks. My friend Jaime likes Dr. Berg's, which is low in sugar and she says it's tasty. I've never used it (or any electrolyte powder for that matter), but it's on my list of things to order STAT. You can also purchase electrolyte tablets at EMS or REI.
My intention is not to worry you with this information. Hyponatremia is not likely to happen, but it's good to be aware that you can overdo it with the water intake. Avoiding dehydration and over hydration are equally important. For a general rule of thumb, take small sips throughout your hike, drink when thirsty and include an electrolyte powder in your water, plus salty snacks.
Unintentionally, I'd packed plenty of salted nuts on my hike that day, which must have balanced out my excessive intake of water. Either way, I'm glad I felt good and didn't learn these lessons the hard way (my usual route). Here's a picture of sweaty, over hydrated me, just enjoying the view. Ignorance can be blissful. And now I know better, and so do you.