Interview with John Seifert: Understanding Hydration as a Bodily Process

For many outdoor enthusiasts, hydration doesn’t appear to be a pressing issue of concern, much less a notion that requires constant vigilance. It’s a no-brainer, right? We feel that familiar dry itch at the back of our throats, the inside of our mouths lose their usual moist condition – so we instinctively reach for drink of water to sooth ourselves and cool down. It may seem as simple as that, but the issues of hydration and rehydration dig much deeper than our bodily thirst indicators.

I was privileged to interact with John Seifert of Montana State University, and through his expertise, gained an enlightening perspective on the idea of hydration. A veteran of the Gatorade physiology lab, Seifert has spent decades studying the relationship athletes and adventurers have with hydration. In this first installment of my didactic interview with Seifert, we discuss everything from preventative measures against dehydration to easy ways to promote better liquid retention while out on the trail.

Let’s begin with a little bit more about you and your expertise:

Well how far back do you want me to go? I have my PhD, which I received from the University of Utah. I’m now at Montana State University where I’m an associated professor at the movement science lab. I go back to the mid-80s with hydration work. I worked in Gatorade’s exercise physiology lab for four years. After earning my PhD, I went to a number of schools, and have been dealing with hydration, dehydration, and rehydration for the past three decades. 

Many of us operate on the concept of “I’m thirsty, so I should drink water.” Let’s take things a step further. How does thirst operate as a hydration status indicator?

We have to divide this into two different components. The first is short term, or acute. We also have long term, also known as chronic. Now thirst, day in and day out, is a good indicator of hydration status. However, in the short term, it’s not the best or most reliable indicator.

 If you go out for a bike ride, run, or hike, and all of the sudden you realize you’re thirsty – you’re already in the realm of dehydration.

What can we do as a preventative measure to make sure we don’t have to deal with being dehydrated?

Start drinking right away. In fact, make sure that before you head out, you take a good drink of water. About 45 minute to an hour before you hit the trail, ingest a big serving of water.  Once exercise starts, just take sips. One of the things we find out is that we can never totally stop dehydration – what we want to do is try to minimize how quickly it sets in. I think the most important thing is the rate of change. If you can start just sipping, most people can develop it into a habit. Take periodic sips and you’ll be ahead of the game.

So, is it better to sip or gulp? I remember the collegiate hung-over mornings spent nursing a beverage I was ordered to ‘sip,’ but in outdoor scenarios where you are down to your last few ounces of liquid, it seems more fruitful to take it down in a large gulp.

Let’s assume you’re drinking plain water. If I say, sit down and drink a quart of water – that’s entirely different from taking in eight ounces of water. Your body responses in a completely different way.

The fluids in your body become concentrated, and as soon as your take that big gulp of water, it goes straight to the kidneys. The issue is that the water you just ingested dilutes the fluid in your kidneys too quickly, and your body simply ends up producing a lot of urine. Your kidneys basically say “hey, there’s too much here,” and works to get rid of it. Your body tends to retain about 50% of the water you’re drinking.

So if you drink too quickly, you may think you’re doing a good thing, but you’re actually being counterproductive. If you slowly drink, and maintain a slow drinking schedule of six to eight ounces, your kidneys don’t detect that rapid dilution like they would if you took 32 ounces in.

What we’re really looking at here is, how quickly do you dilute the fluids in the body? The faster you dilute those fluids, the faster you’ll produce urine – which is where it becomes counter productive. You want to get fluid into the body, but you want to retain it.

How exactly does this process of staying hydrated or rehydrating operate?

Rehydration is made up of three components that work together. First, how fast are fluids emptying from the stomach? Secondly, how fast are they absorbed from the small intestines into the body? Thirdly, how much of those fluids are actually retained by the body?

Water is really good, because it empties from the stomach extremely fast. It has low to moderate absorption properties once it’s in the small intestine – however when we look at retention, we drop off the cliff with only 50-60% retention.  You can drink a quart of water, but you’ll only retain half of that. If you can sip, you tend to retain more fluids for a longer period of time, when speaking in terms of plain water.

Is hydration the same for all sports? Biking through the flat Everglades on a sunny day versus hiking through the Flat Irons in the high altitude of Colorado? 

You’re certainly going to become dehydrated faster when you’re at altitude, just because of the dryness of the climate and the stronger solar radiation. You also have to take into consideration the balance between environmental temperature and humidity. Those two factors can create issues for anyone because when it’s high, humid conditions, it’s very difficult to evaporate sweat.

 When sweat doesn’t evaporate, it’s harder for the body to maintain your body temperature. That’s why if you go hiking or climbing when it’s warm out, you want to wear cotton. This helps maintain the moisture next to the skin, which keeps you cool and will eventually evaporate. When it’s cold out, that cotton is detrimental to the body. So you have to consider both clothing and fluids.

I didn’t realize all the elements involved – I moved six months ago from hot, humid Florida out to Denver, Colorado, and I absolutely noticed all these issues you’re talking about.

Absolutely. Regardless, no matter where you are, you need to remember that the key is to keep sipping water. Keep yourself hydrated.

As a traveler who finds myself constantly trekking to various parts of the country to enjoy wild pursuits that inevitably always leave me panting from exertion, I found the bevy of information I unearthed from Seifert’s pool of infinite hydration wisdom to be a valuable asset added to my outdoor survival skills. Far beyond a thirst quenching moment of satisfaction while out on the trail, ingesting liquids to keep our bodies functioning optimally is a key component in ensuring that we are able to stay out longer, explore further, and conquer our ever-growing tick lists of summits, hikes, and trails.

In my opinion, one of the most resounding messages from this interview was the idea of forming a constant habit of taking periodical sips from your hydration pack or bottle – address hydration before it becomes an issue. Sure, drinking more water may lead to more pit stops on the trail, but when have we ever had an issue with popping a quick squat behind a bush? Seems like a small price to pay for ensuring a continued level of health while out on epic adventures.