Hydration for Lightweight Backpackers

[Stephanie Jordan]

Companion forum thread to:

Hydration for Lightweight Backpackers

[Steven McAllister]

Also not mentioned is about how diuretics, blood pressure and other medicines can contribute to a lack of electrolytes.

I am a fan of "Light Salt". It's cheap, common, and contains sodium and potassium salts.

[Shawn Bearden]

Kevin has clearly done his research because he is 100% spot on throughout his article. Well done, Kevin!

As a side note, because the MD degree was discussed. Folks should be aware that medical schools provide little to no training in either nutrition or the physiology of exercise. Having an MD degree does not mean, per se, that a person knows what they are talking about any more than the next educated person in these areas. Additional training is necessary.

Another post mentioned:
"Light and dark urine is not ONLY caused by dilution. It may be that you are simply not eating enough and your body is metabolizing more fats and protiens from it's stores…"
This is absolutely not true. While I am an expert in the physiology of exercise, I am not an expert in the urine composition under severe starvation but for anything remotely encountered even in survival situations by backpackers or endurance athletes, sources of fuel for energy and what macronutrients (carbohydrates, fats, proteins) you consume will not alter urine color. By the way, the majority of the energy for the exertion levels encountered by most backpackers comes from fat. Fat metabolism is highest (as a percentage of total energy) at rest and declines as carbohydrate utilization increases with higher levels of exertion.

"…don't go into panic mode and start drinking more than you need. This will just flush salt and trace elements out faster."
Again, not quite true. Drinking water, even in large amounts, will not flush electrolytes. The kidney is very good at adjusting electrolyte and water compositions as needed. It is, however, good advice to not force water down if you are not thirsty(with the exception of those reaching a level of dehydration and exhaustion where the body's normal thirst mechanisms are compromised).

If I misinterpreted either of these statements, I apologize but I wanted to clarify for any naïve readers who might interpret them as I did.

Finally, Kevin noted the importance of food in the equation but there isn't any information added that I could see in the article. The importance here should not be underestimated. Sweat sodium losses vary from about 20 to 70 mEq/L of sweat, or about 460 to 1600 mg/L (mEq/L x 23 = mg/L). For a typical day on the trail (if there is one) in warm conditions, one might lose 1-4L in sweat. Typical U.S. intakes of sodium are about 3.5 g/d. I doubt that is the case for many on this forum who are more health conscious but it puts things in perspective. The good news is that many common 'healthy' foods contain lots of sodium. One ounce of beef jerky contains about 0.5 g sodium, one ordinary pickle contains about 1 g sodium, a can of soup and a few pretzels 2 g. Take a look at any dehydrated packaged food you take – much of it has very high sodium content. So they certainly can help replace. In general, MRE's provide Soldiers 3 g sodium per day, plus a salt packet is added and encouraged 'if' weather is hot (6 – 8 L/d sweat losses living in Iraq in summer) and in particular if operational circumstances prevent full consumption of the MRE.

So, be sure to look at your sodium intake in food across the day. There is a very good chance that the vast majority of people on this forum will not need to supplement their drink when food is considered and maybe planned appropriately (such as shifting some of the salty foods already taken to breakfast and lunch rather than all at dinner). Regarding other electrolytes (in addition to sodium), the diet will provide these unless you are eating very poorly.

Again, Kevin…excellent article with very good practical advice that helps to demystify and de-hype the electrolyte and sodium craze.

[James Marco]

"…sources of fuel for energy and what macronutrients (carbohydrates, fats, proteins) you consume will not alter urine color."
I do not believe this is true. Uric acid, a break down product from metabolizing fats and protiens is the primary coloring agent for urine. It is yellow to brownish in color. It is normally excreted through the urine. There are two avenues for the color of the urine. First is water: too much can dilute it a lot, or, too little can cause it to become very concentrated. This is what most hikers think of as watching your urine color. Second is the uric acid itself: producing more or less depends on your diet/excersize level. Eating a large amount of beef jerkey for example will cause your urine to be more yellow without effecting the bodies homeostasis. The excess protien the body does NOT need will be metabolized for energy, causing the nitrogen radical (urea cycle), to be excreted. A normal person's urine color can change over many shades with no hint of dehydration. High protien diets (fresh fish and chicken for example) often cause very yellow urine, despite drinking adequtly (and without the salt usually found in beef jerky.)

"Most of the uric acid is removed from the body in urine. A small amount passes out of the body in stool. But if too much uric acid is being produced, the level in the urine will increase. If the kidneys are not able to remove it from the blood normally, the level of uric acid in the urine will decrease."

Yes. In hot weather (the primary subject here) you sweat. A large amount of eric acid passes out of your body through the sweat. In this context, your skin becomes an organ of excretion, too. This was exactly my point above without the more technical details, of course.

"… Drinking water, even in large amounts, will not flush electrolytes. The kidney is very good at adjusting electrolyte and water compositions as needed. It is, however, good advice to not force water down if you are not thirsty(with the exception of those reaching a level of dehydration and exhaustion where the body's normal thirst mechanisms are compromised)."

Generally yes, I will agree with you. But we are talking about a person sweating a lot of salt out, ie, within normal conditions, but on the low end. Drinking more than you need in such a situation will act as a "sponge" causing the salts to flood into the water. You can easly loose too many salts and go into a hypernatrial state. Be a bit carefull about drinking lots of water with no electrolytes. I just did that on the NPT, drinking more than I needed at a cold stream. I got a bit disoriented and nasueous. I had to sit down and think a minute before recognizing I needed some salt, too. The big clues were I was soaked with sweat, 90+F day, hiking fairly hard for over 2 hours, ate a little, but only a couple bites. I finished my water bottle, filled them up zapped them and drank them, filled them up and zapped them and packed up to leave. About a liter and a half was enough to make me very light headed. This is BEFORE the water even hit my kidneys, maybe 7-8 minutes.

[GD]

It was kind of funny to read your comment about fast packing the Tahoe Rim Trail. I'm actually thru-hiking it right now and, due to a series of unfortunate events, ended up missing Spooner Lake and did an almost-40 mile day in search of water before ending up at the lakeside inn in South Tahoe. Won't make that mistake again, but fortunately I'm pretty much through with the dry sections.

Good article!

[Kevin Sawchuk]

I'm going to specifically comment on this statement as not having full information could lead to problems:

"Drinking water, even in large amounts, will not flush electrolytes. The kidney is very good at adjusting electrolyte and water compositions as needed."

This is generally correct. However the kidney can not control the very large losses of sodium that CAN occur through sweating. You can lose enough sodium from sweat to cause problems. If you're replacing the fluid you've lost with water (or other low/no sodium drink) you will run into problems with hyponatremia.

As for food sources of sodium you are absolutely correct. If you're exercising only in conditions where and to the level of needing 1-3 liters of fluid per day to replenish it is likely that your diet contains enough sodium that you don't need to take additional salt. However I have been on backpack trips where I needed a liter per hour for a good portion of the day. With my hiking days frequently lasting 10-12 hours at a high intensity I have occasionally needed to take salt pills. Everyone needs to consider the conditions they're exercising in, the duration of their exercise, how much they're drinking, how much they're sweating and have the tools on hand to stay hydrated. This MAY include salt supplementation in particular conditions and for certain people. 30 mile days through the Mojave Desert on the PCT will require more than 12 mile days in the High Sierra.

You are also correct that a physician may not have the level of practical information to guide a runner or backpacker. I'll add to my credentials 10 sub-24 Western States finishes, a (now-broken) JMT trail record, serving as medical captain of the Michigan Bluff aid station at Western States and being involved with studies on hyponatremia.

HYOH

[Shawn Bearden]

Thanks, James. This may be a simple case of taking some accurate information and extrapolating too far, coming to incorrect conclusions. Glad I can help to clarify and correct. This happens quite a lot in my classes where my students do the same thing, but it is only natural and part of what drives good research questions. You are certainly thinking along reasonable lines and the logic would seem reasonable at first view but the outcomes you've hypothesized actually aren't quite what results. Although there are a number of factual errors of metabolism in your response, I'll just correct two that are common. Excess protein intake is not used for energy but is rather converted to fat stores. Protein remains less than 10% of energy sources even in prolonged endurance events. I don't know where you are getting your fish or chicken but any change in your urine color is not due to the protein therein. It is true that some micronutrients and food additives can color urine. Vitamin B supplements are a great example, where all the excess turns urine a bright yellow. Happy hiking!

edits: your 'sponge' analogy is a dangerous one and not at all accurate. Your symptoms on the NPT are not uncommon, from your description of the situation, and were unlikely to be a result of the electrolyte composition of your drink during the rest stop. Though clearly there are situations in which added salt to drinks (or drinking sports drinks) is the better choice over water alone.

[Shawn Bearden]

Kevin, quite right again. This is why I thought your article was so well done. It, to my reading, lays out well that there are indeed important conditions under which supplementation is important. And, I hope that readers also appreciate the other quite accurate information included in your article that routinely supplementing all fluids one drinks is typically unnecessary. Reading some of the comments to your article lead to believe that many people, as I find in my own population, over-consume sodium when exercising. In addition to salt-sensitivity, there is also good evidence that overconsumption of salt causes microvascular dysfunction that is initially unnoticed but can contribute to other pathologies in the long term.

Didn't at all mean to infer you aren't qualified, clearly you are! For full disclosure, I am a professor of physiology, director of my university's biomedical research institute, fellow of the American Heart Association, etc., former professional athlete (soccer) and an exercise physiologist by training.

[Kevin Sawchuk]

I LOVE the eclectic group of wierd-ohs who lightweight backpack!! :-)

[Greg Mihalik]

Kevin: "I'll add to my credentials 10 sub-24 Western States finishes, a (now-broken) JMT trail record, serving as medical captain of the Michigan Bluff aid station at Western States and being involved with studies on hyponatremia."

Well, OK, Maybe you can relate.

This is BPL though, and everything and everyone is subject to endless opinion and conjecture.

;-)

Thanks Kevin, for a good article and good follow-up.

[Bob Gross]

Kevin stated "I'll add to my credentials 10 sub-24 Western States finishes, a (now-broken) JMT trail record, serving as medical captain of the Michigan Bluff aid station at Western States and being involved with studies on hyponatremia."

For those who are unfamiliar, the Western States 100-mile Endurance Run happens in California, and the course involves roughly 15,000 feet of vertical gain and 18,000 feet of vertical loss. The mid-point of the course (45 to 55 miles) is the hottest part, and the Michigan Bluff aid station just following that sees more than its share of cases involving dehydration, hyponatremia, heat exhaustion, and (gulp) worse. I think if you had to study these maladies in the field, that would be the place to go. The top competitors can knock this out in about 15 hours.

I remember waiting for one competitor there (I was in the support crew), and it was tough enough just standing around in the shade as we waited.

–B.G.–

[Anonymous]

"Odd that they didn't mention skin turgor."

A possible reason occurs to me: As people age, they lose collagen in their skin and the resulting loose skin tents easily. This could lead to a misdiagnosis in some cases. You might ask how I know. :(

[John Coyle]

The idea of taking high doses of sodium on the trail seems strange to me. High blood pressure runs in my family. My doctor has told me to limit my sodium intake to 1500mg per day. I have done this and reduced my blood pressure quite a bit. I try to stay away from backpacking foods that have more than 500mg of sodium per serving. I limit my sodium intake on the trail and haven't noticed any adverse effects and I hike in the mountains of Northern California, up and down some pretty strenuous trails. Like the author says, everyone is different.

[Nick Gatel]

The article is good as it points out potential problems and should alert most of us to watch our requirements for fluid intake and salt replenishment.

But it does not provide specific universal solutions. When hiking many people are going to sweat out more salt (and other minerals) than they normally would in every day activities. Even if your doctor tells you to limit salt intake, hikes can cause you to lose much more salt than normal and too much is bad.

Since year of us is different, and our needs change over time, we need to know how our individual bodies react to higher levels of exertion. We cannot learn this from an article or a book. We must learn from real world experience.

I often hike in deserts. It is not unusual for me to peel off my shirt after several days of hiking and when it dries the shirt is as stiff as a piece of cardboard, it has so much salt in it. I have to wash my backpacks a couple times a year to get rid of the salt.

My personal experience/needs: Sport drinks or mixes in water do not "quench" my thirst. Only ice tea or plain water quenches the thirst. I don't take tea with me hiking (extra weight). Decades ago, from bad experiences, I learned that too much salt loss made me very sick and was dangerous. I tried salt tablets and they upset my stomach; which is unusual, because I can eat just about anything without and upset stomach. I wasn't about to fool around with cutting salt tablets or bringing salt with me. Too much fiddle factor. But I found that potato chips, Frito's, or similar would do the job.

Also, I don't drink constantly when hiking. I stop about once an hour in hot weather for a 5 minute rest and drink water. In cooler weather, not so often.

This is what works for me, and may not work for you.

At my hourly stop, I drink a little water, and then snack on chips. Somehow my body knows when I have eaten enough. Then I drink some more water until I don't feel thirsty.

[Donna C]

What about coconut water? It seems the new craze for electrolyte replacement. Now it comes in powder form. Any thoughts?

[Jeremy Pendrey]

This is a very interesting article and discussion. Thanks for all the info provided in the comments.

I would just like to emphasize the impact of electrolyte loss on developing muscle cramps and see if others have thoughts on the topic. I am a high sweat hiker so I realize my experience may not apply to everyone.

Years ago I used to drink plain water during hikes and electrolyte mixes in camp in the evening. At the time, I thought drinking electrolytes at the end of the day was enough. On several high exertion trips in the High Sierra I got severe pain in either the hip or outside of the knee that lasted for days and put me out of commission. They resulted in very painful hikes out to trailheads. I eventually learned that I could hunker down for a day and get well enough to continue. The fact that the problem went away quickly and no doctor could find anything wrong of course made me suspicious that I did not have a knee or hip problem. At the time I didn't know what was wrong. But I also learned that using my trekking poles like a foam roller on my hip helped alleviate the pain a bit. This made me suspicious that I was having cramps. (I realize I was a little slow to figure this out but what can I say.)

Then I started adding Nuun tablets to my water on the trail and the problem went away immediately. It apparently had been IT band cramps. And I started supplementing with a salt stick during meal times. The aha moment came when I started to feel the beginning of knee pain, immediately took a salt stick, and the pain went away very quickly (maybe a half hour to an hour).

I pretty much only drink water with Nuun when I backpack now. At times, I've tried to cut back on the electrolytes because I'd prefer not to have so much sodium. But when I've done that the cramps return and sometimes can result in some painful hiking before I work out the problem. Based on the numbers Kevin presented, it appears that maybe I do need as much salt as I'm taking in though. I typically hike all day and try to do moderately long miles over multiple days (e.g., just finished yesterday 8 days on the PCT in the Sierra for 130 miles), so maybe I simply need all the salt.

I relate this info for those that may experience muscle cramps on the trail, but also to see if others have had similar experiences and have found particular methods that prevent cramps. As I said, I'd prefer not to use so much salt but the alternative seems to be not to hike long days and miles in the summer Sierra (unthinkable!).

Thanks.

[Greg Mihalik]

Donna C. –

Coconut Water – This is a concentrate to which you add 8 oz of water –

So 8 servings to get 1 gram of sodium. And with that you would get 4 grams of potassium.
Not a good ratio, IMHO.

If mixed as directed, you also drank 64 ounces (2 liters) of water.

[Rick Burtt]

Great article. I'm a little behind in my reading having just gotten off the trail and I haven't read the entire comment thread, so I apologize if my comments are duplicates of another's. Walking through a couple burn areas and through some dense foliage (in the same section of trail, in Colorado), I definitely started to suffer the effects of dehydration and a little heat exhaustion. One thing I noticed was the effects of altitude on dehydration. Not sure what the exact mechanism is, but I'm sure it has to do with the efficiency of processing oxygen in the blood.

Anyway, I found Gatorade's individual packets of powder to be lifesavers. Adding one packet to 20 oz of water made an immediate difference in my performance. I've never been one for sports drinks, but this stuff really worked. A side benefit is that it made the water taste better which made me WANT to drink more – I find that I just get plain bored of water. I've tried the Nuun tabs but quite frankly found the taste a bit off – had a bit of an Alka Selzer aftertaste no matter the flavor of the tablet.

For my $.02, I recommend the Gatorade packets.

Rick

[Greg Mihalik]

Rick,
"…Gatorade's individual packets of powder…"

Which product? Gatorlytes, Endurance, Natural, or something else?

For their Gatorlyte Powder –

About $0.70 per packet, or $0.90 per gram of sodium.

[Curtis B.]

I put this information to the test this past weekend. I calculated the amount of sodium from my lunch and snacks and the supplementary amount my wife would need if we used the 300mg/hour rule, and 600mg/hour for myself. We added the equivalent amount of table salt to a water bottle and drank a bit at rest stops, rationing this saltwater/limeaid mix throughout the day.

Before now, 10 miles in the White Mountains has been our absolute max distance and we were exhausted, stiff, sore, and bloated by 3-4 lbs for a couple of days afterwards. With the salt additive, we felt fabulous at mile 6, enough to bag another peak that wasn't in the original itinerary. We hiked 17 miles and I still felt amazing at the end of the day. If it weren't for some foot pain, I could have kept going. I felt no soreness the next day, and on the second day I've already lost all the water weight and am down about 1/2 pound from the morning of the hike (my goal is endurance as well as weight loss).

What an amazing difference. My wife was getting ready to give up on the distance hiking because the toll was too great on her body, but now she's excited about giving me a run for my money in the 100 mile wilderness later this month.

Thank you very much to the original author and those who've contributed.I'm a believer!

[Ben Pearre]

"…sources of fuel for energy and what macronutrients (carbohydrates, fats, proteins) you consume will not alter urine color."

Beets.

Yup, if you eat those and forget by the next day, you can misdiagnose yourself just a little :)

[Ben Pearre]

One recent paper ( http://www.biomedcentral.com/content/pdf/1550-2783-7-28.pdf ) found that Gatorade was not a particularly good choice for recovery after high-intensity exercise, and that another drink (Rehydrate by Advocare, containing about the same amount of sodium but a host of other minerals, a different mix of sugars, as well as amino acids) was much better. They used only one measure of recovery; I'm not sure how applicable the measure is, but the authors think that the results show that it could be worth paying attention to more than just salt even for short-duration (but intense) exercise. Any reason to think that water+trailmix won't do about as good a job as the product that their data favour?

I'm just a menial computer scientist, but would the medical people here care to tell me what you think of the conclusion?

Also, I sometimes use WHO rehydration mix (mixed it myself, although commercial versions are available–it's basically sodium and potassium and a whole lot of sugar (and therefore dirt cheap to make)). The glucose makes it perhaps heavier than necessary (although it'd presumably be included in food weight if you were counting on consuming it, although I usually just carry a few packets for emergencies). I think it's designed for rehydrating during diarrhea and other illness that makes normal food consumption difficult, but what do you think of its use as a sports drink? Would the older, higher-osmolarity WHO solution be better for sports rehydration than the modern reduced-osmolarity one?

I like the idea of using sea salt; I'll have to try that the next time I mix up a batch. Sadly, I lack the resources to do double-blind trials of WHOmix with sea salt vs. iodised table salt… but I believe the non-NaCl in sea salt is only present in irrelevant quantities…

[Todd ~]

@Kevin – physicians are quite expert at fluid management. All of them, but especially any in family practice, internal medicine or its subspecialties, anesthesiology, emergency medicine, or any surgical specialty. Those physicians manage intravenous hydration all day, every day, your suggestion that they don't understand what they are doing is laughable. As is your suggestion that one cannot induce hyponatremia by excessive water consumption. Please google "non-psychogenic polydipsia with hyponatremia"

Products designed for running a distance race do not translate especially well for hiking. I use endurolytes tablets when running for electrolyte replacement, along with plain (free) water for hydration, and mango baby food squeeze packets for calories / nutrition. This combination is great because they are the most healthful options I can use without breaking stride.

I don't use any of these when I'm hiking (except plain water). These products are great because they can be consumed on the run. I run endurance events at seven to eight miles per hour. Even my fastest hiking its half that pace.

At three to four miles per hour, one can consume real food that he likes. My favorites for the trail are salty / sweet Sahale snacks nuts, organic beef jerky, and homade empanades. Plus plain water. I also bring some fresh colourful fruit like blueberries or fresh mango. This provides electrolytes, anti-oxidants, micronutrients, calories, and hydration.

One should consume enough plain (free) water with this food while hiking that he is making clear urine every one to one and a half hours. Needing to urinate more frequently than this indicates excessive water comsumption. One should also make clear urine in everyday life, else he is putting undo strain on his kidneys and setting himself up for kidney stones.

[Kevin Sawchuk]

I in no way suggested physicians don't know how to manage fluids. I am a physician. My closest comment, "You are also correct that a physician may not have the level of practical information to guide a runner or backpacker." is correct in many instances. Give a physician a blood pressure (including orthostatics), sodium, BUN, creatinine level and they'll get your fluids right.

Ask a physician not experienced with fastpacking or ultrarunning how much fluid or salt a person needs, how they should plan a drinking, eating, sodium strategy and they'll be unlikely to help you. Especially without the fancy tools we use to guide us.

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