Hydration for Lightweight Backpackers

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.

"…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.

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

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: "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.

"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. :(

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.

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.

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

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!

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…

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.