Electrolyte needs and real food

" … one potential benchmark is the American College of Sports Medicine hydration guidelines. Sports beverages for use during prolonged exercise should generally contain four to eight percent carbohydrate, 20-30 meq/L of sodium, and 2-5 meq/L of potassium."

From http://www.ncbi.nlm.nih.gov/pubmed/11480505 –
"Thirteen male soccer-team players and 100 sedentary students from the same high school were evaluated for 8 d, during which the players were training.

"The authors analyzed 208 sweat samples to determine losses of iodine, sodium, potassium, and calcium in sweat. The mean losses in sweat following a 1-hr game were 52 microg [of iodine], 1,896 mg [of sodium], 248 mg [of potassium], and 20 mg [of calcium]…"

A more common value for sodium loss through sweat is 1 gram/liter. If you are drinking a liter every two hours, you need a gram of sodium per liter to stay even.

If you are walking up to Woods Landing, and then Muir Pass, in the summer, you are probably going to need more than 20-30 meq of sodium per liter, if you want to balance losses. (Unless your primary snack is potato chips.)

YMMV

[edit: added units ….. picky picky picky ….. but if you're gonna do it, do it right.]

I think there's a units problem here.
"meq/L' is a U.S. unit "milli-Equivalents" per L
An "Equivalent" is just a Mole adjusted for valence (i.e. 1 Mole of a divalent ion is 2 Equivalents)

Assuming the sodium ions come from common salt,
NaCl is 58 g/mol
20 meq/L of sodium ions requires 20 mmol/L of NaCl
20×58 = 1150 mg/L of NaCl

So 20-30 meq/L (Na+) means 1150-1750 mg/L (NaCl)

edited for typos

As for getting your electrolytes… well, it really depends on your eating habits.

If you're exercising at high intensity for more than about 2 hours, to perform optimally you need to be eating steadily the whole time, not just drinking (ask a pro cyclist…)

The ideal is to be munching constantly during the your hike, and provided you munch on energy bars or salty snacks, they have plenty of salt, you don't need to be adding electrolytes to your water.

However, a lot of people can't stomach eating constantly — and indeed, from an energy perspective, your body can work just fine (if sub-optimally) if you delay your calorie intake to a big meal when you stop. But electrolyte depletion can debilitate you quite quickly, and especially on hot days when people tend to lose appetite.

So I think the bottom line is – ideally, just eat all the time. If not, adding electrolytes to your water on hot days is a good idea.

“So 20-30 meq/L (Na+) means 1150-1750 mg/L (NaCl)”

OK. If you say so.

But This Site says 20meq/L is only 460 mg/L.

Apologies for not making it explicit that I'd done the mEq conversion before comparing sources with standards. The 30 mEq of Na/L is ~ 700 mg/L, and the 5 mEq of K/L is ~ 60 mg/L. To get 3L worth of the K, that's your ounce of raisins, but to get the 3L worth of Na, that'll take you your pound of salted nuts, if that's your only source.

"If you're exercising at high intensity for more than about 2 hours, to perform optimally you need to be eating steadily the whole time, not just drinking (ask a pro cyclist…)"

If you're backpacking (trail-running) at the energy output levels of a pro cyclist (or a middle of the pack competitive amateur racer, for that matter), you're going to want to approach nutrition and hydration differently from what a steady-pace 20-25 mile/day backpacker can do.

"The ideal is to be munching constantly during the your hike, and provided you munch on energy bars or salty snacks, they have plenty of salt, you don't need to be adding electrolytes to your water."

Right, though some of those energy bars and snacks are processed enough that you *might* actually need to think about potassium, too. When you get out of the realm of real food, it's not necessarily just about sodium any more. But I'd ask what you mean by "constantly"? I doubt strongly whether a healthy person would have any problem with stopping for an appropriately nutritious snack every hour or two.

"However, a lot of people can't stomach eating constantly"

It'd be interesting to know what proportion of backpackers would have any stomach problems from snacking while they walk, at 2.5-3 mph, for instance, or from stopping a few minutes for a snack and then continuing to walk while it digests. I can't say I've known any regular hikers/backpackers who have had trouble identifying foods that work for them on the trail, but maybe my sample is un-representative.

"– and indeed, from an energy perspective, your body can work just fine (if sub-optimally) if you delay your calorie intake to a big meal when you stop. But electrolyte depletion can debilitate you quite quickly, and especially on hot days when people tend to lose appetite"

Do you have reason to think that a healthy person walking at 2.5-3 mph in hot conditions would be in danger of electrolyte depletion as a result of going 1-2 hours between snacks?

Cheers,

Bill S.

""So 20-30 meq/L (Na+) means 1150-1750 mg/L (NaCl)"

"OK. If you say so.

"But This Site says 20meq/L is only 460 mg."

Ralph included the Chloride in the weight he provided.

Bill S.

"From http://www.ncbi.nlm.nih.gov/pubmed/11480505 –
"Thirteen male soccer-team players and 100 sedentary students from the same high school were evaluated for 8 d, during which the players were training.

"The authors analyzed 208 sweat samples to determine losses of iodine, sodium, potassium, and calcium in sweat. The mean losses in sweat following a 1-hr game were 52 microg [of iodine], 1,896 mg [of sodium], 248 mg [of potassium], and 20 mg [of calcium]…"

A more common value for sodium loss through sweat is 1 gram/liter. If you are drinking a liter every two hours, you need a gram of sodium per liter to stay even."

Note that the above sample is taken from a presumably American high school, and we Americans eat a diet abnormally high in sodium.

Other research (sorry, no links) suggests that as dietary sodium goes down, sodium loss through sweat goes down as well. Those of us on low sodium diets for health reasons could be jeopardizing ourselves if we ingested sodium at the recommended rates for intense exercise.

YMMV.

Note that the above sample is taken from a presumably American high school, and we Americans eat a diet abnormally high in sodium.

From the link above –
"Institute of Environmental Health Sciences, College of Medicine, National Yang-Ming University, Taipei, Taiwan"

Those of us on low sodium diets for health reasons could be jeopardizing ourselves if we ingested sodium at the recommended rates for intense exercise.

Agreed. If you are "out of norm" your operating parameters will be different.

Bill,

"Do you have reason to think that a healthy person walking at 2.5-3 mph in hot conditions would be in danger of electrolyte depletion as a result of going 1-2 hours between snacks?"

No, of course that's fine – eating "frequently" would have been a better phrasing on my part than eating "constantly".

I think at average hiker-type intensity of activity, with a sensible diet, there should rarely be any need for electrolytes. I never use them, even when I'm going hard and fast – but I do eat all the time – always munching as I'm walking, not just on breaks. But it's something to consider if you can't eat fairly steadily – either because of a long intense multi-hour effort without breaks where you ust can't stomach proper food, if it's excessively hot, if you have diarrhea or loss of appetite etc. I do think electrolyte imbalance can hit you much more quickly than "bonking" from energy depletion.

"But This Site says 20meq/L is only 460 mg/L"

Just be careful weighing out that 1/10 teaspoon of sodium ions if there aren't any counterions present.
They will take your eye out… along with the mountain that you're standing on.

"If you are walking up to Woods Landing, and then Muir Pass, in the summer"

Perhaps you refer to Woods Crossing.

–B.G.–

*) What do these sources say about Ca and Mg? I note that virtually all commercial sports drinks include those two as well.

*) Do not assume that everyone starts out with plenty of sodium. Most Americans get too much sodium in their daily diets, but that is mainly from processed foods. I have very little processed food in the house and am fine with the taste of the unprocessed food as is. I find I have to deliberately add a little salt to some things or else I get cramps of my calves and feet.

*) Eating steadily is a matter of personal preference. I used to do that, but less so these days because I like my hiking poles and using them discourages constant snacking. I can easily drink steadily from a hydration bladder, though, so including some CHO and electrolytes makes sense to me.

*) Getting all calories and electrolytes from your "normal diet" while hiking — the question I have is timing. How much does it help to have these things during the day as opposed to waiting for supper time? I have found that I perform better with a steady intake of the calories in my homemade sports drink. I am less clear on how immediate the electrolytes need to be.

*) Average hiker needs — I am more interested in understanding what happens when the hiker is in good shape and is pushing hard.

–MV

Robert,
Your last point is why questions like these kept becoming topics. What works for 10 mile a day hikers may not work for those that push 30 plus a day. Those doing short mileage likely could eat what they do everyday and do just fine. I found that the needs for electrolytes in particular really increased when mileage approached 30mpd.

Here's an interesting data point from my PCT thru hike. It was just under a hundred days with the vast majority of days north of 30 miles. Those that were shorter likely involved massive amounts of snow. I learned from my training hikes that electrolytes really helped cramping. On my PCT hike that was indisputably confirmed. Every resupply had electrolyte capsules, I had a supply of over 500. I only had cramps two nights when I laid down the entire trip. Those were two night that I was out of capsules due to a missed resupply. That confirmed to me the value of the electrolytes.

If I had been on a more relaxed pace would I have needed them? Likely not.

I'd have to prop up my eyelids on some of those studies.

Boys? Don't be so engineer-y. Don't overthink it. Carry a wide variety of foods and know if meds you take make it so you absorb nutrients differently. (I used to take a med that left me potassium-low for example).

I typically carry kettle potato chips, dried fruits (apricots and bananas are good choices), seeds (nuts if my youngest isn't there). I've learned over the years, that for MY body, kettle chips and water goes far: hydration, sodium, potassium. Stops muscle cramps.

But that is me.

"Don't be so engineer-y."

No fun in that.

–B.G.–

"*) What do these sources say about Ca and Mg? I note that virtually all commercial sports drinks include those two as well."

The study cited above described a 20 mg Ca loss. As far as I am aware, Ca loss from a sweat would not be likely to have any short-term physiological effect in the absence of other significant endocrine problems. The body has a 1 kg store of calcium from which it can readily draw small amounts to maintain homeostasis. (There is some reason to believe that chronic calcium loss through sweat may have an affect on bone density, so it's probably wise for long-distance backpackers to have some good calcium sources in their diet.)

AFAIK, Mg has been somewhat less studied, but a 2006 report in "Magnesium Research" suggested that strenuous exercise might increase Mg requirements by 10-20%. In a diet of real food, see above, I doubt that adding a bit more from a tablet is going to be necessary or to make a difference. Adding too much magnesium is a good way to get an upset stomach, among other problems.

"**) Do not assume that everyone starts out with plenty of sodium. Most Americans get too much sodium in their daily diets, but that is mainly from processed foods. I have very little processed food in the house and am fine with the taste of the unprocessed food as is. I find I have to deliberately add a little salt to some things or else I get cramps of my calves and feet."

100% agreement. If I ate on the trail what I eat at home, I'd be hyponatremic. Real food doesn't have very much sodium.

"*) Eating steadily is a matter of personal preference. I used to do that, but less so these days because I like my hiking poles and using them discourages constant snacking. I can easily drink steadily from a hydration bladder, though, so including some CHO and electrolytes makes sense to me."

Personal preferences are fine. I use trekking poles, and prefer to stop every once in a while for a couple of minutes to pop a snack in my mouth, or carry my poles for a few steps to eat while walking, instead of going to the CHO/electrolyte drink mix. I like real food better, I get to drink plenty of the other stuff when I'm cycling, and I don't like dealing with the funk in my bottle, or even trickier, in a hydration bladder. If you prefer the drink mix solution, that's all good. My comments about electrolyte needs are all about what one needs *if* one is eating real food.

"*) Getting all calories and electrolytes from your "normal diet" while hiking — the question I have is timing. How much does it help to have these things during the day as opposed to waiting for supper time? I have found that I perform better with a steady intake of the calories in my homemade sports drink. I am less clear on how immediate the electrolytes need to be."

Waiting a few hours isn't going to hurt you, but I'd need to know a lot about your individual physiology even to begin to guess how long you might go safely. For myself, if I don't start out in deficit and have a good breakfast with a few hundred mg of Na, I know I can go without significant sodium intake for several hours when traveling at a moderate pace, ~ 3 mph, in fairly hot conditions. (Since I typically eat real food, I don't actually know what would happen if I had no potassium.) I don't think it'd be all that smart to wait until dinner, though, certainly not if I had a choice.

"*) Average hiker needs — I am more interested in understanding what happens when the hiker is in good shape and is pushing hard."

Let's put some objective labels on that and see if we can come up with some relevant comparisons. Average pace backpacking (along with some info about pack weight and elevation changes)? Average pulse rate? Comparing condition is maybe a little trickier, at least for me, unless you're a cyclist and have direct or indirect power data. Without more info, it's hard for me to know what you really mean by good shape and pushing hard.

Cheers,

Bill

"On my PCT hike that was indisputably confirmed. Every resupply had electrolyte capsules, I had a supply of over 500. I only had cramps two nights when I laid down the entire trip. Those were two night that I was out of capsules due to a missed resupply. That confirmed to me the value of the electrolytes."

If I remember right from other threads, you were getting a lot (most?) of your calories from maltodextrin. If you could thrive on maltodextrin *without* adding electrolytes, it would be shocking – they'd need to re-write all the science of sodium and potassium balance. What you don't get from your "food," you have to get some other way.

Bill S.

sbill9000 made a really, really good point about individual variation.

For example, my peculiar system doesn't like food for the first 2 hours in the morning; if I do eat during that time, I invariably feel very nauseated…so I just don't eat until later. This in no way seems to affect my hiking. In fact, I went from Guitar Lake to the summit of Whitney in 2:58 with zero food and only 2-3 sips of coffee. I felt great.

My husband, on the other hand, has to eat constantly, and cannot understand how I can hike without eating.

"If I remember right from other threads, you were getting a lot (most?) of your calories from maltodextrin. If you could thrive on maltodextrin *without* adding electrolytes, it would be shocking – they'd need to re-write all the science of sodium and potassium balance. What you don't get from your "food," you have to get some other way."

I was consuming between 1200-1800 calories from Malto on most days. May sound like a lot but I was eating a total of 6-8000 calories per day. On the days that I didn't have my electrolytes I also didn't have my Malto. So those days were fairly normal hiking food, which isn't saying a lot about nutrition. But I suspect that I wouldn't have had to supplement with electrolytes if I ate 6-8000 of real non hiker food. But the weight of that would have been a show stopper on a three to five carry.

Thanks for the clarification, Malto. That makes it a lot more interesting. Is it easy for you to list what you would have had for food on those days? It might suggest a likely answer as to which electrolyte would most plausibly have been limiting.

Bill S.

Where I mostly hike (deserts), I go through a lot of water because I sweat a lot.I probably sweat less than most who hike in deserts because I am acclimated to it.

I have tried all kinds of electrolyte supplements and also salt tablets, etc.

I find that plain water "quenches" my thirst better than anything.

Years ago, when I was extremely dehydrated and got ill, I found that eating potato chips along with drinking plain water fixed me up in less than an hour. That was an eye opener.

So for the past 30 years I eat breakfast and dinner, snack on the stuff most people snack on, and bring potato chips or similar on the hot days. It works for me and might not work for others.

Each person is just going to have to out and figure out what works for them.

I'll echo everything Nick said.
Potato chips are my snack choice for the same reason. I've done a Grand Canyon R2R2R in a day, many mountain 50Ks, many road marathons, Kearsarge Pass to Whitney Portal in a day, and a few Joshua Tree crossings…
I also had a previous life as a distance road bike rider, regularly riding 200 mile days, much of it in the Mojave Desert.
I've experimented with just about everything along the way.
I've never had cramps, never suffered from any serious dehydration issues (except for ones I inflicted upon myself as tests), and no longer use anything but water and some salty snacks mixed in throughout the day whether doing long distance type stuff or just general backpacking. Luck? I have no idea. But it works for me.

But in the end I don't expect that my system will work for anyone else and I've found other people's systems don't work for me.

""*) Average hiker needs — I am more interested in understanding what happens when the hiker is in good shape and is pushing hard."

Let's put some objective labels on that and see if we can come up with some relevant comparisons. Average pace backpacking (along with some info about pack weight and elevation changes)? Average pulse rate? Comparing condition is maybe a little trickier, at least for me, unless you're a cyclist and have direct or indirect power data. Without more info, it's hard for me to know what you really mean by good shape and pushing hard."

Two scenarios come to mind:

1) A long distance hiker, such as Malto, averaging about 30 mpd for a prolonged period

2) A well conditioned shorter-term hiker — weekends to a week or 10 days, hiking at 70%-75% HRR normally, from 80% HRR up to LT on the uphills. Long-ish days, covering 20-30 mpd. The kind who does the JMT in 10 days with no resupply.

–MV

"hiking at 70%-75% HRR normally, from 80% HRR up to LT"

Lots of fancy terms here, but that doesn't make much sense, unless your abbreviations mean something other than the usage that I'm aware of.

%HRR is the percentage of the available range beween resting pulse and max pulse,
so if (say) resting pulse is 60 and max is 180, 75% HRR is 150.

Nobody is sustaining anything remotely close to 75% HRR — that IS pretty much lactate threshold, even for somebody very fit.