Reminder About Hiking in Extreme Heat

Maybe I’m missing something, but the article seriously suggests 1 liter per mile of hiking?

I claim no expertise, but anecdotally, that seems like way too much water for me, even in extreme heat. The heat index is around 102 here lately, and I’ll take a 2-3 mile walk and carry nothing with me.

Is it common for people to drink that much water in the heat? I’ve felt the side affects of over hydration before, and it was drinking water at a pace well-below what they suggest.

I would like to see some sources a little more authoratative than a couple of newspaper
writers. Those numbers do not correlate with my experience hiking in hot weather. I would be particularly wary of drinking a liter of water per hour, and running the risk of hyponatremia. In any case, when temperatures rise much above the mid 90s, I would be inclined to go to ground and hike in the evening or, better yet, very early in the morning, when the temperature will be at its lowest.

while 1 liter per hour does seem high, 1 liter per 2 hours is definitely not high, depending on conditions and intensity level of output. That is the key for me, not just how hot it is, but how much you are exerting yourself in the heat. When I run ultras in heat I easily consume 20 oz or more per hour, and still lose weight.

I think the key to avoiding hyponatremia is to also consume an appropriate level of electrolytes while consuming the water.

The quote I’m referring directly to is this:

Subervi suggests avoiding outdoor activity during this heat wave. But if hikers insist, he said, they should begin hydrating 24 hours before a planned hike then drink 32 ounces for each mile they travel.

A liter an hour would be high for me, but perhaps reasonable. However, a liter per mile seems borderline absurd. That’s 2-3 times more than a liter per hour. Even if I was replacing electrolytes via sodium or supplements, that much water would certainly make me feel quite ill.

Art, I agree that a liter per two hours does not seem overly much. It’s probably what I drink backpacking on a hot day.

Maybe they meant hour, not mile? Still, if it was, I’d expect better from the Washington Post…

I agree 100% that 1 litre of water per mile is very, very high; one’s electrolytes would go all out of whack very quickly.  For whatever reason, the media ALWAYS uses that metric (1L/mi); it’s not just the Washington Post — maybe it’s a tactic to try to scare people off?

The only feasible way to handle that heat is to stay out of it.  If you’re on a thru-hike and you have no choice but to be out in that heat, as Tom said: night hike or use an early/rest/late approach; and veg out in the shade for the hottest part of the day.

The tragedy here is that all of the people were on day hikes — so the heat could have been easily avoided by starting pre-dawn and turning around early.

What some of these guys are suggesting could lead to death by hyponatemia: death from drinking too much water. The idea that you need to drink that much has been an urban myth for some time, and since so many people quote it, so many more copy them and also quote it. Does not make it true though.

If you want to read more about it, try
http://bushwalkingnsw.org.au/clubsites/FAQ/FAQ_Noakes.htm
Dr Noakes has the advantage that he knows what he is talking about – and has done so for decades.

What matters more is not the amount of water you drink as how hot your brainstem is getting. If that gets too hot you suffer heat stress then heat stroke. After that, you can die. Cold water poured over the back of your head and neck can be extremely reviving. Dehydrating so much you stop sweating is dangerous, but you can recover very quickly once you cool down.

Believing stuff written in the newspapers is a good way to get yourself killed.

Cheers

.

Living, hiking and riding in the desert has taught me a few things. But first, notice some particulars about the deaths.  Many tourists. One personal trainer, the bike rider.

• I have never known the Washingon Post to be a scientifically or medically accurate rag.  For that matter, no newspaper could claim to be.  At least on the internet, one can read peer reviewed medical journals.  They are not perfect, but better than the 6 o’clock news.
• The body is very complicated.  Blaming a death on one simple variable is unwise. There can be hidden medical issues or issues unknown or not understood by a simple newpaper reporter.
• There is physiological adaption to heat.  The military says ~3-4 days for gross and as much as 14+ days for stable adaption.  Several of these deaths were tourists with little time in the heat before hiking. http://www.autonomicneuroscience.com/article/S1566-0702(16)30007-8/fulltext
• Rodger is right, it is the heat that kills, not the lack or excess of water in most all cases. If your heat production from exercise is high enough combined with high environmental heat, no matter how much water you drink you will still overheat. Perspiration and heat loss thru evaporation can only cool so much.  Proven by the dead trainer who rode for many hours in the heat of the day.
• Not enough water will hasten the previous point but drinking tons of water will not keep one totally safe either. One death proved that running out of water begs for a bad outcome.
• The body can only absorb about 1 liter per hour.  More than that is useless to drink. As Roger says, if you have more water, pour it over your head, don’t drink it.
• The risk of clinically important hyponatremia is minimal if intake of water is less than 800ml per hour.  No proof sports drinks prevent hyponatremia.  See a review in the Nephrology literature.  http://cjasn.asnjournals.org/content/2/1/151.full
• Bergmann’s rule from the 1800’s states that fat people have a lower surface to heat production ratio and overhead faster. Polar bears do not do well at the equator.
• Desert survival courses teach traveling at night when the temperature is lower.  Irrespetive of the amount of water one has.

90s and humid here today. My synthetic T was completely saturated in <10 minutes.
Being “in training”, I push mowed my grass instead of using the riding mower(roughly equivalent to hiking 5 or 6 miles), and followed it up with a bike ride.
Considering my 7.4lbs(7x17oz bottles) of water intake and weight difference from my daily weigh-in, I guesstimate that I had sweated out ~13lbs of water after no more than 3hrs of moderately strenuous activity.
Hardly establishes a rule or anything, but does come out to a couple liters per hour.
Less a concern in drier climes, but when you don’t have the benefit of much evaporative cooling, you sweat profusely the entire time you’re active.

Hyponatremia and urban myth go well in a sentence together. You would practically have to force yourself into that condition, which is why it’s almost unheard of, while heat casualties due to inadequate hydration are quite common.
Along with being forced to drink water unnecessarily in the military, particularly in training, I’ve been working in high heat environments for decades, so what someone who hasn’t says doesn’t mean much to me.
It’s true you can bounce back quickly from dehydration, but likewise true that you can take in multiple gallons per day if sweating a lot and even drink so much water that you’re peeing every 15 minutes with no ill effects, so I’ll find something better to worry about.

My initial reaction was that I’d prefer to dump the water on my head. Good to know that my inclination to do so was not unfounded. :)

I doubt many here have actually hiked in 120F weather. I have and 1 liter per hour along with enough salty food is the number that works for me. Normally, in this kind of weather, I try not to hike in the heat of the day, but the temps will still be over 100F at midnight. Overnight lows may not go below 90F.

Last week I re-packed the wheel bearings on my trailer in 123F temps (50.6C for Roger). Not as strenuous as backpacking, but I was drinking about a liter an hour without trying to monitor or maintain a level of hydration; I was drinking whenever I was thirsty.

That is uninhabitable : )

10 years ago, i ended up in the hospital twice in one year with low electrolytes – once it was hyponatremia, and once it was low potassium (hypokalemia). i wasn’t backpacking either time, just exerting myself in the summer and drinking a lot of water. i wasn’t doing anything extreme, and haven’t had this kind of problem since — it’s a bit of a mystery.

i don’t have much to add besides, it’s real, it happened to me, be safe and learn to listen to your body :)

It’s definitely doable, hyponatremia, I mean. I can’t drink much over a gallon of water per day without getting dizzy spouts (without supplements), but I also have a pretty low sodium diet. I was on the border of it a few years back and I’d only managed about a gallon and a half before feeling pretty bad.

I think it’s easier to get than is generally assumed. Or maybe I just need more salt in my diet. Probably both.

There may be two different populations in the mix:  oblivious tourists who aren’t drinking much in the first place vs. the fitness crowd who have been conditioned to hydrate.

If I’m running in the mountains here in the summer (hot, but more tiring, humid) like Art I drink around 500ml/hour and take electrolytes.

But what like others are saying what makes a big difference is try to cool your body down. Every cold river I cross I put a neck gaiter in the water to cool down the neck. I have also started using arm sleeves instead of long sleeve shirts because I can put them more easily in the cold water as well. Sometimes I just cross the river and soak my feet as well.

Another thing is I try to remind myself to ease into it. Your heart will work harder when it is that hot. So watch the heart rate more than say a time goal you had in mind.

Every time I don’t do either of these three things I suffer for it later in the day with headaches or stomach issues.

And I like to go out in the rain, (if there is no all out tropical storm or danger of landslides from the amounts of rain). Takes aways the direct sun, lowers the temps 2~3˚C and a bit of cooling from the rain itself.

Saw this pop up today.

http://www.azcentral.com/story/news/local/phoenix/2016/06/28/phoenix-proposes-hiking-ban-during-hot-temperatures-rescue-summer/86438476/

Not really sure how I feel about it. Hm.

In an attempt to ban stupidity, Lake Mead National Recreation Area started closing some trails in summer starting a couple years ago. Trails are a rarity in the NRA.  The two most popular trails are about 5 miles long, easy walking and terminate at the Colorado River in Black Canyon, which means there are millions of gallons of easily accessible water. I often hike these trails and even in summer could do them without carrying water, but it would not be comfortable. The ban was put in place after a troop of incompetent Boy Scouts suffered heat stroke and their more inconpent leader died in June of 2013 hiking the trail — an occurrence I can’t comprehend as it is such an easy short trail. In the first 7 months in 2014, these easily accessible and easy navigation trails accounted for 37 incidents, resulting in three fatalities, 35 patients and 13 medical transports. Other than the trail closures will not put SAR personnel at risk, I disagree with the policy. We need to let evolution do its job and cull the herd, especially since we never had these problems before the Internet or Facebook. Technology in the hands of dummied-downed populace makes for many more Darwin Award candidates.

In summer Anza Borrego State Park closes most of the entire 30,000 acres of the Coyote Canyon watershed so Big Horn Sheep will have easy access to limited desert water. I agree with this policy. Big Horn Sheep are more important than dumb people, some of whom, would die in the extreme heat, especially since there is no cell phone reception.

The Skyline Trail, on the desert side of the San Jacinto Mountains is not an official maintained trail, but has become popular via the Internet and Facebook. Most of the area is closed a few months each year to also protect Big Horn Sheep — a worthy trail closure goal, but it is impossible for authorities to enforce the ban. Rescues are difficult and dangerous for the Riverside County SAR, and most years there is usually at least one death due to heat exposure. Some years, usually around Memorial Day, there can be multiple deaths in a single day. My solution is to post a sign at each of the two trail heads with a a running total of the number of deaths, block cell phone and satellite signals on the entire west side of the San Jancito, outlaw SAR activities in the area, and place a warning on the sign that if you are a stupid person you will probably die because no one is interested in risking their lives to save your sorry butt. BTW, I often hike the trail around Memorial Day.

As a society, we are experiencing de-evolution to the point that government is deciding when it is safe for you to hike and not hike.

Other than that, I have no opinion on the subject ;-)

Rescue insurance

Although such things will probably result in even more stupidity.

I prefer your Darwinian model, Nick. I remember the days before GPS and cellphones and our plan in the winter Whites was a) don’t get into trouble, b) if you do, be prepared to self-rescue and c) be prepared to kiss your a$$ goodbye.

+1 to Nick’s comments, you can’t legislate against stupidity.

We have always operated with Bob’s three layers of decision making.

“I doubt many here have actually hiked in 120F weather.”

That’s awfully hot! When I was younger, I worked a lot of double shifts, even the occasional triple, on a very strenuous job in that kind of heat, but I got to take almost an hour of breaks in an air conditioned room per shift and go home afterwards. The idea of backpacking in those temps, and being out for days on end, just….ow.

It can get pretty hot late July in Oklahoma, but never that high. Perhaps the heat index might raise that high, but never the temperature. Triple digits is not uncommon, though. However, I do drive in those temperatures in a car with no air conditioning. It’s at least 120 on a bad day. :) Quite unpleasant. If I had to do those temps often, I’d probably get into the habit of wearing a water-soaked shemagh.

I think the biggest issue in the US, especially with tourists, is that they rarely come from a social or cultural background that has already long-established how to deal with intense heat.

Nick, I also agree with you, upon further contemplation. I have a feeling that unfortunate incidents will only get worse, too, given the recent trend of backpacking appearing in popular culture.

The free market can solve all our problems.
Open the trails to concession stands, and rent GPS tracking tags.