Strategies for Backpacking in the Heat: Daily Routine and Gear Considerations

[Jeff Podmayer]

Companion forum thread to: Strategies for Backpacking in the Heat: Daily Routine and Gear Considerations

In this article, Jeff Podmayer discusses strategies for daily routine and choosing your gear when backpacking in the heat.

[Mark Verber]

Thanks for the article.

One thing I would add is bring electrolyte tablets or powder to add to water. A few years ago I was on a trip that was unexpectedly hot (expected 70F, was 95F – inland Ventana wilderness is more like Salinas than Big Sur… doh!). At the end of the day my whole body started to cramp. Any movement resulted in pain. couldn’t add pressure to the cramping area because the movement to reach it caused new craps. Thankful, a friend has gifted me some electrolyte tablets which I had thrown into my bag on a lark. I had to fight through the cramping to get them out of my pack. Around 30 minutes later all the cramping stopped.

As to water needs… lifted from my water page

I developed a sense of my water needs by repeatedly running an experiment. I would weighing myself naked, get dressed. engaged in activities at different MET intensities and temperatures (no peeing during the experiment) for 1-4 hours, removing clothing, drying with a towel, and then weighing myself measure weight loss due to sweating / perspiration / breathing. I lost 1L every three hours when it’s 30-60F and I am moderately active (MET 3-6), around 1L for every 1.5-2 hours 60-80F, and 1L every hour when it’s more than 80F.  When >9 METs water lost was 3x my normal rate. When I gave chat-gpt the prompt “what’s the rate of water loss in humans at different MET and temperatures? How does variance of humidity effect this?” I got results compatible with my self experimentation and some added nuance.

[Jerry Adams]

Yeah, electrolytes

I think I’ve had this problem forever, like 60 years.

One symptom is leg cramps at night.  Another is i get very tired after a few hours.

There was a recent thread about this, and a gear skeptic video

[Terran Terran]

And that’s why Bobby slipped away. Just follow the Big Sur river down to the beach and you won’t be hot.

I find what I drink makes a big difference. Mostly cutting out alcohol and sugary drinks. You sweat out your poisons. Having clean sweat is more efficient.

[Jerry Adams]

One thing you sweat out is sodium, and other minerals

After a few hours there’s a shortage in your blood, so you start getting symptoms.  Some people have more sodium stored up so it’s less of a problem.  Or they sweat out less sodium. Potassium is another mineral.  Calcium and magnesium also to lessor degree

[Drew Smith]

Excellent article, lots of good info here. A couple of adds:

If you are not a fan of electrolyte drinks (I am not), salty snacks and dried fruits will meet your electrolyte needs.

I carry all my water in 1 or 2 liter containers. Two reasons – 1) if you get a leak or seam blow out in a 6L bladder (not likely, but it happens) then you are in trouble. It’s much easier to deal with losing a smaller bladder. 2) Easier to balance out that water weight in your pack with multiple small bladders than one large one.

[Terran Terran]

If we didn’t sweat out salt, we’d turn into jerky. The body stays in balance. If you’re eating healthy, staying hydrated, not on medication, and not sweating excessively you’re just going to sweat out what you put in. If you’re sweating excessively, you need to get out of the heat.

[Murali C]

Regarding taking a break between 12 and 5 – it seems like when it is hot, and the surrounding air is so hot that unless you find a large tree that provides shade, isn’t it better to be moving – even slowly? (Finding such trees in the desert is next to impossible).

 

[Terran Terran]

If you’re in a wash, one side is often shaded. When you find shade , take a break. A small tarp can work. Often the wind will shift around 1 pm and you’ll get a breeze. Counting on that breeze, I keep going. If it was a survival situation though, I’d stop and cool down. Under a bush if I had too.

[Bill Budney]

Regarding taking a break between 12 and 5 – it seems like when it is hot, and the surrounding air is so hot that unless you find a large tree that provides shade, isn’t it better to be moving – even slowly? (Finding such trees in the desert is next to impossible).

I think it depends. When the air is above the temperature of our core, cooling becomes limited. Bright sun makes it worse, but dry air at least allows sweat to evaporate. Low humidity seems more important than air temperature alone. Wind can make a huge difference, as well.

With the right clothing and weather/climate, walking could be fine. As you say, control your pace as appropriate.

If it is hot and humid with no breeze, then that might be a time to experiment with man-made shade and a siesta. Maybe two layers of space blankets with an air gap in between?

It seems as though somebody, somewhere, must have come up with a pocket size hot-weather Super Shelter by now.

[AK Granola]

I echo the electrolytes. With naturally low blood pressure, I didn’t realize how much they would help me until I tried some in a 10k one time. I always use them now, esp in hot weather.

I will forever be mystified by the sun hoody. Wearing a hood around my neck and ears is soooo uncomfortable in hot weather. I am of the big floppy hat tribe, letting air flow free around my head. But I recognize that a lot of folks who recreate in the desert do seem to like those hoodies. I would sweat buckets.

 

[jj]

Good topic and informative article. Not only do the majority of my hikes have long water carries in warm to hot weather, I work outside year-round in heat quite a bit more humid than what’s covered here. That said, the commentary and tips offer good advice for hot/humid weather for the most part. I would add that carrying UL electrolytes like salt stick caps is super important, and sun hoodies arent always the best option for hot/humid, because hot/humid usually implies biting insects. I prefer a woven, collared, button up worn in conjunction with a full brim hat and umbrella. Surplus boonie hats can be wet down and worn to cool ya a bit. unfortunately, with increasing humidity and heat during southeastern summers, understanding wet-bulb temperature is crucial to safety. I use the this military guide for planning activity in the heat, specifically, pg 6 – https://home.army.mil/wood/application/files/8416/2765/1794/Heat_Illness_Pocket_Guide.pdf

This is also a good source for understanding safe activity levels in high heat conditions – https://ph.health.mil/PHC%20Resource%20Library/cphe-heat-ehip-guide.pdf

[David D]

From the heat guide “Salt tablets are not recommended”.

Why’s that?  Salt caps or equivalent are the standard recommendation

[Mark Verber]

Because you lose other electrolytes… if you take just salt it will produce a larger imbalance which can actually worsen dehydration.

[John S.]

https://www.texasheart.org/heart-health/heart-information-center/frequently-asked-patient-questions/if-salt-keeps-water-in-the-body-why-do-salt-tablets-make-dehydration-worse/

“The only good thing sbout salt tablets is that they are very poorly absorbed. This limits the damage they can do.

The definition of dehydration is the condition that results from the net loss of WATER. The concentration of sodium in our body fluids is closely regulated by the kidneys. In most cases, water is lost via perspiration and breathing. This fluid is HYPOTONIC meaning that the concentration of sodium in it is low compared to body fluids. To correct or prevent it, all that is needed is to take in more water. The small amount of sodium loss is easily replaced from a normal diet.

In hot, dry climates like Arizona, the normal kidney will adjust and water is all that is needed. When we become dehydrated, the sodium concentration in the body is already elevated. Adding salt (sodium) only aggravates the condition by forcing the kidneys to excrete more water in order to eliminate the extra salt.

In circumstances such as EXTREME exertion in hot and dry weather, severe vomiting, and diarrhea, and illnesses like cholera, special electrolyte solutions (not just sodium) are required and may need to be given intravenously. The average athlete with normal kidneys needs water. Supplements such as GatorAde can be used in situations during and following strenuous workouts, but should be in addition to, not in place of plain water. I recommend drinking 12 oz. of water before the workout and supplementing it every 45 min. during the run/ workout. The sensation of thirst indicates the onset of dehydration. If the athlete can pass urine immediately following his workout, he has kept himself well hydrated. All athletes should understand this.”

[David D]

I took “salt” to mean all electrolytes.  If they mean sodium only, ok.  After a lit survey, recommendation was Salt stick Caps (50 min mark):

Taking too much water without electrolytes can cause hyponatremia

My feet and hands swell when I hike hard in high heat and hydrate regularly, these salt stick caps avoid it.

[Terran Terran]

I take “salt” to mean all salts. Not just sodium. I think salt tablets were mostly sodium when less was known. However they weren’t straight sodium nitrate. A lot depends on the quality of your water. Especially if you’re drinking purified water. Ordinarily we don’t need to supplement with salts. When I was laying block in 120* humid weather, I’d occasionally  drink unflavored Pedialyte. It may have helped a little. It think mostly it was a placebo. The guys who used it regularly also drank a lot of beer and sweated a lot more. Alcohol creates an in balance. Electrolytes are often over promoted and as a result overused.

[Ian H]

My Renal Physiology Professor was quite adamant and correct , it’s almost impossible for a normal, healthy human to run out of sodium/electrolytes even if severely sweating. Kidneys are clever and do their job well. Vomiting, diarrhoea etc is a different story. Most ‘sport electrolyte’ drinks are marketing, not medically needed.

But running out of water is easy, like nutrition expert Dr Michael Mosely on a short walk on a hot Greek island, no shade and reflected heat from rocks. In Central Australia, the National Parks rangers close the walks when the anticipated temperature is over 36 C (97F) because there have been too many deaths of tourists. This week in Alice Springs it was 43 C (110F), at the start of summer.

An easy 5km walk like the Valley of the Winds (https://uluru.gov.au/things-do/activities/walks/kata-tjuta-walks/valley-winds-walks/) which I did with kids 3, 8, and 13 had killed 2 German tourists a few months earlier. I was asking the ranger why they were closing at a common (not very hot for the Northern Territory) temperature of 36C, and she explained that after these last 2 deaths (they had one small waterbottle each, I carried over 4 litres) the National Parks Service had to close walks for safety.

Prehydrate (drink up before starting), continuously hydrate while walking (a bladder with a tube near my mouth reminds me better than a bottle on the back), and take a big swig every rest stop. At least a litre per hour for walking over 35C, and I’ll always carry extra. That burden of an extra bottle vanishes when you find the ‘permanent’ creek on the map is dry.

[Mark Verber]

Ian: I appreciate that healthy adult bodies are good at maintaining balance, but my experience in the field is even when sufficiently hydrated it’s possible to sweat out enough electrolytes to produce significant cramping. The day I mentioned it’s likely I was sufficiently hydrated.  I consumpted approx the same weight of water that I lost due to sweat while performing similar intensity activities in similar conditions.  When I peed… color was typical of being hydrated, and I was drinking anytime I felt at all thirsty.

I am sure I have reviewed papers about read studies about electrolytes being helpful. but not finding them in my archives. The following isn’t  the best paper, but one I quickly found via chat-gpt which suggests there is merit to elecrtrolyes for rehydration. https://bmjopensem.bmj.com/content/5/1/e000478

[David D]

The vid I posted reviews studies of sodium loss and efficacy of different electrolytes

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