Do you walk in a heatwave?

[madmacca]

Note however, the longer the duration of an activity that requires a high volume of hydration, the harder it is to maintain electrolyte balance. So, maintaining electrolyte balance becomes quite difficult on these extreme weather days. It ain't easy and will expose many risks even for the best equipped.

Yeah, electrolyte balance can be harder, as there is no easy test like colour of your urine for hydration. Also, the amount of salts you lose can vary significantly - if you exercise regulary in the heat, your body will adapt and excete less salt in your sweat. If you exercise only in temperate conditions, if you start exercising in the heat, you will lose a lot more salts, although your body does start to adapt after just a few days.

I always carry electrolyte powder, and my rule of thumb is that if I find myself drinking (as against cooking with) more than 2 litres a day, I will mix in some electrolyte powder during a break. If I am drinking more than 4 litres a day, I will do this twice a day.

I have read some of the scientific research on electrolytes, water consumption and hyponatremia, and while I won't claim specific endorsement of my 2 litre method, it is broadly consistent with the research.

Soaking your clothing in a creek or the like can give you the cooling effects of evaporation for half an hour or so, with the loss of salts through sweating.

[GPSGuided]

Given the risks involved and the fact that if I get into trouble I may take emergency services away from other critical activities I consider that it is not only my wishes but the possible needs of others that mean I stay away from the bush during high risk days.

Good consideration. It affects not just the individual.

[nq111]

Some dangerous situations there.

Some other considerations
- You can only absorb a limited amount of water per hour (i think it is a bit less than one litre for most). Lose more than that and you need to stop to rehydrate back to normal.
- Humidity makes a big difference (check the heat index charts e.g. BOM) - to me 32 degrees at 80% humidity is harder to exercise in than 40 degrees at 15% humidity. Wetting your shirt or a headband in humid heat makes next to no difference in the humidity. Thinking north queensland conditions here - not southern australian dry heatwaves.
- The more acclimated to the heat the less electrolytes (salt) you will lose through your sweat (someone else mentioned this)
- Salt (from sweat) and dirt on the skin can significantly slow evaporation (what you need for cooling) through osmotic pressure. A swim or wash where possible is a useful strategy.

[icefest]

Back to the heat-wave question. I've Just came back from the Frankland range. Even though it wasn't too hot (I doubt it was over 30 degrees in the shade on the tops) it hadn't rained much for the preceding two weeks and everything was getting very dry.

I ended up skipping the last two hills (Lloyd+terminal) because water was getting very hard to find.
I ended up wading/swimming in lake Pedder instead.

TL;DR only if there's plenty of fresh water, swimming, low bushfire risk, or no other choice.

[tibboh]

I only have limited opportunities to hit the bush so cancelling may mean going without for a long time....so I would probably go but take the relevant precautions re pace, water etc. Having said this, I have never walked in 40+ extremes so this may change my perspective a little (or alot). Perhaps if on an extended walk, get up at dawn and walk till 11am, get in the shade for 4-5hrs for a siesta then walk for another 3-4hrs late in the day????? I suppose every walk is different so it's hard to think of all the possibilities.....Be prepared!!!

[Onestepmore]

Hubby has just cancelled his overnighter.
I'm glad

[Tortoise]

Soaking your clothing in a creek or the like can give you the cooling effects of evaporation for half an hour or so, with the loss of salts through sweating.

+1 Even when we only had the occasional muddy puddle, wetting our hats thoroughly whenever we could made a huge difference in a heatwave in the middle of an extended walk.

if i was caught in a heatwave on a trip, i'd cut it short and switch to walking in the early morning... and stop before the heat of the day

+1 On the same walk, we sat in a creek till about 6pm, and walked till about 10pm. Decided that on a short day, with a big climb and no more water till the next campsite, we'd leave it till the evening.

[ULWalkingPhil]

Not anymore, unless I have to. I choose to walk in the cooler months now, It's so much easier for me. Humidity is a killer up here this time of the year.

[nq111]

Not anymore, unless I have to. I choose to walk in the cooler months now, It's so much easier for me. Humidity is a killer up here this time of the year.

You may be missing out on some of the best walking ULWalkingPhil. Summer / wet season can be some on the nicest scenery and wildlife across Queensland.

Treat hot weather walking as a project like you do UL walking or may winter walking in NZ or Tas and you may find it can be managed quite ok.

BTW - I am not meaning to be provocative - just hopefully add some food for thought.

[north-north-west]

Sometimes. Usually I'll just find a cooler alternative. A rainforest walk beside a creek, with a waterfall at the end, something like that.

Pushed myself up Druids Thursday afternoon. Not sure what the mercury read, but a subjective assessment would have been 'too *&%$#! hot!' Not really sensible. The mud was an inch deeper on the return, due to all the sweating. The cool change overnight was such a relief . . .

[weighty walker]

Hi all I am just back from a week in Tassie and as said by many, you have to grab the time when you can, so not going wasn't an option.I left the horrible draining heat of qld to get a lovely less hot week in tassie,(or so i thought) doing a few days on the SCT and guess what, the *&%$#! heat followed me .
Much to my embarressment here is a little story of woe.

My journey started on monday when i caught a bus to Geeveston (from hobart) having been told a regular service runs from here to cockle creek. Two hours later i call the bus company to ask where the regular service was and was told I was supposed to call and ask them to pick me up.Well, crossed wires,confusion, it all added up to one less day on the track (pretty pissed off to be truthful)so a uneventful night spent in the Geeveston park(thank goodness for the platypus) that gave me something to do for 6 hours before night!!!!
Up early,packed ready to go, finally bus arrives and journey starts again one day late. Met a lovely man from Switzerland doing 3 weeks solo in the southern ranges,then meeting up with a friend to do another 3 weeks in the western and eastern arthurs. Dropped him off at the moonlight ridge track and i continued on to cockle creek.
Started the walk out to south cape bay around 12.30 and already knew that i was feeling this heat wave. Had i been in qld I would have called it off as i really am no good in heat.But on i went regardless as i was on my holidays and probably wont get back until september if i am lucky and i had already lost a day with the bus mix up.
Anyway by the time i got to the duckboard i was plastered in sweat but determined to get to the beach before having a break and a snack. (its only 7.1 km for goodness sakes)Well i am not sure if my brain fried causing confusion or my stupid stubborn personality wouldn't let me stop, but apart from 2 quick pitstops, one for more sunscreen and one to check time i continued on even though i actually felt exhausted and shivery. Finally after walking in a dream like state i got to south cape bay camping grounds, made my way up the hill (didnt go the stairs)and into a lovely area on the hill. nice cool shady. It was here i finally gave in to my unhappy body and collapsed in a quivering heap.Headache, really bad body cramps, nausea,cold clammy skin but hot to touch,shivers, Heat exhaustion fair and square. It took me at least 2 hours to begin to feel able to move again. i did stumble down to the creek to get more water as my bladder was sucked dry as well as my 1 l bottle. I was lucky i hadn't reached the point of no return but it was a close thing. I am one lucky lady as i have experienced heat related illness on other occasions and this one was an eye opener. Just because i come from a hot state doesn't mean i should underestimate the heat in other states, especially tassie. I have had extreme sunburn in tassie summer before also so am really annoyed at myself for my stupidity. Just a small reminder that no matter what age you are and what experience you have you can still make bad calls and sometimes be really really stupid.
Anyway i am all good and now trying to plan my next trip. Maybe I should always take my hubbie ( he didnt come on this trip)as he always seems to make good decisions and not silly ones like me. Oh well makes for an interesting life. I will post some photos of the trip at some stage soon.I really did enjoy it even though things weren't perfect and i am still enjoying learning from my mistakes. thanks for reading.

[wayno]

god to hear you recovered from that event.
if you're built for comfort, the extra personal insulation will make it more likely to overheat. you might find colder seasons more favourable to walk in...

[nq111]

Thanks for sharing your story weighty walker.

Walking in the heat can be very dangerous - I am glad you recovered ok. I keep saying those conditions need to be planned for as you would going out into a blizzard!

I concur with the power of the high summer Tassie Sun - will burn you in a fraction of the time it does in Queensland.

Did you complete the walk?

[Orion]

Hyperthermia is never on my list of risks where I usually walk. It sure wasn't something I worried about for Tasmania. I always think of Tassie as a place where you could die of hypothermia in high summer.

But walking down from Bechervaise Plateau on 14 January I discovered it could be an issue there. I had climbed Federation first thing that morning and, after a short break, started down with just one liter of water. I reasoned that I could make it to Cutting camp in 3 hours or so. And while I might be a little thirsty the lighter pack would make the "monkey" ridge a bit easier going. To exacerbate matters I wore a long sleeve black shirt to protect my skin from scrub. Right off the bat I was roasting like a turkey in that shirt. I just didn't fully appreciate how hot it was.

After a short while of feeling uncomfortably warm I noticed that I was breathing a bit too hard for the exertion. And my pulse was oddly fast. My mind was also a bit dull as I kept wandering up false leads and having to return. At some point I noticed track features that looked oddly familiar. I wrote that off and kept up whatever pace I could manage, hoping for some forest protection from the intense sun. But then I saw my bootprints in the mud going in both directions. The compass confirmed: I'd turned around somehow and was heading back toward Federation.

About this time I began to feel chills.

I don't have much experience with hyperthermia so I don't if I'm being a drama queen or whether I was really in serious danger. But I took it seriously at the time. I found some shade, rested, drank most of what water I had left. And then headed slowly back up toward the plateau. Once there I spent the afternoon resting in the shade and drinking water. It took a lot of water and a lot of time before I felt even slightly inclined to urinate.

So all was well, and I got to spend a second night in that beautiful alpine location. Much better than the views in the forest but I felt humbled and a bit shamed.

It never cooled off overnight. I didn't need my sleeping bag. The next morning, despite a slight dehydration hangover, I got going early and was sweating in my t-shirt at 6:30am. I figured out from my bootprints where I had gone wrong (although it was probably a fortuitous error) the previous day. At a place where the track divided for a short while I took one leg and then, at the next junction, took the other leg right back to where I started, unaware that I'd reversed course.

On the way out, dreaming of hot chips, I walked all the way to the road only to find all the takeaway places closed. Oh well, it was still a good trip and I'm happy to be alive.

[wayno]

i read an article about a body found in death valley in the states, one of the hottest places on earth, it wasnt more than a few weeks dead when they found the body, when the authorities picked it up, the bones inside rattled it had been so dehydrated, it looked like a mummy and the outside had seperated from the inner dried tissue and bones.....
on a hot day you could be loosing a couple of litres or more of water an hour while you walk.....
on the pacific crest trail people will carry up to ten litres of water with them in the southern deserts to offset water loss..

[weighty walker]

if you're built for comfort, the extra personal insulation will make it more likely to overheat. you might find colder seasons more favourable to walk in...

Ha ha thanks Wayno, I do find cooler weather MUCH more favourable, luck of the draw in Tassie but
You are right nq11 very dangerous, my problem was more being underhydrated to start with, then that intense heat on top, very scary stuff.As for the walk, South cape rivulet is as far as I got did it as a day walk from south cape bay as i wanted to stay closer to civilisation (in case i felt sick again)had a relapse, whatever, but when i got there it was deserted and sooooo beautiful that i walked back packed up my gear and walked back. Spent two nights here before walking out for the bus back on friday.Not a big walk in all but I loved it anyway.
Orion, thanks also for your story, I chose to ignore my symptons much to my own disgust, great learning curve.Glad you were smarter than the average bear

[nq111]

on the pacific crest trail people will carry up to ten litres of water with them in the southern deserts to offset water loss..

That would be right. I regularly carry 10-14 litres around here. And still sometimes getting dry by the next water point.

[wayno]

on the pacific crest trail people will carry up to ten litres of water with them in the southern deserts to offset water loss..

That would be right. I regularly carry 10-14 litres around here. And still sometimes getting dry by the next water point.

do you take extra salt as well?

[north-north-west]

- Humidity makes a big difference (check the heat index charts e.g. BOM) - to me 32 degrees at 80% humidity is harder to exercise in than 40 degrees at 15% humidity. Wetting your shirt or a headband in humid heat makes next to no difference in the humidity. Thinking north queensland conditions here - not southern australian dry heatwaves.

This is an individual thing. I am one of the minority who struggle in dry heat and find humid conditions much more comfortable.
Give me a steamy 40 over a dry 30 any day.

[nq111]

on the pacific crest trail people will carry up to ten litres of water with them in the southern deserts to offset water loss..

That would be right. I regularly carry 10-14 litres around here. And still sometimes getting dry by the next water point.

do you take extra salt as well?

Nope, i just really on food with a good salt / mineral balance and that being reasonably heat-acclimated I don't lose a terrible load of electrolytes (you know when you are getting acclimated as your sweat is fresh not salty).

[nq111]

- Humidity makes a big difference (check the heat index charts e.g. BOM) - to me 32 degrees at 80% humidity is harder to exercise in than 40 degrees at 15% humidity. Wetting your shirt or a headband in humid heat makes next to no difference in the humidity. Thinking north queensland conditions here - not southern australian dry heatwaves.

This is an individual thing. I am one of the minority who struggle in dry heat and find humid conditions much more comfortable.
Give me a steamy 40 over a dry 30 any day.

I am sure everyone is different. Those head indexes are developed from sampling a number of people under varying heat / humidity conditions, basically asking 'how hot do you feel', and then fitting the best curve to what comes back. I am sure there are outliers and also the results would be relative to the conditions the sample group is acclimated to.

However there is also a component of raw physics to humidity feeling hotter - that being evaporative cooling (sweating) cannot work as effectively and so it is always harder to shed heat at 35 degrees - 80% humidity than at 35 degrees - 30% humidity.

[Dolerite Walker]

No. Bushwalking is an activity that should be considered strictly weather dependent. I still chuckle (shake my head) at the news footage of some Sydneysiders pressing on with their regular morning exercise routines during a blanketing dust storm a few years ago. Weather extremes mandate flexibility with walk plans/dates. Pushing on with a walk when bad weather is forecast (be it rain, cold, heat, wind), even if you have apparent time restrictions, is going to end in tears.

[maddog]

Exercise in the heat and your body will adapt. From Human Adaptations to Heat and Cold Stress (NATO):

Humans have remarkable ability to adapt to heat stress, and given adequate water and protection from the sun, a healthy acclimated persons can tolerate extended exposure to virtually any natural weather related heat stress...Heat stress results from the interaction of environmental conditions (temperature, humidity, sun), physical work rate (body heat production) and wearing of heavy clothing / equipment that impedes heat loss. Environmental heat stress and exercise interact synergistically to increase strain on physiological systems...This strain is manifested by high skin and core temperatures, excessive cardiovascular strain and reduced performance. Heat acclimation results in biological adaptations that reduce these negative effects of heat stress. One becomes acclimated to the heat through repeated exposures that are sufficiently stressful to elevate both core and skin temperatures and provoke perfuse sweating. These biological adaptations occur from integrated changes in thermoregulatory control, fluid balance, and cardiovascular responses…

http://ftp.rta.nato.int/public/PubFullT ... 6-$KN4.pdf

The adaptation of Australian Aboriginals to heat is interesting. See:

http://phys.org/news/2014-01-protein-th ... ature.html

[nq111]

Thanks maddog, that is great information and agrees with other studies I have read (though the physiology stuff is new).

Which goes back to some of my original points that people can manage walking in hot conditions if they take it seriously, train for it and build gear and clothing lists around the conditions. For some reason many walkers relish the challenge of taking on snow and ice, but stay clear of giving hot weather a go.