Nov 24, 2013 at 10:46 am #1310176
Still feeling my way around here–what, where, & how many times over & over–but here goes. Was struck by this recent photo of runners wearing arm-warmers in the NY Marathon.
It harkened to something I'd read about polar explorers paying extra attention to wrist insulation, and then reading I'd dug into about ateriovenous anastamoses–hairless skin regions akin to your car's radiator: exactly where you can an should apply heat or cold if you want to warm or cool. Here's a good read:
The article immediately points out the complexity of dealing with the thermoregulatory defense of vasoconstriction. (To say nothing of the "psycho" part of each individual's phychothermodynamics.) But, (yes, you knew there was some peeve involved)-if you want a hot water bottle up in your biddness at night, do it for pleasure but not because "warming your femoral" is a goodway to warm yourself efficiently.
I think: if you want to warm up by applying external heat, apply to hands and feet. If you want to cool off on a hot day, put your feet in the stream. Does anyone ever cool off by throwing water on their femorals? If you needed to cool a hot engine, would you blow cool air on the intake manifold or the radiator? Now, vice versa? Language abounds with examples: "lets roll up our sleeves and get to work."
I never did buy a down vest and now think I can intuit why. I wonder if any of you carry down sleeves but no down vest?Nov 24, 2013 at 12:58 pm #2047659
@ewolinLocale: Hampton Roads, Virginia
What the OP says makes sense, but for years all winter (incl. X-C skiing) I wore a light wool jacket with a warm vest when it got colder, plus a windbreaker if needed. I.e. I insulated my core, not my extremities, and it worked fine. I only wore long sleeves in the coldest weather, e.g. winter camping when I first woke up or when cooking dinner and getting ready for bed.
Maybe this was not the lightest strategy, but it certainly worked.Nov 24, 2013 at 2:42 pm #2047683
"Does anyone ever cool off by throwing water on their femorals?"
I have had good luck with snow down the shorts. Let's just say all the guys know just how cold it feels when you are wading into cold water and the water reaches a certain point :)
However, I do agree on the external application of heat or cold in general. Sticking your hands in cool or hot water will bring about a fast change – back of the neck is excellent as well. And yet I'll still go with keeping the core warm if I want to stay warm. The extremities serve well as quick heat loss or gain points, but if the core cools or overheats it takes time to get the core temp to move. Which may be why the fastest way to warm up seems to me to be internal – a liter of hot liquid will warm me up all over pretty darn fast.Nov 24, 2013 at 6:20 pm #2047745
@rexLocale: Central California Coast
We must distinguish between techniques that make you feel warmer or cooler, versus techniques that actually make you warmer or cooler.
For example, a couple of shots of whiskey will make you feel warmer, but in the long run can cool you down more rapidly.
Putting a wet rag or ice on the back of your neck makes you feel cooler, but doesn't cool your core or brain all that much.
And sometimes, you don't want to warm or cool too rapidly. Do not simply drop a hypothermia victim in a hot tub, you could create all kinds of additional problems, including death.
It's pretty complicated. I learned a lot taking WFR classes, and advice changes over time.
— RexNov 24, 2013 at 6:31 pm #2047749
As mentioned its more complicated … There is a difference between feeling cold and being cold
The core temp makes a large difference … If its too low the body will channel the blood to the core to keep warm
This lead to frostbite if the body does this to combat hypothermia
Heres an example of how raising the core temp can help …
Researchers at the Department of National Defence have developed the Torso Heating for Dexterity in the Cold system, a close fitting battery-powered vest with a built-in thermostat. Rather than covering the hands with a heated glove, the vest increases the wearer’s core temperature to the point where the body can keep fingers warm on its own. It’s the first of its kind in the world, says Darren Menabney, business development officer at Defense Research and Development Canada. “There’s nothing out there that really does the same thing.”
The vest uses a built-in control system to monitor the wearer’s finger temperature, and turns up the heat when they’re chilly. This fools the core into thinking that the body is overheating, triggering an automatic response to send warm blood to the extremities.
;)Nov 24, 2013 at 9:12 pm #2047793
Paul, I know you pants vent around the thighs. If I'm skiing and hot all over, have done everything else, I'd welcome upper leg venting and would try snow in the shorts. The more effective–take my boots off–will be my last move because of the trouble involved. You do what you can. Seems like a hot drink drunk will go right to the core. Because the paper I link is a PDF, I can't cut and quote, but I'll type an early entry:
"Cold stressed individuals are by nature vasoconstricted. Thus, the application of a warm stimulus to the general skin surface, while effective for increasing skin temperature, has little immediate effect on the temperature of the body core. Afterdrop–a continued decline in core temperatures of hypothermic individuals after removal from the cold and initiation of superficial heat application–is well documented…" "When treating heat or cold stressed individuals, the challenge is to deliver an appropriate thermal load to the body core despite the physiological defense mechanisims."
So…to support the points made that feeling cool/warm not-equal cooling/warming. Which I think would be the case wading into that cold lake much past your ankles…initially anyway.
I think the understanding is wide how the body sacrifices appendages to protect the core (as a way of really protecting the brain, I think), but that core is the largest body part, the greatest ratio of volume to surface area, so actually the least vulnerable. That's why, Eliot, I think it's pretty easy to be comfortable with a vest. When I had a fiberfill one, I could easily ski in it without overheating.
I'm not trying to convince anyone to drink ovaltine when they prefer cocoa, just trying to dig a little for people using arm insulation approaches in the interest of going lighter and actually BEING warmer. "Protect the hands, and the core will follow," or the like. Because I know for myself what "works for me" and has been a "great success" is uniformly…just what I do, and for that reason alone, pleases me greatly. Therefor it's up for review. ;)Nov 25, 2013 at 8:24 am #2047871
I find that pulling my sleeves up and maybe taking my gloves off is a great way to cool down a bit without stoping for a full layer removal while skiing up a steep section. I also find that unzipping just the neck section of my cap 4 or r1 has similar effect as it exposes my neck veins to the cool air.
You can get insulated sleeves for keeping your arms (and, by proximity, hands) warm while allowing your core to vent. I think the main purpose of this is when you are active in extreme cold but need warm hands. See outerlayer option 1 here:
(this was a bit of a silly machine assisted trip where they towed shipping container shelters to live in … I don't know it the sleeves would be worth the weight for light weight human powered trips).Nov 25, 2013 at 8:37 am #2047883
spelt with a tParticipant
@speltLocale: SW/C PA
If I am moving, it has to be quite cold before I need arm- and leg-specific insulation. Vest plus gloves works very well for me.Nov 25, 2013 at 10:45 am #2047916
Just found a conflict between my training (from multiple sources) and the only first aid book I have within reach, 'The Outward Bound Wilderness First Aid Book'; Jeffrey Issac, P.A.-C, ISBN 1-55821-682-0.
My training has always been for severely hypothermic patients to strategically place hot water bottles or hand warmers near their femoral and brachial arteries. Stands to reason that this should be effective for someone who's just trying to warm up.
From the Outward Bound regarding severe hypothermia treatment:
"First package the patient in dry insulation, ideally on a foam pad in a sleeping bag. Wrap the whole package in a vapor barrier such as a tent fly or ground cloth. Adding heat sources to the insulation layer in the form of chemical heat packs or warmed water bottles will have minimal effect and may not be worth the weight."
FWIW I received this book when I took the WFR class. While the class was outstanding, the book is very basic and I'm sure there are better ones out there.Nov 25, 2013 at 10:54 am #2047919
@sbhikesLocale: Santa Barbara (Name: Diane)
I got a bee sting on my neck once and put an ice pack on my neck and got brain freeze pretty bad.
I do carry fleece sleeves rather than a fleece vest. Wearing them on arms or legs does add significant warmth for me and can make a light jacket feel like a real jacket fairly well. I seem not to tolerate having cold air on bare skin once I start to get cold.
I ride a motorcycle and I can be well-insulated all over but if any cool air is blowing on my wrists, I just can't stand it. It's not like it actually makes my body temperature drop, though. Oddly, on very cold days my extremities begin to get cold, stiff and then numb and somehow I can tolerate that better than the sensation of cold air blowing on my skin.
If I get very hot and can't seem to cool down with the usual methods, full-body dunking is often the only remedy. This might be considered somewhat equivalent to pouring water on the femorals. However, putting snow in my hat also works so long as it's not packed so tightly it freezes my scalp but instead slowly melts through my hair.Nov 25, 2013 at 12:43 pm #2047959
Jeremy and AngelaParticipant
@requiemLocale: Northern California
Regarding severe hypothermia (i.e. comatose, shivering has stopped) my own WFR book (the Buck Tilton one) is unfortunately at home. I do have access to two others, so here's an /extremely/ abbreviated version of their suggestions on re-warming:
Medicine for Mountaineering (Wilkerson, 6th ed., 2010) says that unless you can get a heli evac or carry out the person in under an hour, re-warming on the spot may be best. (Longer carry-outs almost inevitably provoke fibrillation.) Re-warming can be expected to raise core temps very slowly (e.g. 1 degree per hour); you will need plenty of time and fuel!
The other book I have handy, Medicine for the Outdoors (Auerbach, 5th ed., 2009) suggests the use of hot water bottles, recommends immediate evac, but also notes that re-warming should be limited to preventing further heat loss.
Note: for anyone taking notes from this, rough handling should /always/ be avoided, as cold/acidic blood from the limbs can be harmful (e.g. stop the heart).
The WFR course I just completed made suggestions in line with the Auerbach book. What I take from all of the above is that re-warming will be sufficiently slow that hot water bottles will be making only a minimal contribution, particularly if one is going for a strategy of evacuation.Nov 25, 2013 at 1:46 pm #2047975
Jeremy and AngelaParticipant
@requiemLocale: Northern California
The OP's linked paper on glabrous skin surfaces (palms, soles, parts of face) reminds me of a few cool stories, one being a "cooling glove" that enables significant improvements in physical output. It unfortunately doesn't really account for the use of arm warmers.
One thing I recall from WFR is an anecdote regarding using the soles of feet for cooling as opposed to pulse points. I believe this was in the context of heat stroke rather than hypothermia, but it goes along with the OP's idea.
My other recollection (possibly picked up from a random thread here, FWIW) is that the arms provide a "feeling warm"/"feeling cold" signal that influences the core to increase or shed heat.Nov 25, 2013 at 2:07 pm #2047981
"Putting a wet rag or ice on the back of your neck makes you feel cooler, but doesn't cool your core or brain all that much."
This part is not true. The first thing you should do for someone who is overheating is to put wet or cold things near the arteries close to the skin.. aka neck, armpits, thighs. that cools the blood that is circulating and cools everything down.
from a Prehospital trauma book (paramedic book)
Heat stroke treatment " rapid, immediate cooling by water immersion or wet patient or wrap in cool wet sheets and fan vigorously" "ice packs should be placed on lateral neck, groin area and axillae"
the other half about the alcohol is true.. it always boggles my mind when people think that is a good solution when it's cold out.Nov 25, 2013 at 8:41 pm #2048120
Seems like there is a significant difference in modes of heating and cooling the body, due primarily to the vasoconstriction that the body uses to conserve heat in the core. To wit: if I am hot I can cool off pretty effectively by way of my extremities, since blood flow to them is good, and with their high ratio of surface to volume I can expose a lot of skin, and thus a lot of capillaries, to the cold air or water and thus get a good cooling effect. But at the other end of the spectrum, if I am cold and my extremity circulation is reduced, I cannot as effectively heat by way of the extremities. Doesn't mean you can't gain some warmth that way, it just won't be as effective as cooling by that pathway.
I also think that in this discussion we should be cognizant of the difference between warming when you are simply a little cold and warming when you are hypothermic. That is to say, you may feel cold and may have some vasoconstriction going on and yet your core temperature could still be normal or very nearly so, and you still have feeling in your extremities – you are not hypothermic, just cold. in that situation not only is it easier to warm yourself back to comfortable (simply because you don't have as far to go), but also you have fewer limitations on how to do it, and fewer risks involved with overdoing it or warming too fast.
But getting back closer to the original question, I've always tended to go for a roughly equal layer of insulation all over, and that has always worked well for me. Just as a puffy jacket and shorts doesn't make sense to me, Thin pants with a thick torso layer seems inefficient. Of course this is modified by the practicalities of layering and the ease with which some areas can be covered and uncovered, while others have to stay more or less the same. I can't easily adjust what I have on my feet while I'm on the move – whatever footwear I'm wearing, be it shoes, boots, or ski boots, they only fit right with a particular thickness of sock. So the feet are not where the adjustments get made while on the move. Hands and head, conversely, are very easy to adjust layers on, and so they are a great place to fine-tune the thermal envelope. Legs are harder than arms – though shell pants with zippered vents can be very effective.
I also think that exertion level and the particular activity make for different choices. When I used to run in cold weather, I would find myself plenty warm except for my hands – in fact I could be sweating and have my hands quite cold. So I'd run in shirt, shorts and gloves – rather counter to my usual even layer, but for that activity it worked. So the arm warmers on runners may be an extension of that.Nov 26, 2013 at 7:58 am #2048221
Jeremy B: "The OP's linked paper on glabrous skin surfaces (palms, soles, parts of face) reminds me of a few cool stories, one being a "cooling glove" that enables significant improvements in physical output. It unfortunately doesn't really account for the use of arm warmers."
That's the one. Same guy/thing, Jeremy. The author's name on my cited link kept popping up in many search results. & my recollection was his The Glove was hypo-baric as a way to trick vasoconstriction. That's what this paper discusses in it's tests. Must confess I haven't read every word of the reading I assigned, but recalled earlier account mentioned going beyond palms up to wrists. Not all the marathoners had "armings," but most all had gloves & many notable with long cuffs. While The Glove story documented weight training improvement via core-cooling, the paper treats cooling AND re-warming of scuba divers.
Dealing with constriction already underway is a difference, no doubt, (re-warming v. cooling) but really is traffic management of the same doorway.
Obvious plus to water bottles in groin & armpits of unconscious victim is their stability. Plus contacting more skin while just sitting there. And while hand blood vessels may have shut all the way of, arteries never will (til end).Nov 26, 2013 at 9:09 am #2048237
Ryan Bressler–thx for the link leading to Paramo & their "overlaying sleeves." Special bonus was reading in a comment a new Brit-slang slur: "spod"–someone who spends too much time in discussion rooms. The more people i can render needlessly offended my my appearance, the greater the value of my existence. :) And, Piper, per your testimonial, I'm going to MYOG some for myself. My backpacking season is about to begin, will arrive with snow.
Also think I will find some real felt to add to the soles of my Feathered Friends booties. As nice, plush, & downy all around as they are, I now fear they lack a little…sole.Nov 26, 2013 at 9:20 am #2048239
@fluffinreach-comLocale: no. california
interesting thread, and LOTS of good info.
i may relate that a few times i was rafting for many hours,a nd then stopped (to pee), i felt fine when i hit the gravel bar, and walked a few steps, then the frozen blood from my legs hit the core, and it dropped me like a rock.
just one of those little things to be aware of.
nice thread !
v.Nov 26, 2013 at 2:01 pm #2048316
@ouzelLocale: Pacific Northwest/Sierra
"Obvious plus to water bottles in groin & armpits of unconscious victim is their stability. Plus contacting more skin while just sitting there. And while hand blood vessels may have shut all the way of, arteries never will (til end)."
This is one situation where a Platy would come in really handy-more surface area for hot water to transfer heat to the victim's body.Dec 22, 2013 at 2:40 am #2056778
Very interesting thread and discussion.
I'm kind of surprised that the glabrous skin regions and corresponding subcutaneous vascular structures are restricted to the palms of hands, soles of feet, ears and regions of the face. I.e. not the wrist, neck, ankles for example, which seem to work really well for me in regulating my body temperature.
I mean I understand it can cool me, or at least make me feel cooler, even if that thermal load is not transported so fast to my core. I guess I just expected these heat exchange vascular structures also to reside there.
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