Sweating underwater!

[Hatul]

Under normal environmental conditions, our body (even at rest) produces excess heat that needs to be dissipated. We typically perspire when the air temperature is well below 35° C / 95° F, attempting to release our extra heat energy. If we’re surrounded by water that hot, we are less able to effectively dissipate energy and could overheat. I think (but cannot find the reference) that thermal equilibrium for a human body at rest immersed in water is right around 34° C, so you could well be in the range of overheating. Unlike in a hot tub when your head is exposed to air, underwater there is nowhere else for the heat to go. So to me it sounds like it could be early signs of hyperthermia. Sensitivity naturally varies with individual.

I like this answer. Normally we sweat to cool ourselves by evaporative cooling, but underwater this obviously cannot take place, so this cooling mechanism does not work. Your body does not know this and continues to sweat, which can result in overheating and dehydration.

 

[DanLW]

Another vote for a combination of heat stress and dehydration.

If the water temperature was 95F, I'm guessing the air temperature on the surface was in the 100-110 range. In such a case, your body likely found it hard to cool off whether on the surface or underwater. Strangely enough, being on the surface in the hotter air likely cooled you off better than the cooler water since in air evaporation does it's thing to cool you off. In such an environment, 8 glasses of water per day won't cut it. When I was in Djibouti, I was easily drinking more than 1 gallon of water per day.

 

[DCBC]

i know it sounds odd, but my last dive was definitely a strange one for me.
i was diving in Doha, Qatar and was enjoying taking photos of the reef fish when i suddenly felt light headed.
i checked my guges, signalled my buddy that i wasn't okay and tried to remain calm. i was escorted by my buddy out of the dive site, but the feeling still haunts me and im trying to figure out what happened. the water was very warm 35 celcius/ 95 fahreheight which i thought was the cause but none of the other divers experienced this.... any thoughts
thanks moe

Because of my background, I'd relate your question to using a hot-water suit. The system when working properly delivers about 4 gallons per minute (3 to the suit and 1 to the breathing gas heater) at approximately 100 to 110 degrees F. As the Diver is working, s/he perspires.

Sweating is controlled by the autonomic nervous system, the part of the nervous system that is not under your control. Because sweating is the body's natural way of regulating temperature, people sweat more when it's hot outside, when they exercise, or in response to situations that make them nervous, angry, embarrassed, or afraid. As you lose water you may become dehydrated and experience: fatigue, thirst, headache, confusion and be dizzy or lightheaded.

I suspect that you simply hadn't drunk enough liquid for the conditions you were operating in. Hydration is extremely important to commercial divers working and using a hot-water suit.

 

[tracydr]

Even when inside the AC, here in AZ, I they'd to drink at least a gallon a away, due to the dry air. If I go outside at all, that goes up to one quart per hour, especially if i exercise. I guarantee that's the case because when I go to my my PT appointment, which is still in AC, I drink 2 quarts. One while I'm doing my workout and one while I'm driving to-from the appointment. The drive only takes me 15 minutes each way, with my AC running and the appointment lasts about 60-90 minutes. I might be outside in the 105 degree heat for a few minutes. Otherwise, I'm in the AC and my workout is relatively easy, just some light weight lifting.
If I work in my garden, my water intake is even higher. It becomes very difficult to keep up with hydration when temperatures are over 100 degrees and I work outside for any length of time, even in the shade. I've never adapted, partly because I don't sweat very well. However, because I don't sweat well, I don't get as dehydrated as somebody who does. I just overheat. But, somebody who sweats normally will need even MORE water than I do.
I've suffered several cases of heat injury since living in AZ and they sound very similar to what you experienced. My last, mild episode sounded very similar, except that I had tachycardia ( rapid heart rate). Did you happen to take your heart rate?

 

[Gachnar]

Under normal environmental conditions, our body (even at rest) produces excess heat that needs to be dissipated. We typically perspire when the air temperature is well below 35° C / 95° F, attempting to release our extra heat energy. If we’re surrounded by water that hot, we are less able to effectively dissipate energy and could overheat. I think (but cannot find the reference) that thermal equilibrium for a human body at rest immersed in water is right around 34° C, so you could well be in the range of overheating. Unlike in a hot tub when your head is exposed to air, underwater there is nowhere else for the heat to go. So to me it sounds like it could be early signs of hyperthermia. Sensitivity naturally varies with individual.

You actually dissipate heat better in water. Sweat works because it (water) is a better thermal conductor. You can't compare air temp and water temp as apples to apples.

Think of it this way, If you have ever stood around in 60 degree calm air all day you would be fine. But if you wore the same clothes in 60 degree water all day, you'd be hypothermic. In fact with very long exposure you can get hypothermic in 80 degree water with no exposure protection because in any water cooler than 98.6 you are losing body heat.

Now in 95 degree water you wouldn't lose much heat, and if you are moving at all certainly overheating is more of a concern than hypothermia because the temp variation is so small. Dehydration certainly could be a factor, or overexertion. If you had a headache that persisted I also wouldn't rule out CO.

 

[windapp]

Sweat works because it (water) is a better thermal conductor.

This is patently incorrect. Sweat works because, in the process of evaporation, the vapor removes heat from the water that is left behind which, in turn becomes cooler.

When you are submerged in water, there is no evaporation from your skin, so the sweat does not help cool. It only acts to dehydrate you.

The thermal conductivity of water is much greater than that of air, but it is still finite. As the temperature of the water approaches body temperature, you do get to a point where you the thermal loss to the water exceeds the heat being produced by the body. That temperature is below 98.6 degrees.

 

[Tom Winters]

I guess not a lot of people posting here ever did laps in an overheated pool.
Of course you can get overheated - serious swimmers come out of too-warm pools sweating like SOB's because the water doesn't vent off body heat fast enough.
Divers working in the Red Sea are closely watched since they can get heat stroke in as little as 15 minutes if they're doing really strenuous work underwater.
Diving in 95° water - you sure it was that hot? The Red Sea runs about 85° on a nice toasty day. Whatever it is, be careful there.

 

[DCBC]

If you're hydrated, sweating isn't the problem. The hazard exists when you become dehydrated, lose electrolytes and eventually stop sweating (which can result in heat stroke). Sweating is a good sign, just keep hydrated...