Multiple US Olympians wore the dhamaSPORT cooling device on their wrists in Rio - Is it a solution for hot weather?

Its not just temperature. We remove 14 watts of heat and this is very cold.

John Clendon wrote:

It only cools to 44F? That isn't that cold. I feel like it would be easy to find a cheap substitute to do the same thing.

milage_man,

The heat dissipate is 14 watts with a COP of 1.3. In no means the magnitude of cooling is negligible. Our basal metabolic rate is 90W and its for the whole body.

The testing of our devices was independently done by Army Sports Institute in India and they have submitted the paper with results to a peer reviewed journal and its being reviewed right now and should be published in a month. Once published we will put them up on our website. Additionally we are getting a Independent clinical trial done at University of Connecticut Storrs (Korey Stringer Institute) for core body temperature evaluation. We are very serious and thorough about our science and research.

Our heat sink does not depend on just evaporation. The dissipation of heat is done by converting heat into chemical energy. Our heat sink is charged and form weak bonds with water and these are broken through which heat is dissipated.

dingle wrote:

So, this is a heat sink that depends on evaporation to ultimately transfer its heat to the atmosphere.

I'm not a physicist, but can someone explain how could this be better than sweating?

It removed 14 watts of heat and works very well. We have not paid anyone to vouch for us. The product speaks for itself. We have a 30 day money back guarantee (no questions asked) and that shows how much we trust our product.

That's we need, another damn gimmick.

Bad Wigins wrote:

Putting something cold on your wrists is pointless. Putting something cold on your palms, which direct blood flow near the skin over a large surface area to maximize heat exchange with the air, would make sense - except that it causes vasoconstriction and reduces the blood flow.

Training in heat until your body adapts to the heat is the sensible thing to do. Which Chelanga didn't.

Runners from hot Eritrea commonly hold their hands open which allows them to cool better without sweating.

And certain top runners like Farah and Lagat shave their heads clean bald, which allows sweat to evaporate directly from their scalps. Sweat that soaks into your hair is useless, the change of state only cools your hair when it finally evaporates.

Where do you find your information? The skin on the inside of your wrists is very thin and close to the blood vessels. This is one of the fastest spots to cool your blood externally.

kranthi vistakula wrote:

Our heat sink does not depend on just evaporation. The dissipation of heat is done by converting heat into chemical energy. Our heat sink is charged and form weak bonds with water and these are broken through which heat is dissipated.

dingle wrote:

So, this is a heat sink that depends on evaporation to ultimately transfer its heat to the atmosphere.

I'm not a physicist, but can someone explain how could this be better than sweating?

Thanks, that does make more sense.

Again, I say:

"How is this much different than wearing arm sleeves during a hot weather race and putting ice in them beforehand? Watch any hot weather ultramarathon and you'll see ice bandannas, ice arm sleeves, women putting ice in their sports bras, ice hats, etc." All of this is significantly cheaper than what you are offering and has been around for YEARS.

I appreciate the company clarifying a few things here.Brojos, this should be a lesson to you to perhaps temper your enthusiasm about any given product.

MeHereYouWhere?! wrote:

Again, I say:

"How is this much different than wearing arm sleeves during a hot weather race and putting ice in them beforehand? Watch any hot weather ultramarathon and you'll see ice bandannas, ice arm sleeves, women putting ice in their sports bras, ice hats, etc." All of this is significantly cheaper than what you are offering and has been around for YEARS.

I think weight would be the obvious answer. And length of effectiveness next. If ice weighs 3x's the device and only lasts a fraction of your race, the device is going to be superior.

I agree $200 seems steep. If I were a pro, maybe I could justify it. But not as a weekend warrior.

Well of course it cools you. They already proved that that's one of the places where you can rub an ice cube to cool someone on some science tv show. There were one or two other spots but I can't remember. Also, drink something warm instead of something cool. Sounds ass backwards compared to this but you can't argue with science.

kranthi vistakula wrote:

It removed 14 watts of heat and works very well. We have not paid anyone to vouch for us. The product speaks for itself. We have a 30 day money back guarantee (no questions asked) and that shows how much we trust our product.

How many joules per fill of water?

MeHereYouWhere?! wrote:

Again, I say:

"How is this much different than wearing arm sleeves during a hot weather race and putting ice in them beforehand? Watch any hot weather ultramarathon and you'll see ice bandannas, ice arm sleeves, women putting ice in their sports bras, ice hats, etc." All of this is significantly cheaper than what you are offering and has been around for YEARS.

To be very clear, all these other options are available but they become use less in a short while. Where as our wrist device maintains a consistent 44 deg F at at ambient of 98 F at 60% humidity for the entire duration of the device. Our 2 hours dhamaSPORT cools your for two hours at the same temperature and weight only 130 grams. If you want ice to do that you need at least 500 grams and then also the temperature is not consistent. To compare our device to ice packs and bandannas is like comparing iphone to pre smart phone era phones without touch screens.

dingle wrote:

How many joules per fill of water?

Absolute capability is 2400 joules for one mole i.e. 18 ml of water

If this was a paid article, we would have made sure the product and company name are spelled right- its DHAMA not DHA-R-MA and our website for the use is www.dhamausa.com. The article points to a site dedicated for indian consumers. This is just the tip of the iceberg with all the errors in the article.

LetsRun.com wrote:

Details here. What do you think?

http://www.letsrun.com/news/2017/02/struggle-run-heat-dhamasport-cooling-wristband-answer-prayers/

Don't know if it works, but there have lots of trends over years like Bee Pollen, Endurox, Breath Right and Compression socks that elites have favored and then fell out of favor. However, if you think it works, it probably doesn't hurt.

kranthi vistakula wrote:

dingle wrote:

How many joules per fill of water?

Absolute capability is 2400 joules for one mole i.e. 18 ml of water

50 Kcals per liter?

kranthi vistakula wrote:

milage_man,

The heat dissipate is 14 watts with a COP of 1.3. In no means the magnitude of cooling is negligible. Our basal metabolic rate is 90W and its for the whole body.

The testing of our devices was independently done by Army Sports Institute in India and they have submitted the paper with results to a peer reviewed journal and its being reviewed right now and should be published in a month. Once published we will put them up on our website. Additionally we are getting a Independent clinical trial done at University of Connecticut Storrs (Korey Stringer Institute) for core body temperature evaluation. We are very serious and thorough about our science and research.

Hi Kranthi, thank you for your time. I especially appreciate your providing the information that your device dissipates 14W. This information should really be added to your website.

I will say that 14 W is somewhat higher than I was expecting. But a better comparison than bmr is metabolic rate while running. For example, during a race my metabolic rate is between 1400 W and 1800 W (assuming 120 calories per mile, 4.5-6 minute pace). So your claim of 14 W is on the order of 1% of metabolic activity.

However, you have just stated this number without any description of methodology. What are the measurement conditions? I'd imagine the true number could be substantially lower under realistic use conditions. I'll look forward to seeing some actual information, but in the meantime I remain skeptical.

Also, it doesn't make much sense to report COP without operating conditions. What expected conditions are you assuming in making this statement?

dingle wrote:

kranthi vistakula wrote:

Absolute capability is 2400 joules for one mole i.e. 18 ml of water

50 Kcals per liter?

32 kcals per liter, right? And according to the 14 w figure, the device will go through a half cup of water every 24 minutes.

Kranthi, could you say more about how the heat sink works? That part sounds pretty interesting. I was initially very skeptical when you said the heat was being absorbed by the breaking of...hydrogen bonds? But perhaps the large internal surface area of the heat sink ("fractal microsurfaces") makes this viable.

Can you clarify the 2400 J figure - is that the capacity of the heat sink to absorb energy via bond breaking? And what sort of bonding are we talking about here? Finally, what is is the volume and effective internal surface area of each heat sink?

I spent all my money on a pair of winky blinky safety shorts they were advertising a couple months ago so I'll have to save up some money. Lucky its the middle of winter.