Public Health

With temperatures rising worldwide, it's essential to know how to stay cool by reducing your body heat. It’s important to keep hydrated and wear breathable clothing, but if you want to cool off quickly, the military has a trick to reduce body temperature in minutes.

According to a CBS report, research shows that submerging your forearms and biceps in ice-cold water can help prevent overheating. That’s why the military uses arm immersion tables when training in hot weather or stationed in places where the heat is unbearable and it's impossible to get to an air-conditioned room.

"It's low-tech, it's inexpensive, it's easy to implement," Lt. Col. Dave DeGroot, who runs the Army Heat Center at Fort Moore, told CBS. "It's a bucket of water." Arm immersion tables are long, narrow troughs filled with ice-cold water that stand on four legs.

To cool down, soldiers place their hands, arms, and wrists in the cold water for 3 to 5 minutes. Then, they raise their arms above their heads. This allows cooled blood to circulate throughout the body, lowering its temperature. It also allows the water to drip down their arms, cooling their core from the outside.

Soldiers who practice the technique say that while their arms are submerged, they feel the cold water circulate throughout their body, starting in the chest and then moving to their back.

"Your car has a radiator. Well, so do we. It's our skin," DeGroot said. "Our blood is going to cool off and circulate back to the core and eventually, with several minutes of exposure, bring the core temperature down.”

Arm immersion tables cool approximately 13% of the body, enough surface area to transfer body heat to the water. According to TechLink, immersing one's arms in cold water can reduce core body temperature by 2° F in 3 to 10 minutes. Two degrees may not sound like much, but considering that the average body temperature is usually between 97 and 100 degrees, it makes a huge difference.

In severe situations where hot soldiers appear pale, wobbly, or mentally incapacitated, the military uses ice sheets to cool them down. "An ice sheet is nothing more than a simple bed sheet that we use," Fort Jackson safety specialist Vinson Washington told the U.S. Army. “We submerge these in ice, and when a casualty overheats, we wrap them in these to cool them down until we can get medical personnel on the scene."

"We put them in a human taco, basically," 1st Sgt. Brendan Cain, an Air Assault School instructor, added. In the event a soldier goes down with a heat injury, they use the sheets to "cool down the (soldier's) core temperature," then "it's an automatic call to 911."

Arm immersion tables and ice sheets work because, according to TechLink, the heat transfer of water is 25 times greater than that of air. So, to cool someone off, it’s much more effective to immerse them in water than to place them in front of a fan.

There's no need to worry if you’re looking to beat the heat and don’t have a military-grade arm immersion tank. You can make something similar by taking a large cooler filled with ice water and placing it on a table or by filling your kitchen sink with water and adding some ice.