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Hyper and Hypothermia - Seen on National Geographic Channel  

Fight Science Special Ops with Stew Smith

YouTube Version

On the Fight Science – Special Ops Episode, you saw effects of body core temperature in both extremes (high and low body core temperatures) and how science is able to manage them both.  By definition:

Hyperthermia is abnormally high body temperature.  It can be due to exposure to extreme temperatures, high humidity, and heavy work loads. .  Heat related injuries are more common than ever now due to high levels of exertion in desert combat areas with heavy insulation of protective gear.  In the extreme, hyperthermia can result in heat stroke which can lead to death if not treated properly. 

Hypothermia, or abnormally low body temperature, resulting from excessive heat loss due to cold exposure.  Hypothermia results in a rapid degradation of operational ability both cognitively and physically

Not only are these heat conditions potentially deadly, the increase of heat in the body also affects physical performance.  Probably the most significant factor in limiting muscular performance during prolonged, high level work is the build up of heat in the muscles and the body core.  A device called Core Control ( that can get this heat out of the body as efficiently as possible has been researched and developed by physiologists from Stanford University, Dr. Craig Heller and Dr. Dennis Grahn.  It maybe a year or so before a usable model is on the market, but you will see on Fight Science that the current stationary model works and works quickly! I was the guinea pig testing this device after cold water exposure and during maximal performance workouts where I produced excessive bodily heat that would have affected my performance had I not had the benefit of accelerated cooling during brief rest periods. 

Here is the workout I did on the show to induce hyperthermia: (not shown on show)

Maximum Pullups – I did 29 until I failed and then with no rest

Max pushups in 1 min (70+), and then with no rest

Max abs in 1 min ( 50+) and then with no rest

Ran on a treadmill for 90 secs (¼ mile)

Then I rested THREE minutes with the AvaCore device on my hands cooling my body through my hands.

I repeated this cycle FIVE times with some decreases in performance, but I was still able to total 120 pullups in FIVE sets, which I have NEVER done.  Usually, without the cooling, I get 100 pullups on a good day in FIVE sets without adding the run portion.

(This workout is a great workout to help push your maximum Pt scores – many folks who do this one can go from 10-15 pullups to 25-30 pullups in a few months if done ONLY once a week) Workouts like these and others are located at the Fitness Center eBook Store

The developer of the CoreControl device, Dr. Craig Heller of Stanford states, “It is amazingly simple, yet goes against dogma.  The simple conclusion is that muscle performance during conditioning is limited by the generation and accumulation of heat in the muscle.  If you can remove that heat efficiently, you can get much more work out of the muscle.  If you up the intensity of workouts, you get a conditioning effect.  Pure and simple – Core Control is an alternative to steroids!!!”

Hmmm, I never thought of it as being an alternative to steroids, but he is right!  The reason people take steroids is to get more out of the muscle with less rest and recovery.  It is a shame that this device was not seen on the show as it is truly a marvelous invention.

Here are a few questions I asked Dr. Heller on how we can utilize this science during regular training and PFT sessions:

Question #1:  Doc, Can you re-warm using cups of hot water in hands - the reason I ask, is I remember during Hellweek at SEAL training, when we ate inside we all would get warm water and wrap our hands around it and it seemed to help .

“Stew, the answer is yes, but it’s effectiveness is limited.  When you are cold, you are tightly vasoconstricted.  If the cup is hot enough, it will cause a reflex vasodilation and therefore heat will be transferred.  Once the contents of the cup is cool enough to drink, it is best to drink it and get all of the heat inside.  What the vacuum of the Core Control does is to facilitate the vasodilation.  The vacuum in itself cannot induce the vasodilation, so the warm/hot stimulus is necessary, but once the vessels are dilated, the vacuum dramatically  increase the heat flow.”

On the another segment of the Fight Science show(not shown), after 60+minutes in 45 degree water, I was amazed at how quickly I quit shivering and my body temperature increased back to normal, especially after my body temp dropped to 96 degrees in about 3 minutes of getting out and running around.  The cold extremities were getting re-warmed from the core temp blood thus cooling the core temp on return to the heart.

Question #2:  Doc, Can the same approach be used in the reverse?  Say using ice water bottles in your hands during rest periods OR would the constriction be so much that it would be useless?  Are there some results using cold ice water bottles??

Most of what we currently do with Core Control is enhance heat loss and cool people down.  Someone who is overheated because of working in the heat is already vasodilated and losing heat from the hands.  Contact with a cold surface will facilitate that.  However, if the surface is too cold, there will be a reflex vasoconstriction which will stop effective heat exchange.  The vacuum seems to lower the threshold for vasoconstriction so that the vessels remain open to lower temperatures and amplifies the blood flow through these vessels thus enhancing heat loss.  We have recently completed a study in which we have compared the maximum heat loss capacity of different skin surfaces, and the palms are about 10 times other surfaces per area.

Question #3:  The reason I ask is that I tried this a few times and last summer one of my guys successfully ran the Chicago marathon using cold bottles on his hands while running when many runners were suffering from heat illness and even heat stroke.  Do you think holding the cold bottles helped?

Yes, for sure it would help.  Of course, he would have gotten more benefit from the cold bottle by drinking it as then none of the cold would have been wasted on the hot environment, however, drinking too much during a marathon can be dangerous.  You need to replace water loss, but this is not easy to do by massive drinking as the rate of absorption from the gut is limited.  When you are exercising hard, the blood flow to the gut is diminished.  There are frequent cases in which people have consumed lots of water during marathons and when they stop, all of a sudden there is massive absorption of the water that is in their stomachs.  This can dilute the blood to the extent that they pass out and even die.”

 Related article:  Can You Die If You Drink Too Much Water?

 Question #4:  I am trying to show people that, as you have discovered, special blood vessels in the palms, the soles, and the face are the body’s natural heat exchangers. The Core Control device optimizes these natural heat exchange adaptations, but aren’t there common experiences in which we use these special avenues of body warming or cooling?  

 “Sure, there are many common experiences that illustrate the effectiveness of our natural radiators.  When you are cold and approach an open fire, what do you do?  You hold out your hands.  If you don’t have a fire, you might rub them together vigorously to produce heat by friction. Or, as you mentioned, you grasp a very hot cup of hot chocolate, tea, or coffee between your palms.  In the heat, remember how good it feels to dangle your feet in water or taking Grandma's advice to run cool tap water over your wrists.  You can also put a cool towel on your face. Without thinking we exploit the special heat loss blood vessels in the palms of our hands, the soles of our feet, and the face.”

 Folks, you have to see it for yourself.  This science works and on the Fight Science show you will learn how to properly heat and cool someone if hyperthermia or hypothermia occurs.  


Stew Smith is a former Navy SEAL and fitness author certified as a Strength and Conditioning Specialist (CSCS) with the National Strength and Conditioning Association. If you are interested in starting a workout program to create a healthy lifestyle - check out the Fitness eBook store and the
Stew Smith article archive at To contact Stew with your comments and questions, e-mail him at



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