A New Device I Was Introduced to and Tested
Nearly 15 Years Ago (as Seen on Huberman Lab Podcast)

From @realcoolmitt Instagram Page

Back in 2008, I did a TV show called Fight Science – Special Ops Episode, on National Geographic Channel. The full show explained the 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. I did this part of the show - the ice bucket challenge!  I ran a very short obstacle course and had to distinguish shoot or no shoot targets at the end. Then I had to do it again after 50 minutes in an ice tub. It went like this:

The Test with the CoolMitt

A piece of what I filmed ended up on the cutting room floor and was never seen again. I did a Max Rep Set Workout of pullups, pushups, situps, and running to get maximum reps in as few sets as possible. Having done this many times, I knew my abilities and limits, but was shocked by a 25-30% increase in performance by just cooling my hands each set. Ever since this experience I have been coaching students to understand that half of your fatigue is body heat. Find ways to cool yourself and you will perform better. Now there is a device you can use:

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 CoolMitt (www.CoolMitt.com) 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 took some time to get to market but it is already being used by Olympians, pro-athletes/teams, and making it's way into the military special ops programs. 

The history of this product was a DARPA research project through Stanford University.  A way to cool soldiers working in the desert was a high priority in the early 2000's, giving this project the green light for development.   

I was the guinea pig testing this device during a maximal effort performance workouts (to cool my core). I produced excessive bodily heat that would have affected my performance had I not had the benefit of accelerated cooling during brief rest periods.

The goal was to see how quickly (how few sets) I could get 100 pullups, 200 pushups, and 300 situps, running 90 second 400m each set. Here is the workout I did on the show to induce hyperthermia. This was not featured on the show as watching a dude do hundreds of reps of calisthenics is just not that fascinating I guess...

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

Max Pushups in 2 min (70+), and then with no rest

Max Situps in 2 min ( 75+) and then with no rest

Ran on a treadmill for 90 secs (¼ mile)

Then I rested THREE minutes with the CoolMitt 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 / 280 pushups in FIVE sets, which I had NEVER done before. Usually, without the cooling, I get 100 pullups on a good day in 5-6 sets without adding the run portion. This time I got 100 pullups / 200 pushups / 300 situps in 4 sets - a record.

The developer of the CoolMitt 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 – CoolMitt is an alternative to steroids!!!”

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 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 CoolMitt 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 CoolMitt 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 through convection. 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 #2: 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.”

Question #3: 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 CoolMitt 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.”

For more information on the CoolMitt - check out their website and videos of athletes using the product. It is an amazing tool that helps you get rid of the body heat that is leading to fatigue. together with more carbs, water, electrolytes, you can take your performance and recovery to the next level with the CoolMitt. 

I have used various methods to cool myself and students after hard workouts in the heat after learning this ability. One example that proves to me that heat is 50% of your fatigue is after a hard run / PT workout for an hour or more, going to the pool to swim feels impossible. That is until you sit in the water for 5 minutes (cooling down) and then you have this second wind and able to complete the full swim workout. We do the same at the beach when overheated from running / rucking. Get wet and keep on moving!