Summary
Shane Larson of The Gametime Guru interviews Kyle Sela, physical therapist, strength coach, and founder of AVA Cooling Technology, about his palmar cooling device and the science behind it. Kyle explains how he discovered palmar cooling through Andrew Huberman's appearance on the Joe Rogan podcast while hiking with a weighted vest in the Idaho summer heat. The concept immediately resonated — the research from Dr. Heller at Stanford showed a 60% improvement in bodyweight dips with NFL players. Kyle walks through the core physiology: exercise raises body temperature, which causes fatigue at both the muscle cell level (enzyme configuration changes) and the brain level (hypothalamic motivational shutdown). Glabrous skin on the palms, soles, and face contains arteriovenous anastomoses (AVAs) — direct artery-to-vein circuits that efficiently dump heat. His own testing showed 18% improvement in shoulder press and 28% improvement with shorter rest intervals. The conversation covers practical applications across sports — basketball, volleyball, tennis, and softball all work well due to built-in rest breaks. Kyle discusses the importance of the device being cool (45-60 degrees F) but not ice cold, which would trigger vasoconstriction. He also describes a sleep protocol where athletes roll their feet on the cooled bar and hold it in bed after evening competitions, helping lower body temperature faster for better sleep.
Key Points
- Kyle discovered palmar cooling from Huberman on Joe Rogan and built his own prototype after the Stanford CoolMitt had a 9-month waitlist at $1,200-1,500
- The device is made from aluminum with high specific heat capacity and conductivity — stays cool for 45-60 minutes of intermittent use
- The optimal cooling temperature is 45-60 degrees Fahrenheit; ice cold triggers vasoconstriction and blocks the cooling effect
- Sports with built-in rest breaks benefit most: basketball, volleyball, tennis, softball; football is harder due to gloves
- Oklahoma University softball used the devices going into the College World Series; Jocelyn Alo grabbed the bar after hitting a grand slam
- Cooling the neck can actually backfire by telling the hypothalamus it's cold, potentially triggering heat-preservation mode
- Boise State basketball uses the bars as a sleep aid — athletes roll feet on the bar and hold it in bed after night games to lower body temperature faster
- The device retails for $59.95 and is manufactured almost entirely in the USA using materials sourced from Georgia and fabricated in Idaho
Key Moments
How AVAs in glabrous skin regulate body temperature
Kyle explains the specialized blood vessel network under glabrous skin — arteriovenous anastomoses that form a direct artery-to-vein circuit without capillaries — and how this system is already used intuitively when we stick a foot out from under the blanket or warm our hands by a fire.
"He was looking at what's called glabrous skin. So glabrous skin is parts of our bodies on the palms of our hands, on the soles of our feet, and like the hairless portions of our face. These are all areas that have like zero hair follicles, right? So there's parts of our body that seem hairless, but you actually, if you look at it, there's little hair follicles. But like on those three areas, like the palms, the soles, and the hairless parts of our face,"
60% improvement in dips with Stanford research
Kyle describes the Stanford dip study showing 60% improvement in total reps, driven by both more reps per set and athletes not receiving the neural shutdown signal, allowing them to keep doing more sets.
"And again, they wouldn't, you know, they would just say, go to failure every set. You're going to take three minutes. You're going to hold, hold onto something cool to dump heat out of, and then you're going to repeat. And they had like a, like something like a 60% improvement in dips done in that workout, which is insane. That's okay. Yeah. If you know anything about working out, yeah. If you've been working out like that, that number just sounds insane. And honestly, to me as a physical therapist and strength coach, you know, I kind of thought it sounded like BS. Like it just seemed like too good to be true. Um,"
Cool not cold — the 45 to 60 degree sweet spot
Kyle explains the critical temperature principle — the cooling surface must be between 45-60 degrees Fahrenheit. Too cold triggers vasoconstriction, shutting down the blood vessels in the palm and blocking the heat exchange.
"if it's freezing cold like your nervous system is going to perceive that as as being too cold and it's going to like vasoconstrict And it's going to shut down those blood vessels in your palm or wherever you're cooling. And you're not going to circulate that. So the trick here is to be like cool, but not cool. So like what we found is like 45 to 60 degrees is like the sweet spot of temperature"
Sleep protocol — using palmar cooling after night games
Kyle describes a sleep protocol used by Boise State basketball where players take the cooled bar home after night games, roll their feet on it, and hold it in bed to lower body temperature faster for better sleep.
"We have a protocol where we have them actually go home, immediately cool their bar. And while they're like, you know, eating or typing or playing video games, they're like rolling their feet on it because that's one of the soles of the feet. Right. And then when they're done, like kind of using their hands and actually get in the bed, they hold on to it for a few more minutes. And we've actually seen like the players are loving it, using it as a sleep aid because it gets their body temperature back down, kind of calms them down."
