If you've ever taken an ice bath or cold shower, then headed to a workout and felt like you were absolutely unstoppable, there's a reason – and you're about to find out why, and how to use this phenomenon to maximum effect (and whether you should use cold before a workout). What you are about to read is an epic guest post from Brad Kearns, who first appeared on my podcast in the episode: “Doubling Your Testosterone Levels, Tactics From The World Of Speed Golf, Primal Endurance & More With Brad Kearns!”
Brad has been doing some very interesting experimentation in the realm of combining cold thermogenesis with exercise, and I found his experimentation so intriguing that I decided to feature his entire protocol below. Enjoy, and please post in the comments section below how YOU feel if you try pre-cooling your body before intense exercise in a similar manner as Brad.
The Unfrozen Caveman Runner
I want to share with you an amazing recent discovery of engaging in a devoted session of cold exposure, followed immediately by an aerobic jog to rewarm, followed by explosive all-out sprints.
Here’s what I’ve experienced after carefully testing this process a couple dozen times to date:
My rewarming jog feels effortless, with a heart rate some 10 beats below a normal run at the same pace. Then, buoyed by the scientifically-validated 200-300% norepinephrine boost that lasts for an hour after cold exposure, I can blast a fantastic sprint workout with less stress, less inflammation, better focus, more explosiveness, and faster recovery. Importantly, I’m fully warmed up from a minimum 30-minute rewarming job and primed with extensive preparatory drills and wind sprints before launching into all-out sprints.
I’m calling this strategy the “The Unfrozen Caveman Runner”, as demonstrated on this soon-to-be-viral video. Old-time Saturday Night Live fans may recognize the ode to the hilarious recurring sketch called Unfrozen Caveman Lawyer, featuring the late Phil Hartman as Keyrock, a prehistoric caveman discovered frozen in ice who was thawed out, went to law school, and became an unbeatable trial lawyer. Check out the video below.
In any case, thanks to Ben and other trendsetters, I’ve developed an increasing passion for cold therapy in recent years. After starting with cold showers, dealing with the hassles of a livestock tank and frequent ice bag purchases at the local mini-mart, I eventually reached the highest level of sophistication with my practice: the chest freezer. This 15 cubic foot beauty is by far the most affordable and convenient option for 24/7 home access to temperature therapy. Who wants to drive to the Cryotherapy clinic and pay 45-plus bucks a pop when you can get a chest freezer in your back yard? By the way, Ben has an entire article here on how to create your own ice bath at home: “The Ultimate Guide To DIY Cold Thermogenesis: The Cold Tub Secrets Of Some Of The Top Biohackers On The Planet & How To Make Your Own Cold Tub Setup”.
Of course, getting heat therapy going at home is also awesome, and I’ll bet that someday you’ll become very interested in being like me and pairing your chest freezer with a surprisingly affordable home-use sauna. These are easy to assemble and enjoy in even a small backyard, home or garage space. Surprisingly, my guests are invariably more interested in trying my sauna than the cold tub – go figure. I can at least talk most into some super-relaxing contrast therapy.
My chest freezer runs on a timer for just a few hours a day, maintaining a water temperature of 34°F-38°F (1.1°C-3.3°C). Each morning without fail, I plunge into the tub, submerge my head for about 20 seconds, then commence 20 cycles of deep, diaphragmatic breaths. This is a meditative experience for me, as I am compelled to focus only on my breath cycles in order to withstand the cold water without a panic reaction and early exit. At first, the 20 breaths took about three minutes, but now I slow things down, spontaneously hold an occasional inhale or exhale for a longer period, and my duration in the tub is typically 5-6 minutes. Here is a video where I do a demo, communicate some scientific benefits, and provide step-by-step logistics to get going.
Dr. Rhonda Patrick published an excellent research paper on cold exposure. Visit this link at her website, subscribe to her newsletter, and you can download the report for free. In the report, she details how even brief exposure (20 seconds at 40°F, 4.4°C) to extreme cold delivers a 200-300% boost in norepinephrine that lasts for an hour. Being both a hormone and neurotransmitter, norepinephrine boosts sympathetic nervous system function in both brain and body. You experience a noticeable boost in vigilance, focus, attention, and mood, along with improved oxygen delivery, blood circulation, antioxidant function, mitochondrial biogenesis, and reduced perceived exertion, pain, and inflammation. You can read more details about the benefits of cold therapy in any of Ben's articles and podcasts below:
- Tips For Burning More Fat With Cold Thermogenesis (And Why Icing Really Does Work)
- How You Can Use Cold Thermogenesis To Perform Like Lance Armstrong And Michael Phelps
- Cool New Research On Cold Thermogenesis
- Conquer The Cold And Get Quantum Leaps In Performance In This Exclusive Interview With The Amazing Iceman Wim Hof.
- The Iceman Returns: Wim Hof On Climbing Frigid Mountains In Underwear, Eating Only Once A Day, Activating Hormones With Breathing & More.
- What Doesn’t Kill Us: Why Your Body Needs Freezing Water, Extreme Altitude & Environmental Conditioning.
- Cracking The Code Of Wim Hof Breathing, Writing A Bestseller In 30 Days, Barefoot Ultrarunning & More With Kasper van der Meulen
- The Ultimate Guide To DIY Cold Thermogenesis: The Cold Tub Secrets Of Some Of The Top Biohackers On The Planet & How To Make Your Own Cold Tub Setup
The “Free” Endurance Training Session
My Unfrozen Caveman Runner discovery came one day when I got a little shivery after my tub session. This is not uncommon to have a delay whereby you feel fine during the tub session, then have some difficulty rewarming afterward (time for turbo-charged fat burning—good stuff!)
Instead of puttering and chattering around the house, I decided to head out for a jog to try and rewarm. I immediately noticed that my perceived exertion was vastly lower than usual. I remember running along the Sacramento River, engrossed in quality podcast content (e.g. Ben Greenfield Fitness on the Get Over Yourself podcast) and going for an hour—double the duration of my usual morning jog—without even realizing it!
Here’s what I theorize was happening: First, the norepinephrine spike muted the usual sensations of effort and cumulative fatigue, and I was distracted by the main goal of rewarming. Secondly, because my body temperature was below normal at the start and working back to baseline during the 30 minutes of running, the prominent performance-limiting factor that is the gradual elevation of muscle and core temperature did not contribute to my sensation of fatigue as it would in a typical workout.
Realize that the brain is extremely vigilant against the extreme danger that is overheating and will send a very strong message to the peripheral muscles to slow down to prevent getting into the danger zone. Overheating is obviously a huge issue and performance limiter in hot weather, but even in mild outdoor weather or a temperature-controlled gym, your body temperature climbs, and the brain moderates your energy expenditure accordingly. This honors the essence of the Central Governor Theory advanced by Dr. Timothy Noakes and others—that the brain is the main limiter of physical performance, not the muscles. Noakes asserts that symptoms of fatigue during exercise are “utterly and completely illusory,” and simply a way for your brain to protect your body against physical damage if you were to continue—to overheat in this example, or tear your muscles to shreds with repeated reps, for another example. We’ll discuss the profound impact of keeping body temperature under control during exercise shortly, referencing a Stanford study of the RTX Cooling Glove.
The best way to explain my sensation on the rewarming run is that I feel like I’m getting a “free” endurance training session for the 30 minutes it takes to return to what feels like normal or slightly warm body temperature. Indeed, I often head out for an evening round of Speedgolf (listen to me discuss Speedgolf on Ben’s podcast) on the same day as a morning rewarming run. My favorite sport adds your golf score to your running time on the course for a total Speedgolf score.
In a similar manner to the Winter Olympics biathlon, you must combine the precision of good golf (carrying only a handful of clubs), along with cardiovascular fitness to run at a good tempo between shots. I’ll typically play 12 holes, running around 4 miles, before it gets dark.
Now, as a 54-year-old just trying to stay fit, pursue some healthy competitive outlets, and promote longevity, I’m not inclined to conduct “doubles” (two training runs on the same day) like an elite athlete, but I feel fine and recover normally even with the added volume of the morning session.
Amazing “Unfrozen Caveman Runner” insights continued on another occasion where I spontaneously headed over to the running track after 30 minutes of rewarming jogging to throw down some sprints.
Cruising along on the norepinephrine high, it felt like the track was calling my name. So, I hopped over the fence (I know, what’s up Kennedy High, Sacramento?) and proceeded to deliver one of my most explosive performances ever. While I have always enjoyed my sprint workouts, there is no denying that some pain and suffering is involved when you open up the throttle all the way. It’s definitely an effort to muster the motivation and focus to get to the track and maintain high quality for each repetition. After a good session, sufficient recovery for mind and body is necessary; hence the longtime recommendation from my man Mark Sisson and The Primal Blueprint of sprinting just once every 7-10 days.
Now that I’ve done the pattern of cold exposure-rewarming jog-sprint session many times, I conclude that these sprint sessions are much easier to motivate for, focus during, and recover from because they are less stressful and inflammatory to the body. I have a reliable indicator for the past 13 years of devotion to regular sprint workouts: next day muscle tightness in my calves and arches. I always sprint barefoot or in Vibram Five Fingers and also tend to have tight calves in general. Watch how I cured a 15-year case of plantar fasciitis with just a few weeks of special stretches. In any case, I can count on walking around gingerly for the next couple days after sprinting. Except the soreness was almost nonexistent after that first Unfrozen sprint session, and the next few as well!
Full confession here: After reviewing my initial footage envisioned for the Unfrozen Caveman Runner video, I decided to reshoot everything two days later for better sound and lighting. For the sprinting portion at the stadium, I was just going to fake some sprints since I’d sprinted for real just 40 hours prior.
When I got to the track after the cold tub and rewarming run, I felt so good I completed my usual entire workout: numerous strenuous technique drills (hopping, bounding, hamstring kickouts, high knees, high heels, etc.) followed by five times 100 meters at full speed with leisurely recovery time between sprints. I felt fine in the ensuing days, certainly in recovery mode, but realizing that my normal sprint recovery time of at least a week had compressed down to two days!
It seems hard to believe for me too, but the Stanford Cooling Glove study does lend some validity to the science-minded skeptic.
Cool Performance Benefits
When you become overheated during exercise (which happens easily even in a temperate environment during a moderate workout, and happens dramatically when you perform in a warm environment and/or at high intensity or prolonged duration), a key enzyme involved in energy production called pyruvate kinase becomes misshapen and starts to malfunction.
This inhibits the production of ATP in the muscles, causing you to become fatigued, slow down, cramp up, and eventually just stop. Breaking a sweat is the first indication that you are becoming overheated. Sweating is functional, and a critical survival mechanism but it’s obviously a metabolically expensive, last resort mechanism. If you’re exercising in hot ambient temperatures, sweating isn’t even that effective, causing further performance limitations. Overheating is one of the most, if not the most, significant limiters of physical performance.
More than a decade ago, biology researchers at Stanford University made a stunning discovery in the exercise laboratory: by merely sticking one’s hand into their cooling glove contraption (a permeable glove, enclosed in a toaster-sized chamber filled with circulating cold water, that applies gentle vacuum pressure against the glove, one can quickly achieve a cooling of core body temperature. This cooling glove works by acting on the arteriovenous anastomoses—AVAs—an extremely temperature sensitive network of veins concentrated in the palms of your hands that regulate body temperature with a highly variable blood flow based on environmental temps (AVAs are also concentrated on the soles of your feet and non-hairy facial areas.)
AVAs are your body’s radiators—they attract heated blood from your inner body and exchange it with cooler blood from the atmosphere to recirculate (think how an overheated dog extends her tongue to generate an evaporative cooling effect). Your brain will always cool first, followed by internal organs and then muscles. If an athlete becomes overheated during a workout, using the glove for a few minutes can dramatically accelerate the natural, homeostatic cooling process. This will be revealed by a cessation of sweating—a sign that internal temperature has returned to normal. This can enable an athlete to a workout beyond the usual limitation of overheating. The prototype product is known as the RTX Cooling Glove (Rapid Thermal Exchange). It’s not yet commercially available but has been tested by leading professional sports teams and elite military groups operating in hot climates.
One of the researchers at Stanford, Vihn Cao, served as a super-fit guinea pig to demonstrate the profound performance increases facilitated by the cooling glove. To establish a baseline, Cao performed 180 pull-ups in a single workout performed in sets of 50 with three-minute breaks between sets. Not bad, for a Stanford researcher! After training with the glove for six weeks, Cao was able to perform a mind-blowing 620 pull-ups in a single workout!
The researchers applied the cooling method to other types of exercise – bench press, running, cycling. In every case, rates of gain in recovery were dramatic, without any evidence of the body being damaged by overwork – hence a “better than steroids” claim in the original article headline. Versions of the glove have since been adopted by the Stanford football and track and field teams, as well as other college athletics programs, the San Francisco 49ers, the Oakland Raiders, and Manchester United soccer club.
Wait? Why not just jam your hands into a bucket of ice mid-workout to cool down? This would have the opposite of the intended effect, because the excessively cold ice water would shock the AVAs and cause them to constrict, again as a safety mechanism from an environmental threat perceived as too cold. This was validated by Stanford researchers who had athletes exercise indoors until they were sweating heavily, then ushered them into a room air-conditioned to 62°F (17°F).
The room was too cold to facilitate a lowering of core temperature, instead of causing their AVAs to constrict instead of radiate. Ditto for splashing your face with cold water during a hot workout; you’ll get a temporary psychological refresher, but do nothing to promote cooling of your core temperature. With the glove, because the water temperature is only around 60°F (15°C), and it’s not even directly touching the skin—it’s circulating around outside the glove, body temperature will drop quickly and efficiently. Once internal body temperature has stabilized, the glove will just be cooling the user’s hand a bit.
It follows that the glove is useless unless the user has an elevated core temperature (one professional team testing the glove proclaimed that it didn’t work—athletes were trying it some twenty minutes after their workout concluded when natural cooling had already been achieved).
Ready To Become An Unfrozen Caveman Runner?
I’ve solicited feedback from leading health and scientific experts to confirm that my wonderous observations are validated by science. Dr. Kelly Starrett, legend of San Francisco CrossFit, MobilityWOD and Becoming A Supple Leopard, related the following to me:
“Indeed, heat f&*k’s you up, and staying cool is expensive in energy cost that could otherwise be applied to performance. Your muscle fibers actually work better at lower temperatures. The issue is that your connective tissues do not!”
This is where major warnings and disclaimers enter the picture. You have to be very careful pairing cold exposure with exercise because you can get injured performing high-intensity exercise with cold joints and connective tissue. My friend Dave Kobrine, lifelong super athlete (the only person alive to have played NCAA Division 1 college basketball for the #1-ranked team in the nation, UCLA, and then completed the Hawaii Ironman the following year while still at UCLA!) and major cold plunge enthusiast, had his best pull-up session ever in the process of rewarming after a tub session. Alas, after the smoke cleared, he realized he’d blown out his elbows and has been struggling with tendonitis for over a year since his ill-fated workout.
Note: the anecdote from the researcher in the Stanford study is different because he was merely cooling his hand in 60-degree water, not dunking his entire body into near-freezing water.
Always follow cold exposure with very gentle aerobic exercise to rewarm gradually with minimal joint stress. Just walk, pedal or choose another low-impact option if you have any injury concerns with jogging. Once you fully rewarm, you can then take advantage of your super-primed central nervous system and deliver a breakthrough explosive effort with sprinting or any other activity that you are fully prepared for.
If you want to get out of the gate with easy logistics, you can start with a cold shower (especially if it’s cold outside, hence cold pipes delivering your water), but remember the research referenced by Dr. Patrick suggests that you want a pretty challenging experience. The norepinephrine boost came from a 20-second immersion into 40°F water. Another study revealed cyclists immersing for 15 minutes into 60°F/15°C water four times per week showed fitness improvements.
I keep my chest freezer just above freezing for maximum hormetic response and hormone spike, and also so I don’t have to spend more time in there!
Brad's Step-by-Step Protocol
Start with full underwater immersion into chest freezer for around 20 seconds (don’t be stupid when holding your breath in freezing water), then come up for air. What’s great is I’m so happy to get to breathe I don’t worry about the cold! Then, I commence 20 deep, diaphragmatic breaths. I concentrate entirely on breath cycles as a meditative experience and watch hummingbirds visit my two nearby feeders. I finish with another full submersion of 15 seconds. I’ve started at three minutes and have become naturally more resilient over time to go twice as long, but I never force it. It’s essential to exit before you start shivering or feel distressed about the cold. Kelly Starrett says, “Get out before you start shivering, otherwise you’re just showing off!”
2. Rewarming Jog
Dry off, throw on some shoes, and get out the door! I don’t dress warmly because I want to do all the work to rewarm. You definitely get weird looks from the neighbors (sorry Jolene, I didn’t know you lived on my route…), but you must soldier on in the name of science and peak performance. Walk or jog very slowly at first until your feet feel supple and your stride coordinated. Monitor heart rate to ensure the entire run is at or below your maximum aerobic heart rate, aka Dr. Phil Maffetone’s MAF calculation of “180 minus age” in beats per minute. At 54, I’m running at a maximum of 125 bpm (okay, maybe 130 bpm if I’m excitedly narrating a selfie video…)
After a minimum of 30 minutes rewarming, complete extensive preparatory drills to ensure you are fluid and flexible enough to deliver an explosive effort. I favor brief, explosive sprints that are each of extremely high quality, thanks to extended recovery time and short duration sprints. Enjoy Dr. Craig Marker’s excellent article advocating for HIRT (High-Intensity Repeat Training) instead of the potentially more stressful and destructive HIIT (High-Intensity Interval Training).
After reading Marker’s article and consulting with him, I have shortened my sprints from 15-16 seconds down to 10 seconds each and taken what he and Pavel Tsatsouline, his luminous sidekick, describe as “luxurious rest intervals.” With the extra rest and shorter duration sprints, I get a fantastically explosive training stimulus on each rep, with the last rep just as O.G. as the first (i.e., not very O.G., but okay for an aging endurance machine who still holds the Hawaii Ironman 24&Under American age group record after 30 years). Secondly, I prevent acid and ammonia accumulation in my cells by stopping before my cells get too deep into energy debt on any single effort. After sprinting, cool down gradually with 10 minutes of light jogging and end with stretching if desired.
Thanks for your interest, good luck with your pursuits. For more interesting hacks and practical performance tricks I've discovered, check out my Get Over Yourself Podcast sometime, especially my interview with Ben, in which we talked about all manner of peak performance strategies and empowering daily habits and rituals.
Do you have questions, thoughts or feedback for Brad or Ben? Leave your comments below and one of us will reply!