We’re in the Norwegian Arctic, in a quaint but frigid, snow-capped fishing village; intercutting between shots of ominous 37-degree water and two doctors explaining how swimming in that open sea has a real risk to Chris Hemsworth’s life.
“Yep,” Hemsworth somberly responds, rubbing his face.
The Aussie confesses to us that despite his hatred of the cold, he’s been cajoled into swimming 250 yards in this deathtrap of a bay— for the sake of improving his longevity.
Hemsworth’s brothers, Liam and Luke, are tagging along, and the trio bounce down the road in a blacked-out Land Rover Defender (that I very much covet), providing an opportunity to rib Chris as he mans the wheel: “Feather that clutch, mate,” Luke chirps.
Hemsworth blames thick boots for being unable to feel the pedals, drawing cheeky shade from Liam: “We’ve let the worst driver of all drive us.”
Riding shotgun is Ross Edgley, a British sports scientist and extreme athlete, who believes that the extreme temperatures will benefit Hemsworth. Edgley, Hemsworth explains, is one of the fittest humans on the planet, the guy who takes everything to the limit.
Case in point: he’s the only person in the world to swim all the way around Great Britain—in 157 days straight. And he’s an ice cold water swimmer.
Edgley looks like an extremely-yoked Steve-O and exudes the energy of Tony Little; that bubbly, gym class instructor vibe you initially loathe, but come to appreciate by the end of the class.
“I believe humans only thrive in the face of adversity,” Edgley shares with a toothy grin. “You find out about your physiology, your mentality. And there are now theories that subjecting your body to extreme temperatures can help your body live longer.”
Which brings us to the crux of Episode 2’s theme: Shock.
Most people believe comfortable temperatures are the proper ones for a healthy life, but new scientific research indicates that subjecting yourself to extreme cold and extreme heat can force your body to upgrade its defenses, Hemsworth explains, by powering up microscopic repair systems. These enhancements can cut your risk of disease and maybe add years to your life.
“Enduring extreme conditions could help me fight inflammaging, manage pain, and boost my immune system,” he says. “It can trigger repairs inside my cells, and even improve my mental wellbeing. This isn’t a battle against cold, it’s a battle against what time could do to me.” (Dun, dun, dunnnn!)
Why this undertaking? Hemsworth believes lifestyle changes can improve his lifespan and healthspan.
That premise is our guiding maxim here at The Edge, and Limitless does a spectacular job presenting dense scientific concepts surrounding longevity in an engaging and digestible manner.
We’re recapping our favorite learnings from each episode, so here are 11 of the most interesting takeaways about shock training with extreme cold and extreme heat.
1 - Cold Water Exposure Training Looks Positively Brutal
“My ears are about to snap off; they’re like little icicles and I’m concerned,” Hemsworth laments. Slipping down a dock—literally, because hail is pelting the surface—toward the water, Edgley instructs Hemsworth to strip down to his trunks, hop in, and “just experience the cold at its rawest form for a few minutes. Think of it like a baptism.”
“Cold water triggers really powerful survival mechanisms,” says Edgley. “If you’re training for an ice swim, those reactions work against you. I need Chris to understand what they feel like so he can tame them.”
Edgley warns Hemsworth that once they’re in the water, the timer has started on hypothermia, and, “bluntly, consciousness and life.” The duo shed their clothes and—I cannot stress this enough—calmly descend a ladder into 37-degree Fahrenheit water.
Neither hesitate; there’s no pause before their groins meet the frigid water. The dark water is so cold, it looks ominous (unless that’s some color correction trick during post-production).
Hemsworth’s reflexively gasping, a normal reaction, per Edgley, who is more chipper here than on land. He’s talking Hemsworth through overcoming growing hyperventilation: “It’s self-preservation; your body’s going, ‘Get out!’ Override that.”
A minute in, Edgley says, “So now we’ve gotten over that gasping reflex and—”
“No, no, we haven’t,” Hemsworth gasps.
The Hemsworth siblings come out to troll Chris—“What’s the level of shrinkage?”—and Hemsworth’s had enough: “I think we’ve proved our point, right? Can we get out?” he pleads, discomfort in his voice.
Edgley gleefully denies him, demanding another 30 seconds, following it up with, “Can you feel that blood going away from your extremities?” This must be the only time in recorded history a man has said this statement while grinning like the Cheshire Cat.
2 - Hemsworth’s Clearly Not Faking This
Hemsworth feels all sortsa pain, so Edgley issues a quick dexterity test: how fast can he move his fingers? Casually, Edgley cycles through touching his thumb to each finger with alarming speed and laser-precision.
Hemsworth slowly accomplishes a few connections before missing, then gives up, opting to just make fists. Edgley laughs, and shares they’ve spent 2:50 as human popsicles, bobbing in this harbor. Hemsworth re-ups his plea to stop, and Edgley asks for another 30 seconds but he’s kidding and does let Hemsworth emerge.
You can see the debilitating effects on Hemsworth as he tries to climb the ladder. “I can’t feel my hands.” Indeed, he doesn’t seem to be able to grip the ladder well, he’s sluggish in rising out of the water, and his body is redder than Rudolph’s nose. He hobbles inside—“I can’t feel my toes, either”—as Edgley explains returning to room temperature slowly will be vital to the recovery from the shock.
Who's Ross Edgley?
3 - Cold Plunges Mitigate Inflammaging
As you get older, one thing to look forward to is your defense system [your immune system] could get more trigger happy, says Hemsworth. “Throughout the body’s blood vessels, an unwelcome surge of immune cells can cause collateral damage, doing more harm than good.”
“The resulting breakdown in tissues and organs is called ‘inflammaging’ and it fuels two of the biggest killers in the modern world: heart disease and diabetes. The theory that dialing down our reactions to the cold can reset our immune system and cut the risks of deadly disease in old age.”
4 - Extreme Cold Rewires Pain Receptors, Too
We meet Johanna Nordblad, as she trudges through knee-deep snow, tugging a sled in Heinola, Finland. After smashing her leg in a cycling accident, Norblad’s fractures healed, but her pain never stopped. “It felt like fire in my bones,” she tells us.
When conventional medicines and prescriptions failed her, doctors suggested a new treatment, based on the theory that cold water can scramble pain signals before they reach the brain. The professional free diver says that when her leg first immersed in the water, the pain ceased for the first time since her accident.
As she saws through the crust of a frozen lake, she says, “The treatment took away my fear of the cold,” slipping beneath the surface, elegantly gliding around under the thick ice. “If you keep calm, you can stay much longer.”
5 - Repeated Cold Exposure May Help Infection-Proof You
“By swimming in cold water, you get ill far less often,” claims Nordblad. “I feel healthier and full of energy.”
The right dose of shock could enhance your ability to fight off infection, Hemsworth adds. “In one study, people who flipped to cold for the last 30 seconds of their daily shower took almost 30 percent fewer sick days.”
This is true, but there’s one caveat that the show glazes over. “This is a subtle but important point: Participants who took the cold showers actually reported feeling ill just as many days, on average, as the people who showered normally,” says Dr. Geert A. Buijze, that very study’s author. “But either their symptoms were less severe or they felt more energetic, so they were better able to push through the sickness and function anyway.”
6 - Hemsworth’s a Remarkable Surfer
Hemsworth’s lured back into the angry surf with a board for prolonged exposure, along with a surfing pal. They trudge through the snow on the beach to the water and jeez, that’s a sentence.
A wet-suit-clad Hemsworth gets on with it, rushing into the 37 degree water with far more zeal than I could muster. As Hemsworth cools in the sea, “he’ll experience a significant loss in muscle strength and his coordination is gonna go to pieces,” Edgley smiles. The goal is mobility retention: how long can he keep moving?
Hemsworth, who has been obsessed with surfing since he was 10, ends up getting a solid wave, taking it all the way in, but it’s not long before he affirms Edgley’s proclamations: it’s harder to move, his strength is zapped, and his balance is off. His second attempt at a promising wave ends with him getting hammered within seconds of standing and he calls it quits.
READ OUR EPISODE 1 RECAP
7 - Extreme Heat Exposure Releases Disease-Fighting Proteins
Dr. Peter Attia, a longevity expert, and Hemsworth trapise barefoot through the snow to a sauna. Hemsworth’s pulse at the onset is around his baseline—64 beats per minute—but with the temp cranked to 195-degrees, it’ll skyrocket soon, Attia says. “We’re uncomfortable right now because we’re hot,” Attia says.
“In response, our body is trying to cool us off. It’s pumping harder so that your heart can quickly get the blood to the outside of your body and, just as exercise is known to help with cardiovascular disease, I think sauna has a number of those benefits as well.” A recheck of Hemsworth’s pulse reveals it has shot up to 135 bpm.
Our body wants to stay in a comfortable temperature range, explains Attia, and right now they’re way outside that zone and, in the process of adaptation, our body protects us by increasing the production of special molecules called heat shock proteins, which are extremely effective at fighting disease.
8 - Frequent Saunas Reduce Alzheimer’s Disease Risks
“Deep in our cells, heaps of molecular junk are piling up from the wear and tear of age,” Hemsworth says. “Hoarding all that trash could lead to serious problems. But the blistering heat of the sauna tells my body to send in a cleanup crew: heat shock proteins. These tiny heroes get to work giving my cells the ultimate spring cleaning.”
The two places Attia says where frequent saunas—fired up to 170 degrees Fahrenheit—are the most beneficial are cardiovascular disease, where there’s about a 50 percent reduction in risk of death, and Alzheimer’s disease, where there’s about a 66 percent reduction. (Verified. More research over here.)
9 - There’s No Point Increasing Your Lifespan Without Increasing Your Healthspan
The Hemsworth clan clamber into the ocean for a brisk swim before playing soccer at a local outdoor field—The Grand Tour fans will recognize this very soccer pitch. (Hi, I really like cars)—and then back into the ocean. It’s the repetitive cycling of these exposure doses that helps break the body’s resistance to the cold.
Later, soaking in a hot tub with his brothers, Hemsworth sums up the notion of healthspan aptly: “You want to live a longer life, but [it’s] not just living longer; [it’s] living longer and stronger. Especially having kids, you want to be able to play with the grandchildren. We have an opportunity to live longer and better.”
10 - Cold Plunges Train Your Mindset to Overcome Fear and Adversity
As a trio of Shugendo monks move through the mountainous Kansai Region of Japan, we meet Mr. Shinbo, on a years-long journey to join the order. One test during this ordination process: standing under a waterfall of melted snow that is “so cold it can cause heart failure.”
“To pass,” Hemsworth says, “Shinbo needs to withstand this freezing cascade until his master is satisfied.” And so Shinbo, outfitted only in a white cotton robe that looks to be no thicker than the average bedsheet, picks his way through slippery rocks to serenely stand beneath the falls, cleaving the torrent with his body.
From his side, Shinbo says this feels like an electric shock. But putting yourself in a place where you feel fear; that’s the test, Shinbo tells us. “There’s a story about baby eels. If you add a predator like a catfish to the tank, they say more of the young eels will survive. Humans also excel in the face of adversity.”
We’re not privy to the actual duration Shinbo spends within the waterfall, but it seems lengthy; throughout, Shinbo is as still as a statue. Only his mouth moves, deeply breathing. His master appeased, Shinbo’s egress is as calm as his ingress. This Shugendo rituals show that confronting fear and enduring the cold can build a stronger mindset, says Hemsworth.
More on Longevity
11 - Of Course, Hemsworth Crushes the Open Water Swim
Plunking a Marvel movie star in a life-threatening situation for our benefit requires heavy precautions, evidenced the voluminous safety team on swim day. There are two ambulances, several doctors, three jet skis with tow boards to yank Hemsworth out, and a sizable Zodiac go-fast boat, to zip him back to shore. Despite “having all these people around, I’m really nervous,” Hemsworth says.
A winter storm is coming. There’s a headwind, it’s snowing, it’s frigid, and this landscape of the lurking snow-capped mountains with an angry, frothy sea more resembles a realm Thor would be exiled to by Loki than Earth. The wind ratchets up ten knots, sending the fur fringe on Liam’s hood completely horizontal.
The water’s dipped a degree to 36 F when Hemsworth—wearing only board shorts and goggles—begins. Ten strokes in, it burns, he says. Then “the worst ice cream headache” kicks in and he slows down. “My arms and legs feel like lead balloons,” he sighs. “I just feel paralyzed.” Edgley’s eternally sunny disposition has been replaced with the fiery steel of a world-class athlete, and he barks encouragement from the boat alongside Hemsworth. It’s enough for Hemsworth to surge forth again, reaching the goal buoy.
Hemsworth definitely does not exit the ocean with the same grace that he revered in Shinbo—the actor’s huffing and puffing and shaking—but he does seem to possess more of his faculties than in prior cold shock exposures.
To build shock into his routine, Hemsworth pledges to adopt early morning ice baths thrice weekly, sauna regularly for 20 minutes at 170-degrees, and flip to cold water for the last 30 seconds of every shower.
Watch all six episodes of Limitless with Chris Hemsworth on Disney+.