Wales are gunning for the Six Nations' Grand Slam next weekend against France, but a core part of their success lies far across Europe in a sub-zero medical unit in Poland.
The cryotherapy division of the Olympic Sports Centre in Spala, 100 kilometres (60 miles) southwest of the capital Warsaw, has become legendary since Wales came here in June 2011 and four months later powered into the World Cup semi-finals in New Zealand.
The Spartan-sounding location has infused rugby lore with tales of Welsh cryotherapy neophytes banging on the door to be let out. But now it seems they can't get enough of what flanker Sam Warburton dubs the "evil sauna".
Stints at as low as -160 Celsius (-256 Fahrenheit) are only part of a fitness programme that has helped Warren Gatland's young squad shine like Wales's golden generation of the 1970s.
"Cryotherapy's not magic," said Adam Beard, Wales' head of physical performance.
"A lot of people are asking, 'Why are you letting the cat out of the bag? Isn't it your trade secret?' Well I don't think it is," he told AFP by telephone.
"We use it around a training programme we've adapted for the last four or five years."
But Beard is still clear about its benefits.
"Cryotherapy reduces inflammation. It dampens the nervous system, so it gives you that painless feel, and it allows you to flush toxins away from the working muscles pretty quickly, because obviously you're in extreme temperatures and the blood wants to move away from the limbs to regulate the core temperature," he explained.
"Once you get out, there's a feeling of freshness. That's the endorphins rushing through your system."
Wales like it so much that they bought a portable unit, though Beard said he prefers the real thing, and they returned to Poland to prepare for the Six Nations.
"To be quite honest, the boys would far rather do that than an ice bath," he joked.
While the concept of deploying cold for medical purposes has been around for over a century -- think cold compresses for headaches or ice-packs on sprains -- the idea of a deep-freeze unit was perfected by Polish scientists in the 1990s.
"This is all about exploiting the impact of low temperatures on the human organism," said Doctor Tadeusz Kilian, head of Spala's medical arm.
"Besides helping athletes' regeneration, it has a general role in speeding recovery, from rheumatism or spinal injury, for example," he said.
The unit opened in May 2000, adding to facilities such as a hydrotherapy wing, running tracks and gyms.
At 320 zloty (77 euros, $103) for a five-day course of two sessions a day, the centre draws around 500 people a year, two-thirds of them from the sports world.
"They're from a host of disciplines, though rugby put us in the limelight," said staffer Agnieszka Zakrzewska-Iskierka.
"It's a mixture of nervous first-timers, and others who've been here a lot and know what to expect."
Since experience beats speculation, AFP took the plunge alongside a group of Polish sportsmen.
Stripped to the waist, and decked in a bizarre outfit of shorts, knee-socks, gloves, ear-protection and a surgical mask, the men stood in line, joking to while away a seemingly interminable wait for another group to finish.
In fact, the sessions last only three minutes.
A weighty door swung open and a group of women in sky-blue tops and shorts emerged amid a cloud of ice-vapour.
"If you don't feel OK, wave through the window," physiotherapist Pawel Binczyk told AFP as he ushered the five-man group into a -60 Celsius (-76 Fahrenheit) cool-down room.
After 30 seconds, it was time to move into the three-square-metre (10-square-foot) cryotherapy chamber.
The cold bit was hard but far from unpleasant. The group circled and did deep knee-bends to get the benefit of the iciest air.
After what seemed like less than a minute, Binczyk opened the door and called, "Time's up!"
The sensation was one of well-being -- and the participants hit the gym.
"I had a spinal injury, and my doctor prescribed this," said wrestler Kamil Dzitkowski, 21.
"The first session's a bit bizarre but it gets easier each time," he said.
Olympic race-walking medal hopeful Rafal Sikora, 25, said cryotherapy was a boon.
"Above all, it helps deal with pain and aids regeneration after training. I come here two or three times a year. I think it's great," he said.