What do sports stars Cristiano Ronaldo, Jamie Vardy and Sam Warburton have in common? It is nothing to do with goals, tries or fast cars. All three regularly undergo whole-body cryotherapy, an extreme-cold treatment that proponents say can speed recovery, reduce injuries, increase energy and improve sleep.

Two major sporting achievements have helped drive a boom in its use. Some saw it as a decisive factor in the Welsh rugby union team reaching the 2011 World Cup semi-finals, while others believe it helped Leicester City overcome odds of 5,000-1 to win last season’s Premier League title. Today, it is used at the top level in many sports and is increasingly being marketed to keen amateurs seeking an edge.

Beauty salons and spas claim it can burn calories, improve our skin and make us happier. Almost inevitably, Lindsay Lohan, Jennifer Aniston and Daniel Craig are reported to be fans. So far, so profitable. But does whole-body cryotherapy work? Or more realistically, are the claims made for it supported by sound scientific evidence?

If you have ever put a bag of frozen peas on an injury, you have used cryotherapy. The use of cold in medicine has a long history, from freezing warts and killing cancer cells, to slowing metabolic processes during trauma surgery. Whole-body cryotherapy takes place in sauna-style, walk-in chambers, with sessions normally lasting just two or three minutes. Those using liquid nitrogen to cool the air inside them can get down as low as -160C.

First developed in Japan, the therapy arrived in Europe in the 80s. In Poland, it is used to treat many conditions including rheumatoid arthritis, multiple sclerosis, psoriasis, sleep disorders and depression.

“It helps recovery and rehabilitation processes,” says Ian Saunders, co-founder of CryoAction, a UK company that supplies many top rugby and football teams with cryotherapy facilities. “Vasoconstriction reduces blood flow to the extremities, which reduces inflammation around soft-tissue injuries, stopping them progressing. The release of adrenalin relieves pain and generates the feelings of exhilaration that players report.”

Too cold for comfort? A woman in a cryotherapy chamber. Photograph: Alamy Stock Photo

The evidence from scientific studies, however, is mixed. In 2015, a small German study found endurance athletes recovered more quickly and were able to perform better in the second of two running tests separated by an hour if they underwent whole-body cryotherapy in between. A Cochrane review – the gold standard in healthcare evidence – pooled the results of four previous studies involving 64 physically active adults and concluded there was insufficient evidence to support its use to relieve muscle soreness after exercise.

“We saw some potential in the initial evidence of beneficial effects, but until more evidence and better-quality studies are published, we can’t say for sure whether it is effective or not,” says Dr Joseph Costello, lead author of the Cochrane review and senior lecturer in exercise physiology at the University of Portsmouth.

Proponents say whole-body cryotherapy activates the body’s “fight or flight” mechanisms, driving extra energy to muscles and narrowing blood vessels so that fewer inflammation-causing white blood cells reach injuries. Extreme cold may have some of these effects, but some of the claims made for the treatment on this basis are extrapolations based on flimsy and often contradictory evidence. Another company, 111Cryo, has launched 3-minute whole-body cryotherapy sessions in both Harvey Nichols and Harrods in London in the last year, claiming these can boost focus, determination and energy levels, as well as improving skin tone and burning up to 800 calories. Of the calorie-burning claim, 111Cryo founder Dr Yannis Alexandrides, a Harley Street plastic surgeon, admits: “It’s an extrapolation, not medical data.”

One French study found the therapy had no significant effect on adrenalin levels. Some research has suggested it reduces levels of inflammation markers and the stress hormone cortisol, while increasing testosterone, but other studies have produced contradictory results.

The BMI private hospital in Hendon, north London, charges £50 for a whole-body cryotherapy session and states that it can help treat rheumatoid arthritis, osteoarthritis, fibromyalgia, tendinitis, muscle strains and back pain”. The US Food and Drug Administration last year stated there was insufficient evidence to support such claims.

The therapy certainly lowers tissue temperatures. A 2014 study carried out on rugby players found it caused falls of up to 12C on the skin. Another study recorded drops in muscle temperature of between 1.2C to 1.6C.

Of course, there are other ways to cool the body. Tennis star Andy Murray and other athletes swear by sitting in cold, or even ice-filled, baths after exertion to ease pain and recovery. Research published last month found men who underwent cold-water immersion at 8C for 10 minutes saw greater drops in tissue temperatures and bloodflow than those who did whole body cryotherapy at -110C for two minutes.

So if greater effects can be achieved with cold water, why bother with whole body cryotherapy? “We’re yet to find anybody who says they prefer the invasive, penetrative cold of cold water immersion to being in a cryotherapy chamber,” says Saunders.

So what does it actually feel like? I went to the Saracens rugby union team training ground in St Albans to find out. Bare-chested and in shorts, knee-length socks, a woolly hat, gloves and a face mask, I spent two-and-a-half minutes in a CryoAction chamber, which reached -125C. It was cold, similar to being near an open chest freezer. I felt no exhilaration and my aches from a run the previous day were still present two days later.

Perhaps my problem was scepticism. Research has shown that when patients attend a medical facility and are told a procedure can reduce pain, this can itself boost levels of neurotransmitters that can improve symptoms. “Even if whole-body cryotherapy isn’t having any direct physiological impact, someone who believes it is doing so might experience a powerful placebo effect that could be beneficial to recovery,” says Costello.

Costello remains open-minded about the therapy’s powers pending further research, but points out amateurs can probably achieve more by focusing on the basics. “Interventions such as cryotherapy are 1%-ers that elite athletes, for whom such margins are important, might want to explore. Recreational athletes might be better focusing on the 99%-ers – rest, rehydration, refuelling and allowing the appropriate time to repair.”