Why people are stepping into subfreezing chambers that are -300 degrees Fahrenheit

• Cryotherapy works by exposing your body to temperatures between -200 and -300 degrees Farenheit.
• This causes the blood vessels closest to your skin to constrict, which limits the flow of blood.
• It can help with weight loss, anxiety and depression, and injury recovery.

Whole-body cryotherapy is a treatment that involves briefly stepping into a small chamber full of extremely cold air. Proponents say that cryotherapy has many benefits, including faster muscle healing and weight loss, but more research is still needed to determine how effective it is.

Here's what you need to know about how cryotherapy works and what the research says.

What is whole body cryotherapy?

Whole body cryotherapy works by exposing your body to very low temperatures, generally between -200 and -300 degrees Fahrenheit.

The cold air, created by liquid nitrogen, cools your skin, along with the blood that runs close to the skin's surface. When this happens, the blood vessels closest to your skin will constrict, limiting the flow of blood.

If you have any kind of bodily pain going into the treatment, "cold exposure can slow nerve signals from the area to the brain, which reduces sensation, causing numbness or reduction in pain," says Catriona Rose, PhD, a public health researcher at the University of Sydney. For this reason, whole body cryotherapy is most often used to help athletes recover faster from injuries.

Whole body cryotherapy generally lasts between two and four minutes. "Due to the extremely cold temperatures, it is only safe to be exposed to cryotherapy for a maximum of five minutes," Rose says. And it's best to only stay for a full five minutes if the chamber is on the warmer side, around -95 degrees, Rose adds.

Though whole body cryotherapy is becoming more popular, the US Food and Drug Administration (FDA) says there isn't enough research yet to say for sure that the procedure is safe.

A cryotherapy chamber generally has one of two different setups:

• You stand alone in a tube-shaped chamber that's open at the top. Your body will be enclosed in the chamber, while your head stays out in the open air above.
• You sit or stand in a larger, totally enclosed chamber along with other people. In this set-up, both your head and body are exposed to the cold temperatures.

Cryotherapy costs about $30 per session on average and depending on what condition you're treating, you may need at least 10 sessions to see results. "It is expensive," Rose says, "It requires an advanced machine, a trained operator, as well as nitrogen gas canisters."

The benefits of cryotherapy

Some evidence shows that cryotherapy has many benefits. Here are some things that cryotherapy may be able to help with:

Quicker recovery after an injury

When you get injured or go through an intense workout, your muscles will take on some damage. Your body then sends immune cells to clear out any debris and rebuild new cellular structures in your muscles. "However this clearing process is often not very sensitive, and results in healthy neighboring cells being damaged," Rose says.

Whole-body cryotherapy slows your blood flow, which limits the amount of immune cells that can reach your muscles. This can help prevent pain from extra damage and actually speeds up the repair process, Rose says.

There are several studies that show the healing benefits of cryotherapy:

• A 2011 study looked at trained runners who had whole body cryotherapy, other interventions, or no treatment immediately after an intense running exercise. The runners who had cryotherapy felt less muscle pain and tiredness than the other runners as early as one hour after exercise.
• A 2015 study found that synchronized swimmers had lower levels of muscle fatigue and better tolerance for intense exercise after going through two two-week periods of daily cryotherapy.

However, there are also some studies that go against this theory.

• A small 2017 study found that cryotherapy didn't help with muscle soreness for marathon runners and that a cold water bath was more effective.
• A 2015 review of four studies found no strong evidence that cryotherapy helps with muscle soreness after exercise.

Anti-aging

Whole-body cryotherapy may help reduce free radicals, particles that can damage your cells and contribute to the aging process.

A small 2019 study found that after 10 sessions of cryotherapy, subjects had higher levels of antioxidants, compounds that help fight the damage caused by free radicals.

However, more research is still needed to see if whole body cryotherapy can actually slow the aging process. "The best practice doses, timings, and frequency of treatments for significant impact are unknown," Rose says.

Weight loss

Experts believe that cryotherapy can imitate the effect of exercise on your body, which may lead to weight loss.

This is because when you go through cold treatments, your cells adapt by increasing the amount of brown fat in your body, Rose says. Brown fat is important because unlike regular fat, it contains cells that burn calories and fat stores in order to warm your body.

A small 2015 study conducted tests on active and non-active obese men before and after doing daily cryotherapy sessions over 10 days. At the end of the study, the non-active subjects had gained higher levels of irisin, a protein that helps convert regular fat into brown fat.

But though these results are promising, more evidence is still needed to see if whole body cryotherapy can actually cause weight loss, Rose says.

Reducing anxiety and depression

Whole body cryotherapy may help improve mental health symptoms when it's used alongside regular treatment.

A 2020 study found that depressed people who received cryotherapy had significant improvements in mood and depression symptoms, compared with those who only had standard treatment.

The researchers believe this may be because cryotherapy can improve sleep quality and reduce inflammation, which are both contributors to depression.

In a small 2008 study, people who underwent 15 sessions of cryotherapy scored lower on both anxiety and depression scales compared to their scores before treatment.

What conditions can cryotherapy help treat?

• Chronic inflammatory diseases: Whole body cryotherapy may help fight the painful effects of chronic inflammatory diseases by decreasing your levels of pro-inflammatory proteins and raising your levels of anti-inflammatory proteins.
• Fibromyalgia: A small 2018 study looked at how cryotherapy can affect people with fibromyalgia, a chronic pain condition. The researchers found that after 10 sessions of cryotherapy, the subjects had lower levels of pain and fatigue, compared with those who didn't get treatment.
• Rheumatoid arthritis: A 2015 study found that people with rheumatoid arthritis had lower levels of pain and fatigue after a two-week program of whole body cryotherapy.

Insider's takeaway

Cryotherapy comes with risks if you exceed the recommended two to four minutes. "There is a risk of hypothermia if someone were to remain in the chamber for longer than an appropriate amount of time," says Rose.

"Further, if there is any metal jewelry, or if the skin is damp in any way, there is a risk of frostbite," Rose adds.

Whole-body cryotherapy may offer some relief for people with chronic pain conditions, but more research is still needed to prove its other benefits and make sure that it's safe.

However, these risks can be lessened if the chamber is controlled by a trained professional. "There should always be someone outside running the chamber, never run by the person using it," Rose says.