It wasnt just the Force that helped the cast of Star Wars: The Last Jedi get through those grueling lightsaber fight scenes.

Daisy Ridley, Adam Driver, Mark Hamill and Oscar Isaac had a not-so-secret power to help them train harder and longer without injury: a compression sleeve that surrounds weary muscles with ice-cold temperatures.

The $300-and-up sleeves, made for professional medical use only, are used by professional athletes around the country. The sleeves provide both compression and icing, two of the basic functions of recovery, known by the acronym RICE: rest, ice, compression and elevation.

Normally, we could train [actors] two times a week, but with this recovery technique, we can work with them five times a week, sometimes more, says Christopher Vincent of Los Angeles-based sports-medicine company Altus Health, which he runs with his brother, Paul. Not only has their team worked on the past three Star Wars movies (and the next one, Solo: A Star Wars Story, out in May), but theyve trained actors in many other major action movies, Blade Runner 2049 among them. Theyve also been credited with helping Carrie Fisher drop 30 pounds for 2015s The Force Awakens, and guiding Harrison Ford through an ankle injury with on-set rehab therapy.

We wanted to prepare their fitness and strength so that they could do that activity for 12 hours a day, five days in a row.

There are several brands of compression sleeves on the market these days. The ones the Star Wars cast uses are from Game Ready, the choice of such powerhouses as Serena Williams and Lady Gaga, as well as members of the Knicks, Mets, Rangers and Giants.

The sleeves can fit over several parts of the body, from the ankles to the arms, and can be plugged in or run on an attached battery pack. Though many machines have a warming function, the common use is a combination of pressure and cold. The coldness, which circulates 38-degree water through an ice reservoir for 20 to 40 minutes, has been found to reduce pain and swelling.
Its not always pleasant to put cold things on your body, so it took a little coaxing for people to use [it], Vincent says.

The compression part of the sleeves, which feels similar to getting your blood pressure read, helps flush post-workout blood to flow away from muscles, reducing inflammation and aches.

When the tight cold sleeve is removed, healthy, re-oxygenated blood flows back to the muscles. Though this process normally happens on its own, the sleeve speeds recovery time something vital, Vincent says, when youre training for the physically demanding roles in Star Wars.

Before any of the actors could wield those lightsabers, they needed to strengthen their core muscles, Vincent says. That meant actors Ridley, Driver and Hamill were doing a lot of plank-based exercises, along with old-fashioned pullups and pushups to strengthen their arms and shoulders, in addition to martial arts training.

Teams from Altus Health joined the cast and crew on the set in London and Ireland, often with basic equipment such as resistance bands, medicine balls and free weights. Vincent says diet also played a major role in the casts Jedi-ripped physiques.

Wed feed them more in line [with] a marathon runner, which is [a] higher-fat and -protein and lower-carbohydrate diet, he says. Their diet was very high in vegetables and probiotic foods like kombucha the gut really affects your recovery, your acuteness of the brain, your immune system.

Between training sessions, and sometimes even between takes, therapists would use the sleeves to make sure the demanding stunts wouldnt result in overuse injuries. This made it possible to continue the 100 or so days of filming without any holdups from injuries.

If one actor is down, it can mess up the whole shooting schedule and cost the production company millions for not being able to shoot that scene, Vincent says. We wanted to prepare their fitness and strength so that they could do that activity for 12 hours a day, five days in a row.

The practice used with the Star Wars cast of icing sore or injured muscles has been around for ages, says Dr. Joshua Dines, an orthopedic surgeon at Manhattans Hospital for Special Surgery. The only real difference, he says, is that technology has streamlined the process.

Dines says he uses the compression system with his patients, including players for the Mets and Rangers. The sleeves help athletes feel better and return to play faster, he says, and are useful in helping those who have had surgery find relief without relying too much on pain medication.

While he says theres no evidence yet that icing injuries helps performance, he cites a 2012 study in the British Journal of Sports Medicine that supports the benefits of compression on recovery.

If it makes the athletes feel better, to get them back on the field in a safe way, then its a benefit, he says, adding that actors such as the ones in Star Wars are like pro athletes when theyre shooting films like that.