When Jose Caraballo entered the CrossFit room at McVeigh Sports and Fitness Center, he had no idea what kind of workout awaited him.

Afterward, the Joint Base Lewis-McChord Solider said he enjoyed the surprise element of the high-intensity workout. Caraballo has been participating in the free class offered at the base fitness center a handful of times and is already noticing a physical improvement.

"I had to keep coming back because it improves what I do in my PT," Caraballo said. "This is improving me and I feel like I'm getting stronger. The pain was worth it. It felt like you actually worked out."

Since CrossFit was introduced to JBLM a couple years ago, it has quickly gained popularity. During PT hours, the CrossFit room at McVeigh is full, fitness specialist Susan Jackson said. And the classes, offered Monday through Thursday and Saturdays, attract up to 40 participants.

Arnold Authement, a civilian nurse at Madigan Healthcare System as well as a Soldier in the Army Reserves, volunteers up to 10 hours a week as an instructor at McVeigh.

When Authement was on active duty, he scored well on his PT test, but while in the Reserves, his score began to slacken. Two years ago he gave CrossFit a shot and stuck with it ever since. He slimmed down, toned up and scored 300 on his Army Physical Fitness Test.

"I'm healthy like I was back in my 20s," the 46-year-old volunteer instructor said.

Authement gets his own workout in before or after he instructs and participates alongside those in the class, offering encouragement along the way.

"What I preach to these guys is don't be in competition with each other, be in competition with yourself," Authement said.

The hourlong class starts with a warm-up. A recent class started with a lap around the track at Cowan Stadium followed by running the stairs of the bleachers. The session transitioned into a variety of squats and ended with a burnout workout using a kettlebell.

The classes are for all fitness levels and encourages participants to work at their own pace. A benefit of the functional fitness workout is how it translates into every day living.

"Everything we do around here translates to doing stuff around the house," Authement said. While Saturday classes tend to be smaller, those who attend opt to change up the routine and visit neighboring CrossFit gyms in the community, or participate in fun runs or hikes. "Come work out with us for about a month, two-three days a week," Authement said. "See how great you feel and if you're having fun and enjoying it, that's what keeps you coming back."