Matthew Grashen, a 23-year-old Marine who was injured by a makeshift bomb last month in Afghanistan, participates in a wheelchair lacrosse clinic at the Walter Reed National Military Medical Center. (Jahi Chikwendiu/The Washington Post)

They had strapped on gloves, donned helmets, grabbed their lacrosse sticks and lobbed balls around the gym Tuesday in preparation for a scrimmage. And then they got one key piece of instruction:

It’s better to throw the ball over a teammate’s head than at his feet, especially if, like the small group gathered at the Walter Reed National Military Medical Center lacrosse clinic, the teammate is in a wheelchair.

Wounded and recovering service members lined up Tuesday on a court in Bethesda to see how the fast-paced sport commonly played on a field would translate to two wheels in a room.

Sports such as wheelchair basketball and wheelchair rugby are better known; they’ve become staples of the Paralympic Games. Wheelchair lacrosse, by comparison, is a little less established.

It’s very similar to field lacrosse, with the same gear, same sticks and same basic rules.

Wounded veterans and their lacrosse instructor, Ryan Baker, right, prepare for a scrimmage during a wheelchair lacrosse clinic for patients at the Walter Reed National Military Medical Center. (Jahi Chikwendiu/The Washington Post)

“We have taken the men’s field game and tried to translate it, as best we could, to wheelchairs,” said Ryan Baker, who co-founded Wheelchair Lacrosse USA in 2009.

Baker, who was paralyzed in a car crash the day after he graduated from high school in 1991, was at Walter Reed putting on the clinic and is scheduled to do the same thing Wednesday at Fort Belvoir. He held a similar clinic at Walter Reed in the spring.

On Tuesday, Baker moved around, giving tips to the eight service members participating and advice such as why it’s easier to grab a ball thrown over the head than at the feet.

The clinic was offered as part of a program that provides recreational athletic activities to wounded service members as a way to help them recover from their injuries.

The games aren’t just about providing physical activities, said Amanda Kelly, who helps coordinate adapted sports at Walter Reed. They can also provide an outlet for some of the veterans.

Army Spec. Joshua O’Neil, an Annapolis native, suffered a broken back and pelvis from an explosive device in Afghanistan this year. He said that when he first got to Walter Reed, he didn’t know anyone so he mostly stayed in his room. The first lacrosse clinic helped him branch out and meet other people.

“It’s a kind of therapy all on its own,” said O’Neil, 24, who plays in weekly pickup games at Walter Reed. “It may not help me physically, but it definitely helps me mentally.”

Not all of the participants in Tuesday’s clinic needed wheelchairs. O’Neil can walk now, but he can’t run because of a metal plate attached to his hips, so wheelchair lacrosse gives him a chance to move quickly while playing a sport.

O’Neil, who has played lacrosse for most of his life, said the wheelchair game actually has an edge over the field game in one category.

“There’s a little more physical contact,” he said.

His fellow players agreed, saying they liked this aspect of the game.

Baker said Wheelchair Lacrosse came about because he wanted to play something team-oriented — and physical. Lacrosse is “a little more aggressive than basketball,” he said.

For veterans who used to play football and miss the hyper-physicality of the sport, that’s a selling point. Marine Lance Cpl. Matthew Grashen, who played strong safety in high school, likes that lacrosse combines elements of football and basketball.

“It’s appealing because it’s a contact sport,” said Grashen, 23, of North Chicago. Grashen lost one leg below the knee and the other above the knee in Afghanistan last month. He had never played lacrosse before Tuesday’s clinic.

“It’s very difficult,” he said. “But I’ll keep practicing at it and I’ll get it.”