COEUR d'ALENE - Meet the burpee.

It's the exercise that sounds and looks simple, until you try it. Chances are when you try it, you're already tired because trainers like to sprinkle them into the middle of workouts, almost like an insult or rubbing salt in your eye.

They don't do that to annoy you, the trainers swear, they do it because there's no better exercise around. It's their job, after all, to get you as fit as you can be.

"Everybody loves to hate them," said Kelly White, personal trainer at 360 Fitness, who runs a boot camp class where athletes are constantly in motion for a half hour and burpees play a big part of the moving. "And they hate me for them."

Say hello to the burpee. It's the exercise where you fall to the ground, push yourself back up, then jump and clap your hands over your head. Don't jump high, maybe 6 inches. It's easy. Try it.

Up, down, clap, up down clap ... So simple, yet so compact.

"It's hard core," said White. "It's basically a full body exercise, and it's fast."

While the burpee has been around for years - at least 100 years according to its Wikipedia page, and yes, it has its own Wikipedia page - the movement is becoming more of a household name of late because an increased amount of gyms are straying away from, say, dumbbell curls and focusing on one's ability to efficiently move his or her own body weight.

Take a gym like CrossFit, a gym that preaches functional fitness and relies on the burpee.

In 2008, there were about 300 CrossFit gyms worldwide - now there are well over 5,000.

By dropping down to the ground, pushing yourself up, and jumping up and clapping, you work everything from your thighs through your chest and arms - no fancy equipment required.

It's the ideal cardiovascular workout, trainers say. Simple, efficient, and the heart rate spikes quickly.

"They're very, very effective," said Eve Fatz, owner of Lotus CrossFit in Coeur d'Alene that uses the exercise. "But people do hate them because they're so painful ... It uses all kinds of muscles."

In fact, Fatz's gym uses them as pure punishment. If someone's late, the whole class has to hit the deck.

"It's a big incentive for people to get there on time," she said.

According to the Wikipedia page, the exercise originated when Royal H. Burpee, an American psychologist, designed the Burpee test to measure one's agility and coordination. The United States Army liked it, and adopted it as a way to assess the fitness level of recruits when the U.S. entered World War II. Even the Washington Post and New York Times has written about them, and they say the Navy adopted them, too.

Today?

"We try and introduce them (quickly)," said Sgt. Lawrence Hurtado, a Marine for 10 years who works in the recruitment office in Hayden.

Once a candidate walks into the office looking to join, burpees are one of the first things the newbie will have to do. Why?

It was unveiled in no time whether the potential recruit has asthma, Hurtado said. Having asthma automatically disqualifies applicants. Ten or 20 in a row will show the Marine Corps if the recruit is allowed to even get on the bus.

But if the recruit does pass, the Marines still use burpees to train them before shipping them off to boot camp. The military scores recruits on the timed number of pull-ups, crunches and run time. The burpee conditions to improve all three at once, Hurtado said. Besides that, it's a realistic movement: Diving, pushing up and jumping are what soldiers do out in the field.

"It's not for punishment," Hurtado said. "It's to help the recruit."

The exercise has spawned a family tree since the days of Mr. Burpee: Dozens of combinations exist.

There are burpees which use strict squats before the athlete gets down and does a strict pushup. Other versions, the athlete is allowed to flop down any way he or she chooses, so long as the chest hits the deck. There are burpees where instead of jumping and clapping, you jump to a bar and do a pull-up. Or the burpee mile. It's exactly as it sounds. Do a burpee, then broad jump as far as you can, and where you land do another burpee. Repeat until a mile has passed.

"Exhausting, least favorite and punishment" are how some athletes at several Coeur d'Alene gyms described the movement.

"Once you get down to the ground you want to rest," said Camile Alvarez, learning about the movement in the Lotus teenage class. "You want to stay down."

"Awful," said Heather Rebal, who performed 30 of them among other exercises Monday at 360 Fitness. "Everybody hates them."

"Burpees make you feel like an idiot really quick," wrote Wendy White Stidham, a member at the CrossFit Coeur d'Alene on Fourth Street on a Facebook post asking about the movement. "You think, how hard can it be to do 25 in a minute? You find out how hard on No. 10."

But the real beauty is their simplicity.

Up, down, clap, repeat. One athlete, who didn't want to give his name for this portion of the story, learned about them in jail. It was a jail without weight equipment, so exercises during exercise time were limited. He shed more than 30 pounds that way.

"I actually like them," he said.

So if you can't get to a gym, it's no problem. Going on vacation? Still no sweat. With something so simple, there's little room for excuse, said Derek Hutchison, CrossFit Coeur d'Alene owner.

"You have a floor, don't you?" he said.