There’s a reason we didn’t mention that the ‘Flight Simulator’ is a jump rope workout in the headline: You’d never read it. That’s because most guys tend to only associate jumping rope with kindergarten girls on the playground or boxers conditioning for a fight.

However, James Fitzgerald, winner of the inaugural 2007 CrossFit Games and founder of OPEX Fitness in Scottsdale, Arizona, wants to change that mindset. He believes everyone should incorporate the exercise into their workout routine.

But fair warning: He’s not talking about mindlessly skipping over the rope at your own pace. He’s talking about double-unders or “dubs”—two passes of the rope in one hop—for multiple unbroken reps and sets. You should be going so fast that you look like you’re inside a whirring, blurred speed rope egg.

Double-unders aren’t a new move, but they became popular among the CrossFit crowd again after they appeared in the 2009 Games. Fitzgerald watched as some of the best athletes in the world couldn’t complete more than a couple of reps in a row.

“When you do a double under, there’s a greater chance of messing up,” he says. And knowing this ultimately messes with your head.

Suddenly, the simple task of jumping over a rope becomes an excruciating physical and mental challenge. And the Games’ creators are well aware of this. That’s why they’ve included them in four of the last six competitions.

So after the 2009 Games, Fitzgerald immediately programmed the ‘Flight Simulator’ into his clients’ workout routines. While the workout has become popular among CrossFit athletes everywhere, the name comes from a few of his clients who are also airplane pilots.

“They do flight simulations that test for anxiety, how you deal with pressure—like how you’ll deal with a wing that’s not working effectively. It’s the same thing with ‘Flight Simulator’ workout. The higher you get up in numbers, the anxiety starts to rise,” he explains.

Here’s how you do it: Grab a stopwatch and perform unbroken double-unders with a speed rope in a pyramid fashion.

Start with 5 dubs, and then stop. Then perform 10 dubs, and then stop. Do 15 dubs, and then stop. Continue to repeat this process by adding 5 reps to every round until you reach 50 unbroken dubs.

Then reverse the pattern—45, 40, 35, and so on—until you complete just 5 dubs.

The directions are simple, but there are two rules Fitzgerald requires that you follow:

1. You must come to a full stop between each round. “The rope can’t keep spinning, and it can’t go underneath you. Your feet have to be flat on the floor. You can’t be in a jumping motion,” Fitzgerald says. “And you can’t go to singles. You have to come to a complete stop.”

2. You must do every round unbroken. Essentially, you can’t mess up. If you do, you have to start the round again.

For example, if you’re on the round of 50 reps but you only finish 49 before, say, you do only a single pass instead of a double, you must start your 50-rep round again. This means a round may take 2, 3, or 17 attempts before you nail it.

Fitzgerald’s elite athletes can finish the entire workout in just over 4 minutes. A good goal for everyone else: 10 minutes. That timeframe allows you to mess up a few rounds, but gain your composure so you can do it again seamlessly, he says.
But the only way you’ll make it from 5 reps to 50 reps, and back to 5 reps again is if you pace yourself and you keep your frustrations in check, says Fitzgerald. In fact, you may have more whip marks on your hands and ankles than successful dubs the first time you try it.

If you rarely or never jump rope, then you’ll need to master the basics first. Start with the goal of doing one double-under.

“Keep your elbows back and your hands down, be as tall as possible, and gain rhythm,” coaches Fitzgerald, who is reiterates the importance of cadence when trying to master this skill. Feel and hear the top hitting twice.

“Then work on stringing together two. And now work on stringing together 10 in a row. And now try to do 10 sets of 10 in a row. If you can get to the point where you can do 10 sets of 20 in a row, then you deserve to enter the fray that is ‘Flight Simulator,’” says Fitzgerald.