When you think of major championship tournaments like the U.S. Open and Wimbledon, the first thing that comes to mind is probably a roster of insanely fit tennis superstars. Even if you’re not a tennis fan, you’ve likely at least heard of some of the game’s top players like Venus and Serena Williams or Karolina Pliskova.

And it makes sense that the athletes take the spotlight. They’re not only some of the fittest athletes in the world, but to rise to the top of their field they’ve had to develop nearly superhuman speed, agility, power, strength, and quickness to track and return some of the trickiest shots in the game. “It’s not easy” is a severe understatement.

But there’s another set of elite athletes on the hardcourt to whom you probably haven’t been paying as close attention, yet their training requires the same level of focus on explosive speed, power, and dexterity during a match.

Enter: the ballpeople.

Tasked with ensuring that the game runs smoothly, the ballpeople are required to squat, crawl, and quickly sprint on and off the court to gather up wayward balls and hand out towels to sweaty tennis legends—and trust us, it’s not easy. In fact, it’s a job that you have to seriously train for if you want any hope of making it through the tryouts.

If you have aspirations to become a ballperson, it’s important to focus on exercises that’ll boost your lateral quickness, according to Reebok speed and agility expert Luis Badillo Jr.

Kick off your training with these five drills, developed by Badillo with ballpeople specifically in mind, to improve your speed and agility skills both on and off the hardcourt.

Drill 1: Getting off the line quickly

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Directions: Set up a standard agility ladder, and run through it with high knees, focusing on pulling your knees to your chest.

“Exaggerated movements like high knees help you practice technique so you’re ready for the real situation when it comes,” says Badillo. This particular drill will teach you “to stay light on your toes while moving fast, which is crucial to developing speed starting from a crouched position.”

Drill 2: Picking strays up on the fly

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Directions: Set up two cones about eight feet apart. Run by them, staying low enough to tap the top of the cones with your hand as you pass them.

“Staying low is important so you can pick up balls without breaking your stride,” Badillo explains. It’s crucial because you don’t want to waste time running upright and then have “to bend down to pick up the balls.”

Drill 3: Sprinting across the court

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Directions: Set up hurdles a few feet apart across the length of the court, and sprint over them as fast as you can.

“The hurdle is for explosiveness, or how fast you can get your feet off the ground,” Badillo says. This drill is particularly useful because it “teaches you to achieve maximum speed over a short distance.”

Drill 4: Stopping on a dime

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Directions: Set up two cones about four feet apart. Run two ovals around them, then continue your run across the length of the court.

“Ballpeople have to be comfortable changing direction quickly,” Badillo explains. When performing this drill, you want to make sure to “lean forward and keep your center of gravity low so you can take sharp turns without falling down.”

Drill 5: Picking up multiple balls at once

Courtesy of Reebok

Directions: Set up a ladder, and place two tennis balls on either side, evenly spaced apart. Run through the ladder with two feet in each box and then two feet out, picking up the balls as you pass them.

A large part of a ballperson’s job is to pick up many tennis balls at once, so it’s important to practice hand and arm dexterity while running quickly on and off the tennis court.