“Everyone wants to have fun. Everyone wants to have fun with their children. You think you are being a good parent, spending time with your child, having fun – and the next thing you know your whole life changes.”

So opens the first post on Alisha Carlo’s The Fracture Factory, a blog where “it’s all fun and games until your kneecaps end up in your thighs.”

Carlo chronicles her family’s experiences with a local trampoline park – from her sister’s ACL tear, to Carlo’s self-imposed ban on family trips to the park, to her husband Jamie’s flouting of that ban, to Jamie’s bi-lateral patella tendon rupture (that’s a double kneecap injury) and long recovery.

The titular “Fracture Factory” comes from one of the nicknames the local hospital uses for the trampoline park. Others call it “The Fractury,” and some joke that the hospital’s surgeons must have invested in the trampoline park.

Carlo’s story has taught me all manner of things I wish I didn’t know. I now know to always read the seemingly routine liability waivers at family fun centers before signing. The waiver for the trampoline park near my home, for example, tells me that “Participants may die or become paralyzed, partially or fully, through their use of the Sky Zone facility and participation in Sky Zone activities.”

I now know that trampoline park injuries are on the rise, from 581 to 6,932 between 2010 and 2014. I now can’t un-know what kneecaps look like when they’re six inches out of place. In short, I now know to avoid trampolines.

At the same time, I’m also sensitive to the problems caused by campaigns to “boost awareness.” Many of these campaigns are problematic because the resulting awareness makes people scared of non-existent threats. I’ve made that argument about many awareness campaigns, whether the focus is moldy Sophiespuffy coats, or E. coli in raw cookie dough.

Trampolines may be one of the rare cases when parents actually need more awareness.

As toys, trampolines cause injury

Healthychildren.org, the parent-oriented website run by the American Academy of Pediatrics, offers simple advice about trampolines: “Don’t buy a trampoline for your home!”

Actually, the advice is even broader. The AAP recommends against trampolines in gym classes and on playgrounds and asserts that trampolines belong in “supervised training programs” only. That advice may seem like an overreaction to parents, especially when the most popular home trampolines have thousands of positive Amazon reviews.

It’s difficult to determine the overall risks posed by trampolines because we’re missing a denominator. As Slate’s Melinda Wenner Moyer points out, we have an estimate of how many injuries occur to kids under age 18.

In 2016, there were an estimated 103,512 emergency department visits as a result of trampolines. Although we could probably figure out how many trampolines are sold in the U.S., that number doesn’t tell us how safe trampolines are because we don’t know who exactly is jumping on them, or for how long.

Imagine, for example, that there were only 103,512 trampolines. In 2016, that would have meant an average one injury per trampoline. That would be pretty concerning.

But imagine there were 20 million trampolines, or, as Wenner Moyer suggests, 20 million trampoline jumping hours per trampoline. That would be concerning, but perhaps no more dangerous than many other forms of entertainment.

Without data on trampoline ownership and use, Wenner Moyer instead relies on injury rates. She compares the injury rates for playground equipment to the injury rates for trampolines and finds there were actually fewer playground injuries in 2016 than trampoline injuries.

“I don’t have any data on this,” Wenner Moyer admits, “but I suspect that American kids collectively spend a lot more time climbing on playgrounds than they do jumping on trampolines.”

It’s hard to determine exactly what proportion of trampoline users are likely to get injured, but it seems that they are being injured at a higher rate than playground users. Their resulting injuries tend to be more severe than those sustained on the playground.

Injuries like Carlo’s husband’s double patella tendon rupture aren’t freak accidents, but consequences of the physics of trampolines. As Wenner Moyer explains, if a young child lands on the trampoline just after it has moved upward from another jumper, the force is strong enough to break that child’s legs.

Wenner Moyer is not a killjoy out to ruin your fun with trampolines. She’s both an owner of a mini trampoline and a parent to young children, now “panic-wondering” about whether or not a trampoline constitutes an acceptable risk.

The goal of her excellent piece “is not to scare you into dumping your trampoline in the garbage; the point is to provide you with facts so that whatever decision you make will be informed, and so that you can minimize the danger by setting a few guidelines if you want.”

As sporting equipment, trampolines prevent injury

After reading about Carlo’s family’s experiences and Wenner Moyer’s analysis of trampoline safety, I won’t be buying a trampoline. My concern is not that trampolines are dangerous. Like Wenner Moyer, I see the value in kids’ risky play.

The problem with trampolines isn’t so much safety as it is categorization. Wenner Moyer categorized trampolines as toys, comparing them to playground equipment. But what if that’s the wrong comparison?

When we categorize trampolines as sporting equipment rather than toys, they start to look much different. Trampolines aren’t viewed as a danger to athletes. In fact, they’re often considered a safety device.

When you think of Olympic diving practice, you probably picture a pool. Most professional divers, however, do significant amounts of dry-land training. The training is, in part, a response to practical problems: If you can’t rent time at a swimming pool, you can still practice on the trampoline. But trampolines also help divers avoid injury while practicing new techniques.

Divers are not simply bouncing around. They use specialized equipment that allows them to practice dives without impact. Unlike amateur trampolinists, divers use spotting rigs when they practice on the trampoline, which allows them to perform complicated moves in safety. Essentially, they’re training at a Sky Zone…except they have safety equipment.

Divers aren’t the only Olympians who use trampolines as safe training devices. Freestyle aerial skiers put in a lot of practice on the trampoline before attempting their skills at death-defying heights.

One group that doesn’t use the trampoline to practice new skills is Olympic trampoliners. They practice new skills while firmly planted on the ground.

How to trampoline like a serious athlete

When treated as a toy, a trampoline can lead to serious injury and occasionally death. When treated as a piece of sporting equipment, a trampoline can make a dangerous sport less dangerous.

Parents and kids who want to keep their trampolines might do well to follow the safety guidelines that athletes do. For example, many athletes practice with a safety harness until they have mastered a particular skill.

Although a safety harness may not be a practical solution for home trampoline use, the following three safety rules can dramatically reduce the risk of injury:

1 | Jump one person at a time

This is the rule most likely to be broken by at-home users and the cause of the majority of trampoline-related injuries. If you review the Olympic training videos above, you’ll see that serious athletes never break this rule. That’s because there is real danger to life and limb when multiple people use a trampoline at the same time.

2 | Make it impossible to fall

Athletes don’t get injured from falling off trampolines. That’s not because athletes are better trained than backyard trampoliners. It’s because there is often nowhere to fall. Athletic training facilities use foam pits and other padded surfaces that make falling from a trampoline impossible.

3 | Don’t jump without supervision

A coach or trainer should always watching.

If your child complains about these rules, you can always remind her that following them may get her to the Olympics.