Just as kids love to bounce on beds, they are also drawn to the joy of jumping on trampolines — a pastime that has likely become more popular since Canadian Rosie MacLennan clinched gold in the Olympic version of the sport.

But doctors warn that backyard and other recreational trampolines pose a significant risk of injury, especially to younger children.

In an updated policy statement issued Monday, the American Academy of Pediatrics (AAP) "strongly discourages" the use of recreational trampolines, either at home or in commercial indoor parks that feature the high-flying gymnastics equipment.

In January, the Canadian Paediatric Society reaffirmed a similar position statement last issued in 2007.

"The key thing is that three-quarters of injuries occur when there are multiple users on the mat," said Dr. Michele LaBotz, co-author of the AAP statement.

"And you see that all the time: adults like to be on the trampoline, bouncing with the kids," LaBotz said from Portland, Me., where she practises pediatric sports medicine. "And especially when you get those disparate sizes — you get a real big person and a real small person — the small person is much more likely to get injured, 14 times more likely to get injured.

"And the injury sustained by a smaller person is much more likely to be severe. So in children less than the age of five, for instance, their rate of fractures and dislocations is 48 per cent."

Unique form of injury

Injuries can range from broken wrists, dislocated shoulders and sprained ankles to severe head and neck trauma. About one in 200 trampoline injuries leads to permanent neurological damage, a U.S. study in 2000 found.

One injury unique to trampoline use is a form of broken leg called a proximal tibia fracture that is primarily seen in children under age six, she said.

"Most of them have occurred on the trampoline with older folks. One principle a lot of us kind of overlook when we think about the trampoline is that most injuries actually occur on the centre mat itself.

"If you get an adult who's about 170 pounds bouncing with a kid who's 40 to 50 pounds, the recoil of the mat, when that kid lands — and especially if he's not landing right — he generates about the same amount of force as if he went from nine feet (three metres) onto a hard surface.

"And you don't think of that because the mat's kind of soft and bouncy," LaBotz said.

That means that netting around a trampoline, aimed at stopping a jumper from falling off the equipment, or protective coverings on the surrounding springs, will not prevent about two-thirds of injuries, which occur on the central mat.

Head and neck injuries most often result from a failed flip or air-borne somersault on the trampoline, she said.

"So that's why we have such a strong recommendation against that particular stunt."

Almost 98,000 trampoline-related injuries are estimated to have occurred in the U.S. in 2009, the latest year for which statistics are available, down from a high of more the than 109,500 in 2006.

In Canada, 4,247 cases of trampoline injuries were reported over the five most recent years of data. That figure does not represent all such injuries in Canada, but only those treated in the emergency departments of 15 hospitals in the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP).

More than 40 per cent of injuries involved children aged five to nine, and more than eight per cent of all those injured had to be hospitalized. Between 2005/06 and 2009/2010, the rate of trampoline injuries almost doubled in Canada, CHIRPP found.

Lower limbs were the most frequently injured (43 per cent), followed by the upper extremities (36 per cent) and the head, face and neck (15 per cent). Overall, fractures accounted for 43.5 per cent of all injuries, while about three per cent involved brain trauma.

In the U.S., the number of trampoline injuries started declining in 2007, though it's not clear why, LaBotz said. One theory is that children and teens began spending more time on computers.

Growth of trampoline parks

However, that trend could be changing with the advent of trampoline parks — large indoor structures with contiguous trampolines that are a popular venue for kids' birthday parties, she said.

With the societal push to get kids more physically active due to the growing childhood obesity epidemic, some parents may see the trampoline as a fun way to get kids moving.

LaBotz said backyard trampolines are marketed as "play toys or playground types of equipment," with pictures of children, and even a whole family, all bouncing together.

"And parents are struggling now to pull their kids away from the computer and the video games. And it's easy to see how it might seem like a good, fun, relatively inexpensive thing to do.

"But it's not."

The emergence of trampoline as a competitive sport — it was added to the Summer Olympics in 2000 — has also likely driven its popularity as a recreational activity.

Canada's Rosannagh MacLennan, from King City, Ont., holds up her gold medal for the women's trampoline at the 2012 Olympic Games in London on Aug. 4.Canada's Rosannagh MacLennan, from King City, Ont., holds up her gold medal for the women's trampoline at the 2012 Olympic Games in London on Aug. 4. (Canadian Press/Ryan Remiorz)

David Ross, MacLennan's coach at Skyriders Trampoline Place in Richmond Hill, Ont., north of Toronto, acknowledged that backyard trampolines are fun for kids.

But he advised parents to treat the bouncy platforms the same way as they would a swimming pool, making sure the yard is enclosed by a fence and that the equipment is used properly.

"I'm not saying it's a bad thing to have a backyard trampoline; it's certainly better to exercise than not to exercise," he told The Canadian Press. "But it does give the sport a bad name because there are so many people doing unsupervised, maybe stupid things on their backyard trampolines.

"The biggest danger of any trampoline is if you land upside-down. So if you're on a backyard trampoline that doesn't allow you to jump very high, you probably shouldn't be doing flips. Or if you do them, you should have learned how to do them first somewhere."

For pediatricians, however, there is no safe way to use a recreational trampoline, stressed LaBotz.

But if children are determined to emulate soaring athletes like MacLennan — "How do you keep a kid from putting a cape on and jumping off the house thinking he's Superman" — she recommends a structured training environment, similar to Skyriders.

"The coaches are all highly trained, there's only one person on the trampoline at a time. When risky manoeuvres (like) the air-borne somersaults are initially attempted, until somebody's proficient, they're always in a safety harness, which prohibits the neck impact.

"So it's fundamentally a different activity the whole way around."