A park of trampolines are wounds "like a hammer", says a researcher

An engineer from Virginia who spent years researching the designs of trampoline parks publishes his discoveries for the first time. He explains that the way in which many trampolines are linked in these parks can create an unsafe energy transfer – a possible explanation for some of the nearly 18,000 emergency room visits resulting from injuries sustained by a trampoline park in 2017.

Dr. Pete Pidcoe told CBS News' Meg Oliver that he has been testing trampoline parks for about six years. The biomechanical engineer and university professor tests trampolines found in trampoline parks and compares them to gymnastic trampolines.

"We found that there was a transfer of energy between the trampoline beds," Pidcoe said. "It's really a big trampoline."

He said that it was dangerous because it makes "the system unpredictable".

"The surface of the trampoline is changing in height, have you ever walked for a step that is not there, imagine it happening on a trampoline," he said.

A video taken in a New Jersey trampoline park, showing a father who doubles his son's leap and, as a result, breaking the child's femur, illustrates how energy transfer works.

"The biggest bone in your body, it takes about 900 pounds to break it," said Pidcoe. "Now, it's a child, so maybe say half."

Pidcoe tests trampolines with a pulse hammer and accelerometers to study the rebound effect. He measured the strength that a 220-pound father could transfer into his 30-pound son on a constantly changing surface.

"What we notice is that the father transfers 400 pounds of force to the son, but the most important number is the speed with which this force is actually provided," he said. "It's like being hit with a hammer."

Dr. Craig Cook, a trauma surgeon in Utah, said he treated about 100 critically injured patients in a trampoline park: leg fracture, spine fracture, and head trauma.

"These are the types of injuries that we would see with a high-speed trauma-like accident that rolls 90 miles at the time or an accident in which a patient victim is ejected from his motorcycle and they fly 100 feet," said Cook. .

Rob Arnold is CEO of Launch Trampoline Park, which has more than 30 parks in the country and dozens more under construction. He said: "Not all trampoline parks are created equal."

Even though he had a neck injury in one of his parks, he does not believe that it makes the park too dangerous.

"It's as if someone puts on a pair of skis and goes down a mountain, you know, there is a risk inherent in what you do," Arnold said.

A park in New York City, which opened last November, said it had not been seriously injured. Arnold believes that the benefits of jumping far outweigh the risks.

"Autistic children love the facilities, we have obese children … and they did not want to play sports, they were caught," Arnold said. "And all they wanted to do was come to the launch."

Arnold estimates that over 100,000 people visit each of his parks each year. Despite the lack of federal regulation, Arnold said that safety was a top priority.

Launch covers their springs and uses redundant trampolines – a second trampoline underneath. Pidcoe said that a second layer of protection is helpful but that there are always risks.

"If the top breaks, you have a second one, the problem is that if the top goes far enough to hit the second, the trampoline system will be changed," said Pidcoe.

Launch connects their trampolines with a steel bar. Pidcoe's research indicates that it can reduce energy transfer but do not eliminate it. Experts believe that the cable and chain links used in many parks are defective.

Over a four-year period, approximately 15,000 people were injured in trampoline parks across the country, and CBS News has confirmed at least six deaths since 2012.

What Pidcoe wants everyone on a trampoline to know that "everyone in this system influences the leap of all others".

In the coming months, Pidcoe hopes to publish the data collected in a sports medicine journal.

CBS News asked Rob Arnold if Launch could survive if they removed forced arbitrage from their contracts, which reduces the lawsuits that people can incur against the parks. Arnold was confident that they could. He also told us that he supported the federal regulations and that he was willing to work with lawmakers.