Indoor trampoline parks have cropped up around the country in recent years, offering customers a chance to bounce, flip and jump on wall-to-wall trampolines.
Citing broken necks, shattered leg bones and one death, some doctors say the parks are dangerous and can lead to serious injuries that eclipse any benefits.
Governments are starting to take notice, with proposed regulations in Utah and California among the first attempts in the country to address concerns about safety in the burgeoning industry.
Operators of the trampoline gyms say severe injuries are rare and safety fears are overblown.
They claim an injury rate lower than organized sports such as baseball or soccer and point out the gyms offer a place for adults and kids to have fun and get much-needed exercise.