June 3 (HealthDay News) -- Trampoline fun can end in injury if too many people bounce at the same time, say British doctors who analyzed 50 case studies of trampoline-related injuries treated at their hospital over six weeks.

The researchers at Ninewells Hospital and Medical School in Dundee, Scotland, found the risk of injury is highest if many people are using a trampoline simultaneously, with the lightest user having a five times greater risk of injury.

The doctors also concluded that the severity of an injury increases when children are using a trampoline with adults. For example, a child of 20 kilograms (44 lbs.) can experience a force equivalent to a 3.5-meter (11.5-foot) fall when bouncing with an adult who weighs 80 kg (176 lbs.).

Adult supervision is crucial "to ensure safety guidelines are followed, exuberance is controlled, and help is provided with setting up and dismounting from the trampoline," Andrew Bogacz and colleagues wrote in a letter in the June 3 online issue of BMJ.

They also noted that children can be hurt while bouncing with or being supervised by adults who've been drinking alcohol.

"Adults, please note that lager, wine and trampolines do not mix," the doctors concluded.

SOURCE: BMJ, news release, June 2, 2009