BAKERSFIELD, Calif. -- Each year 75,000 American children are treated at emergency departments for trampoline-related injuries -- a figure that is double the rate seen in the early 1990s.

Nearly all of these trampoline accidents occur at home so doctors are warning parents to be careful when sending children out to play with personal trampolines.

Researchers in the United Kingdom reviewed 50 cases of trampoline injury in kids and found certain factors that increased the odds of children being hurt.

Accidents occurred when too many people used the trampoline at once, and the lightest bouncers tended to sustain the worst injuries.

Kids also got hurt while bouncing with adults -- the difference in weight becomes a problem if the adult jumps too high.

But adults should be present when kids are on the trampoline, experts said. Children were more likely to be injured if they were unsupervised or supervised by adults drinking alcohol.

Some pediatricians recommended against purchasing home trampolines altogether, saying kids are better off in a gym class under the watch of trained experts.