Never share a trampoline, say researchers from Ninewells Hospital in Dundee. Writing in BMJ, they report that the greatest risk of injury occurs when children share trampolines with adults, and risks increase the greater the mismatch between child and adult weights. A child of 20 kg can experience an impact equivalent to a 3.5 metre fall when bouncing with an adult weighing 80 kg. The sample was only 50 cases, but the findings confirm guidance from the Royal Society for the Prevention of Accidents. Read it here.