Otero-Agra M, et al. - Researchers examined the biomechanical aspects involved in Cardiopulmonary Resuscitation's compression depth by children. They identified anthropometric characteristics of children to have more influence on chest compression depth obtained by children than their body position. To perform compressions with an acceptable quality, the approximate age is 12years-old. The use of steps increased arm angle, getting it closer to 90° but did not increase quality CPR when compared with performance on the floor.