A team of Spanish researches reported that the link was found in more than 1,400 school children aged between 12 and 17 in Northern Galicia, Spain, according to a report on the British journal Archives of Disease in Childhood.

　　The pupils were split into four groups based on the weight of their bags. Those in the group with the heaviest bags had a 50-percent higher risk of back pain, and a 42-percent higher risk of back pathology, compared with the group with the lightest bags.

　　A common back pathology in pupils is scoliosis, which is an abnormal curvature of the spine.

　　"The results obtained have strong implications," co-author of the study, Professor Alberto Ruano, of the Unviersity of Santiago de Compostel in Spain said in the journal.

　　"We strongly encourage the medical and educational community to start advising parents and school children about the risk posed by heavy school bags and the fact that this risk can be easily reduced," he added.