The Back Pain Association is convinced that schools are a significant source of back problems."
It said schools had paid little attention to buying ergonomic furniture for children, with the main consideration being the "lowest unit price".
Research dating back to the 1990s suggests the size measurement on which most children's furniture was based on the average size of children in the 1960s, when they tended to be shorter.
However, sizes have been updated by manufacturers and the report urged ministers to ensure the greater use of adjustable furniture in the new schools that are being built under England's school rebuilding programme.