Gütersloh (dpa) – schoolbags are often too heavy according to doctors. «The parents would have to remember more often to take unneeded books, folders, or the popular game boy along with sports matters again in the evening from the school Tornister out», the orthopedist Martin Bauer in Gütersloh of the dpa said on Tuesday. Bauer is a senior consultant at the hospital for sports injuries Hellersen in Lüdenscheid, a clinic of Landessportbund. On Tuesday was the first day of school for the Erstklässler in Nordrhein-Westfalen. In the long term, too hard packed knapsack can lead to postural according to Bauer’s. «Children, who are often too heavy loads, risk, as adults get back pain, as we see in our ambulances.» Also heavy knapsack could have a negative effect on the school performance of the child. «If the spine of the children is overloaded, this costs energy – energy that is then missing from the concentration in the classroom course», the doctor said. As a rule of thumb for the weight that should bear a child, Bauer provides the following rule of thumb: ten percent of body weight than load are the best. In other words, a 45 kg child can bear loads up to 4.5 kilograms. The hospital for sports injuries have for the first time can confirm the validity of this rule in a study for the Gemeindeunfallversicherungs Association of Westphalia.