It has been shown through research with motion sensors and video cameras that students carry heavy school bags on average for two hours per day.
In 1999 more than 3400 students in a USA were seen for backpack related issues.
Unfortunately, many students and schools have abandoned lockers among security concerns and general delay between classes.
Students should not carry more than 10% of their body weight. Their backpacks should be well designed with adjustable straps and multiple compartments. A backpack should always be correctly worn on both shoulders and heavy text books minimised where possible.