We’ve all wondered what, if any effect they have on kids backs. Now a new study has shown the level of compression kids experience when carrying a heavy backpack.

Let’s start by pointing out that this study was only done on 8 children, so we should be careful about generalising these results to everyone. But from what I read in the study, they were 8 normal enough kids, average age 11, average weight 40kg. The researchers did an MRI image of their lower back before they were carrying anything, then gave them a 4kg backpack and did another MRI, and another two with 8kg and 12kg backpacks.

The authors concluded that “Backpack loads are responsible for a significant amount of back pain in children“. They found a significant amount of disc compression, which can put pressure on the nerves in your lower back and legs.

What I’m saying is they COULD SEE the height of the disc shrinking the heavier the backpack got. Now, I look at these scans fairly regularly, and detecting a difference in height can be pretty hard. If they were saying they could see a SIGNIFICANT difference when they went from 4kg to 8kg, I think that finding is noteworthy to say the least.

There were a number of other measurements, probably the most telling was that the spine can curve under the strain of the backpack, probably because the children were trying to find a comfortable position. The danger here is that in addition to the compression, if they shift their weight to one side then that side takes a lot more of the load; over time this lop-sided compression will cause problems. Also, when asked how much pain the backpack caused, the children reported that the heavier the backpack, the more pain they felt.

Take home message: The lighter you can make their backpacks at this crucial stage of physical development, when they are getting taller and stronger, the better.

You can read the and other news reports here and here.