Heavy backpacks have been suggested to have a pathogenic role in experience of low back pain among children. We have conducted a repeated-measure study to investigate the backpack-induced changes in lumbo-pelvic coordination of forty gender-balanced college age students when they walked and jogged on a treadmill with two different types of backpacks: normal and ergonomically modified. The backpack-induced changes in lumbo-pelvic coordination were larger when carrying an ergonomically modified vs. a normal backpack as well as when jogging versus walking. The larger changes in lumbo-pelvic coordination when carrying an ergonomically modified backpack were likely due to kinematic restraints imposed by rigidity and enhanced attachments devised in the backpack for increased comfort. Given the role of lower back biomechanics in low back pain, the effects of such larger mechanical abnormalities in the lower back when carrying an ergonomically-modified backpack on risk of low back pain among children requires further investigation.