Kinematic Evaluation of Sagittal Spine Motion During Walking With Internal Frame and Frameless Backpacks

The purpose of this study was to examine sagittal spinal movements during walking with frameless and internal frame backpacks.

Twenty adult students from a chiropractic college walked on a treadmill while wearing inertial measurement units mounted on the head, T1 and T12 vertebrae, and sacrum. They walked without a backpack, with a backpack loaded with 6.8 kg, and after 15 minutes walking with the loaded pack. Day 1, they wore a backpack with no structural support; day 2, they wore an internal frame backpack with a hip belt and chest compression straps. Cyclic sagittal flexion and extension endpoints were identified using an application written in the R language.

Participants walked with the lumbar spine in slight flexion throughout all trials with both packs; flexion significantly increased with load and with time, more so with the frameless pack. The thoracic region showed progressive extension with load and time, significant only for the frameless pack. The cervical region trended toward progressive extension with load and time, with no significant changes for either pack.

In this group of adult students walking on a treadmill, there were trends of increasing lumbar flexion, thoracic extension, and cervical extension, with changes more pronounced with a frameless backpack than one with an internal frame.