Development of activity monitoring for determining load carriage patterns in school students.

The loads that school students are carrying to, around and from school is an issue of increasing concern particularly as the long term effects of excessive load carriage on school students' musculoskeletal health is unknown. A greater understanding of the temporal patterns of students' load carriage, which usually involves backpacking, would assist in determining the magnitude of the problem that is faced by school students. The aim of this study was to determine the duration of school students' walking, running and stair climbing while backpacking and identify when students take off and put on their backpacks using activity monitoring and video, and therefore validate activity monitoring as a tool for measuring the temporal patterns of backpacking in school students. An activity monitor was secured in the backpacks of six school students while they completed a predefined physical activity course. Participants firstly completed the course following a set time pattern ('set course') and then repeated the course while performing activities as they pleased ('free course'). Video footage and activity monitor data were captured simultaneously. The activity monitor provided consistent visual differentiation between walking, running and taking off and putting on a backpack. The greatest variation between measures was for walking during the 'free course' (mean 8, SD 7 seconds), while the least variation between measures was for stair climbing during the 'set course' (mean 3, SD 2 seconds). There were no statistical differences between the activity monitor and video camera determined durations for any of the activities. These preliminary results suggest that activity monitoring may enable valid analysis of the temporal patterns of backpacking with little disruption to the user, although more work is required to verify this.