We express thanks for the special interest and the questions raised pertaining to our article. With a cross-sectional design, our study explored the relationship between putative cause and effect i.e., backpack weight and postural angles in conveniently selected population. The population was stratified, excluded for larger measurement variability and represented homo-genous postural stability for a complex functional task (functional reach) than simple loading task measured in our study set-up. This reduces the impact of anthropometric confounding factors such as subcutaneous fat and height and their influence on postural angles in present study. Moreover good precision obtained in measured postural angles dictates good reproducibility with a valid ImageTool for the measurements taken.

To put clearly, data only on backpack weight and postural angles would not allow the role of duration of the carriage, predicting morbidity, or of other causes, to be explored.

Studies have reported that heavier backpack carriage in school children associated with fatigue symptoms(1), dorsal and low back pain(2), significant increase in disc compression and lumbar curvature(3), unable to recover from backpack induced lumbar lordosis following the removel of the backpack load(4), shoulder, neck and back pain and combination of bodily pain(5). Contrary to above findings, studies have also reported no independent relationship between backpack use and back pain(6), and active form of carrying backpack may decrease the odds of getting neck and back pain(7). Some authors have suggested regular optimal spinal backpack loading for healthier back and they cautioned back pain in children should be viewed from a biopsychosocial behavioral model rather than pure mechanical model similar to adult back pain(8,9).

Various factors such as physical, mechanical, psychological, social, environmental, ergonomic, socioeconomic, anthropometric and demographic characteristics are need to be examined before predicting backpack related morbidity in this population.

Although more studies are needed to explore to find a causal link between backpack use and back and neck pain due to heavier backpack carriage, the major unanimous concern is an urgent need to conduct longitudinal and prospective studies so that various confounding factors associated with nonspecific low back pain in children can be explored.