Postural effects of symmetrical and asymmetrical loads on the spines of schoolchildren

Non specific low back pain in schoolchildren is a topic of growing prominence in the literature [1-5]. The scientific community has recently been alerted to the problem of backpacks (a characteristic daily load for subjects in this age group), both because they proportionally exceed legal limits set for adult workers [6-9] and because they seem to be related, although not directly, to low back pain [7]. The problem if backpacks can generate or not back pain is controversial, and today there is a lack of proves either ways [1,2,4,10]. Postural variations have been considered as possible risk factors for low back pain in schoolchildren, even though their relationship to hyperlordotic posture is uncertain in some studies [11-13], with hyperkyphotic posture appearing not to constitute a risk factor [11-13]. Loading – particularly non axial loading – of the spine prompts postural adjustments [14,15] but only recently a few studies have considered the biomechanical implications of backpack carrying in populations of schoolchildren. Pascoe et al. [14] studied a population of 11–13 year olds, demonstrating, through a three-dimensional approach, how a backpack alters, significantly, posture and gait. Grimmer et al. [15] analysed modifications of the head-neck angle, while Hong and Brueggeman [16] considered the problem solely from the gait analysis perspective. Chow recently developed a series of studies on the topic, focusing on load carriage both in normals and adolescent idiopathic scoliosis patients [17-21].When considering the possible relationship between non specific low back pain, posture and backpack carrying in a population of schoolchildren, it is also necessary to evaluate postural adjustments due to the (symmetrical and asymmetrical) loading of their spines and to the fatigue caused by backpack carrying. The aim of the present study was therefore to reproduce the 'loading conditions' seen in schoolchildren daily and to investigate the instantaneous postural adju