Chow Daniel H K, Kwok Monica L Y, Cheng Jack C Y, Lao Miko L M, Holmes Andrew D, Au-Yang Alexander, Yao Fiona Y D, Wong M S
Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
Gait Posture. 2006 Oct;24(2):173-81. doi: 10.1016/j.gaitpost.2005.08.007. Epub 2005 Sep 27.
Concerns have been raised regarding the effect of carrying a backpack on adolescent posture and balance, but the effect of backpack loading combined with other factors affecting balance, such as adolescent idiopathic scoliosis (AIS), has not been determined. This study examines the effects of backpack load on the posture and balance of schoolgirls with AIS and normal controls. The standing posture of 26 schoolgirls with mild AIS (mean age 13, Cobb angle 10-25 degrees ) and 20 age-matched normal schoolgirls were recorded without a backpack and while carrying a standard dual-strap backpack loaded at 7.5%, 10%, 12.5% and 15% of the subject's bodyweight (BW). Kinematics of the pelvis, trunk and head were recorded using a motion analysis system and centre of pressure (COP) data were recorded using a force platform. Reliable COP data could only be derived for 13 of the subjects with AIS. Increasing backpack load causes a significantly increased flexion of the trunk in relation to the pelvis and extension of the head in relation to the trunk, as well as increased antero-posterior range of COP motion. While backpack load appears to affect balance predominantly in the antero-posterior direction, differences between groups were more evident in the medio-lateral direction, with AIS subjects showing poor balance in this direction. Overall, carrying a backpack causes similar sagittal plane changes in posture and balance in both normal and AIS groups. Load size or subject group did not influence balance, but the additive effect of backpack carrying and AIS on postural control alters the risk of fall in this population. Therefore, load limit recommendations based on normal subjects should not be applicable to subjects with AIS.
人们对背负背包对青少年姿势和平衡的影响表示担忧，但背包负重与其他影响平衡的因素（如青少年特发性脊柱侧凸，AIS）相结合的影响尚未确定。本研究探讨了背包负重对患有AIS的女学生和正常对照者姿势和平衡的影响。记录了26名轻度AIS女学生（平均年龄13岁，Cobb角10 - 25度）和20名年龄匹配的正常女学生在不背背包以及背负标准双肩背包时的站立姿势，背包负重分别为受试者体重（BW）的7.5%、10%、12.5%和15%。使用运动分析系统记录骨盆、躯干和头部的运动学数据，并使用测力平台记录压力中心（COP）数据。仅能从13名AIS受试者中获得可靠的COP数据。背包负重增加会导致躯干相对于骨盆的前屈显著增加，头部相对于躯干的后伸增加，以及COP运动的前后范围增加。虽然背包负重似乎主要在前后方向影响平衡，但两组之间的差异在内外方向上更为明显，AIS受试者在这个方向上表现出较差的平衡。总体而言，背负背包在正常组和AIS组中都会导致姿势和平衡在矢状面上发生类似的变化。负荷大小或受试者组不会影响平衡，但背负背包和AIS对姿势控制的叠加效应会改变该人群的跌倒风险。因此，基于正常受试者的负荷限制建议不适用于AIS受试者。
