Motmans R R E E, Tomlow S, Vissers D
Product Ergonomics Research Centre, Katholieke Hogeschool Limburg, Belgium.
Ergonomics. 2006 Feb 10;49(2):127-38. doi: 10.1080/00140130500435066.
The daily load of carrying schoolbags is influenced by the mode of carriage. Electromyographic (EMG) activity from rectus abdominis and erector spinae was recorded bilaterally in five static conditions: no bag; shoulder bag; backpack; front pack; double pack. Nineteen students carried a load of 15% of their body weight. A double pack, with the load equally distributed in a front and a backpack, showed no significant differences in EMG activity compared with unloaded standing. The activity levels of erector spinae significantly decreased while carrying a backpack and increased with a shoulder bag and a front pack. Rectus abdominis revealed significantly higher EMG levels in the backpack trial. Asymmetrical activity between the right and the left part of the back muscles was clearly observed while carrying a shoulder bag with the weight at the right side of the body. The abdominal muscles revealed a slightly significant asymmetry for the shoulder bag and, surprisingly, also for the backpack. These findings suggest that the physical stresses associated with carrying book bags can be minimized by the design of a double pack. Asymmetry in muscle activity may indicate a failure of trunk stabilization and contribute to the development back pain.
书包的日常负重受携带方式的影响。在五种静态条件下双侧记录腹直肌和竖脊肌的肌电图（EMG）活动：无书包；单肩包；双肩包；前背包；双背包。19名学生背负相当于其体重15%的重物。双背包将重物均匀分布在前背包和双肩包中，与无负重站立相比，其EMG活动无显著差异。背负双肩包时竖脊肌的活动水平显著降低，而背负单肩包和前背包时则升高。在背负双肩包试验中，腹直肌的EMG水平显著更高。当身体右侧负重背单肩包时，背部肌肉左右两侧的活动明显不对称。对于单肩包，腹部肌肉也显示出轻微但显著的不对称，令人惊讶的是，对于双肩包也是如此。这些发现表明，通过双背包的设计可以将与背书包相关的身体压力降至最低。肌肉活动的不对称可能表明躯干稳定功能失效，并导致背痛的发生。
