Kim M H, Yi C H, Kwon O Y, Cho S H, Yoo W G
Department of Rehabilitation Therapy, The Graduate School, Yonsei University, Republic of Korea.
Ergonomics. 2008 Jun;51(6):890-901. doi: 10.1080/00140130701852747.
This study tested the effects of three alternative types of backpack on head posture and neck muscle electromyography (EMG) in children. Four loading conditions were tested: no pack; a backpack; a double pack; a modified double pack (designed with a backpack and a front pack weighing 10% and 5% of body weight, respectively). Dependent variables were neck muscle activity, forward head angle and forward head distance (the perpendicular distance from C7 to a vertical line through the tragus of the ear). Fifteen children were asked to walk at a speed of 0.8 m/s on a treadmill. The EMG activity of upper trapezius, sternocleidomastoid and midcervical paraspinals muscles and the forward head angle and forward head distance were all significantly higher when carrying a backpack than for the other conditions. When carrying a double pack, there was a backward head posture characterised by an increased negative forward head angle, decreased forward head distance, increased sternocleidomastoid EMG signal and decreased midcervical paraspinals EMG signal, compared to carrying no pack. When carrying a modified double pack, the forward head angle and forward head distance decreased when compared to carrying a backpack. These findings indicate that the modified double pack minimises postural deviation.
本研究测试了三种不同类型的背包对儿童头部姿势和颈部肌肉肌电图（EMG）的影响。测试了四种负重情况：无背包；单肩背包；双肩背包；改良双肩背包（设计为一个背包和一个前背包，分别重体重的10%和5%）。因变量为颈部肌肉活动、头部前伸角度和头部前伸距离（从C7到穿过耳屏的垂直线的垂直距离）。15名儿童被要求在跑步机上以0.8米/秒的速度行走。与其他情况相比，携带背包时，上斜方肌、胸锁乳突肌和颈中棘旁肌的肌电图活动以及头部前伸角度和头部前伸距离均显著更高。与不背包相比，携带双肩背包时，出现头部后倾姿势，其特征为头部前伸角度负值增加、头部前伸距离减小、胸锁乳突肌肌电图信号增加以及颈中棘旁肌肌电图信号减小。与携带单肩背包相比，携带改良双肩背包时，头部前伸角度和头部前伸距离减小。这些发现表明，改良双肩背包可将姿势偏差降至最低。
