Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
Ergonomics. 2010 Nov;53(11):1359-67. doi: 10.1080/00140139.2010.519055.
Few studies have endeavoured to measure balance control during manual material handling. This study examined the effects of load weight during a stationary manual material handling task. In total, 36 healthy participants completed 180° lateral transfer tasks of a loaded (5% of body weight) and an unloaded box. The projection of the centre of mass onto the base of support, as measured via a passive-marker 3-D motion analysis system, was used to quantify balance control. Muscle activities of lower extremity muscles were also measured. When moving the loaded box, individuals ventured ≥ 1 cm closer to the edges of the base of support and increased centre of mass movement up to 14%. In addition, muscle electromyographic activity on both sides of the shank increased. In summary, during loaded configurations, vulnerability to loss of balance was increased and individuals appeared to adapt by increasing co-contraction of the shank muscles suggesting increased ankle stiffness. STATEMENT OF RELEVANCE: Industries requiring manual material handling have a particularly high rate of injuries due to falls. This study suggests that larger load weights during lateral material handling tasks adversely affect balance control and may create a vulnerability to imbalance throughout the entire manoeuvre.
很少有研究致力于测量手动搬运过程中的平衡控制。本研究考察了在固定手动搬运任务中负载重量的影响。共有 36 名健康参与者完成了装有（体重的 5%）和未装盒子的 180°侧向转移任务。通过被动标记 3D 运动分析系统测量的质心在支撑基础上的投影用于量化平衡控制。还测量了下肢肌肉的肌肉活动。当移动装有物品的盒子时，个体冒险将质心移动到支撑基础边缘≥1 厘米以内，并将质心运动增加了 14%。此外，小腿两侧的肌肉肌电图活动增加。总之，在负载配置下，平衡丧失的脆弱性增加，个体似乎通过增加小腿肌肉的共同收缩来适应，这表明踝关节的刚性增加。相关性陈述：需要手动搬运材料的行业因跌倒而导致受伤的比率特别高。本研究表明，在侧向搬运任务中使用更大的负载重量会对平衡控制产生不利影响，并可能在整个操作过程中造成失衡的脆弱性。
