Szeto Grace P Y, Straker Leon M, O'Sullivan Peter B
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
Eur J Appl Physiol. 2009 May;106(2):243-51. doi: 10.1007/s00421-009-1019-4. Epub 2009 Mar 3.
Past studies on work-related musculoskeletal disorders (WMSD) have reported increased median muscle activities in terms of 50th% of amplitude probability distribution function (APDF), and this was thought to be a manifestation of altered motor control--an important mechanism contributing to WMSD. The present study aimed to examine whether such altered motor control was also present in other parameters of APDF--the 10th and 90th% values, which can be considered indicators of the low and high measures of muscle activity. The difference between 10th and 90th% APDF can be considered an indicator of the variation in muscle activity amplitude (the "APDF range"). Surface electromyography was examined in female office workers as Case (n = 21) and Control (n = 18) subjects. The APDF variables were measured in cervical erector spinae (CES) and upper trapezius (UT) muscles during typing, mousing and type-and-mouse, for 20 min each. The Case Group had significantly higher CES activity in the 10th, 90th% and APDF range compared to Controls. The UT muscles showed similar trends but the between-group differences were not statistically significant. These results have demonstrated the robustness of the APDF variables as sensitive indicators of motor control variations in symptomatic subjects with musculoskeletal disorders.
过去关于工作相关肌肉骨骼疾病（WMSD）的研究报告称，就幅度概率分布函数（APDF）的第50百分位数而言，肌肉活动中位数增加，这被认为是运动控制改变的一种表现——这是导致WMSD的一个重要机制。本研究旨在检验这种运动控制改变是否也存在于APDF的其他参数中——第10和第90百分位数，这两个值可被视为肌肉活动低水平和高水平测量的指标。第10和第90百分位数的APDF之间的差异可被视为肌肉活动幅度变化的一个指标（“APDF范围”）。对女性办公室职员进行了表面肌电图检查，分为病例组（n = 21）和对照组（n = 18）。在打字、使用鼠标以及打字和使用鼠标同时进行的过程中，对颈竖脊肌（CES）和上斜方肌（UT）肌肉的APDF变量进行了测量，每次测量20分钟。与对照组相比，病例组在第10、第90百分位数以及APDF范围的CES活动明显更高。UT肌肉呈现出类似趋势，但组间差异无统计学意义。这些结果证明了APDF变量作为肌肉骨骼疾病有症状受试者运动控制变化敏感指标的稳健性。
