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Abstract：
OBJECTIVE: The object of this study was to quantify the contribution of sub-maximal normalisation to the overall variance of exposure parameters describing erector spinae (ES) activity, and to provide guidelines for task selection which minimize methodological variance.
METHODS: ES EMG was measured from three locations (T9, L1 and L5 levels) on fifteen men performing a manual materials handling task in the laboratory on three separate days. Four repeats of each of eleven sub-maximal normalisation tasks (eight static, three dynamic) were collected, work data were normalised to each task and repeat, and exposure parameters calculated. The unique contribution of normalisation to the overall variance was determined for each task and exposure parameter using variance component analyses. Normalisation tasks were scored according to their relative contributions to the overall variance and coefficients of variation.
RESULTS: A prone task, similar to the Biering-Sørensen test posture, was the most repeatable for all electrode locations and across all exposure parameters. Thoracic level normalisation typically showed poorer repeatability than lumbar normalisation.
CONCLUSIONS: To maximize measurement precision, we recommend that future ES EMG studies employing sub-maximal normalisation utilise said prone task. An alternate normalisation task specific to thoracic level ES muscles may be warranted.
METHODS: ES EMG was measured from three locations (T9, L1 and L5 levels) on fifteen men performing a manual materials handling task in the laboratory on three separate days. Four repeats of each of eleven sub-maximal normalisation tasks (eight static, three dynamic) were collected, work data were normalised to each task and repeat, and exposure parameters calculated. The unique contribution of normalisation to the overall variance was determined for each task and exposure parameter using variance component analyses. Normalisation tasks were scored according to their relative contributions to the overall variance and coefficients of variation.
RESULTS: A prone task, similar to the Biering-Sørensen test posture, was the most repeatable for all electrode locations and across all exposure parameters. Thoracic level normalisation typically showed poorer repeatability than lumbar normalisation.
CONCLUSIONS: To maximize measurement precision, we recommend that future ES EMG studies employing sub-maximal normalisation utilise said prone task. An alternate normalisation task specific to thoracic level ES muscles may be warranted.
摘要：
目的：本研究的目的是量化次最大归一化对描述竖脊肌（ES）活动的暴露参数的总体方差的贡献，并为任务选择提供指导，以最大程度地减少方法上的差异。
方法：从三个位置（T9，L1和L5水平）测量了15名男性的ESEMG，这些男性在三个不同的日子里在实验室执行手动材料处理任务。十一个次最大标准化任务中的每一个重复四次(八个静态，三个动态)被收集，工作数据被标准化为每个任务，并重复，并计算曝光参数。使用方差成分分析确定每个任务和暴露参数的归一化对总体方差的独特贡献。标准化任务根据其对总体方差和变异系数的相对贡献进行评分。
结果：一项容易完成的任务，类似于Biering-Sørensen测试姿势，对于所有电极位置和所有暴露参数都是最可重复的。与腰椎正常化相比，胸腔水平正常化的可重复性通常较差。
结论：为了最大限度地提高测量精度，我们建议未来采用亚最大标准化的ESEMG研究利用所述易发任务.可能需要针对胸部水平ES肌肉的替代标准化任务。
方法：从三个位置（T9，L1和L5水平）测量了15名男性的ESEMG，这些男性在三个不同的日子里在实验室执行手动材料处理任务。十一个次最大标准化任务中的每一个重复四次(八个静态，三个动态)被收集，工作数据被标准化为每个任务，并重复，并计算曝光参数。使用方差成分分析确定每个任务和暴露参数的归一化对总体方差的独特贡献。标准化任务根据其对总体方差和变异系数的相对贡献进行评分。
结果：一项容易完成的任务，类似于Biering-Sørensen测试姿势，对于所有电极位置和所有暴露参数都是最可重复的。与腰椎正常化相比，胸腔水平正常化的可重复性通常较差。
结论：为了最大限度地提高测量精度，我们建议未来采用亚最大标准化的ESEMG研究利用所述易发任务.可能需要针对胸部水平ES肌肉的替代标准化任务。
