Wall Rudolf, Lips Oliwia, Seibt Robert, Rieger Monika A, Steinhilber Benjamin
Institute of Occupational and Social Medicine and Health Services Research, University Hospital Tuebingen, Germany.
Physiol Meas. 2017 May;38(5):701-714. doi: 10.1088/1361-6579/aa6711. Epub 2017 Mar 15.
Prolonged standing is associated with multiple risk factors for musculoskeletal and venous disorders. In Germany over 50% of the working population spend most of their working time in a standing position. Basic understanding of prolonged standing physiology is lacking. We therefore plan to investigate the influence of 5 h standing (including breaks) on lower limb oedema measured by waterplethysmography (WP) and bioelectrical impedance (BI) and fatigue in the triceps surae muscle using muscle twitch force (MTF). In order to interpret our results, test-retest and inter-rater reliability of these measurement methods was evaluated first.
20 subjects (9 female) were included to test each method three times (M1, M2, M3) in 30 min periods with two raters (R1, R2) on separate days. Intraclass correlation coefficient (ICC; 2,1), standard error of measurement (SEM) and smallest real difference (SRD) were calculated for both raters.
The SEM and SRD calculated for WP were 27 and 75 ml, respectively, for R1 and 23 and 64 ml, respectively, for R2 with an ICC of 0.98 (p < 0.0001). Statistically significant mean differences between M1 and M2 (R1 = 23 ml, p = 0.004; R2 = 19 ml, p = 0.027) but not significant mean differences between M2 and M3 (R1 = -6 ml, p = 0.45; R2 = 4 ml, p = 0.27) were calculated for both raters. BI data revealed SEM and SRD values of 3.8 and 10.5 Ω, respectively, for R1 and 3.4 and 9.4 Ω, respectively, for R2 with an ICC of 0.24 (p = 0.001). The differences between M1 and M2 (R1 = 3.9 Ω, p = 0.0001; R2 = 2.4 Ω, p = 0.049) and between M2 and M3 (R1 = 2.3 Ω, p = 0.012; R2 = 2.0 Ω, p = 0.008) were found to be statistically significant for both raters. SEM and SRD for MTF were 0.19 and 0.53 N, respectively, for R1 and 0.23 and 0.64 N, respectively, for R2 with an ICC of 0.71 (p < 0.0001). Mean differences between M1 and M2 were statistically significant for rater 1 but not for rater 2 (R1 = 0.13 N, p = 0.022; R2 = 0.12 N, p = 0.082) and the same was found for the difference between M2 and M3 for both raters (R1 = 0.04 N, p = 0.37; R2 = 0.08 N, p = 0.12).
All three measurement methods showed good reliability and should be suitable for detecting effects of standing work on oedema development and fatigue as seen in previous results of long term standing experiments. Inter-rater reliability is found to be satisfactory as well, demonstrated by the small differences in SEM values of R1 and R2. Statistically significant differences shown for all three measurement methods could be due to lacking standardisation of leg placement and thus an actual lower leg volume change between measurements, indicating possibilities for further improvement of SEM values.
长时间站立与肌肉骨骼和静脉疾病的多种风险因素相关。在德国，超过50%的劳动人口在工作中的大部分时间处于站立姿势。目前缺乏对长时间站立生理学的基本认识。因此，我们计划研究5小时站立（包括休息）对通过水容积描记法（WP）和生物电阻抗（BI）测量的下肢水肿以及使用肌肉抽搐力（MTF）评估的腓肠肌疲劳的影响。为了解释我们的结果，首先评估了这些测量方法的重测信度和评分者间信度。
纳入20名受试者（9名女性），由两名评分者（R1、R2）在不同日期的30分钟时间段内对每种方法进行三次测试（M1、M2、M3）。计算了两名评分者的组内相关系数（ICC；2,1）、测量标准误差（SEM）和最小真实差异（SRD）。
R1对WP计算的SEM和SRD分别为27和75毫升，R2分别为23和64毫升，ICC为0.98（p＜0.0001）。两名评分者计算得出M1和M2之间存在统计学显著的平均差异（R1 = 23毫升，p = 0.004；R2 = 19毫升，p = 0.027），但M2和M3之间无显著平均差异（R1 = -6毫升，p = 0.45；R2 = 4毫升，p = 0.27）。BI数据显示，R1的SEM和SRD值分别为3.8和10.5Ω，R2分别为3.4和9.4Ω，ICC为0.24（p = 0.001）。两名评分者发现M1和M2之间（R1 = 3.9Ω，p = 0.0001；R2 = 2.4Ω，p = 0.049）以及M2和M3之间（R1 = 2.3Ω，p = 0.012；R2 = 2.0Ω，p = 0.008）的差异具有统计学显著性。R1对MTF的SEM和SRD分别为0.19和0.53N，R2分别为0.23和0.64N，ICC为0.71（p＜0.0001）。M1和M2之间的平均差异对评分者1具有统计学显著性，但对评分者2不具有统计学显著性（R1 = 0.13N，p = 0.022；R2 = 0.12N，p = 0.082），两名评分者对M2和M3之间的差异也有相同发现（R1 = 0.04N，p = 0.37；R2 = 0.08N，p = 0.12）。
所有三种测量方法均显示出良好的信度，应该适合检测站立工作对水肿发展和疲劳的影响，如先前长期站立实验的结果所示。评分者间信度也令人满意，R1和R2的SEM值差异较小证明了这一点。所有三种测量方法显示出的统计学显著差异可能是由于腿部放置缺乏标准化，因此测量之间小腿实际体积发生了变化，这表明进一步改善SEM值存在可能性。
