Mangum L Colby, Henderson Kaitlin, Murray Kyle P, Saliba Susan A
University of Virginia Exercise and Sport Injury Laboratory, Charlottesville, Virginia, USA.
J Ultrasound Med. 2018 May;37(5):1225-1231. doi: 10.1002/jum.14466. Epub 2017 Oct 27.
The traditional activation ratio divides contracted muscle thickness by resting muscle thickness while an abdominal draw-in maneuver is performed during hook lying. Ultrasound imaging during function, such as standing or gait, or peak knee flexion in a single-leg squat allows for further visualization of muscle activity. The goal of this study was to examine activation ratio calculations for transverse abdominis function in supine versus loaded conditions to determine the most informative normalization strategy for muscle activity based on thickness values.
Transverse abdominis thickness was measured via ultrasound in 35 healthy participants under 4 different conditions. Comparisons were made between the traditional activation ratio tabletop, standing activation ratio (standing abdominal draw-in maneuver thickness/quiet standing thickness), and functional activation ratio (single-leg squat thickness/quiet standing thickness). Additionally, a cued activation ratio (single-leg squat with cued abdominal draw-in maneuver thickness/single-leg squat thickness) during the single-leg squat was obtained. Activation ratios of greater than 1.0 indicated that participants could activate the muscle during activity, and values were compared by analysis of variance.
The participants included 23 women and 12 men with a mean age ± SD of 21.3 ± 2.7 years, mass of 66.1 ± 14.4 kg, and height of 168.5 ± 10.1 cm. Activation ratios exceeded 1.0 in 94.3% for the traditional activation ratio, 85.7% for the standing activation ratio, 82.9% for the cued activation ratio, and 82.9% for the functional activation ratio. With groups defined as tabletop activated or not, the standing, cued, and functional activation ratios were all significantly different (all P < .05).
Normalizing muscle thickness to the corresponding functional position quiet value provides a useful functional activation ratio and may help clinicians better understand the transverse abdominis role during complex functional tasks. Assessment techniques using various formulas for activation ratios reveal that the muscle functions differently during weight bearing compared to traditional measures.
传统激活率是在钩状卧位进行收腹动作时，用收缩时的肌肉厚度除以静息时的肌肉厚度。在诸如站立或步态等功能状态下，或单腿深蹲时的最大屈膝角度下进行超声成像，可进一步观察肌肉活动情况。本研究的目的是检查仰卧位与负重条件下腹横肌功能的激活率计算，以根据厚度值确定最能提供肌肉活动信息的标准化策略。
在35名健康参与者的4种不同条件下，通过超声测量腹横肌厚度。对传统激活率（桌面位）、站立激活率（站立收腹动作时的厚度/安静站立时的厚度）和功能激活率（单腿深蹲时的厚度/安静站立时的厚度）进行比较。此外，还获得了单腿深蹲时的提示激活率（提示收腹动作的单腿深蹲时的厚度/单腿深蹲时的厚度）。激活率大于1.0表明参与者在活动期间能够激活该肌肉，并通过方差分析比较各值。
参与者包括23名女性和12名男性，平均年龄±标准差为21.3±2.7岁，体重为66.1±14.4 kg，身高为168.5±10.1 cm。传统激活率的激活率超过1.0的占94.3%，站立激活率为85.7%，提示激活率为82.9%，功能激活率为82.9%。以是否在桌面位激活分组，站立、提示和功能激活率均有显著差异（均P<0.05）。
将肌肉厚度标准化为相应功能位的静息值可提供有用的功能激活率，并可能有助于临床医生更好地理解腹横肌在复杂功能任务中的作用。使用各种激活率公式的评估技术表明，与传统测量相比，该肌肉在负重时功能不同。
