Pitcher Mark J, Behm David G, MacKinnon Scott N
School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL A1C 5S7, Canada.
Appl Physiol Nutr Metab. 2008 Feb;33(1):52-60. doi: 10.1139/H07-132.
Maximal voluntary isometric activations (MVIA) are frequently used as inputs for models attempting to predict muscle force and as normalization values in studies assessing muscle function. However, pain may adversely affect maximal muscle activation. The purpose of this study was to assess reliability of MVIA force and electromyographic (EMG) activity during prone isometric back extension in subjects with and without low back pain (LBP). A novel sub-maximal method using the percentages of the estimated mass of the head-arms-trunk (HAT) segment was also investigated. Repeated measures on 20 male volunteers divided into an LBP (n=10) and a control group (n=10) were made on 4 occasions. Force and EMG activity were recorded bilaterally from upper lumbar erector spinae (ULES), lower lumbar erector spinae (LLES), and biceps femoris (BF). Subjects exerted a maximal extension effort against a harness assembly that was attached to a force transducer. Submaximal exertions were also performed with an additional resistance of 100%, 110%, 120%, 130%, 140%, 150%, 160%, and 170% of HAT. Mean MVIA forces were significantly (p<or=0.05) lower in LBP vs. control. Intraclass correlation coefficients (ICC) for MVIA force, right and left ULES, and LLES EMG indicated high reliability in controls (R>0.90), but were significantly less in LBP (R=0.36-0.80). EMG of BF demonstrated excellent reliability across both groups (R>0.90). The resistance at 100% HAT demonstrated the highest reliability for LBP patients, whereas higher percentages of HAT showed either similar or higher reliability for controls. Force output and back EMG activity are less reliable with LBP individuals and should be taken into consideration when testing.
最大自主等长收缩（MVIA）常用于为试图预测肌肉力量的模型提供输入，并作为评估肌肉功能研究中的标准化值。然而，疼痛可能会对最大肌肉激活产生不利影响。本研究的目的是评估有和没有下腰痛（LBP）的受试者在俯卧位等长背伸过程中MVIA力量和肌电图（EMG）活动的可靠性。还研究了一种使用头-臂-躯干（HAT）节段估计质量百分比的新型次最大方法。对20名男性志愿者进行重复测量，将其分为LBP组（n = 10）和对照组（n = 10），共进行4次测量。双侧记录上腰竖脊肌（ULES）、下腰竖脊肌（LLES）和股二头肌（BF）的力量和EMG活动。受试者对连接到力传感器的安全带组件施加最大伸展力。还进行了次最大用力，额外施加HAT的100%、110%、120%、130%、140%、150%、160%和170%的阻力。LBP组的平均MVIA力量显著低于对照组（p≤0.05）。MVIA力量、右侧和左侧ULES以及LLES EMG的组内相关系数（ICC）表明对照组具有高可靠性（R>0.90），但LBP组显著降低（R = 0.36 - 0.80）。BF的EMG在两组中均表现出极好的可靠性（R>0.90）。100%HAT的阻力对LBP患者表现出最高的可靠性，而更高百分比的HAT对对照组表现出相似或更高的可靠性。LBP个体的力量输出和背部EMG活动可靠性较低，在测试时应予以考虑。
