P.W. Hodges, PhD 1 2 *, L.H.M. Pengel, MSc 3, R.D. Herbert, PhD 3, S.C. Gandevia, DSc 1

1Prince of Wales Medical Research Institute and the University of New South Wales, Sydney, New South Wales 2031, Australia
2Department of Physiotherapy, University of Queensland, Brisbane, Queensland 4072, Australia
3School of Physiotherapy, University of Sydney, Sydney, New South Wales 1825, Australia

Keywords: fascicle length • isometric contraction • muscle thickness • pennation angle • ultrasonography

Abstract
To investigate the ability of ultrasonography to estimate muscle activity, we measured architectural parameters (pennation angles, fascicle lengths, and muscle thickness) of several human muscles (tibialis anterior, biceps brachii, brachialis, transversus abdominis, obliquus internus abdominis, and obliquus externus abdominis) during isometric contractions of from 0 to 100% maximal voluntary contraction (MVC). Concurrently, electromyographic (EMG) activity was measured with surface (tibialis anterior only) or fine-wire electrodes. Most architectural parameters changed markedly with contractions up to 30% MVC but changed little at higher levels of contraction. Thus, ultrasound imaging can be used to detect low levels of muscle activity but cannot discriminate between moderate and strong contractions. Ultrasound measures could reliably detect changes in EMG of as little as 4% MVC (biceps muscle thickness), 5% MVC (brachialis muscle thickness), or 9% MVC (tibialis anterior pennation angle). They were generally less sensitive to changes in abdominal muscle activity, but it was possible to reliably detect contractions of 12% MVC in transversus abdominis (muscle length) and 22% MVC in obliquus internus (muscle thickness). Obliquus externus abdominis thickness did not change consistently with muscle contraction, so ultrasound measures of thickness cannot be used to detect activity of this muscle. Ultrasound imaging can thus provide a noninvasive method of detecting isometric muscle contractions of certain individual muscles. Muscle Nerve 27: 682-692, 2003



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Tracy L. Wallwork, Julie A. Hides, Warren R. Stanton


STUDY DESIGN: Within-session intrarater and interrater reliability study. OBJECTIVE: To establish the intrarater and interrater reliability of thickness measurements of the multifidus muscle in a parasagittal plane, conducted by an experienced ultrasound operator and a novice assessor. BACKGROUND: There is considerable evidence for the important role of the multifidus muscle in segmental stabilization of the lumbar spine. The cross-sectional area of the multifidus muscle has been assessed in healthy subjects and patients with low back pain using real-time ultrasound imaging. However, few studies have measured the thickness of the multifidus muscle using a parasagittal view. METHODS AND MEASURES: The thickness of the multifidus muscle was measured at rest, using real-time ultrasound imaging, in 10 subjects without a history of low back pain at the levels of the L2-3 and L4-5 zygapophyseal joints. The measure was carried out 3 times at each level by 2 assessors (1 experienced, 1 novice). Intrarater (model 3) and interrater (model 2) reliability was assessed by calculation of an F statistic (analysis of variance), the intraclass correlation coefficient (ICC), and the standard error of measurement (SEM). RESULTS: On the basis of an average of 3 trials, the 2 operators showed very high interrater agreement on the measurement of thicknesses at the L2-3 level (ICC2,3 = 0.96; 95% CI:0.84 to 0.99) and the L4-5 vertebral level (ICC2,3 = 0.97; 95% CI:0.87 to 0.99), with no systematic differences in muscle size across operators (p>.05). Interrater reliability was relatively lower for the L2-3 level (ICC2,1= 0.85; 95% CI:0.51 to 0.96) than the L4-5 level (ICC2,1 = 0.87; 95% CI:0.52 to 0.97) when a single trial per rater was used, but these values still indicated a high level of agreement. In addition, the novice and experienced operator produced reliable intrarater measurements at L2-3 (ICC3,1 = 0.89; 95% CI: 0.72-0.97 and 0.94; 95% CI: 0.86-0.99) and at L4-5 (ICC3,1 = 0.88; 95% CI: 0.68-0.97 and 0.95; 95% CI: 0.86-0.99), with no systematic differences in muscle size across trials (P>0.05). The consistently low SEM values also indicate low measurement error. CONCLUSION: A novice and an experienced assessor were both able to reliably perform this measure at rest for 2 vertebral levels using real-time ultrasound imaging. An average of 3 trials produced higher interrater reliability scores, though a single trial per rater was also reliable.

J Orthop Sports Phys Ther. 2007;37(10):608-612, published online 29 May 2007. doi:10.2519/jospt.2007.2418

KEY WORDS: back muscles, lumbar spine, muscle assessment, repeatability, ultrasonography


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Maria Stokes, Julie A. Hides, Kyle B. Kiesel, James M. Elliott, Paul W. Hodges

SYNOPSIS: Interest in rehabilitative ultrasound imaging (RUSI) of the posterior paraspinal muscles is growing, along with the body of literature to support integration of this technique into routine physical therapy practice. This clinical commentary reviews how RUSI can be used as an evaluative and treatment tool, and proposes guidelines for its use for the posterior muscles of the lumbar and cervical regions. Both quantitative and qualitative applications are described, as well as measurement reliability and validity. Measurement of morphological characteristics of the muscles (morphometry) in healthy populations and people with spinal pathology are described. Preliminary normal reference data exist for measurements of cross-sectional area (CSA), linear dimensions (muscle depth/thickness and width), and shape ratios. Compared to individuals without low back pain, changes in muscles' size at rest and during the contracted state have been observed using RUSI in people with spinal pathology. Visual observation of the image during contraction indicates that RUSI may be a valuable biofeedback tool. Further investigation of many of these observations is required using controlled studies to provide conclusive evidence that RUSI enhances clinical practice.

J Orthop Sports Phys Ther. 2007;37(10):581-595, published online 29 August 2007. doi: 10.2519/jospt.2007.2599

KEY WORDS: cervical muscles, lumbar muscles, lumbar spine, neck, morphometry, sonography


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Kyle B. Kiesela, Tim L. Uhlb, Frank B. Underwoodc, Donald W. Roddd, Arthur J. Nitzae

Received 7 March 2005; received in revised form 14 February 2006; accepted 2 June 2006

Abstract
Rehabilitative Ultrasound Imaging (RUSI) has been validated as a noninvasive method to measure activation of selected muscles. The purpose of this study was to determine the relationship between muscle thickness change, as measured by ultrasonography, and electromyography (EMG) activity of the lumbar multifidus (LM) muscle in normal subjects.

Bipolar fine wire electrodes were inserted into the LM at the L4 level of five subjects. Simultaneous EMG and RUSI data (muscle thickness) were collected while subjects performed increasingly demanding postural response tasks thought to activate the LM muscle. To determine the relationship between muscle thickness change and EMG activity, the normalized EMG data were correlated to normalized RUSI data. To determine if the tasks increased the demand on the LM, the mean EMG data were compared over each of the four tasks.

Muscle thickness change as measured by RUSI was highly correlated with EMG activity of LM in asymptomatic subjects ().

Mean EMG data showed increasing levels of activation across tasks (19–34% of maximum voluntary isometric contraction (MVIC)). The results of the repeated measures ANOVA demonstrated theses differences were significant ().

Measurement of muscle thickness change utilizing RUSI is a valid and potentially useful method to measure activation of the LM muscle in a narrow range (19–34% of MVIC) in an asymptomatic population.

Keywords: Rehabilitation, Electromyography, Ultrasonography
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