STUDY DESIGN: Validation study. OBJECTIVES: To investigate the association between changes in electromyographic (EMG) signal amplitude and sonographic measures of muscle thickness of 4 abdominal muscles, during 2 clinical tests, in adults with and without lumbopelvic pain (LPP). BACKGROUND: There is a trend in rehabilitation to use ultrasound imaging (USI) to determine the extent of abdominal muscle contraction. However the literature investigating the relationship between abdominal muscle thickness change and level of activation is inconclusive, and has not included clinically relevant tasks. METHODS: Simultaneous recording from fine-wire EMG and USI was performed for 4 abdominal muscles in 7 adults (mean ± SD age, 29.7±12.0 years) with and 7 adults (32.0±10.6 years) without LPP, during an active straight leg raise  (ASLR) test and an abdominal drawing in manoeuvre (ADIM). Cross-correlation functions and linear regression analyses were used to describe the relationship between the 2 measures. Analyses of variance (ANOVA) were used to compare individuals with and without LPP, with a set at 0.05. RESULTS: Across all muscles, peak cross-correlation values were low (ASLR; r=0.28±0.09, ADIM; r=0.35±0.11) and there was large variability in associated time lags (ASLR; τ=0.69s±2.56s, ADIM; τ=0.53s±3.75s). Regression analyses did not detect a systematic pattern of association between EMG signal amplitude and RUSI measurements and ANOVAs revealed no differences between cohorts. CONCLUSION: These results suggest a weak relationship between EMG amplitude and abdominal muscle thickness change measured with USI during the ADIM and ASLR, and raises question about using thickness change derived from USI as a measure of muscular activity for the abdominal musculature.

J Orthop Sports Phys Ther, Epub 30 April 2013. doi:10.2519/jospt.2013.4440

KEY WORDS: EMG, external oblique, internal oblique, rectus abdominis, transversus abdominis, ultrasound imaging

STUDY DESIGN: Cross-sectional, case-control study. OBJECTIVES: To measure and compare the resting thickness of the 4 abdominal wall muscles, their associated perimuscular connective tissue (PMCT), and interrecti distance (IRD) in persons with and without lumbopelvic pain (LPP), using ultrasound imaging. BACKGROUND: The muscles and PMCT of the abdominal wall assist in controlling the spine. Functional deficits of the abdominal wall muscles have been detected in populations with LPP. Investigations of the abdominal wall in those with LPP are primarily concerned with muscle, most commonly the transversus abdominis (TrA) and internal oblique (IO). Because the abdominal wall functions as a unit, all 4 abdominal muscles and their associated connective tissues should be considered concurrently. METHODS: B-mode ultrasound imaging was used to measure the resting thickness of the rectus abdominis (RA), external oblique, IO, and TrA muscles; the PMCT planes; and IRD in 50 male and female subjects, 25 with and 25 without LPP (mean ± SD age, 36.3 ± 9.4 and 46.6 ± 8.0 years, respectively). Univariate correlation analysis was used to identify covariates. Analyses of covariance (ANCOVAs) and the Kruskal-Wallis test (IRD) were used to compare cohorts (α = .05). RESULTS: The LPP cohort had less total abdominal muscle thickness (LPP mean ± SD, 18.9 ± 3.0 mm; control, 20.3 ± 3.0 mm; ANCOVA adjusted for body mass index, P = .03), thicker PMCT (LPP, 5.5 ± 0.2 mm; control, 4.3 ± 0.2 mm; ANCOVA adjusted for body mass index, P = .007), and wider IRD (LPP, 11.5 ± 2.0 mm; control, 8.4 ± 1.8 mm; Kruskal-Wallis, P = .005). Analysis of individual muscle thickness revealed no difference in the external oblique, IO, and TrA, but a thinner RA in the LPP cohort (LPP mean ± SD, 7.8 ± 1.5 mm; control, 9.1 ± 1.2 mm; ANCOVA adjusted for body mass index, P<.001). CONCLUSION: To our knowledge, this is the first study to investigate the morphological characteristics of all 4 abdominal muscles and PMCT in individuals with LPP. The results suggest that there may be altered loading of the PMCT and linea alba secondary to an altered motor control strategy involving a reduced contribution of the RA. Further, the change in RA and connective tissue morphology may be more evident than changes in external oblique, IO, and TrA thickness in persons with LPP. The causes and functional implications of these changes warrant further investigation, as does the role of the RA muscle in the development and persistence of LPP.

J Orthop Sports Phys Ther 2013;43(1):11-19. Epub 16 November 2012. doi:10.2519/jospt.2013.4450

KEY WORDS: linea alba, oblique abdominals, rectus abdominis, reliability, transversus abdominis

Letters to the Editor-in-Chief of JOSPT as follows:

• "Early Prognostic Factors in Patients With Whiplash" and Author's Response
• "Staying Current in the Use of Ultrasound Imaging" and Author's Response
• "Differentiating the Soleus From the Gastrocnemius With the Heel Raise Test" and Author's Response

J Orthop Sports Phys Ther 2011;41(12):983-987. doi:10.2519/jospt.2011.0202

JOSPT offers invited reviews of current titles. The July 2011 column includes 5 reviews of the following books: Treat Your Own Shoulder; Musculoskeletal Ultrasound With MRI Correlations; Clinical Prediction Rules: A Physical Therapy Reference Manual; MRI for Orthopaedic Surgeons; and Examination of Musculoskeletal Injuries: Third Edition.

J Orthop Sports Phys Ther 2011;41(7):536-540.

SYNOPSIS: There is a growing trend in the physical therapy profession to use conventional grayscale brightness (B-mode) ultrasound imaging (USI) as a tool to assess the morphological (form and structure) and morphometric (measures of form) characteristics of muscle, and to use these findings to draw conclusions regarding muscle function. This trend is reflected in numerous published investigations. As many physical therapists may lack training in the principles and instrumentation underlying USI use, it is critical that therapists gain a clear understanding of the information that USI can, and cannot, provide about muscle function before employing the technique for either research or clinical applications. Failure to do so may result in the propagation of inaccurate terminology and beliefs. This paper aims to clarify the role that USI has in the assessment of muscle function, first, by briefly reviewing how conventional grayscale B-mode ultrasound images and clips are generated, and second, by summarizing the types of information that these images can provide. It also discusses the various factors that need to be considered when interpreting a dynamic USI assessment of muscle specifically as it relates to the assessment of muscle function.

J Orthop Sports Phys Ther 2011;41(8):572-580, Epub 7 June 2011. doi:10.2519/jospt.2011.3682

KEY WORDS: morphology, morphometry, sonography

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To determine if changes in transversus abdominis (TrA) and internal oblique (IO) muscle thickness and side-to-side symmetry differ in individuals with and without unilateral lumbopelvic pain while at rest and during the abdominal drawing-in maneuver (ADIM). BACKGROUND: Although the ADIM has been found to produce a symmetrical change in TrA and IO muscle thickness in healthy subjects, how these muscles are activated in those with unilateral lumbopelvic pain during the ADIM remains unknown. METHODS: Fifteen subjects with lumbopelvic pain and 15 age- and gender-matched control subjects were recruited. To investigate a similar subgroup of patients with lumbopelvic pain that has been used in previous research, subjects were required to have unilateral symptoms, a positive sacroiliac provocation test, and a positive active straight-leg raise test. Ultrasound images were obtained bilaterally at 2 different points during each trial of the ADIM: (1) at rest and (2) while maintaining the ADIM. Average percent change in thickness of the TrA and IO muscles was obtained over 3 trials. RESULTS: The percent change in thickness of the TrA was 20.9% less in those with lumbopelvic pain compared to the control group (P = .035), while the percent change in IO thickness was equivalent between groups (P = .522). No differences were observed for the TrA or IO muscles between the symptomatic and asymptomatic sides in those with (TrA, P = .263; IO, P = .172) or without (TrA, P = .780; IO, P = .635) lumbopelvic pain during the ADIM. Changes in TrA muscle thickness were greater than the IO muscle during the ADIM for both groups (P<.001). Specifically, the increases in TrA muscle thickness in those with and without lumbopelvic dysfunction were 32.7% and 47.3% greater, respectively, compared to changes in the IO muscle. CONCLUSIONS: Individuals with unilateral lumbopelvic pain demonstrated a smaller increase in thickness of the TrA muscle during the ADIM. This finding provides an element of construct validity for the use of the ADIM for assessing TrA muscle thickness in those with unilateral lumbopelvic pain. However, both groups demonstrated a symmetrical side-to-side change in TrA and IO muscle thickness despite the symptomatic group having unilateral symptoms. Further, we detected a preferential change in TrA muscle thickness during the ADIM in both groups.

J Orthop Sports Phys Ther 2009;39(11):791-798, Epub 15 October 2009. doi:10.2519/jospt.2009.3128

KEY WORDS: internal oblique, lumbar stabilization exercise, sacroiliac dysfunction, transversus abdominis, ultrasound imaging

J Orthop Sports Phys Ther. 2007:37(8):487-498; published online 20 June 2007. doi:10.2519/jospt.2007.2548

KEY WORDS: levator ani, sonography, therapeutic exercise, transabdominal ultrasound imaging, transperineal ultrasound imaging

The use of ultrasound imaging by physical therapists is growing in popularity. This commentary has 2 aims. The first is to introduce the concept of rehabilitative ultrasound imaging (RUSI), provide a definition of the scope of this emerging tool in regard to the physical therapy profession, and describe how this relates to the larger field of medical ultrasound imaging. The second aim is to provide an overview of basic ultrasound imaging and instrumentation principles, including an understanding of the various modes and applications of the technology with respect to neuromusculoskeletal rehabilitation and in relation to other common imaging modalities.

J Orthop Sports Phys Ther. 2007:37(8):434-449; published online 30 May 2007. doi:10.2519/jospt.2007.2530

KEY WORDS: elastography, magnetic resonance imaging, rehabilitation, sonography

Rehabilitative ultrasound imaging (RUSI) of the abdominal muscles is increasingly being used in the management of conditions involving musculoskeletal dysfunctions associated with the abdominal muscles, including certain types of low back and pelvic pain. This commentary provides an overview of current concepts and evidence related to RUSI of the abdominal musculature, including issues addressing the potential role of ultrasound imaging in the assessment and training of these muscles. Both quantitative and qualitative aspects associated with clinical and research applications are considered, as are the possible limitations related to the interpretation of measurements made with RUSI. Research to date has utilized a range of methodological approaches, including different transducer placements and imaging techniques. The pros and cons of the various methods are discussed, and guidelines for future investigations are presented. Potential implications and opportunities for clinical use of RUSI to enhance evidence-based practice are outlined, as are suggestions for future research to further clarify the possible role of RUSI in the evaluation and treatment of abdominal muscular morphology and function.

J Orthop Sports Phys Ther. 2007:37(8):450-466; published online 30 May 2007. doi:10.2519/jospt.2007.2558

KEY WORDS: morphometry, obliquus internus abdominis, rectus abdominis, sonography, transversus abdominis