Use of real-time ultrasound imaging for feedback in rehabilitation

Automated analysis of pectoralis major thickness in pec-fly exercises: evolving from manual measurement to deep learning techniques

This study addresses a limitation of prior research on pectoralis major (PMaj) thickness changes during the pectoralis fly exercise using a wearable ultrasound imaging setup. Although previous studies used manual measurement and subjective evaluation, it is important to acknowledge the subsequent limitations of automating widespread applications. We then employed a deep learning model for image segmentation and automated measurement to solve the problem and study the additional quantitative supplementary information that could be provided. Our results revealed increased PMaj thickness changes in the coronal plane within the probe detection region when real-time ultrasound imaging (RUSI) visual biofeedback was incorporated, regardless of load intensity (50% or 80% of one-repetition maximum). Additionally, participants showed uniform thickness changes in the PMaj in response to enhanced RUSI biofeedback. Notably, the differences in PMaj thickness changes between load intensities were reduced by RUSI biofeedback, suggesting altered muscle activation strategies. We identified the optimal measurement location for the maximal PMaj thickness close to the rib end and emphasized the lightweight applicability of our model for fitness training and muscle assessment. Further studies can refine load intensities, investigate diverse parameters, and employ different network models to enhance accuracy. This study contributes to our understanding of the effects of muscle physiology and exercise training.

Spinal Muscle Thickness and Activation during Abdominal Hollowing and Bracing in CrossFit® Athletes

Exercises that improve muscle activation are essential for maintaining spinal stability and preventing low back pain. The purpose of this study was to compare the effects of abdominal hollowing and bracing on the activation of the core muscles in CrossFit® participants using ultrasound and electromyography (EMG). Twenty-four healthy adults aged 21 to 42 years old with at least two years of CrossFit® experience performed three core stability exercises (plank, side plank, bridge) with abdominal hollowing and bracing. We measured the ultrasound relative thickness of the local core muscles (transversus abdominis, internal oblique, and lumbar multifidus), and the EMG percentage of maximal voluntary contraction (MVC) of the global core muscles (rectus abdominis, external oblique, and iliocostalis lumborum). Analysis of variance tests showed that the relative thickness of the local core muscles was greater (p = 0.016) during hollowing (range from 26.8 ± 5.33 to 88.4 ± 11.9% of rest) than bracing (range from 15.9 ± 3.54 to 61.2 ± 15.9% of rest), while the EMG of the global muscles was greater (p = 0.001) in bracing (range from 24.4 ± 7.30 to 72.5 ± 9.17% of MVC) than hollowing (range from 16.4 ± 3.70 to 56.6 ± 7.65% of MVC). These results indicate that the recruitment of spinal muscles during popular exercises is achieved with both hollowing and bracing. Nevertheless, it appears that hollowing tends to recruit more of the local muscles, whilst bracing recruits more of the global muscles. The grading of the exercises varied between muscles and varied between maneuvers, especially for the surface abdominals and lumbar muscles. CrossFit® practitioners can choose to use either hollowing or bracing to activate their core muscles more selectively or more appropriately, depending on the goal and purpose of the exercise.

Investigation of Real-Time Diagnostic Ultrasound as a Means of Biofeedback Training in Transversus Abdominus Re-Education of Patients with Non-Specific Low Back Pain: A Prospective Randomized Controlled Pilot Study

Background: It is believed that ultrasound-guided imaging of activation/contraction of the deep abdominal muscles (such as transervsus abdominis) is useful for assisting deep muscle re-education, which is often dysfunctional in non-specific low back pain (NSLBP). Thus, this pilot study aimed to evaluate the use of real-time ultrasound (US) as a feedback device for transverse abdominis (TrA) activation/contraction during an exercise program in chronic NSLBP patients. Methods: Twenty-three chronic NSLBP patients were recruited and randomly assigned to a US-guided (n = 12, 8 women, 47.6 ± 2.55 years) or control group (n = 11, 9 women, 46.9 ± 4.29 years). The same motor control-based exercise program was applied to both groups. All patients received physiotherapy twice per week for seven weeks. Outcome measures, tested at baseline and post-intervention, included Numeric Pain Rating Scale, TrA activation level (measured through a pressure biofeedback unit-based developed protocol), seven established motor control tests, Roland-Morris Disability Questionnaire and Hospital Anxiety and Depression Scale. Results: For each group, all outcome variables yielded statistical differences post-intervention (p < 0.05), indicating significant improvements. However, there were no significant group x time interactions for any of the outcomes (p > 0.05), thus, indicating no superiority of the US-guided group over the control. Conclusions: The addition of US as a visual feedback device for TrA re-education during a motor control exercise program was not proven superior to traditional physiotherapy.

MSK Ultrasound - An IJSPT Perspective

MSK ultrasound is a valuable imaging technique which has become increasingly popular in recent years. This efficient technique proves beneficial in a variety of ways. MSK ultrasound effectively streamlines the process by enabling practitioners to securely and accurately image and assess structures all in one simple step. By allowing healthcare providers to access critical information quickly and conveniently, MSK ultrasound can help identify conditions early when interventions are most effective. Moreover, it may be able to shorten diagnostic times and reduce costs through more cost-effective use of resources such as imaging and laboratory testing. Furthermore, MSK ultrasound can provide additional insights into musculoskeletal anatomy and help improve patient care and outcomes. In addition, utilizing this method reduces exposure to radiation and provides enhanced patient comfort with its quick scan duration. MSK ultrasound has a high potential to provide quick and accurate diagnosis of MSK disturbances when used correctly. As clinicians become more comfortable and familiar with this technology, we will continue to see its use expand for various MSK assessments. In this commentary we'll explore how ultrasound can be used in physical therapy, specifically for musculoskeletal assessment. We'll also look at some of the potential benefits and limitations of using ultrasound in PT practice.

The reliability of video fluoroscopy, ultrasound imaging, magnetic resonance imaging and radiography for measurements of lumbar spine segmental range of motion in-vivo: A review

BACKGROUND

Lower back pain (LBP) is a principal cause of disability worldwide and is associated with a variety of spinal conditions. Individuals presenting with LBP may display changes in spinal motion. Despite this, the ability to measure lumbar segmental range of motion (ROM) non-invasively remains a challenge.

OBJECTIVE

To review the reliability of four non-invasive modalities: Video Fluoroscopy (VF), Ultrasound imaging (US), Magnetic Resonance Imaging (MRI) and Radiography used for measuring segmental ROM in the lumbar spine in-vivo.

METHODS

The methodological quality of seventeen eligible studies, identified through a systematic literature search, were appraised.

RESULTS

The intra-rater reliability for VF is excellent in recumbent and upright positions but errors are larger for intra-rater repeated movements and inter-rater reliability shows larger variation. Excellent results for intra- and inter-rater reliability are seen in US studies and there is good reliability within- and between-day. There is a large degree of heterogeneity in MRI and radiography methodologies but reliable results are seen.

CONCLUSIONS

Excellent reliability is seen across all modalities. However, VF and radiography are limited by radiation exposure and MRI is expensive. US offers a non-invasive, risk free method but further research must determine whether it yields truly consistent measurements.

DIFFERENTIAL EFFECTS OF THE ABDOMINAL DRAW-IN MANEUVER IN DIFFERENT POSITIONS ON MUSCLE THICKNESS AND BALANCE RATIO IN NONSYMPTOMATIC ADULTS

Core stability mediated by the abdominal draw-in maneuver (ADIM) has been proven to be an important component of neuromuscular motor control before movement. However, no previous research has investigated which position is best for performing ADIM to achieve optimal core stability. This study aimed to define the effectiveness of performing ADIM in three different positions (prone, supine, and hook lying) on abdominal muscle thickness in nonsymptomatic participants. In total, 30 nonsymptomatic participants (mean age: [Formula: see text] years) were randomly assigned to a trial sequence using the random sequence method. The clinical outcomes were transverse abdominis (TrA), external oblique (EO), and internal oblique (IO) muscle thicknesses, which were evaluated using ultrasonography (US) and muscle thickness balance ratio. One-way repeated-measures analysis of variance (ANOVA) was used to evaluate the US data to determine if the resulting TrA, IO, and EO muscle thicknesses from the three different positions were statistically significant. Bonferroni correction was used as a post hoc test if statistical significance was found. The [Formula: see text] value was set to 0.013. One-way ANOVA showed a significant difference in the thickness of the TrA, IO, and EO muscles resulting from the different positions ([Formula: see text]). Post hoc analysis using Bonferroni correction revealed that the prone position resulted in greater changes than the supine and hook-lying positions ([Formula: see text], respectively). ANOVA did not show a significant change in the TrA, IO, and EO muscle thickness balance ratios ([Formula: see text], 0.44, and 0.59, respectively). The results provide innovative clinical evidence that performing ADIM in different positions (prone, supine, and hook lying) has different effects on abdominal muscle thickness in nonsymptomatic participants.

Ultrasound: an emerging modality for the dysphagia assessment toolkit?

PURPOSE OF REVIEW

Videofluoroscopy (VFSS) and fibreoptic endoscopic evaluation of swallowing (FEES) are established instrumental techniques to support differential diagnosis and treatment of oropharyngeal dysphagia. Whilst their value is undisputed, each tool is not without limitations. The COVID-19 pandemic has restricted access to VFSS and FEES leading clinicians to explore alternative or augmentative tools to support swallowing assessment.Ultrasound (US) is an established tool for visualisation of head and neck anatomy, including structures implicated in swallowing. Although US has been utilised in swallowing research for many years, its application has not translated into common clinical practice. This review presents and debates the evidence for and against use of US for clinical swallowing assessment.

RECENT FINDINGS

Evaluation of swallowing muscle morphometry and measurement of isolated swallowing kinematics are two primary uses of US in swallowing assessment that have been identified in the literature. Use of US to detect bolus flow, aspiration and residues is in its early stages and needs further research.

SUMMARY

US shows promise as an adjunctive modality to support assessment of swallowing. With standardisation, these measurements may have potential for transition into clinical care. Reliability and validity testing and development of normative data are imperative to ensure its use as an evidence-based instrumentation.

Exercising on Different Unstable Surfaces Increases Core Abdominal Muscle Thickness: An Observational Study Using Real-Time Ultrasound

BACKGROUND

The training of abdominal muscles has a positive impact on the functional capacity of healthy adults, being applied practically in fields of athletics and fitness through rehabilitation for lower back pain.

OBJECTIVE

The study compares abdominal muscle activity while performing graded isometric exercises on stable and unstable surfaces. The authors also examined perceived stability and comfort for the different surfaces.

METHODS

A total of 30 young, healthy adults performed 3 graded isometric exercises on a Pilates table, foam roller, and Oov (a newly developed tool). Ultrasound investigation measured transversus abdominis, internal oblique abdominis, and external oblique abdominis thickness during each task, comparing muscle thickness between conditions using general linear modeling.

RESULTS

Core abdominal activation was greater on the foam roller than the Oov and Pilates table during crook lying (bilateral leg support). Both Oov and foam roller elicited greater contralateral transversus abdominis and internal oblique abdominis thickness than the Pilates table during tabletop and straight leg raises (unilateral leg exercises). For transversus abdominis only, the foam roller elicited more muscle thickness than the Oov during straight leg raises. The Oov was rated more comfortable than the foam roller.

DISCUSSION

Exercises performed on the Oov and foam roller elicit core greater abdominal muscle thickness than those performed on a Pilates table. Unilateral leg exercises in a supine position elicit more contralateral muscle thickness than those with bilateral leg support.

CONCLUSIONS

These results provide information to support choices in exercise progression from flat stable to more unstable surfaces and from those with bilateral foot support to unilateral foot support. The Oov was more comfortable that the foam roller, and this may help with exercise adherence.

Differences in supraspinatus occupation ratio between the symptomatic, the contralateral asymptomatic shoulder and control subjects: A cross-sectional study

ABSTRACT

The relationship between supraspinatus tendon thickness and the acromiohumeral distance (AHD) at both rest position and shoulder elevation is still to be explored in those with chronic shoulder pain. The aim is to compare supraspinatus occupation ratio (OR) at 0° and 60° of shoulder elevation measured by ultrasound imaging in the symptomatic shoulder, the contralateral asymptomatic shoulder and in healthy subjects. This was across-sectional, observational study. A sample of 56 participants with subacromial pain syndrome in their dominant arm was recruited in 3 different primary care centres. Forty participants without shoulder pain were also recruited. The AHD at 0° and 60° of active shoulder abduction as well as the supraspinatus tendon thickness were measured by ultrasound in these groups. Supraspinatus OR at 60° was significantly greater in symptomatic compared to asymptomatic shoulders (P = .04) and healthy shoulders (P = .008). The percentage of change in supraspinatus OR from rest position to 60° was also greater in symptomatic shoulders when comparing with asymptomatic (P = .01) and healthy shoulders (P = .03). No other statistically significant differences for the rest of comparisons were found. Supraspinatus OR may explain shoulder pain in chronic conditions. Further studies at acute and chronic conditions after a physiotherapy treatment are needed to explore its usefulness in clinical practice.

Inconsistent descriptions of lumbar multifidus morphology: A scoping review

Background

Lumbar multifidus (LM) is regarded as the major stabilizing muscle of the spine. The effects of exercise therapy in low back pain (LBP) are attributed to this muscle. A current literature review is warranted, however, given the complexity of LM morphology and the inconsistency of anatomical descriptions in the literature.

Methods

Scoping review of studies on LM morphology including major anatomy atlases. All relevant studies were searched in PubMed (Medline) and EMBASE until June 2019. Anatomy atlases were retrieved from multiple university libraries and online. All studies and atlases were screened for the following LM parameters: location, imaging methods, spine levels, muscle trajectory, muscle thickness, cross-sectional area, and diameter. The quality of the studies and atlases was also assessed using a five-item evaluation system.

Results

In all, 303 studies and 19 anatomy atlases were included in this review. In most studies, LM morphology was determined by MRI, ultrasound imaging, or drawings – particularly for levels L4–S1. In 153 studies, LM is described as a superficial muscle only, in 72 studies as a deep muscle only, and in 35 studies as both superficial and deep. Anatomy atlases predominantly depict LM as a deep muscle covered by the erector spinae and thoracolumbar fascia. About 42% of the studies had high quality scores, with 39% having moderate scores and 19% having low scores. The quality of figures in anatomy atlases was ranked as high in one atlas, moderate in 15 atlases, and low in 3 atlases.

Discussion

Anatomical studies of LM exhibit inconsistent findings, describing its location as superficial (50%), deep (25%), or both (12%). This is in sharp contrast to anatomy atlases, which depict LM predominantly as deep muscle. Within the limitations of the self-developed quality-assessment tool, high-quality scores were identified in a majority of studies (42%), but in only one anatomy atlas.

Conclusions

We identified a lack of standardization in the depiction and description of LM morphology. This could affect the precise understanding of its role in background and therapy in LBP patients. Standardization of research methodology on LM morphology is recommended. Anatomy atlases should be updated on LM morphology.

Age-related changes in trunk muscle activity and spinal and lower limb kinematics during gait

The influence of age on spinal muscle activation patterns and its relation to kinematics is poorly understood. We aimed at understanding age-related changes to spine and trunk muscle activity in addition to spinal and lower limb kinematics during treadmill walking under various conditions. An observational study was conducted evaluating asymptomatic young (n = 10; 3F, 7M; 26.3±2.5yrs) and older (n = 9; 3F, 6M; 67.1±4.2yrs) adults’ treadmill walking at 2km/h and 4km/h, each at 0, 1, 5, and 10% inclination. Unilateral (right side) electromyography (EMG) was recorded from deep and superficial multifidus (intramuscular) and erector spinae and abdominal obliques (surface); trunk and leg kinematics were also measured. Muscle activity was characterised by peak amplitude and duration of activity, and the time-point of peak amplitude in the gait cycle (0–100%). Peak activation in older adults was lower for the superficial multifidus (p<0.0001) and higher for the thoracolumbar (p<0.001) and lumbar erector spinae (p<0.01). The duration of activation was longer in older adults for all muscles (p<0.05) except the superficial multifidus, and longer during faster walking for all participants. The time-point of peak amplitude in the gait cycle was earlier in older participants for the external obliques (p<0.05). Walking speed appeared to influence muscle activity more than inclination. Older adults used less spine, trunk and lower limb motion, except at the ankle. Age-related differences within multifidus and between paravertebral and trunk muscles were inconsistent. Walking at 4km/h at 5–10% inclination may specifically target the lumbar paravertebral muscles.

Using real-time ultrasound imaging as adjunct teaching tools to enhance physical therapist students' ability and confidence to perform traction of the knee joint

Often, physical therapy students struggle with the skill and the confidence to perform manual techniques for musculoskeletal examination. Current teaching methods lack concurrent objective feedback. Real-time ultrasound imaging (RTUI) has the advantage of generating visualization of anatomical structures in real-time in an efficient and safe manner. We hypothesize that the use of RTUI to augment teaching with concurrent objective visual feedback will result in students' improved ability to create a change in joint space when performing a manual knee traction and higher confidence scores. Eighty-six students were randomly allocated to a control or an experimental group. All participants received baseline instructions on how to perform knee traction. The control group received standardized lab instruction (visual, video, and instructor/partner feedback). The experimental group received standardized lab instruction augmented with RTUI feedback. Pre-data and post-data collection consisted of measuring participants' ability to create changes in joint space when performing knee traction, a confidence survey evaluating perceived ability and a reflection paper. Joint space changes between groups were compared using a paired t-test. Surveys were analyzed with descriptive statistics and compared using Wilcoxon Rank Sum and for the reflection papers, themes were identified and descriptive statistics reported. Although there were no statistically significant differences between the control and the experimental group, overall scores improved. Qualitative data suggests students found the use of ultrasound imaging beneficial and would like more exposure. This novel approach to teaching knee traction with RTUI has potential and may be a basis for further studies.

Are regions of the lumbar multifidus differentially activated during walking at varied speed and inclination?

PURPOSE

Lumbar multifidus is a complex muscle with multi-fascicular morphology shown to be differentially controlled in healthy individuals during sagittal-plane motion. The normal behaviour of multifidus muscle regions during walking has only received modest attention in the literature. This study aimed to determine activation patterns for deep and superficial multifidus in young adults during walking at different speeds and inclination.

METHODS

This observational cohort study evaluated ten healthy volunteers in their twenties (three women, seven men) as they walked on a treadmill in eight conditions; at 2km/h and 4km/h, each at 0, 1, 5, and 10% inclination. Intramuscular EMG was recorded from the deep and superficial multifidus unilaterally at L5. Activity was characterized by: amplitude of the peak of activation, position of peak within the gait cycle (0-100%), and duration relative to the full gait cycle.

RESULTS

Across all conditions superficial multifidus showed higher normalised EMG amplitude (p<0.01); superficial multifidus peak amplitude was 232±115% higher when walking at 4km/h/10%, versus only 172±77% higher for deeper region (p<0.01). The percentage of the gait cycle where peak EMG amplitude was detected did not differ between regions (49±13%). Deep multifidus duration of activation was longer when walking at the faster vs slower speed at all inclinations (p<0.01), which was not evident for superficial multifidus (p<0.05). Thus, a significantly longer activation of deep multifidus was observed compared to superficial multifidus when walking at 4km/h (p<0.05).

CONCLUSIONS

Differential activation within lumbar multifidus was shown in young adults during walking. The prolonged, more tonic activation of deep relative to superficial regions of multifidus during gait supports a postural function of deeper fibres.

Fluorocarbon nanodrops as acoustic temperature probes

This work investigated the use of superheated fluorocarbon nanodrops for ultrasound thermal imaging and the use of mixed fluorocarbons for tuning thermal and acoustic thresholds for vaporization. Droplets were fabricated by condensing phospholipid-coated microbubbles containing C3F8 and C4F10 mixed at various molar ratios. Vaporization temperatures first were measured in a closed system by optical transmission following either isothermal pressure release or isobaric heating. The vaporization temperature was found to depend linearly on the percentage of C4F10 in the droplet core, indicating excellent tunability under these fluorocarbon-saturated conditions. Vaporization temperatures were then measured in an open system using contrast-enhanced ultrasound imaging, where it was found that the mixed droplets behaved like pure C4F10 drops. Additionally, the critical mechanical index for vaporization was measured at the limits of therapeutic hyperthermia (37 and 60 °C), and again the mixed droplets were found to behave like pure C4F10 drops. These results suggested that C3F8 preferentially dissolves out of the droplet core in open systems, as shown by a simple mass transfer model of multicomponent droplet dissolution. Finally, proof-of-concept was shown that pure C4F10 nanodrops can be used as an acoustic temperature probe. Overall, these results not only demonstrate the potential of superheated fluorocarbon emulsions for sonothermetry but also point to the limits of tunability for fluorocarbon mixtures owing to preferential release of the more soluble species to the atmosphere.

Physiotherapist-initiated lung ultrasound to improve intensive care management of a deteriorating patient and prevent intubation: a case report

BACKGROUND AND PURPOSE

This case report describes the physiotherapy assessments and interventions provided to a 56-year-old male in an Australian intensive care unit. The non-intubated patient suffered from respiratory deterioration, secretion retention, complete opacification of the left hemithorax on chest X-ray (CXR) and widespread coarse crackles on lung auscultation. The addition of lung ultrasound (LUS) facilitated more accurate diagnosis than what was formed on the basis of CXR and lung auscultation resulting in more effective treatment.

METHODS

The method used is a case report. Written consent was obtained from the patient for these data to be published.

SUMMARY

Secretion retention was initially suspected (based on clinical examination and CXR) and treated with airway clearance techniques, patient positioning and nasopharyngeal suction. Even though this assisted with secretion removal, the patient continued to have a high perceived work of breathing and increasing oxygen requirements. Physiotherapist performed LUS, under supervision, and revealed a large pleural effusion (1500 mL), which was then drained by the medical team.

DISCUSSION

The addition of LUS to the critical care physiotherapist's assessment skills may provide clinical benefit. The increased diagnostic accuracy of LUS compared with other routine assessments warrants further investigation.

Reliability of ultrasound in combination with surface electromyogram for evaluating the activity of abdominal muscles in individuals with and without low back pain

This study investigated the reliability of ultrasound in combination with surface electromyogram (EMG) for evaluating the activity of the abdominal muscles in individuals with and without low back pain during the abdominal drawing-in maneuver (ADIM). The study recruited ten individuals with or without low back pain, respectively. While the participants were performing the ADIM, the activities of the transversus abdominis (TrA) and the internal oblique (IO) were measured using ultra-sound, while the activities of the external oblique (EO) and the rectus abdominis (RA) were measured using surface EMG. Intra-class correlation coefficients (ICC) were used to verify the inter-rater reliability of ultrasound in combination with surface EMG at rest and during the ADIM, and Bland-Altman plots were used to verify intra-rater reliability. The inter-rater reliability for the two groups at rest and during the ADIM was excellent (ICC_2,1 = 0.77–0.95). In the Bland-Altman plots, the mean differences and 95% limits of agreement in the abdominal muscles of the two groups at rest were −0.03∼0.03 mm (−0.66 to 0.60 mm) and −0.12∼ −0.05 (−0.58 to 0.48% MVIC), respectively. The mean differences and 95% limits of agreement in the abdominal muscles of the two groups during the ADIM were −0.04∼0.02 mm (−0.73 to 0.65 mm) and −0.19∼0.05% MVIC (−1.24 to 1.34% MVIC), respectively. The ultrasound in combination with surface EMG showed excellent inter-rater and intra-rater reliability at rest and during the ADIM.

Evaluation of the lumbar multifidus in rowers during spinal stabilization exercise

Lumbar stabilization is important in high performance rowing due to the high incidence of low back pain. The purpose of this study was to evaluate the lumbar stabilizers muscles performance during an exercise of spinal segmental stabilization and in lumbar multifidus muscle thickness in rowing athletes trained and untrained for this exercise. Nine rowers trained with lumbar stabilization (TLS) and eight rowers without training (CON) participated in the study. Lumbar stabilization performance and multifidus muscle thickness were measured during a maximal voluntary isometric contraction. Lumbar stabilization performance was higher (p=0.015) in the TLS (mean 18.38 ± 8.00 mmHg) compared to the CON (9.31 ± 4.91 mmHg) group. Muscle thickness variation was higher (p=0.023) in the TLS (6.92% ± 3.98) compared to the CON (2.81% ± 1.40) group. Lumbar stabilization training is an efficient clinical tool to strengthen lumbar muscles and may help to prevent low back pain in rowers.

Biofeedback in rehabilitation

This paper reviews the literature relating to the biofeedback used in physical rehabilitation. The biofeedback methods used in rehabilitation are based on biomechanical measurements and measurements of the physiological systems of the body. The physiological systems of the body which can be measured to provide biofeedback are the neuromuscular system, the respiratory system and the cardiovascular system. Neuromuscular biofeedback methods include electromyography (EMG) biofeedback and real-time ultrasound imaging (RTUS) biofeedback. EMG biofeedback is the most widely investigated method of biofeedback and appears to be effective in the treatment of many musculoskeletal conditions and in post cardiovascular accident (CVA) rehabilitation. RTUS biofeedback has been demonstrated effective in the treatment of low back pain (LBP) and pelvic floor muscle dysfunction. Cardiovascular biofeedback methods have been shown to be effective in the treatment of a number of health conditions such as hypertension, heart failure, asthma, fibromyalgia and even psychological disorders however a systematic review in this field has yet to be conducted. Similarly, the number of large scale studies examining the use of respiratory biofeedback in rehabilitation is limited. Measurements of movement, postural control and force output can be made using a number of different devices and used to deliver biomechanical biofeedback. Inertial based sensing biofeedback is the most widely researched biomechanical biofeedback method, with a number of studies showing it to be effective in improving measures of balance in a number of populations. Other types of biomechanical biofeedback include force plate systems, electrogoniometry, pressure biofeedback and camera based systems however the evidence for these is limited. Biofeedback is generally delivered using visual displays, acoustic or haptic signals, however more recently virtual reality (VR) or exergaming technology have been used as biofeedback signals. VR and exergaming technology have been primarily investigated in post-CVA rehabilitation, however, more recent work has shown this type of biofeedback to be effective in improving exercise technique in musculoskeletal populations. While a number of studies in this area have been conducted, further large scale studies and reviews investigating different biofeedback applications in different clinical populations are required.

Inter-session reliability of the measurement of the deep and superficial layer of lumbar multifidus in young asymptomatic people and patients with low back pain using ultrasonography

STUDY DESIGN

Reliability study.

OBJECTIVE

To investigate the inter-session reliability of measuring the thickness of deep (dMF) and superficial layer of lumbar multifidus (sMF) using ultrasonography for participants with and without low back pain (LBP).

BACKGROUND

The lumbar multifidus is an important muscle in maintaining spinal stability. The dMF is considered important in maintaining tonic contraction and joint stability. Motor control impairment is also discovered in patients with LBP. However, no study to date has investigated the method of observing both the sMF and dMF through ultrasound imaging (USI).

METHODS

Twenty subjects aged 18-35 years old with LBP (N=10) and without LBP (N=10) were recruited. Every subject extended the upper trunk in prone lying with maximal isometric contraction. Simultaneously, the examiner measured the thickness of the dMF and the sMF using ultrasonography after ensuring the muscle belly was located. The participants performed three trials of isometric trunk extension in each session, with 30 min between each session. The reliability of measuring the change of thickness is represented by the intra-class correlation coefficient (ICC).

RESULTS

Through averaging three trials of measurement, the reliability of measuring the thickness of the dMF or the sMF in static or in the contracted condition, and the change of the thickness during contraction, is reliable (ICC=0.84-1.00).

CONCLUSIONS

The intra-rater inter-session reliability of measurement of the dMF and the sMF with USI has been established. This method could be applied to the qualification of the activation level of the dMF and the sMF with specific tasks.

Effect of motor control exercises versus graded activity in patients with chronic nonspecific low back pain: a randomized controlled trial

BACKGROUND

Motor control exercises to improve control and coordination of trunk muscles and graded activity under the principles of cognitive-behavioral therapy are 2 commonly used exercise therapies, yet there is little evidence to support the use of one intervention over the other.

OBJECTIVE

The objective of this study was to compare the effectiveness of motor control exercises and graded activity for patients with chronic nonspecific low back pain.

DESIGN

This study was a prospectively registered randomized controlled trial with outcome assessment and statistical analyses conducted blind to group.

SETTING

The study was conducted in primary care settings.

PATIENTS

The participants were 172 patients with chronic (>12 weeks) nonspecific low back pain.

INTERVENTIONS

Patients were randomly assigned to receive either motor control exercises or graded activity. There was no attempt to subclassify patients to match them to a treatment. Patients in both groups received 14 sessions of individualized, supervised exercise therapy.

MEASUREMENTS

Primary outcomes were average pain over the previous week (numeric rating scale) and function (Patient-Specific Functional Scale); secondary outcomes were disability (24-item Roland-Morris Disability Questionnaire), global impression of change (Global Perceived Effect Scale), and quality of life (36-Item Short-Form Health Survey questionnaire [SF-36]). Outcome measures were collected at baseline and at 2, 6, and 12 months after intervention.

RESULTS

A linear mixed models analysis showed that there were no significant differences between treatment groups at any of the time points for any of the outcomes studied. For example, the effect for pain at 2 months was 0.0 (-0.7 to 0.8).

LIMITATIONS

Clinicians could not be blinded to the interventions.

CONCLUSION

results of this study suggest that motor control exercises and graded activity have similar effects for patients with chronic nonspecific low back pain.

The effect of abdominal and pelvic floor muscle activation on urine flow in women

INTRODUCTION AND HYPOTHESIS

Interruption of urine flow during micturition has been used as an assessment of ability to voluntarily contract the pelvic floor muscles (PFM). However, the PFM are also activated during specific abdominal manoeuvres. This study aimed to assess the effect of similar abdominal manoeuvres on urine flow and compare this with the effect of PFM contraction.

METHODS

Eight healthy women, of mixed parity, contracted the abdominal muscles and the PFM during urine flow on separate occasions. Differences in urine flow were compared using paired t tests.

RESULTS

All participants were able to interrupt the urine stream using both muscle activation patterns. There was no difference in the time taken to interrupt urine flow (p = 0.78) between the two patterns.

CONCLUSIONS

These data provide evidence that specific abdominal muscle manoeuvres influence urethral closure in continent women, and this is probably mediated by concurrent activation of PFM during the abdominal task.

Use of ultrasound imaging by physiotherapists: a pilot study to survey use, skills and training

OBJECTIVE

This study aimed to design and pilot a questionnaire to survey the use of ultrasound imaging (USI) by physiotherapists in the United Kingdom (UK), the type and content of ultrasound training physiotherapists using USI had undertaken and their perceived future training needs.

BACKGROUND

The use of USI by physiotherapists is becoming increasingly common but is highly operator dependent and there are safety and professional issues regarding use in physiotherapy practice. Currently there are no specific training guidelines relating to physiotherapists using USI.

METHODS

A questionnaire was developed, based on research literature and guidelines. Twelve experts in USI commented on the content and design. The electronic on-line questionnaire was piloted on groups that were likely to be users of USI.

RESULTS

Forty-six respondents completed the questionnaire. Results indicated that USI is used predominantly for biofeedback and there are many unmet training needs. Respondents reported a mismatch between techniques for which they had received training and those that they used in practice and indicated a more structured training framework is required.

CONCLUSIONS

The development and piloting of the questionnaire provides a starting point for a more extensive evaluation of how USI is being used, the training needs of physiotherapists and benefits as a biofeedback tool. Refinement is needed and replication in a larger sample. Results could assist the development of a structured formal training framework encompassing key skills.

Magnetic resonance imaging assessment of regional abdominal muscle function in elite AFL players with and without low back pain

Changes in the motor control of trunk muscles have been identified in people with low back pain (LBP) including elite football players. Previous research has found functional differences in the anatomical regions of abdominal muscles; however, this has not been examined in football players with LBP. The aim of this study was to investigate if the ability to draw-in the abdominal wall is altered among football players with LBP, and to determine if there are functional differences between the middle and lower abdominal regions in participants with and without LBP. Forty-three elite Australian Football League players were imaged using magnetic resonance imaging (MRI) as they drew in their abdominal walls, and the trunk cross-sectional area (CSA) was measured in relaxed and contracted states. At the lower region, participants with LBP (1.1%) reduced their trunk CSA to a lesser extent than those without LBP (3.2%) (P = 0.018). The results also showed that the draw-in of the abdominal wall was smaller in Region 1 (8.8%) compared to Region 2 (16.0%) and Region 3 (19.7%) (P < 0.001). This study provides evidence of regional differences in motor control and altered control of the lower region in participants with LBP. This may direct physiotherapists, especially those treating athletes, to focus on the lower abdominal region in those with LBP.

Application of rehabilitative ultrasound in the assessment of low back pain: a literature review

Low back pain (LBP) is one of the most common work-related conditions affecting all populations both in industrialized and non-industrialized countries, with reported high prevalence and incidence rates and huge direct and indirect costs. Among various suggested causes of LBP, dysfunction of back muscles, particularly lumbar multifidus and transverse abdominis, has been the subject of considerable research during last decades. Of the available imaging techniques, ultrasound (US) imaging technique is increasingly used to assess muscle dimensions and function as a valid, reliable and non-invasive approach. The purpose of the present study was to review the previously published studies (1990-2009) concerning the merit of US imaging of lumbar and abdominal muscles with particular attention to its clinical application in patients with LBP. Studies showed wide variation in terms of methodology, sample size, procedure, definition of LBP, heterogeneous sample, method of analyzing US imaging, US imaging parameters, etc. However, a convincing body of evidence was identified that supports US imaging as a reliable and valid tool both to differentiate patients with LBP from normal subjects and to monitor the effect of rehabilitation programs.

The effects of rehabilitation on the muscles of the trunk following prolonged bed rest

Microgravity and inactivity due to prolonged bed rest have been shown to result in atrophy of spinal extensor muscles such as the multifidus, and either no atrophy or hypertrophy of flexor muscles such as the abdominal group and psoas muscle. These effects are long-lasting after bed rest and the potential effects of rehabilitation are unknown. This two-group intervention study aimed to investigate the effects of two rehabilitation programs on the recovery of lumbo-pelvic musculature following prolonged bed rest. 24 subjects underwent 60 days of head down tilt bed rest as part of the 2nd Berlin BedRest Study (BBR2-2). After bed rest, they underwent one of two exercise programs, trunk flexor and general strength (TFS) training or specific motor control (SMC) training. Magnetic resonance imaging of the lumbo-pelvic region was conducted at the start and end of bed rest and during the recovery period (14 and 90 days after re-ambulation). Cross-sectional areas (CSAs) of the multifidus, psoas, lumbar erector spinae and quadratus lumborum muscles were measured from L1 to L5. Morphological changes including disc volume, spinal length, lordosis angle and disc height were also measured. Both exercise programs restored the multifidus muscle to pre-bed-rest size, but further increases in psoas muscle size were seen in the TFS group up to 14 days after bed rest. There was no significant difference in the number of low back pain reports for the two rehabilitation groups (p=.59). The TFS program resulted in greater decreases in disc volume and anterior disc height. The SMC training program may be preferable to TFS training after bed rest as it restored the CSA of the multifidus muscle without generating potentially harmful compressive forces through the spine.

Abdominal muscle size and symmetry at rest and during abdominal hollowing exercises in healthy control subjects

The symmetry of, and physical characteristics influencing, the thickness of the lateral abdominal muscles at rest and during abdominal exercises were examined in 57 healthy subjects (20 men, 37 women; aged 22-62 years). M-mode ultrasound images were recorded from the abdominal muscles at rest and during abdominal hollowing exercises in hook-lying. The fascial lines bordering the transvs. abdominis, obliquus internus and obliquus externus were digitized and the absolute thickness, relative thickness (% of total lateral thickness) and contraction ratio (thickness during hollowing/thickness at rest), as well as the asymmetry (difference between sides expressed as a percent of the smallest value for the two sides) for each of these parameters were determined for each muscle. Both at rest and during hollowing, obliquus internus was the thickest and transvs. abdominis the thinnest muscle. There were no significant differences between left and right sides for group mean thicknesses of any muscle; however, individual asymmetries were evident, with mean values for the different muscles ranging from 11% to 26%; asymmetry was much less for the contraction ratios (mean % side differences, 5-14% depending on muscle). Body mass was the most significant positive predictor of absolute muscle thickness, for all muscles at rest and during hollowing, accounting for 30-44% variance. Body mass index explained 20-30% variance in transvs. abdominis contraction ratio (negative relationship). The influence of these confounders must be considered in comparative studies of healthy controls and back pain patients, unless groups are very carefully matched. Asymmetries observed in patients should be interpreted with caution, as they are also common in healthy subjects.

A magnetic resonance imaging investigation of the transversus abdominis muscle during drawing-in of the abdominal wall in elite Australian Football League players with and without low back pain

STUDY DESIGN

Single-blinded quasi-experimental study.

OBJECTIVE

To investigate the ability of elite football players with and without low back pain (LBP) to voluntarily draw-in the abdominal wall.

BACKGROUND

While there has been considerable debate regarding the contribution of the transversus abdominis (TrA) muscle to control the lumbar spine and pelvis, there is evidence that retraining motor control of the deep trunk muscles is commensurate with decreases in LBP. Magnetic resonance imaging (MRI) has been used to assess the TrA muscle during the draw-in maneuver, with the contraction of the TrA muscle reducing the circumference of the trunk. Impairments in performance of the draw-in maneuver have been shown in people with LBP.

METHODS

Forty-three elite players from a team in the Australian Football League were allocated to 3 groups: those with "no LBP," "a history of LBP but no current LBP," or "current LBP." MRI was used to image the cross-sectional area (CSA) of the trunk at the level of the L3-4 disc at the start and end of the draw-in maneuver.

RESULTS

There was a significant decrease in the CSA of the trunk with the performance of the draw-in maneuver (P<.001). Subjects in the "no LBP" group were better able to "draw-in" the abdominal wall than subjects with current LBP (P = .015).

CONCLUSIONS

This study provides evidence of an altered ability to draw-in the abdominal wall in footballers with current LBP. Retraining contraction of the TrA muscle may constitute one part of an exercise-therapy approach for athletes with current LBP.

Effect of stabilization training on multifidus muscle cross-sectional area among young elite cricketers with low back pain

STUDY DESIGN

A single-blinded, pretreatment-posttreatment assessment.

OBJECTIVES

To investigate, using ultrasound imaging, the cross-sectional area (CSA) of the lumbar multifidus muscle at 4 vertebral levels (L2, L3, L4, L5) in elite cricketers with and without low back pain (LBP) and (2) to document the effect of a staged stabilization training program on multifidus muscle CSA.

BACKGROUND

Despite high fitness levels and often intensive strength training programs, athletes still suffer LBP. The incidence of LBP among Australian cricketers is 8% and as high as 14% among fast bowlers. Previous researchers have found that the multifidus muscle contributes to segmental stability of the lumbopelvic region; however, the CSA of this muscle has not been previously assessed in elite cricketers.

METHODS AND MEASURES

CSAs of the multifidus muscles were assessed at rest on the left and right sides for 4 vertebral levels at the start and completion of a 13-week cricket training camp. Participants who reported current or previous LBP were placed in a rehabilitation group. The stabilization program involved voluntary contraction of the multifidus, transversus abdominis, and pelvic floor muscles, with real-time feedback from rehabilitative ultrasound imaging (RUSI), progressed from non-weight-bearing to weight-bearing positions and movement training. Pain scores (using a visual analogue scale) were also collected from those with LBP.

RESULTS

The CSAs of the multifidus muscles at the L5 vertebral level increased for the 7 cricketers with LBP who received the stabilization training, compared with the 14 cricketers without LBP who did not receive rehabilitation (P = .004). In addition, the amount of muscle asymmetry among those with LBP significantly decreased (P = .029) and became comparable to cricketers without LBP. These effects were not evident for the L2, L3, and L4 vertebral levels. There was also a 50% decrease in the mean reported pain level among the cricketers with LBP.

CONCLUSION

Multifidus muscle atrophy can exist in highly active, elite athletes with LBP. Specific retraining resulted in an improvement in multifidus muscle CSA and this was concomitant with a decrease in pain.

LEVEL OF EVIDENCE

Therapy, level 2b.

Muscle thickness changes during abdominal hollowing: an assessment of between-day measurement error in controls and patients with chronic low back pain

Spine stabilization exercises, in which patients are taught to perform isolated contractions of the transverses abdominus (TrA) during "abdominal hollowing", are a popular physiotherapeutic treatment for low back pain (LBP). Successful performance is typically judged by the relative increase in TrA thickness compared with that of the internal (OI) and external (OE) oblique muscles, measured using ultrasound. The day-to-day measurement error (imprecision) associated with these indices of preferential activation has not been assessed but is important to know since it influences the interpretation of changes after treatment. On 2 separate days, 14 controls and 14 patients with chronic LBP (cLBP) performed abdominal hollowing exercises in hook-lying, while M-mode ultrasound images superimposed with tissue Doppler imaging (TDI) data were recorded from the abdominal muscles (N = 5 on each side). The fascial lines bordering the TrA, OI and OE were digitized, and muscle thicknesses were calculated. The between-day error (intra-observer) was expressed as the standard error of measurement, SEM; SEM as a percentage of the mean gave the coefficient of variation (CV). There were no significant between-day differences for the mean values of resting or maximal thickness for any muscle, in either group (P > 0.05). The median SEM and CV of all thickness variables was 0.71 mm and 10.9%, respectively for the controls and 0.80 mm or 11.3%, respectively for the cLBP patients. For the contraction ratios (muscle thickness contracted/thickness at rest), the CVs were 3-11% (controls) and 5-12% (patients). The CVs were unacceptably high (30-50%, both groups) for the TrA preferential activation ratio (TrA proportion of the total lateral abdominal muscle thickness when contracted minus at rest). In both the controls and patients, the precision of measurement of absolute muscle thickness and relative change in thickness during abdominal hollowing was acceptable, and commensurate with that typical of biological measurements. The TrA preferential activation ratio is too imprecise to be of clinical use. Knowledge of the SEM for these indices is essential for interpreting the clinical relevance of any changes observed following physiotherapy.

Rehabilitative ultrasound imaging of the posterior paraspinal muscles

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.

The Reproducibility of a Clinical Grading System of Motor Control in Patients with Low Back Pain

OBJECTIVE

Over the past decade, instrument and palpation methods for quantifying the activation and recruitment of the transversus abdominis and lumbar multifidus have been proposed. Palpation methods however have recently been described and therefore have been subjected to little evaluation. One such palpation method is the Wisbey-Roth grading system. The recruitment of the transversus abdominis and lumbar multifidus is assessed in a series of functional body positions and movements. The ability to recruit these muscles is quantified by assigning 1 of 6 defined grades. The purpose of this study was to investigate the reproducibility of this grading system.

METHODS

A total of 2 meetings and 3 pilot trials were held with raters before commencement of the study to establish an agreed grading system protocol. Interrater reproducibility was investigated using a Latin square repeated measures design. Thirty-four subjects (62% male and 38% female; age range, 15-70 years) with a history of low back pain participated. A total of 4 practicing physiotherapists and 1 sports medicine physician graded subjects using the Wisbey-Roth grading system protocol.

RESULTS

Pair-wise weighted kappa values ranged from -0.01 (95% confidence interval [CI], -0.33 to 0.31) to 0.56 (95% CI, 0.25 to 0.87), with average weighted kappa being 0.29. The intraclass correlation coefficient (2,1) was 0.30 (95% CI, 0.15 to 0.48), and the standard error of the measurement was 1.6 units.

CONCLUSIONS

The Wisbey-Roth grading system shows fair to poor reproducibility between raters. Therefore, it should not be used to exchange meaningful information between clinicians. Recommendations are made for further research and toward improving its reproducibility.

Rehabilitative ultrasound imaging: understanding the technology and its applications

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.

Ultrasound imaging assessment of abdominal muscle function during drawing-in of the abdominal wall: an intrarater reliability study

STUDY DESIGN

Test-retest intrarater reliability study.

OBJECTIVE

To examine reliability of abdominal musculature measurements across a broad range of conditions for a physical therapist newly trained in assessment using rehabilitative ultrasound imaging (RUSI).

BACKGROUND

RUSI has previously been used to assess abdominal muscle function during a drawing-in maneuver of the anterior abdominal wall, and measurements conducted by an experienced assessor have been validated by comparison with magnetic resonance imaging. Few studies have examined the reliability of less experienced operators, and only in isolated measurement conditions.

METHODS AND MEASURES

Nineteen subjects (11 female, 8 male) without a history of low back pain performed the abdominal drawing-in maneuver in a supine hook-lying position. RUSI was used bilaterally to assess the thickness of the internal oblique (IO) and transversus abdominis (TrA) muscles at rest and on contraction, as well as changes in the length of the TrA muscle (indicated by slide of the anterior abdominal fascia). The reliability of a novice rater who received 8 hours of training was examined (a) across 3 measurements of the same ultrasound image, (b) across 3 separate ultrasound images (averaged for days and sides of abdomen), and (c) across 2 days (averaged for images and sides).

RESULTS

Reliability of assessing muscle thickness was very high across 3 measurements of the sale image (intrarater correlation coefficients [ICC3.1] were all greater than 0.97), fair to high across 3 images (ICC(3,4) = 0.62-0.82), and fair to high across 2 days (ICC(3,6) = 0.63-0.85). Reliability of measuring the slide of the anterior abdominal fascia was very high across measurements from the same image (ICC(3,1) = 0.98) but very low across images (ICC(3,4) = 0.44) and across 2 days (ICC(3,6) = 0.36).

CONCLUSIONS

High reliability of a novice rater was demonstrated for some measurement conditions. Measures of reliability for recapturing the image and repetition across days ranged from low to high. Inconsistencies in the pattern of results suggest that for a novice assessor using RUSI, training should be performed and reliability assessed for each abdominal muscle and measurement condition intended to be used for research and clinical practice.

The use of real-time ultrasound imaging for biofeedback of lumbar multifidus muscle contraction in healthy subjects

STUDY DESIGN

Randomized controlled trial.

OBJECTIVE

To determine if the provision of visual biofeedback using real-time ultrasound imaging enhances the ability to activate the multifidus muscle.

BACKGROUND

Increasingly clinicians are using real-time ultrasound as a form of biofeedback when re-educating muscle activation. The effectiveness of this form of biofeedback for the multifidus muscle has not been reported.

METHODS AND MEASURES

Healthy subjects were randomly divided into groups that received different forms of biofeedback. All subjects received clinical instruction on how to activate the multifidus muscle isometrically prior to testing and verbal feedback regarding the amount of multifidus contraction, which occurred during 10 repetitions (acquisition phase). In addition, 1 group received visual biofeedback (watched the multifidus muscle contract) using real-time ultrasound imaging. All subjects were reassessed a week later (retention phase).

RESULTS

Subjects from both groups improved their voluntary contraction of the multifidus muscle in the acquisition phase (P<.001) and the ability to recruit the multifidus muscle differed between groups (P<.05), with subjects in the group that received visual ultrasound biofeedback achieving greater improvements. In addition, the group that received visual ultrasound biofeedback retained their improvement in performance from week 1 to week 2 (P>.90), whereas the performance of the other group decreased (P<.05).

CONCLUSION

Real-time ultrasound imaging can be used to provide visual biofeedback and improve performance and retention in the ability to activate the multifidus muscle in healthy subjects.

Measurement of lumbar multifidus muscle contraction with rehabilitative ultrasound imaging

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 (r=.79,P<.001). 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 (F(3,12)=25.39,P<.001). 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.