What is the Latest Research on Ultrasound Retraining?
The following articles are written in a technical language. If you do not posses some medical training, we suggest that you skip this page.
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The following reference list targets research articles which are relevant to studies completed on the transversus abdominis, multifidus, real-time ultrasound retraining and its relationship to low back pain.
(Updated June, 2007)
Tsao H, Hodges PW. Immediate changes in feedforward postural adjustments following voluntary motor training. Exp Brain Res. 2007 May 3; [Epub ahead of print]
There is limited evidence that preprogrammed feedforward adjustments, which are modified in people with neurological and musculoskeletal conditions, can be trained and whether this depends on the type of training. As previous findings demonstrate consistent delays in feedforward activation of the deep abdominal muscle, transversus abdominis (TrA), in people with recurrent low back pain (LBP), we investigated whether training involving voluntary muscle activation can change feedforward mechanisms, and whether this depends on the manner in which the muscle is trained. Twenty-two volunteers with recurrent LBP were randomly assigned to undertake either training of isolated voluntary activation of TrA or sit-up training to activate TrA in a non-isolated manner to identical amplitude. Subjects performed a trunk perturbation task involving arm movement prior to and after training, and surface and fine-wire electromyography (EMG) recordings were made from trunk and arm muscles. Following a single session of training of isolated voluntary activation of TrA, onset of TrA EMG was earlier during rapid arm flexion and extension, to more closely resemble the responses in pain-free individuals. The magnitude of change in TrA EMG onset was correlated with the quality of isolated training. In contrast, all of the abdominal muscles were recruited earlier during arm flexion after sit-up training, while onset of TrA EMG was further delayed during arm extension. The results provide evidence that training of isolated muscle activation leads to changes in feedforward postural strategies, and the magnitude of the effect is dependent on the type and quality of motor training.
Ferreira ML, Ferreira PH, Hodges PW. Changes in postural activity of the trunk muscles following spinal manipulative therapy.Man Ther. 2007 Apr 21; [Epub ahead of print]
Spinal manipulative therapy (SMT) is common in the management of low back pain (LBP) and has been associated with changes in muscle activity, but evidence is conflicting. This study investigated the effect of SMT on trunk muscle activity in postural tasks in people with and without LBP. In 20 subjects (10 with LBP and 10 controls), EMG recordings were made with fine-wire electrodes inserted into transversus (TrA), obliquus internus (OI), and externus (OE) abdominis. Rectus abdominis (RA) and anterior deltoid EMG was recorded with surface electrodes. Standing subjects rapidly flexed an arm in response to a light, before and after a small amplitude end range rotational lumbar mobilization at L4-5. In controls, there was no change in trunk muscle EMG during the postural perturbation after SMT. In LBP subjects there was an increase in the postural response of OI and an overall increase in OE EMG. There was no change in TrA or RA EMG. These results indicate that SMT changes the functional activity of trunk muscles in people with LBP, but has no effect on control subjects. Importantly, SMT increased the activity of the oblique abdominal muscles with no change in the deep trunk muscle TrA, which is often the target of exercise interventions.
Tsao H, Hodges PW. Persistence of improvements in postural strategies following motor control training in people with recurrent low back pain.J Electromyogr Kinesiol. 2007 Mar 1; [Epub ahead of print]
This study investigated long-term effects of training on postural control using the model of deficits in activation of transversus abdominis (TrA) in people with recurrent low back pain (LBP). Nine volunteers with LBP attended four sessions for assessment and/or training (initial, two weeks, four weeks and six months). Training of repeated isolated voluntary TrA contractions were performed at the initial and two-week session with feedback from real-time ultrasound imaging. Home program involved training twice daily for four weeks. Electromyographic activity (EMG) of trunk and deltoid muscles was recorded with surface and fine-wire electrodes. Rapid arm movement and walking were performed at each session, and immediately after training on the first two sessions. Onset of trunk muscle activation relative to prime mover deltoid during arm movements, and the coefficient of variation (CV) of EMG during averaged gait cycle were calculated. Over four weeks of training, onset of TrA EMG was earlier during arm movements and CV of TrA EMG was reduced (consistent with more sustained EMG activity). Changes were retained at six months follow-up (p<0.05). These results show persistence of motor control changes following training and demonstrate that this training approach leads to motor learning of automatic postural control strategies.
MacDonald DA, Moseley GL, Hodges PW. The lumbar multifidus: does the evidence support clinical beliefs?Man Ther. 2006 Nov;11(4):254-63. Epub 2006 May 23.
The contribution of the trunk muscles to spinal stability is well established. There is convincing evidence for the role of multifidus in spinal stability. Recently, emphasis has shifted to the deep fibres of this muscle (DM) and five key clinical beliefs have arisen: (i) that DM stabilizes the lumbar spine whereas the superficial fibres of lumbar multifidus (SM) and the erector spinae (ES) extend and/or rotate the lumbar spine, (ii) that DM has a greater percentage of type I (slow twitch) muscle fibres than SM and ES, (iii) that DM is tonically active during movements of the trunk and gait, whereas SM and ES are phasically active, (iv) that DM and the transversus abdominis (TrA) co-contract during function, and (v) that changes in the lumbar paraspinal muscles associated with LBP affect DM more than SM or ES. This paper reviews the biomechanical, electromyographic, histochemical and morphological data that underpin these beliefs. Although there is support for the importance of the lumbar multifidus and the specific contribution of this muscle to intervertebral control, several of the clinical beliefs have little or no support and require further evaluation. These findings have implications for clinical practice.
Springer BA, Mielcarek BJ, Nesfield TK, Teyhen DS. Relationships among lateral abdominal muscles, gender, body mass index, and hand dominance.J Orthop Sports Phys Ther. 2006 May;36(5):289-97.
STUDY DESIGN: Exploratory. OBJECTIVES: To explore whether hand dominance, gender, and body mass index (BMI) influence the thickness of the lateral abdominal muscles as measured by ultrasound imaging. To document the extent of improvement in response stability when an average of multiple measures was utilized. BACKGROUND: Ultrasound imaging is a relatively new tool used to assess the lateral abdominal muscles. A better understanding of how these muscles contract in a healthy population can provide a reference for comparison to patients with low back pain (LBP). METHODS AND MEASURES: Thirty-two healthy participants (17 males, 15 females) aged 18 to 45 years (mean +/- SD, 31.9 +/- 7.8 years) were studied. Measurements of muscular thickness of the lateral abdominal muscles were obtained bilaterally while the subjects were at rest, and while they performed the abdominal drawing-in maneuver. To determine the possible influence of hand dominance and gender on muscle thickness, t tests were used. Correlation coefficients were used to assess the relationship between BMI and muscle thickness. Standard error of the measurement was used to assess response stability of the ultrasound imaging technique. RESULTS: No differences in the thicknesses of the transversus abdominis (TrA) muscle were measured during rest or while contracted, based on hand dominance (P > or = .73). Men had greater muscular thickness (P<.01), while the TrA in women represented a greater proportion of the total lateral abdominal muscles (P<.01). BMI was positively associated with muscle thickness (r> or =.66). Compared to a singular measurement, response stability improved by greater than 50% when an average of 3 measurements was used. CONCLUSIONS: Future researchers should assess the need to control for gender and BMI as potential covariates in ultrasound imaging studies of the lateral abdominal muscles. Asymmetry in the lateral abdominal muscles in those with LBP would be in direct contrast to the bilateral symmetry measured in those without LBP.
Hides J, Wilson S, Stanton W, McMahon S, Keto H, McMahon K, Bryant M, Richardson C. An MRI investigation into the function of the transversus abdominis muscle during "drawing-in" of the abdominal wall. Spine. 2006 Mar 15;31(6):E175-8.
STUDY DESIGN: An operator blinded dual modality trial of measurement of the abdominal muscles during "drawing-in" of the abdominal wall. OBJECTIVES: 1) To investigate, using magnetic resonance imaging (MRI), the function of the transversus abdominis muscle bilaterally during a drawing-in of the abdominal wall. 2) To validate the use of real-time ultrasound imaging as a measure of the deep abdominal muscle during a drawing-in of the abdominal wall. SUMMARY OF BACKGROUND DATA: Previous research has implicated the deep abdominal muscle, transversus abdominis, in the support and protection of the spine and provided evidence that training this muscle is important in the rehabilitation of low back pain. One of the most important actions of the transversus abdominis is to "draw-in" the abdominal wall, and this action has been shown to stiffen the sacroiliac joints. It is hypothesized that in response to a draw in, the transversus abdominis muscle forms a deep musculofascial "corset" and that MRI could be used to view this corset and verify its mechanism of action on the lumbopelvic region. METHODS: Thirteen healthy asymptomatic male elite cricket players aged 21.3 +/- 2.1 years were imaged using MRI and ultrasound imaging as they drew in their abdominal walls. Measurements of the thickness of the transversus abdominis and internal oblique muscles and the slide of the anterior abdominal fascia were measured using both MRI and ultrasound. Measurement of the whole abdominal cross-sectional area (CSA) was conducted using MRI. RESULTS: Results of the MRI demonstrated that, as a result of draw-in, there was a significant increase in thickness of the transversus abdominis (P < 0.001) and the internal oblique muscles (P < 0.001). There was a significant decrease in the CSA of the trunk (P < 0.001). The mean slide (+/-SD) of the anterior abdominal fascia was 1.54 +/- 0.38 cm for the left side and 1.48 +/- 0.35 cm for the right side. Ultrasound measurements of muscle thickness of both transversus abdominis and the internal oblique, as well as fascial slide, correlated with measures obtained using MRI (interclass correlations from 0.78 to 0.95). CONCLUSIONS: The MRI results demonstrated that during a drawing-in action, the transversus abdominis contracts bilaterally to form a musculofascial band that appears to tighten (like a corset) and most likely improves the stabilization of the lumbopelvic region. Real-time ultrasound imaging can also be used to measure changes in the transversus abdominis during the draw-in maneuver.
Urquhart DM, Hodges PW, Story IH. Postural activity of the abdominal muscles varies between regions of these muscles and between body positions.Gait Posture. 2005 Dec;22(4):295-301. Epub 2005 Jan 19.
The abdominal muscles have an important role in control and movement of the lumbar spine and pelvis. Given there is new evidence of morphological and functional differences between distinct anatomical regions of the abdominal muscles, this study investigated whether there are regional differences in postural activity of these muscles and whether recruitment varies between different body positions. Eleven subjects with no history of low back pain that affected function or for which they sought treatment participated in the study. Electromyographic (EMG) activity of the upper, middle and lower regions of transversus abdominis (TrA), the middle and lower regions of obliquus internus abdominis (OI) and the middle region of obliquus externus abdominis (OE) was recorded using intramuscular electrodes. All subjects performed rapid, unilateral shoulder flexion in standing and six subjects also moved their upper limb in sitting. There were regional differences in the postural responses of TrA with limb movement. Notably, the onset of EMG of the upper region was later than that of the lower and middle regions. There were no differences in the EMG onsets of lower and middle TrA or OI. The postural responses of the abdominal muscles were also found to differ between body positions, with recruitment delayed in sitting compared to standing. This study showed that there is regional differentiation in TrA activity with challenges to postural control and that body position influences the postural responses of the abdominal muscles. These results may reflect variation in the contribution of abdominal muscle regions to stability of the trunk.
Snijders CJ, Hermans PF, Kleinrensink GJ. Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints.Clin Biomech (Bristol, Avon). 2006 Feb;21(2):116-21. Epub 2005 Nov 2
BACKGROUND: Transversely oriented pelvic muscles such as the internal abdominal oblique, transversus abdominis, piriformis and pelvic floor muscles may contribute to sacroiliac joint stability by pressing the sacrum between the hipbones. Surface electromyographic measurements showed that leg crossing lowers the activity of the internal oblique abdominal muscle significantly. This suggests that leg crossing is a substitute for abdominal muscle activity. No previous studies addressed piriformis muscle and related pelvic structures in cross-legged sitting. METHODS: Angles of pelvis and femur were measured in healthy subjects in standing, normal sitting and cross-legged sitting, and were used to simulate these postures on embalmed pelvises and measure piriformis muscle elongation. Deformations of pelvic ring and iliolumbar ligament caused by piriformis muscle force were measured on embalmed pelvises. FINDINGS: Cross-legged sitting resulted in a relative elongation of the piriformis muscle of 11.7% compared to normal sitting and even 21.4% compared to standing. Application of piriformis muscle force resulted in inward deformation of the pelvic ring and compression of the sacroiliac joints and the dorsal side of the pubic symphysis. INTERPRETATION: Cross-legged sitting is common. We believe that it contributes to sacroiliac joint stability. This study demonstrates the influence of the piriformis muscle on sacroiliac joint compression. The elongation of the piriformis muscle bilaterally by crossing the legs may be functional in the build-up of active or passive tension between sacrum and femur.
Richardson CA, Hides JA, Wilson S, Stanton W, Snijders CJ. Lumbo-pelvic joint protection against antigravity forces: motor control and segmental stiffness assessed with magnetic resonance imaging. : J Gravit Physiol. 2004 Jul;11(2):P119-22.
The antigravity muscles of the lumbo-pelvic region, especially transversus abdominis (TrA), are important for the protection and support of the weightbearing joints. Measures of TrA function (the response to the postural cue of drawing in the abdominal wall) have been developed and quantified using magnetic resonance imaging (MRI). Cross-sections through the trunk allowed muscle contraction as well as the large fascial attachments of the TrA to be visualized. The cross sectional area (CSA) of the deep musculo-fascial system was measured at rest and in the contracted state, using static images as well as a cine sequence. In this developmental study, MRI measures were undertaken on a small sample of low back pain (LBP) and non LBP subjects. Results demonstrated that, in non LBP subjects, the draw in action produced a symmetrical deep musculo-fascial "corset" which encircles the abdomen. This study demonstrated a difference in this "corset" measure between subjects with and without LBP. These measures may also prove useful to quantify the effect of unloading in bedrest and microgravity exposure.
Barnett F, Gilleard W. The use of lumbar spinal stabilization techniques during the performance of abdominal strengthening exercise variations.J Sports Med Phys Fitness. 2005 Mar;45(1):38-43.
AIM: The lumbar spinal stabilization techniques in abdominal hollowing and bracing are known to facilitate the level of activity in the muscles transversus abdominis and obliquus internus (TA/OI). The relative timing of activation and the effect of combination with other tasks are currently unknown. The objective of this study was to determine whether the performance of abdominal hollowing and bracing could promote the voluntary preferential recruitment of TA/OI muscles when performed prior to abdominal strengthening exercise variations. METHODS: The trunk muscles TA/OI, rectus abdominis and obliquus externus were investigated using surface EMG. A pressure transducer under the lumbar spine detected spinal movement. Eighteen male subjects performed a series of 4 abdominal strengthening exercise variations. Pressure cuff and electromyographic onset times were collected and analyzed. RESULTS: TA/OI muscle site was recruited significantly earlier than the upper rectus abdominis site for the hollow with curl exercise. The TA/OI site was also ranked as first activated site in the majority of subjects during exercises where stabilization techniques of hollowing and bracing were used. CONCLUSIONS: Abdominal hollowing was an effective method for selective preferential voluntary recruitment of TA/OI site prior to the performance of the curl type abdominal strengthening exercise variation. The other variations brace with curl and hold and hollow with rotation also tend to recruit TA/OI site first, however the timing was not significantly different.
Moseley GL, Hodges PW. Are the changes in postural control associated with low back pain caused by pain interference?Clin J Pain. 2005 Jul-Aug;21(4):323-9.
BACKGROUND: Voluntary limb movements are associated with involuntary and automatic postural adjustments of the trunk muscles. These postural adjustments occur prior to movement and prevent unwanted perturbation of the trunk. In low back pain, postural adjustments of the trunk muscles are altered such that the deep trunk muscles are consistently delayed and the superficial trunk muscles are sometimes augmented. This alteration of postural adjustments may reflect disruption of normal postural control imparted by reduced central nervous system resources available during pain, so-called "pain interference," or reflect adoption of an alternate postural adjustment strategy. METHODS: We aimed to clarify this by recording electromyographic activity of the upper (obliquus externus) and lower (transversus abdominis/obliquus internus) abdominal muscles during voluntary arm movements that were coupled with painful cutaneous stimulation at the low back. If the effect of pain on postural adjustments is caused by pain interference, it should be greatest at the onset of the stimulus, should habituate with repeated exposure, and be absent immediately when the threat of pain is removed. Sixteen patients performed 30 forward movements of the right arm in response to a visual cue (control). Seventy trials were then conducted in which arm movement was coupled with pain ("pain trials") and then a further 70 trials were conducted without the pain stimulus ("no pain trials"). RESULTS: There was a gradual and increasing delay of transversus abdominis/obliquus internus electromyograph and augmentation of obliquus externus during the pain trials, both of which gradually returned to control values during the no pain trials. CONCLUSION: The results suggest that altered postural adjustments of the trunk muscles during pain are not caused by pain interference but are likely to reflect development and adoption of an alternate postural adjustment strategy, which may serve to limit the amplitude and velocity of trunk excursion caused by arm movement.
Urquhart DM, Hodges PW, Allen TJ, Story IH. Abdominal muscle recruitment during a range of voluntary exercises.Man Ther. 2005 May;10(2):144-53.
Various exercises are used to retrain the abdominal muscles in the management of low back pain and other musculoskeletal disorders. However, few studies have directly investigated the activity of all the abdominal muscles or the recruitment of regions of the abdominal muscles during these manoeuvres. This study examined the activity of different regions of transversus abdominis (TrA), obliquus internus (OI) and externus abdominis (OE), and rectus abdominis (RA), and movement of the lumbar spine, pelvis and abdomen during inward movement of the lower abdominal wall, abdominal bracing, pelvic tilting, and inward movement of the lower and upper abdominal wall. Inward movement of the lower abdominal wall in supine produced greater activity of TrA compared to OI, OE and RA. During posterior pelvic tilting, middle OI was most active and with abdominal bracing, OE was predominantly recruited. Regions of TrA were recruited differentially and an inverse relationship between lumbopelvic motion and TrA electromyography (EMG) was found. This study indicates that inward movement of the lower abdominal wall in supine produces the most independent activity of TrA relative to the other abdominal muscles, recruitment varies between regions of TrA, and observation of abdominal and lumbopelvic motion may assist in evaluation of exercise performance.
Ferreira PH, Ferreira ML, Hodges PW. Changes in recruitment of the abdominal muscles in people with low back pain: ultrasound measurement of muscle activity.Spine. 2004 Nov 15;29(22):2560-6.
STUDY DESIGN: Ultrasound and electromyographic (EMG) measures of trunk muscle activity were compared between low back pain (LBP) and control subjects in a cross-sectional study. OBJECTIVES: To compare the recruitment of the abdominal muscles (measured as a change in thickness with ultrasound imaging) between people with and without low back pain and to compare these measurements with EMG recordings made with intramuscular electrodes. SUMMARY OF BACKGROUND DATA: Although ultrasonography has been advocated as a noninvasive measure of abdominal muscle activity, it is not known whether it can provide a valid measure of changes in motor control of the abdominal muscles in LBP. METHODS: Ten subjects with recurrent LBP and 10 matched controls were tested during isometric low load tasks with their limbs suspended. Changes in thickness from resting baseline values were obtained for transversus abdominis (TrA), obliquus internus (OI), and obliquus externus (OE) using ultrasonography. Fine wire EMG was measured concurrently. RESULTS: Study participants with LBP had a significantly smaller increase in TrA thickness with isometric leg tasks compared with controls. No difference was found between groups for OI or OE. Similar results were found for EMG. People with LBP had less TrA EMG activity with leg tasks, and there was no difference between groups for EMG activity for OI or OE. CONCLUSIONS: This study reinforces evidence for changes in automatic control of TrA in people with LBP. Furthermore, the data establish a new test of recruitment of the abdominal muscles in people with LBP. This test presents a feasible noninvasive test of automatic recruitment of the abdominal muscles.
McMeeken JM, Beith ID, Newham DJ, Milligan P, Critchley DJ. The relationship between EMG and change in thickness of transversus abdominis.Clin Biomech (Bristol, Avon). 2004 May;19(4):337-42.
OBJECTIVE: To investigate the relationship between changes in thickness and EMG activity in the transversus abdominis muscle of healthy subjects and the reliability of ultrasound measurements using different modes and transducers. DESIGN: Convenience sampling. BACKGROUND: Chronic low back pain is associated with transversus abdominis dysfunction but EMG studies of this muscle are restricted to invasive techniques. Since the thickness of transversus abdominis changes with activity, such changes measured from ultrasound images might provide insight into this muscle's function non-invasively. In addition, little is known about the comparability of ultrasound measurements from different modes and transducers, nor the reliability of transversus abdominis measurements. METHODS: In 9 healthy subjects (aged 29-52 years, four male) transversus abdominis was studied at rest and during activity (5-80% max) with simultaneous EMG and ultrasound (M mode, 5 MHz curvilinear transducer) measurements. Intra-rater reliability for thickness measurements was studied on 13 subjects using 7.5 MHz linear and 5 MHz curvilinear transducers in B and M modes. RESULTS: Muscle thickness changes correlated well with EMG activity (P < 0.001, R2 = 0.87) and there were no significant differences between subjects (P > 0.05). Using 7.5 MHz head, the ICC for B mode was 0.989 and for M mode was 0.981 for between days reliability. The ICC for between transducer reliability was 0.817. CONCLUSIONS: Changes in thickness of transversus abdominis can be used to indicate changes in the electrical activity in this muscle. RELEVANCE: Ultrasound scanning can be used in the clinical setting to provide objective information about transversus abdominis function.
Kidd AW, Magee S, Richardson CA. Reliability of real-time ultrasound for the assessment of transversus abdominis function.J Gravit Physiol. 2002 Jul;9(1):P131-2.
Transversus abdominis (TrA) has now been established as a key muscle for the stabilization of the lumbar spine and sacroiliac joints. Significantly, dysfunction of this muscle has also been implicated in low back pain. Real-time ultrasound ( US) is a non-invasive procedure that has the potential to evaluate objectively the function of TrA. Objective: To investigate M-mode US as a reliable method of assessing TrA function. Method: M-mode US was used to measure the width of TrA as subjects drew in their lower abdominal wall at a controlled speed to a target depth. Eleven subjects were imaged. Results: the measures of TrA width were reliable and ranged between 3.14mm relaxed and 6.35mm contracted. The standard error of measurement ranged between 0.18mm and 0.57mm. Conclusion: M-mode US provides a reliable non-invasive measure of a controlled contraction of TrA.
Bunce SM, Hough AD, Moore AP. Measurement of abdominal muscle thickness using M-mode ultrasound imaging during functional activities.Man Ther. 2004 Feb;9(1):41-4.
Ultrasound imaging has been previously utilized in the measurement of muscle thickness and cross-sectional area in research studies, and advocated as a clinical biofeedback tool in the rehabilitation of transversus abdominis function following episodes of low back pain. This paper describes how the thickness of the abdominal muscles can be quantified with a new measurement technique using M-mode ultrasound. The technique uses a custom-made transducer holder that facilitates measurement of muscle thickness changes during functional activity. Limitations of the technique and potential future applications are discussed. The M-mode ultrasound technique may provide an effective method for the non-invasive measurement of abdominal muscle thickness during functional activities.
Kladny B, Fischer FC, Haase I. Evaluation of specific stabilizing exercise in the treatment of low back pain and lumbar disk disease in outpatient rehabilitationZ Orthop Ihre Grenzgeb. 2003 Jul-Aug;141(4):401-5.
AIM: The aim of the study was to evaluate the outcome of outpatient rehabilitation in patients with low back pain and lumbar disk disease with a specific stabilizing exercise of the M. multifidus and M. transversus abdominis. METHOD: 99 outpatients admitted to a rehabilitation unit were included in a prospective randomized controlled interventional trial. The interventional group consisted of 50 patients (34 male, 16 female; mean age 41.1 +/- 9.1, range; 21 - 54 years), 49 patients (31 male, 18 female; mean age 37.9 +/- 9.5, range; 19 - 55 years) were in the control group. Outcomes were assessed at the beginning and the end of the treatment and at a three month follow-up with the Oswestry Low Back Pain Disability Questionnaire, the Hannover Functional Ability Questionnaire FFbH-R, the pain scale SES and a numeric rating scale. RESULTS: In both groups there was a significant functional improvement as measured with the Oswestry Score and the FFbH-R. The interventional group showed better values at the end of the treatment. Pain as well could be reduced significantly by the treatment, but no differences were noted between the two groups. CONCLUSION: Outpatient rehabilitation improved functional capacity and pain in both groups. Advantages could be seen in the interventional group concerning functional status. The specific stabilizing exercise approach appears to be effective in conservative treatment programs of low back pain and lumbar disk disease.
Hodges PW, Moseley GL, Gabrielsson A, Gandevia SC. Experimental muscle pain changes feedforward postural responses of the trunk muscles.Exp Brain Res. 2003 Jul;151(2):262-71. Epub 2003 Jun 3
Many studies have identified changes in trunk muscle recruitment in clinical low back pain (LBP). However, due to the heterogeneity of the LBP population these changes have been variable and it has been impossible to identify a cause-effect relationship. Several studies have identified a consistent change in the feedforward postural response of transversus abdominis (TrA), the deepest abdominal muscle, in association with arm movements in chronic LBP. This study aimed to determine whether the feedforward recruitment of the trunk muscles in a postural task could be altered by acute experimentally induced LBP. Electromyographic (EMG) recordings of the abdominal and paraspinal muscles were made during arm movements in a control trial, following the injection of isotonic (non-painful) and hypertonic (painful) saline into the longissimus muscle at L4, and during a 1-h follow-up. Movements included rapid arm flexion in response to a light and repetitive arm flexion-extension. Temporal and spatial EMG parameters were measured. The onset and amplitude of EMG of most muscles was changed in a variable manner during the period of experimentally induced pain. However, across movement trials and subjects the activation of TrA was consistently reduced in amplitude or delayed. Analyses in the time and frequency domain were used to confirm these findings. The results suggest that acute experimentally induced pain may affect feedforward postural activity of the trunk muscles. Although the response was variable, pain produced differential changes in the motor control of the trunk muscles, with consistent impairment of TrA activity.
Storheim K, Bø K, Pederstad O, Jahnsen R. Intra-tester reproducibility of pressure biofeedback in measurement of transversus abdominis function.Physiother Res Int. 2002;7(4):239-49.
BACKGROUND AND PURPOSE: Strength, co-ordination and timing of transversus abdominis muscle contraction may be important in stabilizing the low back, and contraction of this particular abdominal muscle may be one factor capable of preventing and reducing low back pain in sport and in activities of daily living. The function and strength of the transversus abdominis muscle is difficult to measure. The pressure biofeedback unit (PBU) is a device designed to teach and measure transversus abdominis muscle function. The purpose of the present study was to evaluate intra-tester reproducibility of the PBU. METHOD: The study used a test-retest design. Fifteen healthy subjects (mean age 22.2 years, range 19-28 years) with no history of low back pain participated in the study. After two sessions of practising transversus abdominis muscle contraction, its function was measured in prone position with the PBU device placed over the transversus abdominis muscle. Subjects were instructed to draw in the abdominal wall (for example, lifting it away from the device) after a standardized procedure. Two tests were conducted on two different days, with a seven-day interval in between. RESULTS: Coefficient of variance (CV) was 21.0% and the standard deviation (SD) of delta was 1.59. CONCLUSION: The use of the PBU should be improved for scientific purposes. However, the device may have a role in providing biofeedback to assist in the instruction of correct transversus abdominis muscle contraction.
Grimshaw P, Giles A, Tong R, Grimmer K. Lower back and elbow injuries in golf.Sports Med. 2002;32(10):655-66.
Golf injuries to the lower back and elbow are common problems in both the professional and amateur player, and any information regarding the successful treatment of these injuries has important implications for the medical practitioner. This paper presents the successful management and outcome of two case studies associated with low back pain and lateral epicondylitis in golf. Exercise therapy and conditioning has been shown to be an effective treatment modality for these two types of injury. In particular, a dynamic exercise programme which incorporates golf functional rehabilitation, is a modern and accepted method by both the patient and the clinician. Effective programmes need to be golf-specific to maintain the interest of the participant and yet at the same time they need to be able to accommodate other factors such as age, gender and the level of the golfer. Furthermore, it is critical that the clinical practitioner has a fundamental knowledge of normal swing mechanics and a working knowledge of the musculoskeletal requirements needed to swing a golf club. In the case of the lower back injury, evaluation was based on detailed computer tomography and centred on the conditioning of the transversus abdominis muscle. Although this muscle is not considered to be paraspinal, it has particularly important implications in the maintenance of spinal stability so that other more specific golf functioning exercises and rehabilitation can be performed. For the case study of lateral epicondylitis detailed evaluation and consideration of neuropathy was an important factor in the diagnostic process. In part, it was necessary to deviate from conventional treatment to produce an effective outcome. A comprehensive resistance-strength-training programme and golf functional 'hitting' programme was used to treat the problem. The conformity by the patient to complete the exercise regimen has been an issue of concern for clinicians managing and treating golf-related problems. Many golfers are 'fanatical' and unless they can see that by continuing the programme their injury will be overcome, it is difficult trying to restrict their time on the golf course. The two case studies described in this article highlight how an extensive and dynamic golf functional programme could be used as an effective method for managing and preventing golf injuries.
Critchley D. Instructing pelvic floor contraction facilitates transversus abdominis thickness increase during low-abdominal hollowing.Physiother Res Int. 2002;7(2):65-75.
BACKGROUND AND PURPOSE: Low abdominal hollowing in four-point kneeling is used clinically to test and rehabilitate transversus abdominis (TrA) but many people find this exercise difficult to perform. Contracting pelvic floor muscles (PF) during low abdominal hollowing may facilitate contraction of TrA. Thickness increase in the abdominal muscles during low abdominal hollowing has been measured with real-time ultrasound scanning and may indicate muscle contraction. The present study investigated the effect of instructing PF contraction on TrA thickness increase during low abdominal hollowing. METHOD: Twelve females and eight males with no reported pelvic floor dysfunction or low back pain in the last two years were taught low abdominal hollowing in four-point kneeling. Subjects performed low abdominal hollowing with and without instruction to contract PF in random order. Transversus abdominis, obliquus internus (OI) and obliquus externus (OE) thickness were measured with ultrasound scanning at rest and during both tests. RESULTS: Mean increase in TrA thickness during low abdominal hollowing was 49.71% (SD 26.76%), during low abdominal hollowing with PF it was 65.81% (SD 23.53%). Paired Student's t-tests indicated a significant difference between tests (p = 0.015). There were no significant differences between tests for OE or OI thickness increase. CONCLUSIONS: Instructing healthy subjects to co-contract PF results in greater increase in TrA thickness during low abdominal hollowing in four-point kneeling. This may indicate greater contraction of TrA and thus be useful for clinicians training TrA. Further research could investigate the validity of change of thickness as a measure of abdominal muscle contraction, investigate the effect of instructing PF co-contraction on TrA in patients with low back pain and measure PF and TrA activity simultaneously.
Allison GT, Henry SM. The influence of fatigue on trunk muscle responses to sudden arm movements, a pilot study.Clin Biomech (Bristol, Avon). 2002 Jun;17(5):414-7.
OBJECTIVE: To examine fatigue induced changes in trunk muscle latencies following trunk muscle fatigue. DESIGN: A repeated measures within subject design.Background. Trunk muscle responses to sudden movements is of interest in clinical biomechanics and motor control. METHODS: Electromyographic profiles were recorded from transversus abdominis (finewire), internal oblique, rectus abdominis and external oblique and longissimus at the level of the 3rd lumbar vertebrae bilaterally. Four asymptomatic subjects performed arm-raising task using a visual cue before and after an isometric fatiguing trunk extension task. RESULTS: Feed-forward responses were not detected in all muscles for every trial. In general, following fatigue trunk muscle onset latencies occur earlier (left, P=0.0016; right, P=0.0475). CONCLUSIONS: Trunk muscle fatigue alters anticipatory postural adjustments in normal subjects. It remains unclear if there is a pattern for specific muscles changes between individuals and if these are reflected in individuals with low back pain. RELEVANCE: Trunk muscle fatigue and altered trunk muscles latencies to movement perturbations have been associated with low back pain. These findings suggest that there may be a link between centrally mediated response to isometric muscle fatigue and anticipatory motor control strategies.
Bunce SM, Moore AP, Hough AD. M-mode ultrasound: a reliable measure of transversus abdominis thickness?Clin Biomech (Bristol, Avon). 2002 May;17(4):315-7
OBJECTIVE: The purpose of this study was to establish a reliable method for measuring transversus abdominis thickness in asymptomatic human subjects in supine lying, standing and walking. DESIGN AND METHODS: This was a single operator reliability study using ultrasound imaging to measure 22 subjects on three separate occasions. A purpose built high-density foam reinforced belt was used to house and position the transducer over the mid-point of the transversus abdominis. Each subject was imaged in supine, standing, and treadmill walking at 3 kph. Intraclass correlation coefficients and standard error of measurement analysis were used to measure the data. RESULTS: The correlation coefficient data analysis resulted in intraclass correlation coefficients of 0.94 (standard error of measurement 0.35) in supine lying, 0.88 (0.66) in standing and 0.88 (0.56) in walking. CONCLUSION: The method described is a reliable tool for measuring changes in thickness of transversus abdominis in supine lying, standing and walking. RELEVANCE: This procedure has the potential to detect dysfunctional changes in abdominal muscle activity for patients with low back pain in a functional setting.
Richardson CA, Snijders CJ, Hides JA, Damen L, Pas MS, Storm J. The relation between the transversus abdominis muscles, sacroiliac joint mechanics, and low back pain.Spine. 2002 Feb 15;27(4):399-405.
STUDY DESIGN: Two abdominal muscle patterns were tested in the same group of individuals, and their effects were compared in relation to sacroiliac joint laxity. One pattern was contraction of the transversus abdominis, independently of the other abdominals; the other was a bracing action that used all the lateral abdominal muscles. OBJECTIVES: To demonstrate the biomechanical effect of the exercise for the transversus abdominis known to be effective in low back pain. SUMMARY OF BACKGROUND DATA: Drawing in the abdominal wall is a specific exercise for the transversus abdominis muscle (in cocontraction with the multifidus), which is used in the treatment of back pain. Clinical effectiveness has been demonstrated to be a reduction of 3-year recurrence from 75% to 35%. To the authors' best knowledge, there is not yet in vivo proof of the biomechanical effect of this specific exercise. This study of a biomechanical model on the mechanics of the sacroiliac joint, however, predicted a significant effect of transversus abdominis muscle force. METHODS: Thirteen healthy individuals who could perform the test patterns were included. Sacroiliac joint laxity values were recorded with study participants in the prone position during the two abdominal muscle patterns. The values were recorded by means of Doppler imaging of vibrations. Simultaneous electromyographic recordings and ultrasound imaging were used to verify the two muscle patterns. RESULTS: The range of sacroiliac joint laxity values observed in this study was comparable with levels found in earlier studies of healthy individuals. These values decreased significantly in all individuals during both muscle patterns (P < 0.001). The independent transversus abdominis contraction decreased sacroiliac joint laxity (or rather increased sacroiliac joint stiffness) to a significantly greater degree than the general abdominal exercise pattern (P < 0.0260). CONCLUSIONS: Contraction of the transversus abdominis significantly decreases the laxity of the sacroiliac joint. This decrease in laxity is larger than that caused by a bracing action using all the lateral abdominal muscles. These findings are in line with the authors' biomechanical model predictions and support the use of independent transversus abdominis contractions for the treatment of low back pain.
Hodges PW. Changes in motor planning of feedforward postural responses of the trunk muscles in low back pain.Exp Brain Res. 2001 Nov;141(2):261-6.
Changes in trunk muscle recruitment have been identified in people with low-back pain (LBP). These differences may be due to changes in the planning of the motor response or due to delayed transmission of the descending motor command in the nervous system. These two possibilities were investigated by comparison of the effect of task complexity on the feedforward postural response of the trunk muscles associated with rapid arm movement in people with and without LBP. Task complexity was increased by variation of the expectation for a command to either abduct or flex the upper limb. The onsets of electromyographic activity (EMG) of the abdominal and deltoid muscles were measured. In control subjects, while the reaction time of deltoid and the superficial abdominal muscles increased with task complexity, the reaction time of transversus abdominis (TrA) was constant. However, in subjects with LBP, the reaction time of TrA increased along with the other muscles as task complexity was increased. While inhibition of the descending motor command cannot be excluded, it is more likely that the change in recruitment of TrA represents a more complex change in organisation of the postural response.
Hides JA, Jull GA, Richardson CA. Long-term effects of specific stabilizing exercises for first-episode low back pain.Spine. 2001 Jun 1;26(11):E243-8.
STUDY DESIGN: A randomized clinical trial with 1-year and 3-year telephone questionnaire follow-ups. OBJECTIVE: To report a specific exercise intervention's long-term effects on recurrence rates in acute, first-episode low back pain patients. SUMMARY OF BACKGROUND DATA: The pain and disability associated with an initial episode of acute low back pain (LBP) is known to resolve spontaneously in the short-term in the majority of cases. However, the recurrence rate is high, and recurrent disabling episodes remain one of the most costly problems in LBP. A deficit in the multifidus muscle has been identified in acute LBP patients, and does not resolve spontaneously on resolution of painful symptoms and resumption of normal activity. Any relation between this deficit and recurrence rate was investigated in the long-term. METHODS: Thirty-nine patients with acute, first-episode LBP were medically managed and randomly allocated to either a control group or specific exercise group. Medical management included advice and use of medications. Intervention consisted of exercises aimed at rehabilitating the multifidus in cocontraction with the transversus abdominis muscle. One year and three years after treatment, telephone questionnaires were conducted with patients. RESULTS: Questionnaire results revealed that patients from the specific exercise group experienced fewer recurrences of LBP than patients from the control group. One year after treatment, specific exercise group recurrence was 30%, and control group recurrence was 84% (P < 0.001). Two to three years after treatment, specific exercise group recurrence was 35%, and control group recurrence was 75% (P < 0.01). CONCLUSION: Long-term results suggest that specific exercise therapy in addition to medical management and resumption of normal activity may be more effective in reducing low back pain recurrences than medical management and normal activity alone.
Jull GA, Richardson CA. Motor control problems in patients with spinal pain: a new direction for therapeutic exercise. J Manipulative Physiol Ther. 2000 Feb;23(2):115-7.
Recent research into muscle dysfunction in patients with low back pain has led to discoveries of impairments in deep muscles of the trunk and back. These muscles have a functional role in enhancing spinal segmental support and control. The muscle impairments are not those of strength but rather problems in motor control. These findings call for a different approach in therapeutic exercise, namely a motor learning exercise protocol. The specific exercise approach has an initial focus on retraining the cocontraction of the deep muscles (ie, the transversus abdominis and lumbar multi-fidus Initial clinical trials point to the effectiveness of the approach in patients with both acute and chronic low back pain in terms of reducing the neuromuscular impairment and in control of pain.
Hodges PW. Is there a role for transversus abdominis in lumbo-pelvic stability?Man Ther. 1999 May;4(2):74-86.
There has been considerable interest in the literature regarding the function of transversus abdominis, the deepest of the abdominal muscles, and the clinical approach to training this muscle. With the development of techniques for the investigation of this muscle involving the insertion of fine-wire electromyographic electrodes under the guidance of ultrasound imaging it has been possible to test the hypotheses related to its normal function and function in people with low back pain. The purpose of this review is to provide an appraisal of the current evidence for the role of transversus abdominis in spinal stability, to develop a model of how the contribution of this muscle differs from the other abdominal muscles and to interpret these findings in terms of the consequences of changes in this function.
Hodges PW, Richardson CA. Altered trunk muscle recruitment in people with low back pain with upper limb movement at different speeds.Arch Phys Med Rehabil. 1999 Sep;80(9):1005-12.
OBJECTIVE: To compare trunk muscle coordination in people with and without low back pain with varying speeds of limb movement. STUDY DESIGN: Abdominal and back extensor muscle activity in association with upper limb movement was compared among three speeds of movement and between people with and without low back pain. PARTICIPANTS: Fourteen subjects with a history of recurrent low back pain and a group of age- and sex-matched control subjects. MEASURES: The onsets of electromyographic activity of the trunk and limb muscles, frequency of trunk muscle responses, and angular velocity of arm movements. RESULTS: Early activation of transversus abdominis (TrA) and obliquus internus abdominis (OI) occurred in the majority of trials, with movement at both the fast and intermediate speeds for the control group. In contrast, subjects with low back pain failed to recruit TrA or OI in advance of limb movement with fast movement, and no activity of the abdominal muscles was recorded in the majority of intermediate speed trials. There was no difference between groups for slow movement. CONCLUSION: The results indicate that the mechanism of preparatory spinal control is altered in people with lower back pain for movement at a variety of speeds.
Hodges PW, Richardson CA. Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb.J Spinal Disord. 1998 Feb;11(1):46-56.
The temporal parameters of the response of the trunk muscles associated with movement of the lower limb were investigated in people with and without low back pain (LBP). The weight shift component of the task was completed voluntarily prior to a stimulus to move to allow investigation of the movement component of the response. In the control subjects the onset of electromyographic (EMG) activity of all trunk muscles preceded that of the muscle responsible for limb movement, thus contributing to the feed-forward postural response. The EMG onset of transversus abdominis was delayed in the LBP subjects with movement in each direction, while the EMG onsets of rectus abdominis, erector spinae, and oblique abdominal muscles were delayed with specific movement directions. This result provides evidence of a change in the postural control of the trunk in people with LBP.
Hodges PW, Richardson CA. Contraction of the abdominal muscles associated with movement of the lower limb.Phys Ther. 1997 Feb;77(2):132-42; discussion 142-4.
BACKGROUND AND PURPOSE: Activity of the trunk muscles is essential for maintaining stability of the lumbar spine because of the unstable structure of that portion of the spine. A model involving evaluation of the response of the lumbar multifidus and abdominal muscles to leg movement was developed to evaluate this function. SUBJECTS: To examine this function in healthy persons, 9 male and 6 female subjects (mean age = 20.6 years, SD = 2.3) with no history of low back pain were studied. METHODS: Fine-wire and surface electromyography electrodes were used to record the activity of selected trunk muscles and the prime movers for hip flexion, abduction, and extension during hip movements in each of those directions. RESULTS: Trunk muscle activity occurring prior to activity of the prime mover of the limb was associated with hip movement in each direction. The transversus abdominis (TrA) muscle was invariably the first muscle that was active. Although reaction time for the TrA and oblique abdominal muscles was consistent across movement directions, reaction time for the rectus abdominis and multifidus muscles varied with the direction of limb movement. CONCLUSION AND DISCUSSION: Results suggest that the central nervous system deals with stabilization of the spine by contraction of the abdominal and multifidus muscles in anticipation of reactive forces produced by limb movement. The TrA and oblique abdominal muscles appear to contribute to a function not related to the direction of these forces.
Hodges PW, Richardson CA. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis.Spine. 1996 Nov 15;21(22):2640-50.
STUDY DESIGN: The contribution of transversus abdominis to spinal stabilization was evaluated indirectly in people with and without low back pain using an experimental model identifying the coordination of trunk muscles in response to a disturbances to the spine produced by arm movement. OBJECTIVES: To evaluate the temporal sequence of trunk muscle activity associated with arm movement, and to determine if dysfunction of this parameter was present in patients with low back pain. SUMMARY OF BACKGROUND DATA: Few studies have evaluated the motor control of trunk muscles or the potential for dysfunction of this system in patients with low back pain. Evaluation of the response of trunk muscles to limb movement provides a suitable model to evaluate this system. Recent evidence indicates that this evaluation should include transversus abdominis. METHODS: While standing, 15 patients with low back pain and 15 matched control subjects performed rapid shoulder flexion, abduction, and extension in response to a visual stimulus. Electromyographic activity of the abdominal muscles, lumbar multifidus, and the surface electrodes. RESULTS: Movement in each direction resulted in contraction of trunk muscles before or shortly after the deltoid in control subjects. The transversus abdominis was invariably the first muscle active and was not influenced by movement direction, supporting the hypothesized role of this muscle in spinal stiffness generation. Contraction of transversus abdominis was significantly delayed in patients with low back pain with all movements. Isolated differences were noted in the other muscles. CONCLUSIONS: The delayed onset of contraction of transversus abdominis indicates a deficit of motor control and is hypothesized to result in inefficient muscular stabilization of the spine.
Hodges P, Richardson C, Jull G. Evaluation of the relationship between laboratory and clinical tests of transversus abdominis function.Physiother Res Int. 1996;1(1):30-40.
A clinical test of the function of the deep abdominal muscles was compared to a laboratory electromyographic (EMG) investigation of the contribution of transversus abdominis (TrA) to stability of the lumbar spine during limb movement. The two different functions of TrA were evaluated in 15 subjects. The subject group included six subjects with chronic low back pain and nine subjects with no history of low back pain so that the resultant recordings were spread over a wide range for each test. The clinical test involved quantification of the ability of the subjects to specifically displace the anterior abdominal wall in a way consistent with the function of the muscle. This was evaluated by use of a device designed to measure pressure reduction as the abdomen lifted off a transducer in the prone position. The laboratory test involved determination of the onset of contraction of TrA associated with rapid upper limb movement, measured using fine-wire EMG electrodes. The parameter evaluated was the latency between the contraction of TrA and the prime mover of the limb. Data were analysed both as absolute values and as ordinal data of a three-rating scale derived from criteria based on current knowledge of the response to both tests. No significant correlation was found between the absolute magnitudes of the pressure and timing data, however, comparison of the rating scale data indicated a significant relationship between the tests and associated high level of agreement between the two measures. The results of the study indicate that a reduction in the ability to draw in the abdominal wall is related to changes in the coordination of TrA, although the magnitude of the changes were not correlated. The degree of causality between these co-varying but independent manifestations of the function of TrA is uncertain.
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