Test-retest reliability of measurements of abdominal and multifidus muscles using ultrasound imaging in adults aged 50-79 years.

Test-retest reliability of the combined process of ultrasound imaging (USI) and image measurement of thickness of abdominal and upper lumbar multifidus (MF) muscles and MF cross sectional area (CSA) of older adults has not been established. Imaging muscles of older adults can be challenging due to age-related changes in the spine and skeletal muscle so establishing test-retest reliability in this population is important. This study aimed to evaluate test-retest reliability of USI of abdominal and MF muscle thickness and MF CSA for adults aged 50-79 years. One operator took single sets of ultrasound images of abdominal and MF muscles of 23 adults aged 50-79 years participating in a clinical trial of vitamin D supplementation for knee osteoarthritis, on two occasions, one week apart. Images were subsequently measured by a single examiner. Test-retest reliability for abdominal muscle thickness and MF CSA was substantial (intraclass correlation coefficients (ICC) > 0.81) and for MF thickness ranged from fair to substantial (ICC 0.55-0.86). The standard error of measurement (SEM) was low (0.02-0.21) in every case. ICCs were low and SEM values were high for percentage thickness change. The substantial test-retest reliability of abdominal and MF (L4-L5) muscle thickness and of MF CSA supports the use of USI as a clinical and research tool to assess abdominal and MF muscle thickness and MF CSA of older adults.

Predicting football injuries using size and ratio of the multifidus and quadratus lumborum muscles.

Deficits in muscles of the lumbo-pelvic region, such as a relatively small multifidus muscle, have been used to predict lower limb injuries in professional football players. Results have been less consistent for the size of the quadratus lumborum (QL) muscle. Changes in size of the multifidus and QL muscles could be functionally related to each other, and modeling this relationship could improve prediction of lower limb injuries. Ultrasound imaging examinations were performed on male elite football players at the start of the Australian Football League (AFL) pre-season and playing season. Injury data were obtained from records collected by each club. Results indicated that the cross-sectional area of the multifidus muscle was related to the occurrence of an injury in the pre-season (odds ratio [OR] = 2.08/cm2 decrease below the mean; OR for dichotomized measure = 12.2) and in the season (OR = 2.43/cm2 ). The size of the QL muscle was significantly related to an injury in the pre-season (OR = 2.12/cm2 increase above the mean; OR for dichotomized measure = 7.26) but not in the season. A significant link was found between the ratio of the multifidus and QL muscles, and the incidence of pre-season (OR = 14.71) and season injuries (OR = 5.29). The sensitivity and specificity of the model in the pre-season were 75% and 85.7%, respectively; values for the playing season were 88.4% and 62.5%. A model was developed for prediction of lower limb injuries in football players. Combining size measurements of the multifidus and QL muscles improved predictive power. This information may have clinical implications for injury screening and prevention.

The assessment of abdominal and multifidus muscles and their role in physical function in older adults: a systematic review.

BACKGROUND: Age-related changes in the trunk (abdominal and lumbar multifidus) muscles and their impact on physical function of older adults are not clearly understood. OBJECTIVES: To systematically summarise studies of these trunk muscles in older adults. DATA SOURCES: Cochrane Library, Pubmed, EMBASE and CINAHL were searched using terms for abdominal and MF muscles and measurement methods. STUDY SELECTION: Two reviewers independently assessed studies and included those reporting measurements of abdominal muscles and/or MF by ultrasound, computed tomography, magnetic resonance imaging or electromyography of adults aged ≥50 years. DATA SYNTHESIS: A best evidence synthesis was performed. RESULTS: Best evidence synthesis revealed limited evidence for detrimental effects of ageing or spinal conditions on trunk muscles, and conflicting evidence for decreased physical activity or stroke having detrimental effects on trunk muscles. Thicknesses of rectus abdominis, internal oblique and external oblique muscles were 36% to 48% smaller for older than younger adults. Muscle quality was poorer among people with moderate-extreme low back pain and predicted physical function outcomes. LIMITATIONS: Study heterogeneity precluded meta-analysis. CONCLUSION: Overall, the evidence base in older people has significant limitations, so the role of physiotherapy interventions aimed at these muscles remains unclear. The results point to areas in which further research could lead to clinically useful outcomes. These include determining the role of the trunk muscles in the physical function of older adults and disease; developing and testing rehabilitation programmes for older people with spinal conditions and lower back pain; and identifying modifiable factors that could mitigate age-related changes.

Changes in multifidus and abdominal muscle size in response to microgravity: possible implications for low back pain research.

PURPOSE: In microgravity, muscle atrophy occurs in the intrinsic muscles of the spine, with changes also observed in the abdominal muscles. Exercises are undertaken on the International Space Station and on Earth following space flight to remediate these effects. Similar effects have been seen on Earth in prolonged bed rest studies and in people with low back pain (LBP). The aim of this case report was to examine the effects of microgravity, exercise in microgravity and post-flight rehabilitation on the size of the multifidus and antero-lateral abdominal muscles. METHODS: Ultrasound imaging was used to assess size of the multifidus, transversus abdominis and internal oblique muscles at four time points: pre-flight and after daily rehabilitation on day one (R + 1), day 8 (R + 8) and day 14 (R + 14) after return to Earth (following 6 months in microgravity). RESULTS: Exercises in microgravity maintained multifidus size at L2-L4, however, after spaceflight, size of the multifidus muscle at L5 was reduced, size of the internal oblique muscle was increased and size of transversus abdominis was reduced. Rehabilitation post-space flight resulted in hypertrophy of the multifidus muscle to pre-mission size at the L5 vertebral level and restoration of antero-lateral abdominal muscle size. CONCLUSIONS: Exercise in space can prevent loss of spinal intrinsic muscle size. For the multifidus muscles, effectiveness varied at different levels of the spine. Post-mission rehabilitation targeting specific motor control restored muscle balance between the antero-lateral abdominal and multifidus muscles, similar to results from intervention trials for people with LBP. A limitation of the current investigation is that only one astronaut was studied, however, the microgravity model could be valuable as predictable effects on trunk muscles can be induced and interventions evaluated. Level of Evidence Case series.

Retraining motor control of abdominal muscles among elite cricketers with low back pain.

The purpose of this study was to document the effect of a staged stabilization training program on the motor control of the anterolateral abdominal muscles in elite cricketers with and without low back pain (LBP). Changes in the cross-sectional area of the trunk, the thickness of the internal oblique and transversus abdominis (TrA) muscles and the shortening of the TrA muscle in response to an abdominal drawing-in task were measured at the start and completion of a 13-week cricket training camp. Measures were performed using ultrasound imaging and magnetic resonance imaging. Participants from the group with LBP underwent a stabilization training program that involved performing voluntary contractions of the multifidus, TrA and pelvic floor muscles, while receiving feedback from ultrasound imaging. By the end of the training camp, the motor control of cricketers with LBP who received the stabilization training improved and was similar to that of the cricketers without LBP.

Lumbo-pelvic joint protection against antigravity forces: motor control and segmental stiffness assessed with magnetic resonance imaging.

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.

Long-term effects of specific stabilizing exercises for first-episode low back pain.

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.

Multifidus muscle recovery is not automatic after resolution of acute, first-episode low back pain.

STUDY DESIGN: A clinical study was conducted on 39 patients with acute, first-episode, unilateral low back pain and unilateral, segmental inhibition of the multifidus muscle. Patients were allocated randomly to a control or treatment group. OBJECTIVES: To document the natural course of lumber multifidus recovery and to evaluate the effectiveness of specific, localized, exercise therapy on muscle recovery. SUMMARY OF BACKGROUND DATA: Acute low back pain usually resolves spontaneously, but the recurrence rate is high. Inhibition of multifidus occurs with acute, first-episode, low back pain, and pathologic changes in this muscle have been linked with poor outcome and recurrence of symptoms. METHODS: Patients in group 1 received medical treatment only. Patients in group 2 received medical treatment and specific, localized, exercise therapy. Outcome measures for both groups included 4 weekly assessments of pain, disability, range of motion, and size of the multifidus cross-sectional area. Independent examiners were blinded to group allocation. Patients were reassessed at a 10-week follow-up examination. RESULTS: Multifidus muscle recovery was not spontaneous on remission of painful symptoms in patients in group 1. Muscle recovery was more rapid and more complete in patients in group 2 who received exercise therapy (P = 0.0001). Other outcome measurements were similar for the two groups at the 4-week examination. Although they resumed normal levels of activity, patients in group 1 still had decreased multifidus muscle size at the 10-week follow-up examination. CONCLUSIONS: Multifidus muscle recovery is not spontaneous on remission of painful symptoms. Lack of localized, muscle support may be one reason for the high recurrence rate of low back pain following the initial episode.

Magnetic resonance imaging and ultrasonography of the lumbar multifidus muscle. Comparison of two different modalities.

STUDY DESIGN: An operator-blinded dual modality trial of measurement of lumbar multifidus muscle cross-sectional area was performed. OBJECTIVE: To compare two imaging modalities used for measurement of the lumbar multifidus muscle. METHODS: Ten normal female subjects aged 21-31 years were imaged on two separate days using magnetic resonance imaging and ultrasound imaging. Bilateral measurements were made at each vertebral level from L2-S1. RESULTS: No significant difference was demonstrated between cross-sectional area measurements made with the two different modalities. Measurements of multifidus were symmetrical between left and right sides of the spine. For both modalities, a significant difference was demonstrated in the cross-sectional area of multifidus between each vertebral level from L2-S1. CONCLUSIONS: The present study indicated that if a strict protocol for ultrasound imaging is adhered to, real-time ultrasound imaging can be used to document muscle size in young adults. Further studies are required to validate the technique in older subjects and in different conditions.

Evidence of lumbar multifidus muscle wasting ipsilateral to symptoms in patients with acute/subacute low back pain.

The effect of low back pain on the size of the lumbar multifidus muscle was examined using real-time ultrasound imaging. Bilateral scans were performed in 26 patients with acute unilateral low back pain (LBP) symptoms (aged 17-46 years) and 51 normal subjects (aged 19-32 years). In all patients, multifidus cross-sectional area (CSA) was measured from the 2nd to the 5th lumbar vertebrae (L2-5) and in six patients, that of S1 was also measured. In all normal subjects, CSA was measured at L4 and in 10 subjects measurements were made from L2-5. Marked asymmetry of multifidus CSA was seen in patients with the smaller muscle being on the side ipsilateral to symptoms (between-side difference 31 +/- 8%), but this was confined to one vertebral level. Above and below this level of wasting, mean CSA differences were < 6%. In normal subjects, the mean differences were < 5% at all vertebral levels. The site of wasting in patients corresponded to the clinically determined level of symptoms in 24 of the 26 patients, but there was no correlation between the degree of asymmetry and severity of symptoms. Patients had rounder muscles than normal subjects (measured by a shape ratio index), perhaps indicating muscle spasm. Linear measurements of multifidus cross-section were highly correlated with CSA in normal muscles but less so in wasted muscles, so CSA measurements are more accurate than linear dimensions. The fact that reduced CSA, i.e., wasting, was unilateral and isolated to one level suggests that the mechanism of wasting was not generalized disuse atrophy or spinal reflex inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)