Individuals with chronic low back pain do not modulate the level of transversus abdominis muscle contraction across different postures

Trunk Muscle Activity and Ratio of Local Muscle to Global Muscle Activity during Supine Bridge Exercises under Unstable Conditions in Young Participants with and without Chronic Low Back Pain

Core exercises on an unstable surface increase trunk muscle activity, especially for local muscle groups. Therefore, there is a possibility that exercises on an unstable surface would be effective in the rehabilitation of non-specific chronic low back pain (NSCLBP). The present study assessed trunk muscle activities during bridge exercise on the floor and two kinds of unstable surfaces, i.e., a balance ball and the BOSU, for individuals with and without NSCLBP. This study enrolled 17 and 18 young participants with and without NSCLBP, respectively. In the balance ball condition, both groups showed a significant increase in erector spinae activity compared to the floor condition, and the increase in activity was significantly greater in the NSCLBP group than in the control group (p = 0.038). On the other hand, neither group showed significant changes in trunk muscle activities in the BOSU condition compared to those in the floor condition. The control group showed a significant increase in internal oblique/transversus abdominis activity under the balance ball condition (p = 0.020), whereas there were no significant changes in these muscle activities between the balance ball and floor conditions in the NSCLBP group. The present study showed that participants with NSCLBP significantly increased muscle activity of the erector spinae, one of the global back muscles, on the balance ball in spite of small effects on muscle activity of the internal oblique/transversus abdominis, which is one of the local abdominal muscles. Therefore, attention should be paid to the application of bridge exercises on the balance ball for individuals with NSCLBP.

Comparison of transversus abdominis activation characteristics between healthy and chronic low back pain population during upright functional movement

BACKGROUND

Previous literature suggests that transversus abdominis (TrA) activation is diminished in chronic low back pain (cLBP) subjects compared to healthy subjects in less-functional positions. However, few studies have investigated the effects of upright functional movement on TrA activation in cLBP individuals.

OBJECTIVE

This pilot study aimed to compare TrA activation characteristics in healthy and cLBP subjects during the movement of double leg standing (DLS) to single leg standing (SLS) and to a 30∘ single leg quarter squat (QSLS).

METHODS

TrA activation was determined by the percentage change in TrA thickness from DLS to SLS and DLS to QSLS. TrA thickness was measured in 14 healthy and 14 cLBP participants using ultrasound imaging with a probe holder at 20 mm and 30 mm from the fascia conjunction point.

RESULTS

At both measurement points (20 and 30 mm), there were no significant main effects of body sides, lower limb movements and the interactions between them on TrA activations between the healthy and cLBP participants even after covariates were adjusted for (all p> 0.05).

CONCLUSIONS

Results from this study suggest the evaluation of TrA activation during upright functional movements as part of an assessment for cLBP management may not be suggested.

Notes from the Field: The Construction of a Logistical Model for Sports-Related Injury Risk Assessment. A Cross-Sectional Pilot Study

Handball is a high-intensity contact sports activity characterized by repetitive movements, leading to sport-specific muscle patterns. However, at some stage, this pattern may turn into imbalance, predisposing athletes for injuries. The complexity of muscular interactions often makes it difficult to see a whole picture of an athlete's postural disorders and assess them within the framework of his stereotyped movements. We attempted to find an association between the muscle pattern and the number of injuries in a limited group of handball players by constructing a static logistical model. The constructed decision table of the static logistical model included seven conditional attributes of the muscle imbalance as preconditions for injury development and one decision attribute representing the number of experienced injuries of 25 university handball players. The findings displayed a sport-specific pattern of muscle alignment in athletes without or only one injury. However, all players with repetitive injuries had unilateral m. gluteus maximus weakness. In the latter case, impaired core body musculature can lead to increased share forces and stress for the gluteus maximus muscle leading to weakness of this crucial dynamic stabilizer. The logistical model allowed defining muscle imbalance associated with sports-related injuries in a limited group of athletes.

Core Synergies Measured with Ultrasound in Subjects with Chronic Non-Specific Low Back Pain and Healthy Subjects: A Systematic Review

Low back pain represents the leading cause of disability since 1990. In 90% of cases, it is classified as non-specific low back pain, being chronic in 10% of subjects. Ultrasound has proven to be an effective measurement tool to observe changes in the activity and morphology of the abdominal muscles. This article reviews which core synergies are studied with ultrasound in healthy subjects and with chronic non-specific low back pain. A systematic review was conducted on studies analyzing synergies between two or more core muscles. Publications from 2005 until July 2021 were identified by performing structured searched in Pubmed/MEDLINE, PEDro and WOS. Fifteen studies were eligible for the final systematic review. A total of 56% of the studies established synergies between the core muscles and 44% between the homo and contralateral sides of the core muscles. The most studied core synergies were transversus abdominis, internal oblique and external oblique followed by the rectus abdominis and the lumbar multifidus. No studies establishing synergies with diaphragm and pelvic floor were found. Eight studies were conducted in healthy subjects, five studies in subjects with chronic non-specific low back pain compared to healthy subjects and two studies in subjects with chronic non-specific low back pain.

Altered ultrasonographic activity of abdominal muscles during breathing in males with and without nonspecific chronic low back pain

PURPOSE

This study aimed to investigate the altered ultrasonographic activity of abdominal muscles during breathing in males with and without nonspecific chronic low back pain (NSCLBP).

DESIGN

Cross-sectional study.

METHODS

Twenty males with NSCLBP and 20 males without NSCLBP were recruited. Muscle thickness change was measured by ultrasonography during breathing in the end-inspiration and end-expiration phases for the transverse abdominis (TrA), internal oblique (IO), external oblique (EO), and rectus abdominis (RA) muscles. The data were normalized to the end-inspiration thickness. An independent t test was run to analyze the data at a confidence level of 95% (p < 0.05).

RESULTS

The participants with NSCLBP had thicker IO muscles in the end-inspiration (p = 0.030) and end-expiration (p = 0.017) phases as well as greater RA (p = 0.006) and smaller EO (p = 0.003) normalized thickness changes during breathing.

CONCLUSION

The normalized thickness changes during breathing differed between the participants with and without NSCLBP. Reduced EO and increased RA activity may predispose the spine to further injuries. Therefore, normalizing the breathing pattern should be considered in the management of people with NSCLBP.

Prolonged sitting-induced back pain influences abdominal muscle thickness in a sitting but not a supine position

The current study explored whether (i) abdominal muscle thickness differed between non-painful supine and painful sitting positions and (ii) the sitting position was more reliable and useful than the supine position to discriminate between people with and without prolonged sitting-induced lower back pain (LBP). Participants with and without prolonged sitting-induced LBP participated. The thickness of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles was measured using ultrasonography in supine, usual sitting, and upright sitting positions. Analysis of variance was used to compare muscle thickness among the positions. Intraclass correlation coefficients and receiver operating characteristic curves were used to determine which position reliably identified between group. The group with LBP showed significantly greater EO muscle thickness than that without LBP only in the upright sitting position. In the group without LBP, the TrA thickness was significantly greater in the usual and upright sitting positions than in the supine position, but there was no significant difference in TrA thickness among three positions in LBP group. Only EO thickness in the upright sitting position significantly predicted prolonged sitting-induced LBP. The current study suggests that clinicians should assess abdominal activation patterns in the upright sitting rather than supine position before applying abdominal muscle motor control training for patients with prolonged sitting-induced LBP, and to distinguish between those with and without prolonged sitting-induced LBP.

Pain Catastrophizing Is Related to Static Postural Control Impairment in Patients with Nonspecific Chronic Low Back Pain: A Cross-Sectional Study

Purpose

Pain catastrophizing may contribute to the altered trunk muscle activity in patients with nonspecific chronic low back pain (NSCLBP). It is unclear if pain catastrophizing influences static postural control in patients with NSCLBP. This study aimed to investigate the relationship between pain catastrophizing and static postural control in NSCLBP patients.

Methods

Sixty-eight participants with NSCLBP and 40 healthy participants were recruited. Postural control was assessed by the sway area and the sway length of the center of pressure (COP) during balance tests. Pain catastrophizing in participants with NSCLBP was assessed by the Pain Catastrophizing Scale (PCS). Bilateral transversus abdominis (TrA) activation was evaluated by ultrasound imaging-measured percent change in muscle thickness. Associations between COP parameter and PCS/subscales of PCS were examined by multiple linear regression (MLR).

Results

Our results observed a larger COP sway area in NSCLBP group under eyes-closed condition (p < 0.001) and a lower level of voluntary activation of the bilateral TrA (p < 0.001), compared with the healthy control group. The MLR analyses revealed that the COP area sway under eyes-closed condition was significantly associated with the PCS score/helplessness score of PCS, voluntary activation of the left TrA, and age in participants with NSCLBP (β = 0.222/0.236, 0.341/0.344, and 0.328/0.325; p=0.045/0.033, 0.002, and 0.004, resp.).

Conclusions

Static postural control was associated with pain catastrophizing, voluntary activation of TrA, and age in participants with NSCLBP. This indicated that pain catastrophizing may affect postural control and should be considered when interpreting balance test results and managing NSCLBP.

Transverse abdominis activity and ultrasound biofeedback in college golfers with and without low back pain

OBJECTIVES

To compare transverse abdominis (TrA) muscle activity in college golfers with and without a history of low back pain (LBP) and examine the effects of ultrasound biofeedback and a functional golf-setup position on TrA activity.

DESIGN

Crossover study.

SETTING

Laboratory.

PARTICIPANTS

Thirty-two (n = 32) collegiate golfers were stratified into either the LBP group (n = 16, 4.6 ± 4.5 LBP episodes) or non-LBP group (n = 16, 0.1 ± 0.3 LBP episodes) based on LBP episodes in the last 6-months.

MAIN OUTCOME MEASURES

Ultrasound measures of TrA activity were performed during standard contractions and contractions with ultrasound biofeedback. Contraction-type order was randomized between two visits. Testing was performed in two positions, supine and golf-setup positions.

RESULTS

We observed no significant differences in TrA activity between the LBP and non-LBP groups. Overall, TrA activity was greater during biofeedback contractions compared to standard contractions, and TrA activity was lower in the golf-setup position compared to the supine position.

CONCLUSIONS

We observed no differences in TrA activity between college golfers with and without LBP. College golfers with and without LBP demonstrated a greater ability to contract their TrA with real-time ultrasound biofeedback and a lower ability to contract their TrA in the functional golf-setup position compared to the traditional supine position.

Intrasession Real-time Ultrasonography Feedback Improves the Quality of Transverse Abdominis Contraction

OBJECTIVE

The purpose of this study was to compare changes in thickness of the transverse abdominis during performance of the hollowing exercise guided by feedback using ultrasonography images together with verbal guidance and using verbal guidance alone. We also determined the minimal detectable change and agreement between normalized pressures and muscle thickness.

METHODS

Twenty participants without lumbar pain performed the hollowing exercises with or without ultrasonography feedback: 7 men and 13 women, mean (SD) age = 25 (5) years, height = 166 (10) cm, body mass = 64 (6) kg, body mass index = 22.2 (5.8) kg/m². The thickness of the transverse abdominis was quantified during the exercise using musculoskeletal ultrasonography. Basal and 3 repetitions guided by an evaluator were performed. Pressure was determined using a lumbar cushion. Data were compared with a mixed-model analysis of variance and Bonferroni post hoc test (P < .05). Minimal detectable changes were identified and Bland-Altman analysis performed considering normalized thickness and pressure.

RESULTS

Ultrasonography feedback resulted in larger thickness changes (P < .05). The lowest minimal detectable changes were achieved using ultrasonography feedback. Nonagreement was found between normalized thickness and pressure.

CONCLUSION

Contraction of the transverse abdominis is improved using real-time ultrasonography together with verbal feedback. Low changes in muscle contraction estimated by thickness showed nonagreement with a pressure cushion.

Abdominal draw-in maneuver changes neuromuscular responses to sudden release from trunk loading in patients with non-specific chronic low back pain

BACKGROUND

Abdominal draw-in maneuver (ADIM) has been recommended to achieve appropriate trunk muscle response for patients with non-specific chronic low back pain (CLBP). However, it has remained unclear whether the intervention with ADIM could change the trunk muscle response to sudden release from loading, which is considered to contribute mechanical circumstances to low back pain. The purpose of the present study was to investigate the effects of the intervention with ADIM on electromyography (EMG) activities of trunk muscles following sudden release from loading.

METHODS

Seventeen subjects with non-specific CLBP participated. Subjects resisted trunk flexion or extension loading in semi-seated position, and then the loading was suddenly released. EMG recordings of 6 trunk muscles were acquired using a wireless surface EMG system. Onset and offset times were calculated from the EMG data. The intervention with ADIM was provided for 4 weeks. The onset and offset times were compared between pre- and post-intervention with ADIM.

RESULTS

At the post-intervention, the onset of trunk flexors following release from trunk flexion loading became significantly earlier than pre-intervention (P = 0.028). The offset of flexors following release from trunk extension loading of post-intervention was significantly earlier than that of pre-intervention (P = 0.001).

CONCLUSIONS

We showed that the intervention with ADIM changed the EMG activity of trunk flexors in response to sudden release from loading. These results suggest a possibility that ADIM might be effective to improve the neuromuscular control of trunk flexors for the treatment of young patients with non-specific CLBP.

Intra-rater reliability of transversus abdominis measurement by a novice examiner: Comparison of "freehand" to "probe force device" method of real-time ultrasound imaging

A "free hand" real-time-ultrasound method is commonly applied to measure transversus abdominis. Potentially, this increases transversus abdominis measurement error due to uncontrolled variability in probe to skin force, inclination, and roll, particularly for novice examiners. This single-group repeated-measures reliability study compared the intra-rater reliability of transversus abdominis thickness and activation measurement by a novice examiner between free hand and a standardized probe force device method. The examiner captured ultrasound videos of transversus abdominis in a single session in healthy participants (n =  33). Free hand ultrasound featured uncontrolled probe force, inclination, and roll, while probe force device method ultrasound standardized these parameters. Images of transversus abdominis at rest and contracted were measured and transversus abdominis activation calculated. Intraclass correlation coefficient, coefficient of variation, standard error of measurement, and worthwhile differences were calculated. The probe force device method resulted in greater reliability (intraclass correlation coefficient = 0.75-0.96) and lower measurement error (coefficient of variation = 8.89-28.7%) compared to free hand (intraclass correlation coefficient = 0.63-0.93; coefficient of variation = 6.52-29.4%). Reliability was good for all measurements except free hand TrA-C, which was moderate. TrA-C had the lowest reliability, followed by contracted thickness of the transverse abdominis, with resting thickness of the transverse abdominis being highest. Worthwhile differences were lower using a probe force device method versus free hand for resting thickness of the transverse abdominis and contracted thickness of the transverse abdominis and similar for TrA-C. Standardization using probe force device method ultrasound to measure transversus abdominis improved intra-rater reliability in a novice examiner. Use of a probe force device method is recommended to improve reliability through reduced sources of measurement error. Probe force device method intra- and inter-rater reliability in examiners of varying experience, in clinical populations, and to visualize other structures merits exploration.

Lumbopelvic motor control function between patients with chronic low back pain and healthy controls: a useful distinguishing tool: The STROBE study

Although lumbopelvic stability exercise improves lumbopelvic motor control function in patients with chronic low back pain (CLBP), the difference in lumbopelvic motor control function between the patients with CLBP and the healthy controls is unclear. The purpose of this study was to compare lumbopelvic motor control function between patients with CLBP and healthy controls and to determine the prevalence of CLBP according to core stability function.For this study, 278 participants were recruited, including patients with CLBP (n = 137) and healthy controls (n = 141). The participants performed a core stability function test and were classified to either the low or high core stability function group according to their core stability function for CLBP prevalence analysis.Lumbopelvic motor control was significantly higher in the healthy controls than in patients with CLBP. Of the patients in the low lumbopelvic motor control function group, 65.9% had CLBP, whereas 36.8% of the patients in the high lumbopelvic motor control function group had CLBP. Lumbopelvic motor control function demonstrated a significant difference between the patients with CLBP and the healthy controls. The lumbopelvic motor control function test was demonstrated to be an effective diagnostic tool for distinguishing CLBP. This information can be applied in assessments and interventions for CLBP in clinical settings.

Trunk muscle activity during trunk stabilizing exercise with isometric hip rotation using electromyography and ultrasound

INTRODUCTION

The purpose of this study was to clarify the muscle activation during trunk stabilizing exercise with isometric hip rotation in healthy males by comparing that with abdominal crunch (AC) and active straight leg raise (ASLR). Electromyography and ultrasound imaging were used to simultaneously measure muscle activity and thickness of the internal oblique (IO), the external oblique (EO), transverse abdominis (TrA) and multifidus (MF) on the right side during exercise.

METHODS

Twenty healthy participants performed the following exercises in supine position: isometric right or left hip internal/external rotation, AC, and ASLR. Muscle activity was normalized to maximum voluntary contraction (MVC), and muscle thickness was normalized to resting muscle thickness.

RESULTS

Muscle activation and thickness of IO, MF and TrA increased significantly during the isometric hip rotation compared with other exercises. Muscle activation during the trunk stabilizing exercise with ipsilateral isometric hip internal rotation was 21% in IO, 26% in MF, and with ipsilateral hip external rotation was 12% of MVC in EO.

CONCLUSION

These findings suggest that trunk stabilizing exercise with isometric hip rotation exercise may be a more safe and effective exercise to promote trunk muscle activity than AC and ASLR. These findings would be beneficial for therapists engaged in prevention and treatment of low back pain.

Reliability and Validity of the Feedback Sensor for Activating the Transversus Abdominis Muscle

Background:

Core muscle activation is an effective intervention for the management of Low Back Pain (LBP). This study developed new feedback for detecting activation of the transversus abdominis muscle in the lumbar spine. The purpose of this study was to examine the validity and reliability of the feedback device for transversus abdominis muscle contraction.

Methods:

The participants in this study were 20 healthy males and females (aged 24.1 ± 6.8 years). The feedback sensor was attached to the lumbar support at the front of the trunk. The participants performed an abdominal drawing-in maneuver in order to activate the transversus abdominis muscle, and values from the feedback sensor were collected at the same time. Ultrasound imaging of the transversus abdominis muscle was also collected simultaneously. The feedback sensor collected values at different clinical levels of the pressure biofeedback unit at 64, 66, 68, and 70 mmHg. The protocol was repeated with a 24-hr interval. Intra-class correlation coefficient, coefficient of variation and standard error of measurements were used to examine reliability. The validity of the values obtained from the relationship between the feedback sensor and transversus abdominis muscle thickness was analyzed using Pearson’s correlation coefficients.

Results:

Test–retest reliability of the feedback sensor was excellent (ICC = 0.946, CV = 2.6%, SEMs = 0.54%). Values of the feedback sensor reported a significantly moderate correlation with the gold standard ultrasound measurement (r = - 0.514, p < 0.001).

Conclusion:

The feedback device demonstrated potential reliability and validity for clinical use by indicating activation of the transversus abdominis muscle.

Relationship between transversus abdominis muscle thickness and urinary incontinence in females at 2 months postpartum

[Purpose] Urinary incontinence is a frequent postpartum complication. Thus, this study aimed to examine the associations of transversus abdominis muscle thicknesses at rest and during an abdominal drawing-in maneuver with urinary incontinence in females at 2 months postpartum. [Participants and Methods] The participants included 18 females at 2 months postpartum with or without urinary incontinence, and 10 nulliparous females as controls. Transversus abdominis thickness was measured at rest and during the abdominal drawing-in maneuver using diagnostic ultrasonography. The Japanese version of the International Consultation on Incontinence Questionnaire-Short Form was used to evaluate urinary incontinence. [Results] Females at 2 months postpartum were divided into groups with and without urinary incontinence according to questionnaire scores. The muscle thickness during the abdominal drawing-in maneuver contraction was significantly lower in those with urinary incontinence than in those without urinary incontinence and controls. [Conclusion] The results showed significantly reduced transversus abdominis thickness during contraction, which suggested reduced transversus abdominis strength in females with postpartum urinary incontinence. Thus, promoting synergistic contraction of the inner unit, including the transversus abdominis, in exercise therapy may be more effective for postpartum urinary incontinence.

Proprioceptive Stabilizer™ training of the abdominal wall muscles in healthy subjects: a quasi-experimental study

SUMMARY The present quasi-experimental study aimed to assess the transversus abdominis (TrA), internal oblique (IO) and external oblique (EO) thickness in healthy subjects with the proprioceptive Stabilizer™ training in abdominal wall muscles. A sample of 41 healthy participants (age: 31.9 ± 4.5 y; height: 1.7 ± 0.1 m; weight: 68.3 ± 13.1 kg; body mass index, BMI: 22.9 ± 2.7 kg/m2) were recruited to participate in this study. Ultrasound images of the EO, IO, TrA, rectus anterior (RA) and interrecti distance (IRD) were measured and analyzed by the ImageJ software. Measurements were made at rest and during the abdominal drawing-maneuver (ADIM) developed by the patients with the Stabilizer™ located in the low back holding 40 mmHg for 10 seconds with a visual stimulus provided by a circular pressure marker. Ultrasound measurements for the abdominal wall muscles showed statistically significant differences (Π < .05) for a thickness decrease of the EO, IO and a thickness increase of TrA. A proprioceptive Stabilizer™ training produced a thickness increase in TrA muscle and a thickness decrease in EO and IO muscles in healthy subjects. These findings suggest that a proprioceptive Stabilizer™ training could be useful in individuals with low back pain and lumbopelvic pain.

Changes in Muscle Thickness Across Positions on Ultrasound Imaging in Participants With or Without a History of Low Back Pain

CONTEXT

  Injury-prediction models have identified trunk muscle function as an identifiable factor for future injury. A history of low back pain (HxLBP) may also place athletes at increased risk for future low back pain. Reduced muscle thickness of the lumbar multifidus (LM) and transversus abdominis (TrA) has been reported among populations with clinical low back pain via ultrasound imaging in multiple positions. However, the roles of the LM and TrA in a more functional cohort and for injury prediction are still unknown.

OBJECTIVES

  To (1) assess the reliability of LM and TrA ultrasound measures, (2) compare changes in muscle thickness across positions between persons reporting or not reporting HxLBP, and (3) determine the ability to distinguish between groups.

DESIGN

  Cross-sectional study.

SETTING

  Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

  Participants were 34 people who did not report HxLBP (age = 22 ± 7 years, body mass index = 23.7 ± 2.7) and 25 people who reported HxLBP (age = 25 ± 10 years, body mass index = 24.0 ± 3.2).

MAIN OUTCOME MEASURE(S)

  Muscle thickness and changes in muscle thickness of the LM and TrA as shown on ultrasound imaging.

RESULTS

  Intraclass correlation coefficients ranged from 0.641 to 0.943 for all thickness measures and from 0 to 0.693 for all averaged thickness modulations bilaterally. Participants who reported HxLBP had voluntarily reduced TrA thickness modulations compared with those not reporting HxLBP ( P = .03), and the testing position influenced TrA thickness modulations ( P < .01). No differences were observed for LM thickness modulations between groups or positions ( P > .05). A tabletop cutoff value of 1.32 had a sensitivity of 0.640 and a specificity of 0.706, whereas a seated cutoff value of 1.18 had a sensitivity of 0.600 and a specificity of 0.647.

CONCLUSIONS

  In participants reporting HxLBP, TrA thickness modulations were lower and both tabletop and seated thickness modulations were able to distinguish reported HxLBP status. These findings suggest that TrA muscle function may be altered by HxLBP.

Establishing Immediate Reliability of Sonographic Measurements of the Transversus Abdominis in Asymptomatic Adults Performing Upright Loaded Functional Tasks in a Clinical Context Without Delayed Recorded Measurement

OBJECTIVES

This study examined the reliability of sonographic measurements of the transversus abdominis of adults without low back pain during upright loaded functional tasks in real time, without relying on delayed recorded images.

METHODS

A single-group repeated-measures reliability study was conducted on 12 healthy participants without low back pain. Six of these adults reported a prior history of abdominal drawing-in maneuver training without sonographic measurement. The participants performed 3 trials of neutral standing, a loaded forward reach, and a loaded box lift under rest and with abdominal drawing-in maneuver instructions; task order was randomized. Transversus abdominis thickness measurements were obtained by an experienced rater using B-mode sonography in real-time via electronic calipers twice on the same static image during all trials by a rater. The rater was masked to group assignment and on-screen measurement output and required to respond to trivia questions between repeated measurements.

RESULTS

The participants included 6 male and 6 female adults with a mean age ± SD of 26.3 ± 3.7 years. Intra-rater intraclass correlation coefficients (2,3) were high and precise for the rater's first and second measurements for all tasks and instruction conditions for mean transversus abdominis thickness and percent change in thickness measurements (eg, ranges were 0.968-0.997 for intraclass correlation coefficients, 0.01-0.21 mm for standard errors of the measurement, and 0.01-0.58 mm for minimal detectable changes). Calipers cleared by the rater or a research assistant produced similar findings of excellent reliability and precision.

CONCLUSIONS

High intra-rater reliability and precision of transversus abdominis thickness measurements were obtained by a physical therapist in real time from asymptomatic adults performing upright loaded functional tasks under rest and with abdominal drawing-in maneuver instructions.