Changes in lateral abdominal muscle thickness during the abdominal drawing-in maneuver in those with lumbopelvic pain

Novel methods to increase core muscle activity in older adults

[Purpose] This study aimed to test whether a combination of specific postures and movements can increase trunk muscle activity in older adults. [Participants and Methods] Forty-six community-dwelling older adults (mean age: 83.9 ± 4.5 years) were living independently without the need for nursing care. The thicknesses of the external oblique, internal oblique, and transversus abdominis muscles were measured during the following three tasks: task I, natural sitting posture; task II, specific sitting posture to promote activity of the deep trunk muscles; and task III, task II plus a pushing down motion using both upper limbs. During each task, an ultrasound imaging device was used to measure the thicknesses of the external oblique, internal oblique, and transversus abdominis muscles on both the left and right sides according to the time required for expiration. [Results] Significant differences were found in the thicknesses of the internal oblique and transversus abdominis muscles between tasks II and III. Among the three muscles, the transversus abdominis showed the highest increase in thickness. [Conclusion] High activity of the trunk muscles, especially the transverse abdominis, can be achieved via specific sitting positions/tasks and further manipulations to increase the intra-abdominal pressure in both upper limbs.

The automatic activity of abdominal muscles during stable and unstable standing postural tasks in older adults with and without low back pain- A cross-sectional study

BACKGROUND

The postural control and abdominal muscles' automatic activity were found to be impaired in subjects with low back pain (LBP) during static activities. However, the studies are predominantly conducted on younger adults and a limited number of studies have evaluated abdominal muscles' automatic activity during dynamic standing activities in subjects with LBP. The present study investigated the automatic activity of abdominal muscles during stable and unstable standing postural tasks in older adults with and without LBP.

METHODS

Twenty subjects with and 20 subjects without LBP were included. The thickness of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles was measured during rest (in supine), static, and dynamic standing postural tasks. To estimate automatic muscle activity, each muscle's thickness during a standing task was normalized to its thickness during the rest. Standing postural tasks were performed using the Biodex Balance System.

RESULTS

The mixed-model analysis of variance revealed that task dynamicity significantly affected thickness change only in the TrA muscle (P = 0.02), but the main effect for the group and the interaction were not significantly different (P > 0.05). There were no significant main effects of the group, task dynamicity, or their interaction for the IO and EO muscles (P > 0.05). During dynamic standing, only the TrA muscle in the control group showed greater thickness changes than during the static standing task (P < 0.05).

CONCLUSIONS

Standing on a dynamic level increased the automatic activity of the TrA muscle in participants without LBP compared to standing on a static level. Further research is required to investigate the effects of TrA muscle training during standing on dynamic surfaces for the treatment of older adults with LBP.

The Efficiency of Respiratory Exercises in Rehabilitation of Low Back Pain: A Systematic Review and Meta-Analysis

BACKGROUND

Low back pain (LBP) is a common musculoskeletal disorder, and respiratory exercise is considered a nonsurgical management method. Therefore, this systematic review and meta-analysis aims to estimate the results of randomized controlled trials on the effect of respiratory training in reducing LBP and its dose relationship.

METHODS

The present study was conducted from January 2020 to January 2022, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (2020). Relevant studies were searched in multiple databases including PubMed, Web of Science, the Cochrane Library, EBSCO, Scopus, ScienceDirect, Wan Fang and China Knowledge Network, ClinicalTrials.gov, and Google Scholar, using a combination of MeSH/Emtree terms and free-text words. The heterogeneity of the studies was assessed using the I2 statistic.

RESULTS

A total of 14 publications were included in the meta-analysis, with a total sample size of 698 individuals, aged 60-80 years. Respiratory exercise was effective in relieving LBP (standardized mean difference = -0.87, P < .00001) and improving physical disability (standardized mean difference = -0.79, P < .00001). The type of breathing and the total duration of breathing exercises were found to be the source of heterogeneity in this study by subgroup analysis. Subgroup analysis revealed that the most significant effect sizes of breathing resistance exercise to reduce LBP and the most significant effect sizes of breathing relaxation techniques to alleviate physical disability were performed 3 to 5 times per week and period >4 weeks. Respiratory exercise reducing LBP and improving functional disability was most effective when the total duration of the intervention was >500 minutes. Funnel plots showed that the results of the 2 overall studies were reliable without publication bias.

CONCLUSIONS

Respiratory exercise can effectively reduce LBP and improve physical disability. Therefore, these exercises can be regarded as a part of a LBP management plan. We recommend an exercise program with 30 to 50 minutes, 3 to 5 times per week, and >4 weeks of breathing resistance exercise program as the most effective for treating LBP.

Lateral abdominal muscle thickness and contractile function in women with and without stress urinary incontinence

INTRODUCTION AND HYPOTHESIS

Stress urinary incontinence (SUI) primarily results from the weakness of pelvic floor muscles, working synergistically with the abdominal muscles. The current study aimed to compare thickness and contractile function of lateral abdominal muscles in women with and without SUI.

METHODS

Thirty-nine women with SUI (SUI group; age: 38.87 ± 8.96 years, body mass index (BMI): 24.03 (5.94) kg/m2) and 42 healthy women (control group; age: 36.21 ± 11.46 years, BMI: 23.90 (5.85) kg/m2) were included. Transverse abdominis (TrA) and internal oblique (IO) muscle thickness at rest and during abdominal drawing-in maneuver (ADIM) were measured with ultrasound imaging in B-mode using a Logiq S7/Expert device and a 9-11 MHz linear transducer. Percentage change in thickness and contractile function of these muscles were also calculated.

RESULTS

No significant differences in the thickness of TrA and IO muscles at rest and during ADIM between the groups were found (p > 0.05). The percent change in thickness and contractile function of both right and left side TrA muscles and the right side IO muscle were lower in SUI group than control group (p < 0.05). The percentage change in thickness and the contractile function of the left side IO muscle did not change (p > 0.05).

CONCLUSION

Women with SUI had a smaller percentage change in thickness and contractile function of TrA and IO muscle than women without SUI. However, there was no difference in the morphological features of these muscles between the groups. Considering the lateral abdominal muscle, training may be important for management of SUI.

Effect of verbal instructions on trunk muscle activity during volitional preemptive abdominal contraction

OBJECTIVE

This study investigated the effect of Verbal Instruction (VI) strategies on trunk muscle contraction among healthy subjects. The effect of three VI Abdominal Drawing-In Maneuver (ADIM) and two VI Abdominal Bracing Maneuver (ABM) strategies on left Internal (LIO) and External Oblique (LEO) and bilateral superficial Multifidi (sMf) activation was examined.

DESIGN

Within-subjects, repeated measure design.

METHODS

Surface EMG (sEMG) measured LIO, LEO, and sMf activity in 28 subjects (mean age 23.5 ± 5.5 years). Testing included five supine hook-lying and five quiet standing conditions.

RESULTS

One-way ANOVAs demonstrated no significant main effect for ADIM or ABM in supine or standing (p > .05). Muscle activation amplitudes during VPAC conditions demonstrated higher mean values for standing versus supine (p < .05) except for two conditions involving LEO. Friedman Tests for dominant strategy demonstrated a significant main effect for ADIM-VI and ABM-VI strategies. Post-hoc testing generally showed the dominant strategy to be significantly higher versus others.

CONCLUSION

No single preferred VI cue for ADIM or ABM was observed. Each subject's dominant strategy dictated the most suitable VI. Standing was preferred for LIO and sMf activation, whereas position did not change LEO activation. Non-significant correlations between all muscle pairings during all ADIM and ABM strategies were observed. These findings may suggest the need for healthcare providers who understand the intricacies of trunk stability to teach and monitor VPAC with either ADIM or ABM options.

Transversus Abdominis Ultrasound Thickness during Popular Trunk-Pilates Exercises in Young and Middle-Aged Women

The transversus abdominis (TrA) is a core muscle that contributes to functional mobility and lumbar stability. This study aimed to compare the changes in TrA thickness during different Pilates exercises, and to identify the exercise that elicited the greatest TrA activation. Forty-four healthy women were divided into two groups: young (25-35 years old) and middle-aged (36-55 years old). TrA thickness was assessed by ultrasound while the participants performed five Pilates exercises: basic position, hundred, hip roll, side plank, and dead bug. A repeated measures analysis of variance revealed that the dead bug exercise induced a significantly higher increase in TrA thickness (relative to rest) than the other exercises (p < 0.05). The young group also showed a significantly higher overall TrA thickness than the middle-aged group (p < 0.05). The findings suggest that the dead bug exercise is the most effective for enhancing TrA activation among the Pilates exercises tested. The basic position and the hundred exercises can be used as warm-up exercises before performing more challenging exercises such as the hip roll, the side plank, and the dead bug. The sequence of exercises can be similar for both young and middle-aged women.

Application of Feedback Type on Performance of Abdominal Drawing-In Maneuver in Healthy Adults: A Quasi-Experimental Study of Motor Control and Motor Learning

OBJECTIVE

The aim of this study was to compare the effects of verbal, tactile-verbal, and visual feedback on muscle activation of the lumbar stabilizers relative to extremity movers during an abdominal drawing-in maneuver when feedback is withheld.

METHODS

This quasi-experimental study equally divided 54 healthy adults into 3 feedback groups (verbal, tactile-verbal, and visual) who trained twice per week over a 4-week period to perform supine abdominal drawing-in maneuvers. The percentage of maximum voluntary isometric contraction of rectus abdominis, multifidus (MF), erector spinae, and hamstrings (HS) as an outcome measure was acquired using surface electromyography. A 2-way factorial analysis of variance with bootstrapping allowed for comparison of post-pre difference scores across the interaction of feedback and muscle groups.

RESULTS

Hamstring activation decreased in those receiving tactile-verbal feedback relative to an increase in participants given visual feedback. Furthermore, when using verbal feedback, HS activity increased relative to a decline in rectus abdominis, and when presenting visual feedback, HS activity increased relative to a decrease in MF. However, no post-pre changes were seen across muscles with tactile-verbal feedback.

CONCLUSION

Although tactile-verbal feedback did not increase MF recruitment, it produced less HS activity than visual feedback. Undesirable HS recruitment may reflect boredom or feedback dependency.

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

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

Internal and External Oblique Muscle Asymmetry in Sprint Hurdlers and Sprinters: A Cross-Sectional Study

The abdominal muscles are vital in providing core stability for functional movements during most activities. There is a correlation between side asymmetry of these muscles and dysfunction. Thus, the purpose of this study was to evaluate and compare trunk muscle morphology and trunk rotational strength between sprint hurdlers, an asymmetrical sport, and sprinters, a symmetrical sport. Twenty-one trained collegiate sprint hurdlers and sprinters were recruited for the study (Hurdlers: 4M, 7F; Sprinters: 8M, 2F), average age (years) hurdlers: 20 ± 1.2; sprinters: 20.4 ± 1.9, height (cm) hurdlers: 172.6 ± 10.2; sprinters: 181.7 ± 4.5, and weight (kg) hurdlers: 67.6 ± 12.0; sprinters: 73.9 ± 5.6. Using real-time ultrasound, panoramic images of the internal oblique (IO) and external oblique (EO) were obtained at rest and contracted (flexion and rotation) in a seated position for both right and left sides of the trunk. While wearing a specially crafted shoulder harness, participants performed three maximal voluntary trunk rotational contractions (MVC). The three attempts were then averaged to obtain an overall MVC score for trunk rotation strength. Average MVC trunk rotational strength to the right was greater among all participants, p < 0.001. The IO showed greater and significant thickness changes from resting to contracted state than the EO, this was observed in all participants. The IO side asymmetry was significantly different between groups p < 0.01. Hurdlers, involved in a unilaterally demanding sport, exhibited the expected asymmetry in muscle morphology and in trunk rotational strength. Interestingly, sprinters, although involved in a seemingly symmetrical sport, also exhibited asymmetrical trunk morphology and trunk rotational strength.

Extended field-of-view ultrasound imaging is reliable for measuring Transversus Abdominis muscle size at rest and during contraction

Background

The strength and size of core muscles, including the abdominal muscles, are crucial to proper function in most activities. Therefore, it is important to reliably assess these characteristics. Our primary objective was to determine if the length, thickness and cross-sectional area of the transversus abdominis (TrA) can be visualized independently from the internal and external abdominal oblique muscles using extended field of view ultrasound imaging at rest and with contraction and to establish its intra- and inter-tester reliability.

Methods

Twenty-six individuals were recruited to participate in the study (20 F, 6 M), average age 24.0 years (SD 9.4), height 170.7 cm (SD 8.6) and weight 63.9 kg (SD 9.0). From this total number of participants, two groups of 16 randomly selected participants were assessed to determine intra- and inter-tester reliability respectively. Extended field of view ultrasound images were obtained at three vertebral levels during rest and contraction in the side lying position for both the right and left sides of the trunk.

Results

Excellent intra-tester and inter-tester reliability was seen (ICC range of 0.972 to 0.984). The overall average percent standard error of the measurement for all measurements and locations was approximately 4%. The overall average minimal difference for the thickness measurement for the resting and contraction conditions combined were as follows: intratester 0.056 (0.014) cm and intertester 0.054 (0.017) cm, for area intratester 0.287 (0.086) cm² and intertester 0.289 (0.101) cm² and for length intratester 0.519 (0.097) cm and intertester 0.507 (0.085) cm.

Conclusions

Extended field of view ultrasound imaging is an effective method of reliably capturing clear images of the TrA during rest and contraction. It provides an efficient mechanism for the analysis of muscle morphology by being able to measure the cross-sectional area, thickness, and length on one image. This methodology is recommended for studies investigating TrA function and training.

Effect of real-time ultrasound imaging for biofeedback on trunk muscle contraction in healthy subjects: a preliminary study

Background

Real-time ultrasound imaging (RUSI) has been increasingly used as a form of biofeedback when instructing and re-training muscle contraction. However, the effectiveness of the RUSI on a single sustained contraction of the lumbar multifidus (LM) and transversus abdominis (TrA) has rarely been reported. This preliminary study aimed to determine if the use of RUSI, as visual biofeedback, could enhance the ability of activation and continuous contraction of the trunk muscles including LM and TrA.

Methods

Forty healthy individuals were included and randomly assigned into the experimental group and control group. All subjects performed a preferential activation of the LM and/or TrA (maintained the constraction of LM and/or TrA for 30 s and then relaxed for 2 min), while those in the experimental group also received visual feedback provided by RUSI. The thickness of LM and/or TrA at rest and during contraction (T_c-max, T_15s, and T_30s) were extracted and recorded. The experiment was repeated three times.

Results

No significant differences were found in the thickness of LM at rest (P > 0.999), T_c-max (P > 0.999), and T_15s (P = 0.414) between the two groups. However, the ability to recruit LM muscle contraction differed between groups at T_30s (P = 0.006), with subjects in the experimental group that received visual ultrasound biofeedback maintaining a relative maximum contraction. Besides, no significant differences were found in the TrA muscle thickness at rest (P > 0.999) and T_c-max (P > 0.999) between the two groups. However, significant differences of contraction thickness were found at T_15s (P = 0.031) and T_30s (P = 0.010) between the two groups during the Abdominal Drawing-in Maneuver (ADIM), with greater TrA muscle contraction thickness in the experimental group.

Conclusions

RUSI can be used to provide visual biofeedback, which can promote continuous contraction, and improve the ability to activate the LM and TrA muscles in healthy subjects.

Effect of the Abdominal Draw-In Maneuver and Bracing on Abdominal Muscle Thickness and the Associated Subjective Difficulty in Healthy Individuals

We evaluated the trunk abdominal muscle thickness while performing different exercises to identify the most effective training and to investigate the subjective difficulty associated with exercising. Twenty-eight men (mean age: 21.6 ± 0.9 years) without orthopedic diseases were enrolled. Ultrasonic imaging was used to measure the thickness of the transversus abdominis (TA), internal oblique, and external oblique muscles while at rest and while performing the abdominal draw-in maneuver and abdominal bracing. Measurements were made in the supine and sitting positions, and the subjective difficulty in performing each exercise was examined using a 5-level evaluation scale. The TA and internal oblique muscle thicknesses were significantly greater during the abdominal draw-in maneuver (ADIM) than during bracing or resting, in the supine and sitting positions. The subjective difficulty of abdominal bracing (AB) was graded significantly higher than that of ADIM. Additionally, a correlation between subjective difficulty and muscle thickness was found for the TA and IO. Our results may contribute to the choice of more effective exercises for spinal stability.

Influence of Abdominal Hollowing Maneuver on the Core Musculature Activation during the Prone Plank Exercise

This cross-sectional study of repeated measures investigated whether integrating the abdominal hollowing maneuver (AHM) into the prone plank performance is an effective strategy for increasing both the activation of the deep and superficial core musculature. Electromyographical (EMG) responses of rectus abdominis (RA), external oblique (EO), internal oblique (IO), and lumbar erector spinae (LES), and ratings of perceived exertion (RPE) of 20 participants (13 male, 7 female; mean ± standard deviation (SD) age: 24.25 ± 3.54 years; body mass: 66.42 ± 8.40 kg; height: 1.70 ± 9.51 m) were compared across two experimental conditions: the traditional prone plank (STANDARD); and a variation including the AHM (HOLLOWING). Regarding Total Intensity, HOLLOWING resulted in significantly greater EMG response than STANDARD (p < 0.001; Effect size (ES) = 3.01). Specifically, RA showed no significant differences between STANDARD and HOLLOWING (p = 0.056; ES = 0.285). However, for the remaining analyzed muscles, HOLLOWING significantly provided higher EMG activation compared to STANDARD (LES: p = 0.004; ES = 0.619; left EO: p < 0.001; ES = 1.031; right EO: p < 0.001; ES = 1.419; left IO: p < 0.001; ES = 2.021; right IO: p < 0.001; ES = 2.269). Regarding RPE, HOLLOWING reported values significantly greater than STANDARD (p < 0.001; ES = 2.94). In conclusion, integrating the AHM into the prone plank exercise enhances overall abdominal activity, particularly in both obliques. These findings provide updated guidelines for lumbar stabilization and core strengthening in health-related physical fitness programs.

The Effects of Thrust Joint Manipulation on the Resting and Contraction Thickness of Transversus Abdominis in Patients With Low Back Pain: A Randomized Control Trial

OBJECTIVE

To investigate the immediate changes in resting and contracted thickness of the transversus abdominis (TrA) muscle after application of thrust joint manipulation (TJM) vs sham manipulation in participants with low back pain.

METHODS

A pretest-posttest randomized controlled trial design was performed. Consecutive subjects satisfying eligibility criteria completed patient-report outcome baseline measures, pretreatment rehabilitative ultrasound imaging (RUSI) measurements, followed by the randomly assigned intervention then, post-treatment RUSI measurements, and post-treatment & final patient-reported outcome measures. To compare the outcomes of TJM and sham manipulation on the TrA muscle thickness, a 2-by-2 analysis of variance (treatment [TJM and sham manipulation]) by time (pretreatment and post-treatment) was completed for both the TrA muscle thickness at rest and muscle thickness during contraction. Descriptive statistics including independent-sample t tests for continuous variables and χ² tests for categorical variables were used to analyze differences in patient-reported outcome measures between groups.

RESULTS

Sixty-seven eligible participants agreed to participate. No significant interactions were identified for either muscle thickness at rest or contraction.

CONCLUSION

This study did not support the hypothesis that manipulation would result in greater changes in TrA thickness at rest or during contraction in participants with low back pain. Based on prior research that identified subgroups of participants likely to respond to manipulation, future research should include participants more likely to respond favorably to TJM. This study was a priori registered with clinicaltrails.gov (NCT02558855).

Automatic Characterizations of Lumbar Multifidus Muscle and Intramuscular Fat with Fuzzy C-means based Quantization from Ultrasound Images

BACKGROUND

Low Back Pain (LBP) is a common disorder involving the muscles and bones and about half of the people experience LBP at some point of their lives. Since the social economic cost and the recurrence rate over the lifetime is very high, the treatment/rehabilitation of chronic LBP is important to physiotherapists, both for clinical and research purposes. Trunk muscles such as the lumbar multifidi is important in spinal functions and intramuscular fat is also important in understanding pain control and rehabilitations. However, the analysis of such muscles and related fat require many human interventions and thus suffers from the operator subjectivity especially when the ultrasonography is used due to its cost-effectiveness and no radioactive risk.

AIMS

In this paper, we propose a fully automatic computer vision based software to compute the thickness of the lumbar multifidi muscles and to analyze intramuscular fat distribution in that area.

METHODS

The proposed system applies various image processing algorithms to enhance the intensity contrast of the image and measure the thickness of the target muscle. Intermuscular fat analysis is done by Fuzzy C-Means (FCM) clustering based quantization.

RESULTS

In experiment using 50 DICOM format ultrasound images from 50 subjects, the proposed system shows very promising result in computing the thickness of lumbar multifidi.

CONCLUSION

The proposed system have minimal discrepancy(less than 0.2 cm) from human expert for 72% (36 out of 50 cases) of the given data. Also, FCM based intramuscular fat analysis looks better than conventional histogram analysis.

Muscle Thickness During Core Stability Exercises in Children and Adults

Core stability exercises are regular part of exercise programs for asymptomatic individuals across ages. The purpose of this study was to examine deep abdominal and multifidus muscle thickness in children and adults and to determine reliability of the rehabilitative ultrasound (RUSI) imaging. Transversus abdominis and lumbar multifidus thickness at rest and during core stability exercise were examined in pre-pubertal children (N = 23), adolescents (N = 20), young adults (N = 21) and middle-aged adults (N = 22). Thirty-nine participants were re-tested one week after to establish reliability. Muscle thickness at rest was lower in children and adolescents compared with young and middle-aged adults (p < 0.008). Young adults displayed the highest relative transversus abdominis thickness upon contraction (p < 0.008). Lumbar multfidus contraction thickness was greater in young-adults than middle-aged adults and pre-pubertal children (p < 0.008), but it was similar between young-adults and adolescents (p > 0.008). Reliability was high for both muscles (ICC_3,3 = 0.76 - 0.99). The age-related differences in muscle thickness indicate that core stability exercises may be beneficial for children and middle-aged adults.

Transversus abdominis and multifidus asymmetry in runners measured by MRI: a cross-sectional study

Objective

The transversus abdominis muscle (TrA) is active during running as a secondary respiratory muscle and acts, together with the multifidus, as trunk stabiliser. The purpose of this study was to determine size and symmetry of TrA and multifidus muscles at rest and with contraction in endurance runners without low back pain.

Design

Cross-sectional study.

Setting

A medical imaging centre in Melbourne, Australia.

Participants

Thirty middle-aged (43years±7) endurance-trained male (n=18) and female (n=12) runners without current or history of low back pain.

Outcome measures

MRI at rest and with the core engaged. The TrA and multifidus muscles were measured for thickness and length (TrA) and anteroposterior and mediolateral thickness (multifidus). Muscle activation was extrapolated from rest to contraction and compared with the same and contralateral side. Paired t-tests were performed to compare sides and contraction status.

Results

Left and right TrA and multifidus demonstrated similar parameters at rest (p>0.05). However, with contraction, the right TrA and multifidus (in mediolateral direction) were 9.2% (p=0.038) and 42% (p<0.001) thicker, respectively, than their counterparts on the left. There was no TrA thickness side difference with contraction in left-handed participants (p=0.985). When stratified by sex, the contracted TrA on the right side remained 8.4% thicker, but it was no longer statistically significant (p=0.134). The side difference with contraction of the TrA became less with increasing training age.

Conclusions

Right-handed long-term runners without low back pain exhibit a greater right side core muscle activation when performing an isometric contraction. This activation preference diminishes with increasing training age.

Abdominal girth as an index of muscle tension during abdominal hollowing: Selecting the optimal training intensity for the transversus abdominis muscle

The abdominal hollowing technique is used for training the transversus abdominis (TrA). However, the optimal intensity of hollowing is still unclear. The objective of the present study is to verify the validity of estimating the tension of the TrA by measuring the girth of the abdomen with a tape and to determine the optimum intensity of hollowing to effectively train the TrA. Sixteen healthy males performed hollowing with an intensity of 0%, 25%, 50%, 75%, and 100%, estimated from the girth of the abdomen. The shear elastic modulus was measured for the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and TrA at all intensities via ultrasonic shear wave elastography. The shear elastic modulus was considered as the index of the tension of the abdominal muscles at each intensity, and the ratio of the TrA to RA, EO, and IO respectively was calculated as the index of TrA selectivity. As the intensity of hollowing increased, the girth of abdomen decreased and tension of all the four muscles increased. The ratio of TrA to the RA, EO, and IO did not exhibit a significant variation among hollowing intensities of 25% to 100%. It is rational to estimate the tension of the TrA by measuring the girth of the abdomen. Moreover, considering both TrA contraction intensity and selectivity, abdominal hollowing performed at maximum intensity was effective for the maximum contraction training of the TrA.

The effect of therapeutic abdominal drawing-in maneuver using ultrasonography on lateral abdominal muscle thickness and balance

BACKGROUND

Lateral abdominal muscles control the lumbar region and this manages the stability of the trunk through co-contraction. Abdominal drawing-in maneuver (ADIM) is the basis method for spine stabilization to restore proper neuromuscular control.

OBJECTIVE

To investigate the effect of therapeutic abdominal drawing-in maneuver on abdominal muscle thickness and balance.

METHODS

Twenty healthy adults were divided into 2 groups. The experimental group performed a bridging exercise with ADIM whereas the control group performed a bridging exercise without ADIM. The exercise was conducted 3 times a week for 4 weeks. Ultrasonography was used to measure the thickness of abdominal muscles. Balance ability was evaluated using Tetrax device. The Wilcoxon signed ranks test for comparison of pre and post values and Mann Whitney U test for comparison between groups were used.

RESULTS

After 4 weeks, there was a significant difference in the thickness of TrA between groups (p< 0.05) whereas no significant difference in IO and EO (p> 0.05). In stability values, the experimental group showed significant changes in stability indexes of standing with eyes open (NO) and standing on the pillow with eyes closed (PC) after the exercise period and there was a significant difference in NO between two groups.

CONCLUSIONS

Performing the bridging exercise with abdominal drawing-in maneuver is a more effective way to strengthen the abdominal muscles and stabilize the body than bridging exercise only.

Effects of stabilization exercise using flexi-bar on functional disability and transverse abdominis thickness in patients with chronic low back pain

[Purpose] The purpose of this study is to examine the effects of lumbar stabilization exercises using flexi-bar (FB) on pain, functional disability, transverse abdominis muscle (TrA) activation capacity and thickness in patients with chronic low back pain (CLBP). [Subjects and Methods] Twenty-seven patients were randomly assigned to an experimental (14 patients performing stabilization exercises with flexi-bar (FB)) or control (13 patients performing stabilization exercises) group. The patients in both groups then underwent stabilization exercises with or without FB 30 min/day, 3 times a week, for 6 weeks. The main outcome measures were perceived disability based on the pain, Oswestry disability index (ODI), TrA activation capacity and thickness. [Results] Both groups showed improved ODI, VAS, and TrA activation capacity performed for 6 weeks in patients with CLBP, but all outcomes, except for TrA thickness, showed greater improvements in patients following stabilization exercises with FB than following stabilization exercises. [Conclusion] Based on the above results, lumbar stabilization exercises with FB could restoring pain, functional disability and improving TrA activation capacity in CLBP patients.

Influence of Ultrasound Transducer Tilt in the Cranial and Caudal Directions on Measurements of Inter-Rectus Distance in Parous Women

Purpose: An increased inter-rectus distance (IRD) can persist after a pregnancy and may be associated with lumbopelvic dysfunction. Ultrasound imaging (USI) is currently the gold standard for measuring IRD; however, no study has explored the need to standardize the transducer angle during these evaluations. The purpose of this study was to determine whether the angle of the ultrasound transducer relative to the underlying abdominal wall has an effect on measurements of IRD in parous women. Method: Ultrasound images of the linea alba (LA) were captured from 15 women, at rest and during a head lift, beginning with images acquired perpendicular to the LA at the midline, then tilted in 5° increments to 15° in both the cranial and the caudal directions. Repeated-measures analyses of variance were used to test for systematic differences in IRD measurements among the transducer angles in both the rest and the head-lift conditions. An α of 0.05 was used for all tests. Results: No significant effect of transducer angle was found in IRD measurements acquired with participants at rest (F_2.24,31.3=1.814; p=0.18) or during a head lift (F_3.15,44.1=1.315; p=0.28). Conclusion: When using USI, cranial or caudal tilt errors in transducer angle do not appear to pose a problem when measuring IRD.

Audiovisual Biofeedback-Based Trunk Stabilization Training Using a Pressure Biofeedback System in Stroke Patients: A Randomized, Single-Blinded Study

The purpose of this study was to assess the effects of audiovisual biofeedback-based trunk stabilization training using a pressure biofeedback system (PBS) in stroke patients. Forty-three chronic stroke patients, who had experienced a stroke more than 6 months ago and were able to sit and walk independently, participated in this study. The subjects were randomly allocated to an experimental group (n = 21) or a control group (n = 22). The experimental group participated in audiovisual biofeedback-based trunk stabilization training for 50 minutes/day, 5 days/week, for 6 weeks. The control group underwent trunk stabilization training without any biofeedback. The primary outcome of this study was the thickness of the trunk muscles. The secondary outcomes included static sitting balance ability and dynamic sitting balance ability. The thickness of the trunk muscles, static sitting balance ability, and dynamic sitting balance ability were significantly improved in the experimental group compared to the control group (p < 0.05). The present study showed that trunk stabilization training using a PBS had a positive effect on the contracted ratio of trunk muscles and balance ability. By providing audiovisual feedback, the PBS enables accurate and effective training of the trunk muscles, and it is an effective method for trunk stabilization.

TRANSVERSUS ABDOMINIS ACTIVATION AND TIMING IMPROVES FOLLOWING CORE STABILITY TRAINING: A RANDOMIZED TRIAL

Background

Patients with non-specific low back pain (LBP) often present with a decrease in transversus abdominis (TrA) muscle activation and delayed onset of contraction with extremity movements, potentially contributing to recurrent LBP. Core stability is required for extremity movement and if the timing of when the TrA contracts is not corrected patients may continue to experience LBP.

Hypothesis/Purpose

The purpose of this study was to assess the effects of a four-week core stability rehabilitation program on TrA activation ratio and when the TrA initiates contraction during upper extremity movements in subjects with and without LBP. It was hypothesized that those with LBP would experience greater changes in TrA activation and onset of contraction by the TrA compared to the healthy group.

Study Design

Randomized Clinical Trial.

Methods

Forty-two participants volunteered (21 healthy and 21 LBP). Ultrasound imaging measured the TrA activation ratio and time of initial contraction of the TrA during upper extremity movement into flexion. Half of the healthy and LBP participants were assigned to the exercise group. Participants reported twice a week to the athletic training facility to complete an exercise progression of three exercises. After four weeks, all participants returned to have TrA activation and timing measured again.

Results

Pertaining to demographics, there were no differences between the healthy and LBP participants. There was a group interaction for both TrA activation ratio (p=.049) and onset of initial contraction (p=.008). Those in the exercise group showed an increase in TrA activation ratio (1.85 ± 0.09) compared to the control group (1.79 ± 0.08), as well as an improvement in the onset of contraction (2.07 ± 0.08 seconds) compared to the control group (2.23 ± 0.09 seconds) after the four-week rehabilitation program. Strong effect sizes for TrA activation ratio (0.71 [0.06-1.35]) and initial onset of TrA contraction (-1.88 [-2.63 - -1.11]) were found indicating clinical differences related to the interventions.

Conclusion

TrA activation and timing were altered following a four-week core stability program in people with and without LBP. Clinicians should consider incorporating these exercises for improving the function of the TrA.

Level of Evidence

Therapy, level 2b.

Asymmetrical abdominal muscle morphometry is present in injury free adolescent cricket pace bowlers: A prospective observational study

OBJECTIVES

This study aimed to determine if abdominal muscle thickness, activation and symmetry are associated with prospective in-season injury among adolescent cricket pace bowlers.

DESIGN

A quantitative, prospective, observational study design was used.

SETTING

Data was collected at an indoor venue at a secondary school.

PARTICIPANTS

28 injury-free, male, adolescent pace bowlers between the ages of 13 and 18 participated.

MAIN OUTCOME MEASURES

Muscle thickness of the transversus abdominis (TA), internal oblique (IO) and external oblique (EO) muscles were measured at rest and during an abdominal drawing-in maneuver (ADIM) i.e. activation, using ultrasound imaging. Incidence of injury was monitored monthly during the cricket season.

RESULTS

Thickness of the non-dominant IO at rest was greater than the dominant side for pace bowlers who remained injury free during the cricket season (p = 0.01, effect size (ES) = 0.65). This was, however not the case for bowlers who sustained injuries (p = 0.47; ES = 0.24). TA percentage change during ADIM (activation) on the dominant side was less in bowlers who sustained non-contact injuries compared to those who remained injury free (p = 0.03; ES = 1.17).

CONCLUSIONS

Asymmetry in IO thickness may play a protective role against injury, whilst poor TA activation on the dominant side may pose a risk to injury.

The Effect of Distractive Function on Volitional Preemptive Abdominal Contraction During a Loaded Forward Reach in Normal Subjects

BACKGROUND

Volitional preemptive abdominal contraction (VPAC) is used to protect the spine and prevent injury. No published studies to data have examined the effect of distraction on VPAC use during function.

OBJECTIVE

To examine the effect of an auditory distraction ("Stroop task") on healthy subjects' ability to sustain VPAC by use of the abdominal drawing-in maneuver during loaded forward reach.

DESIGN

Within-subjects, repeated-measure cohort design.

SETTING

Clinical laboratory setting.

PARTICIPANTS

Convenience sample of 42 healthy individuals (ages 20-57 years).

METHODS

Transversus abdominis (TrA) thickness was measured with M-mode ultrasound imaging. Each subject performed Stroop versus no Stroop during 4 conditions: (1) without VPAC, quiet standing; (2) with VPAC, quiet standing; (3) without VPAC, forward reach; and (4) with VPAC, forward reach. An investigator blinded to the conditions measured the first 10 subjects to establish intratester reliability of probe/transducer placement and TrA measurement.

DATA REDUCTION

TrA thickness (mm) change represented VPAC performance. A single investigator measured onscreen TrA thickness twice at each second from second-6 through -10 on a recorded ultrasound imaging sequence.

RESULTS

A 2 (Stroop) × 4 (Activity) repeated-measures analysis of variance found no significant Stroop × Activity interaction [F(3, 93) = 0.345, P = .793] and no main effect for Stroop [F (1,31) = 1.324, P = .259] but found a significant main effect for activity [F (3,93) = 17.729, P < .001]. Tukey post-hoc pairwise comparisons demonstrated significant differences between VPAC versus no-VPAC conditions, except between quiet standing/yes-VPAC and loaded forward reach/no-VPAC conditions (P = .051). The interclass correlation coefficient (3,2) for probe/transducer placement reliability was 0.87, 0.91, 0.92, and 0.93 for conditions 1-4, respectively. The interclass correlation coefficient (3,2) for TrA measurement reliability was 0.96, 0.99, 0.99, and 0.99 for conditions 1-4, respectively.

CONCLUSION

A distracting executive function (Stroop task) did not produce a significant negative impact on normal individuals' ability to sustain a VPAC during quiet standing or loaded forward reach activities.

LEVEL OF EVIDENCE

II.

A Randomized Controlled Trial Comparing the McKenzie Method to Motor Control Exercises in People With Chronic Low Back Pain and a Directional Preference

Study Design Randomized clinical trial. Background Motor control exercises are believed to improve coordination of the trunk muscles. It is unclear whether increases in trunk muscle thickness can be facilitated by approaches such as the McKenzie method. Furthermore, it is unclear which approach may have superior clinical outcomes. Objectives The primary aim was to compare the effects of the McKenzie method and motor control exercises on trunk muscle recruitment in people with chronic low back pain classified with a directional preference. The secondary aim was to conduct a between-group comparison of outcomes for pain, function, and global perceived effect. Methods Seventy people with chronic low back pain who demonstrated a directional preference using the McKenzie assessment were randomized to receive 12 treatments over 8 weeks with the McKenzie method or with motor control approaches. All outcomes were collected at baseline and at 8-week follow-up by blinded assessors. Results No significant between-group difference was found for trunk muscle thickness of the transversus abdominis (-5.8%; 95% confidence interval [CI]: -15.2%, 3.7%), obliquus internus (-0.7%; 95% CI: -6.6%, 5.2%), and obliquus externus (1.2%; 95% CI: -4.3%, 6.8%). Perceived recovery was slightly superior in the McKenzie group (-0.8; 95% CI: -1.5, -0.1) on a -5 to +5 scale. No significant between-group differences were found for pain or function (P = .99 and P = .26, respectively). Conclusion We found no significant effect of treatment group for trunk muscle thickness. Participants reported a slightly greater sense of perceived recovery with the McKenzie method than with the motor control approach. Level of Evidence Therapy, level 1b-. Registered September 7, 2011 at www.anzctr.org.au (ACTRN12611000971932). J Orthop Sports Phys Ther 2016;46(7):514-522. Epub 12 May 2016. doi:10.2519/jospt.2016.6379.

Ultrasound Assessment of Abdominal Muscle Thickness in Postpartum vs Nulliparous Women

OBJECTIVE

The purpose of this study was to determine the effect size in measurable change of abdominal musculature morphology using ultrasonography in postpartum women within 1 month of a healthy, vaginal delivery.

METHODS

One hundred fifty-six participants were recruited for this study. B-mode ultrasound imaging was used to measure abdominal muscle thickness on 80 nulliparous women and 76 mothers who had delivered within the past 4 weeks. Measures were taken for the upper and lower rectus abdominus, external and internal obliques, and transversus abdominus at rest.

RESULTS

Statistically significant differences were found in the thickness of the rectus abdominus muscle at both sites; upper (P < .0001) and lower (P < .0001) as well as the internal oblique (P < .0001). All 3 muscles were thinner in postpartum participants (8.29 ± 1.83 mm, 8.89 ± 2.29 mm, and 7.06 ± 1.82 mm, respectively) within the first month of delivery than in controls (10.82 ± 1.93 mm, 11.13 ± 2.38 mm, and 8.36 ± 1.87 mm, respectively). Large effect sizes were found for the influence of pregnancy on the rectus muscle segments (1.35 for the upper rectus abdominus and 1.00 for the lower rectus abdominus) and a medium effect size for the internal oblique (0.71). No significant differences were observed in the remaining 2 muscles.

CONCLUSION

This study showed that there are differences in morphology of the abdominal muscles in pregnant women vs nonpregnant controls. The large effect sizes reported may provide the basis for future studies examining relationships between morphology, functional change, and back pain during pregnancy.

Comparison of changes in the mobility of the pelvic floor muscle on during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction

[Purpose] The purpose of this study was to compare changes in the mobility of the pelvic floor muscle during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. [Subjects] Thirty healthy adults participated in this study (15 men and 15 women). [Methods] All participants performed a bridge exercise and abdominal curl-up during the abdominal drawing-in maneuver, maximal expiration, and pelvic floor muscle maximal contraction. Pelvic floor mobility was evaluated as the distance from the bladder base using ultrasound. [Results] According to exercise method, bridge exercise and abdominal curl-ups led to significantly different pelvic floor mobility. The pelvic floor muscle was elevated during the abdominal drawing-in maneuver and descended during maximal expiration. Finally, pelvic floor muscle mobility was greater during abdominal curl-up than during the bridge exercise. [Conclusion] According to these results, the abdominal drawing-in maneuver induced pelvic floor muscle contraction, and pelvic floor muscle contraction was greater during the abdominal curl-up than during the bridge exercise.

The Effects of Volitional Preemptive Abdominal Contraction on Postural Control Responses in Healthy Subjects

OBJECTIVE

To investigate the effect of volitional preemptive abdominal contraction by using an abdominal bracing maneuver (ABM) on postural control responses.

DESIGN

A within-subjects, repeated-measure, experimental design.

SETTING

Laboratory.

PARTICIPANTS

Sixty-five healthy subjects between 18 and 50 years of age.

METHODS

Subjects performed ABM alternating with No-ABM during 2 rounds of 2 Neurocom computed dynamic posturography tests: the Motor Control Test (MCT) and conditions 1 (eyes open), 2 (eyes closed), and 5 (eyes closed, sway-referenced support) of the Sensory Organization Test (SOT).

MAIN OUTCOME MEASUREMENTS

(1) MCT Response Latency (milliseconds) and Response Scaling (magnitude of active postural correction) and (2) SOT Equilibrium Scores and 2-Dimensional Sway (°/second), and SOT Movement Strategy, which measure postural sway and movement strategies (ankle versus hip strategy), respectively.

RESULTS

The use of ABM (versus No-ABM) produced: (1) a small but statistically significant decrease in SOT Equilibrium Score for condition 2 (-1.0%; P = .004); (2) an increase in SOT 2-Dimensional Sway (°/second) during conditions 1 (16.9%; P = .0001) and 2 (15.0%; P = .0001); (3) a small decrease in SOT Movement Strategy scores during condition 1 (-0.5%; P = .001) and condition 2 (-1.0%; P = .017); and (4) a reduction of MCT Response Latency by 3 milliseconds (-2.1%; P = .005) and reduction of Response Scaling by 0.33°/second (-9.2%; P = .001).

CONCLUSION

Individuals can incorporate the ABM without substantively altering postural control. Although selected SOT and MCT scores exhibited small decreases in postural response integrity, those outcomes did not reflect functionally meaningful changes. These findings can enhance clinicians' confidence in prescribing the ABM as a means to protectively stabilize the spine and potentially prevent injury in healthy subjects without concern for reducing postural control, especially during more complex postural perturbations that introduce sensory conflict.

Reliability of ultrasound imaging of the transversus abdominis muscle in asymptomatic subjects

[Purpose] The purpose of this study was to assess intra-rater and inter-rater procedural reliability of ultrasound imaging measurements of transversus abdominis thickness. [Subjects] Thirty therapists who attended the B Hospital in Hwaseong participated in the study. [Methods] Two examiners assessed transverse abdominis thickness at rest and during contraction. Intra-class correlation coefficient with 95% confidence interval and, standard error of measurement were calculated. [Results] The intra-rater procedural reliability of ultrasound imaging measurements of transverse abdominis thickness, assessed using the intra-class correlation coefficient, was 0.65-0.86 (within-day, 0.65-0.86; between-day, 0.77-0.85). The inter-rater procedural reliability of ultrasound imaging measurements of transverse abdominis thickness, assessed using the intra-class correlation coefficient, was 0.72-0.86 (within-day, 0.72-0.86; between-day, 0.82-0.83). [Conclusion] Ultrasound imaging can be used as a reliable method for measurements of transverse abdominis thickness.

An exploratory examination of the association between altered lumbar motor control, joint mobility and low back pain in athletes

Background:

Low back pain (LBP) is a common cause of lost playing time and can be a challenging clinical condition in competitive athletes. LBP in athletes may be associated with joint and ligamentous hypermobility and impairments in activation and coordination of the trunk musculature, however there is limited research in this area.

Objectives:

To determine if there is an association between altered lumbar motor control, joint mobility and low back pain (LBP) in a sample of athletes.

Materials and Methods:

Fifteen athletes with LBP were matched by age, gender and body mass index (BMI) with controls without LBP. Athletes completed a questionnaire with questions pertaining to demographics, activity level, medical history, need to self-manipulate their spine, pain intensity and location. Flexibility and lumbar motor control were assessed using: active and passive straight leg raise, lumbar range of motion (ROM), hip internal rotation ROM (HIR), Beighton ligamentous laxity scale, prone instability test (PIT), observation of lumbar aberrant movements, double leg lowering and Trendelenburg tests. Descriptive statistics were compiled and the chi square test was used to analyze results.

Results:

Descriptive statistics showed that 40% of athletes with LBP exhibited aberrant movements (AM), compared to 6% without LBP. 66% of athletes with LBP reported frequently self-manipulating their spine compared to 40% without LBP. No significant differences in motor control tests were found between groups. Athletes with LBP tended to have less lumbar flexion (63 ± 11°) compared to those without LBP (66 ± 13°). Chi-Square tests revealed that the AM were more likely to be present in athletes with LBP than those without (X2 = 4.66, P = 0.03).

Conclusions:

The presence of aberrant movement patterns is a significant clinical finding and associated with LBP in athletes.

Reversal time of postprandial changes of the thickness of abdominal muscles employing ultrasound measurements

OBJECTIVES

Low thickness of Transversus Abdominis, Internal Oblique and External Oblique muscles may play a role in development of low back pain. Ultrasonography is increasingly utilized to measure the thickness of these muscles. Prandial state has recently been proposed as a confounding factor in such measurements. We aimed to compare the reversal time of the postprandial thickness of these muscles with preprandial values. The measurement errors of ultrasonographic values were also assessed in both immediate preprandial and postprandial states.

DESIGN

Interventional cross-sectional study.

METHODS

The ultrasonographic thickness of lateral abdominal muscles was measured at rest and during abdominal drawing-in maneuver in 20 healthy participants before and after consumption of a specific meal. Postprandial ultrasound measurements continued every 15 min until their thickness reached 95% of their preprandial values.

RESULTS

There was a statistically significant reduction in postprandial thickness of these muscles (all p-values <0.001 on both sides). The reversal times were 1.5, 1.3 and 1.2 h for Transversus Abdominis, Internal Oblique, and External Oblique muscles, respectively. Standard Error of Measurement and Smallest Detectable Change were in the range of 0.007-0.013 mm and 0.020-0.035 mm, respectively.

CONCLUSIONS

To limit the effects of prandial state on the sonographic thickness of lateral abdominal muscles, we recommend measuring these values at least 1.5-2 h after food consumption. For the future studies, controlling the participants according to their prandial state is recommended.

Reliability of B-mode sonography of the abdominal muscles in healthy adolescents in different body positions

OBJECTIVES

The primary aim of this study was to determine the reliability of abdominal sonographic measurements in adolescents. The secondary aim was to determine whether age, sex, or body position had an impact on the reliability of abdominal muscle sonographic measurements in adolescents.

METHODS

Sixty-nine asymptomatic participants aged 10 to 15 years without any postural faults participated in the study. The participants were divided into 3 age groups: 10 to 11, 12 to 13, and 14 to 15 years, according to their sex. All participants underwent 3 measurements of the thickness of the transversus abdominis, internal oblique, and external oblique muscles on both sides of the body in the supine, sitting, and standing positions. The participants' measurements were taken at the end of normal exhalation, and the values were recorded in millimeters.

RESULTS

Regardless of the participant's age, sex, and body position, the results for the 3 measurements (intraclass correlation coefficient [ICC(3,3)]) for the transversus abdominis and internal oblique ranged from 0.81 to 0.99. With reference to the external oblique, intraexaminer reliability (ICC(3,3)) in the supine position ranged from 0.81 to 0.98, whereas in the sitting and standing positions, it fluctuated from 0.63 to 0.96.

CONCLUSIONS

Sonography for assessment of the internal oblique and transversus abdominis muscles in different body positions in healthy adolescents aged 10 to 15 years was found to have reliability. To obtain high measurement reliability for the transversus abdominis and internal oblique at rest, at least 2 measurements should be performed, regardless of age, sex, or resting body position. Performing 3 measurements of the external oblique guarantees satisfactory reliability only in the supine position.

Association between changes in electromyographic signal amplitude and abdominal muscle thickness in individuals with and without lumbopelvic pain

STUDY DESIGN

Validation study.

OBJECTIVES

To investigate the association between changes in electromyographic (EMG) signal amplitude and sonographic measures of muscle thickness of 4 abdominal muscles, during 2 clinical tests, in adults with and without lumbopelvic pain.

BACKGROUND

There is a trend in rehabilitation to use ultrasound imaging (USI) to determine the extent of abdominal muscle contraction. However, the literature investigating the relationship between abdominal muscle thickness change and level of activation is inconclusive and has not included clinically relevant tasks.

METHODS

Simultaneous recording from fine-wire EMG and USI was performed for 4 abdominal muscles, in 7 adults with lumbopelvic pain (mean ± SD age, 29.7 ± 12.0 years) and 7 adults without lumbopelvic pain (32.0 ± 10.6 years), during an active straight leg raise (ASLR) test and an abdominal drawing-in maneuver (ADIM). Cross-correlation functions and linear regression analyses were used to describe the relationship between the 2 measures. Analyses of variance were used to compare individuals with and without lumbopelvic pain, with an alpha set at .05.

RESULTS

Across all muscles, peak cross-correlation values were low (ASLR, r = 0.28 ± 0.09; ADIM, r = 0.35 ± 0.11), and there was large variability in associated time lags (ASLR, τ = 0.69 ± 2.56 seconds; ADIM, τ = 0.53 ± 3.75 seconds). Regression analyses did not detect a systematic pattern of association between EMG signal amplitude and USI measurements, and analyses of variance revealed no differences between cohorts.

CONCLUSION

These results suggest a weak relationship between EMG amplitude and abdominal muscle thickness change measured with USI during the ADIM and ASLR, and raise questions about thickness change derived from USI as a measure of muscular activity for the abdominal musculature.

A clinical prediction rule to identify patients with low back pain who are likely to experience short-term success following lumbar stabilization exercises: a randomized controlled validation study

STUDY DESIGN

Randomized controlled trial.

OBJECTIVE

To determine the validity of a previously suggested clinical prediction rule (CPR) for identifying patients most likely to experience short-term success following lumbar stabilization exercise (LSE). Background Although LSE is commonly used by physical therapists in the management of low back pain, it does not seem to be more effective than other interventions. A 4-item CPR for identifying patients most likely to benefit from LSE has been previously suggested but has yet to be validated.

METHODS

One hundred five patients with low back pain underwent a baseline examination to determine their status on the CPR (positive or negative). Patients were stratified by CPR status and then randomized to receive an LSE program or an intervention consisting of manual therapy (MT) and range-of-motion/flexibility exercises. Both interventions included 11 treatment sessions delivered over 8 weeks. Low back pain-related disability was measured by the modified version of the Oswestry Disability Index at baseline and upon completion of treatment.

RESULTS

The statistical significance for the 2-way interaction between treatment group and CPR status for the level of disability at the end of the intervention was P = .17. However, among patients receiving LSE, those with a positive CPR status experienced less disability by the end of treatment compared with those with a negative CPR status (P = .02). Also, among patients with a positive CPR status, those receiving LSE experienced less disability by the end of treatment compared with those receiving MT (P = .03). In addition, there were main effects for treatment and CPR status. Patients receiving LSE experienced less disability by the end of treatment compared to patients receiving MT (P = .05), and patients with a positive CPR status experienced less disability by the end of treatment compared to patients with a negative CPR status, regardless of the treatment received (P = .04). When a modified version of the CPR (mCPR) containing only the presence of aberrant movement and a positive prone instability test was used, a significant interaction with treatment was found for final disability (P = .02). Of the patients who received LSE, those with a positive mCPR status experienced less disability by the end of treatment compared to those with a negative mCPR status (P = .02), and among patients with a positive mCPR status, those who received LSE experienced less disability by the end of treatment compared to those who received MT (P = .005).

CONCLUSION

The previously suggested CPR for identifying patients likely to benefit from LSE could not be validated in this study. However, due to its relatively low level of power, this study could not invalidate the CPR, either. A modified version of the CPR that contains only 2 items may possess a better predictive validity to identify those most likely to succeed with an LSE program. Because this modified version was established through post hoc testing, an additional study is recommended to prospectively test its predictive validity.

LEVEL OF EVIDENCE

Prognosis, level 1b-.

Effects of bridging exercise on different support surfaces on the transverse abdominis

[Purpose] The purpose of this study was to identify the effects of bridging exercise on different support surfaces on the thickness of the musculus transversus abdominis and lower extremity muscle activities. [Subjects] Thirty-five students of H University. [Methods] The experimental group (n=18) performed bridging exercise on the sling support surface, and the control group (n=17) performed bridging exercise on a general support surface. [Results] Thickness changes in the musculus transversus abdominis were 0.35 cm in the experimental group, and 0.17 cm in the control group, suggesting that the experimental group showed a more significant change. For the lower extremity muscular activity, there was a significant difference between the experimental group and the control group only in the biceps femoris muscle. [Conclusion] Based on these results, we consider that bridging exercise on a sling support surface would increase the thickness of the transversus abdominis and lower extremity muscle activities in rehabilitation programs for patients with back pain.

Co-contractive activation of the superficial multifidus during volitional preemptive abdominal contraction

OBJECTIVE

To investigate whether the superficial multifidus (MF) muscle at the lower lumbar spine displayed co-contraction during volitional preemptive abdominal contraction (VPAC) through the abdominal drawing-in maneuver (ADIM) or the abdominal bracing maneuver (ABM) in 3 different postural positions.

DESIGN

A within-subject cohort design.

SETTING

A clinical laboratory.

PARTICIPANTS

A healthy convenience sample of 21 women and 13 men; mean age (SD), 25.5 ± 6.5 years.

METHODS

We collected surface electromyographic measurements for the superficial MF at the L5 vertebral level and abdominal wall muscles. Ultrasound imaging was used during screening and testing sessions for confirming transverse abdominis muscle activation while subjects maintained a relaxed state without volitional abdominal contraction (no-VPAC) and performed ADIM and ABM in 3 postural positions: supine, 4-point kneeling, and upright standing.

MAIN OUTCOME MEASUREMENT

The frequency of superficial MF co-contraction occurrences (percentage of the total number of conditions) was measured during ADIM and ABM in 3 different postural positions.

DATA ANALYSES

A Cochran Q test for k-related samples (α = 0.05) was used for data analysis.

RESULTS

Activation of the abdominal wall by using either VPAC strategy resulted in a significantly greater MF co-contraction occurrence when compared with no-VPAC in each position. The ABM produced a significantly higher MF co-contractive occurrence versus the ADIM in the supine position.

CONCLUSION

Both VPAC strategies produced a co-contractive MF response, which appears to be important for lumbar segmental stabilization and control. Analysis of the results suggests that VPAC strategies are appropriate for coactivating the MF, which can enhance spinal protection and rehabilitation responses.

Effect of two different exercise regimens on trunk muscle morphometry and endurance in soldiers in training

BACKGROUND

Limited evidence exists on how strength and endurance exercises commonly used to prevent low back pain affect muscle morphometry and endurance.

OBJECTIVE

The purpose of this study was to analyze the effects of 2 exercise regimens on the morphometry and endurance of key trunk musculature in a healthy population.

DESIGN

The study was designed as a randomized controlled trial.

SETTING

The study was conducted in a military training setting.

PARTICIPANTS

A random subsample (n=340; 72% men, 28% women; mean [±SD] age=21.9±4.2 years; mean [±SD] body mass index=24.8±2.8 kg/m2) from the larger Prevention of Low Back Pain in the Military trial (N=4,325) was included.

INTERVENTION

The core stabilization exercise program (CSEP) included low-load/low-repetition motor control exercises, whereas the traditional exercise program (TEP) included exercises conducted at a fast pace, with the use of high-load, high-repetition trunk strengthening exercises.

MEASUREMENTS

Baseline and follow-up examinations included ultrasound imaging of the trunk muscles and endurance tests. Linear mixed models were fitted to study the group and time effect and their interactions, accounting for the clustering effect.

RESULTS

Symmetry generally improved in the rest and contracted states, but there were no differences suggestive of muscle hypertrophy or improved ability to contract the trunk muscles between soldiers receiving the CSEP or the TEP. Total trunk endurance time decreased over the 12-week period, but endurance performance favored soldiers in the CSEP group. Endurance time was not associated with future episodes of low back pain.

LIMITATIONS

The lack of morphological changes may not be detectable in an already-active cohort, or a more intensive dose was needed.

CONCLUSIONS

Although improved symmetry was noted, neither the CSEP nor the TEP resulted in muscle hypertrophy. Longer endurance times were noted in individuals who completed the CSEP but were not strongly predictive of future low back pain episodes.

A neuromuscular strategy to prevent spinal torsion: backward perturbation alters asymmetry of transversus abdominis muscle thickness into symmetry

Symmetric co-contraction of the transversus abdominis (TrA) muscle is beneficial in terms of increasing trunk stability. The aim of this study was to investigate the symmetry of lateral abdominal muscle thickness during static and dynamic conditions. Fifteen male subjects (27.13 ± 5.51 years old) were instructed to sit on a chair and maintain upright posture. Every individual subject wore a jacket harness that could be backwardly attached to a 9-kg weight through a pulley system. An unexpected drop of the weight induced the transition from static to dynamic condition. The thickness of external oblique, internal oblique, and TrA muscles was measured with ultrasonography. Our results revealed more symmetry of TrA thickness during the dynamic condition (21% vs. 13%, p = 0.019) compared with the static. The symmetric muscle thickness of TrA during the dynamic condition is considered a result of more contraction on the non-dominant side. This phenomenon could be a possible strategy of deep abdominal muscles to prevent spinal torsion during sudden trunk perturbation.

Comparison of the sonographic features of the abdominal wall muscles and connective tissues in individuals with and without lumbopelvic pain

STUDY DESIGN

Cross-sectional, case-control study.

OBJECTIVES

To measure and compare the resting thickness of the 4 abdominal wall muscles, their associated perimuscular connective tissue (PMCT), and interrecti distance (IRD) in persons with and without lumbopelvic pain (LPP), using ultrasound imaging.

BACKGROUND

The muscles and PMCT of the abdominal wall assist in controlling the spine. Functional deficits of the abdominal wall muscles have been detected in populations with LPP. Investigations of the abdominal wall in those with LPP are primarily concerned with muscle, most commonly the transversus abdominis (TrA) and internal oblique (IO). Because the abdominal wall functions as a unit, all 4 abdominal muscles and their associated connective tissues should be considered concurrently.

METHODS

B-mode ultrasound imaging was used to measure the resting thickness of the rectus abdominis (RA), external oblique, IO, and TrA muscles; the PMCT planes; and IRD in 50 male and female subjects, 25 with and 25 without LPP (mean ± SD age, 36.3 ± 9.4 and 46.6 ± 8.0 years, respectively). Univariate correlation analysis was used to identify covariates. Analyses of covariance (ANCOVAs) and the Kruskal-Wallis test (IRD) were used to compare cohorts (α = .05).

RESULTS

The LPP cohort had less total abdominal muscle thickness (LPP mean ± SD, 18.9 ± 3.0 mm; control, 20.3 ± 3.0 mm; ANCOVA adjusted for body mass index, P = .03), thicker PMCT (LPP, 5.5 ± 0.2 mm; control, 4.3 ± 0.2 mm; ANCOVA adjusted for body mass index, P = .007), and wider IRD (LPP, 11.5 ± 2.0 mm; control, 8.4 ± 1.8 mm; Kruskal-Wallis, P = .005). Analysis of individual muscle thickness revealed no difference in the external oblique, IO, and TrA, but a thinner RA in the LPP cohort (LPP mean ± SD, 7.8 ± 1.5 mm; control, 9.1 ± 1.2 mm; ANCOVA adjusted for body mass index, P<.001).

CONCLUSION

To our knowledge, this is the first study to investigate the morphological characteristics of all 4 abdominal muscles and PMCT in individuals with LPP. The results suggest that there may be altered loading of the PMCT and linea alba secondary to an altered motor control strategy involving a reduced contribution of the RA. Further, the change in RA and connective tissue morphology may be more evident than changes in external oblique, IO, and TrA thickness in persons with LPP. The causes and functional implications of these changes warrant further investigation, as does the role of the RA muscle in the development and persistence of LPP.

Abdominal and lumbar multifidus muscle size and symmetry at rest and during contracted States. Normative reference ranges

OBJECTIVES

The purpose of this study was to establish reference values for abdominal and lumbar multifidus muscles at rest and while contracted in a sample of active healthy adults.

METHODS

Three hundred forty participants (mean age ± SD, 21.8 ± 3.9 years; 96 females and 244 males) completed the study. Ultrasound imaging was used to assess the thickness of the transversus abdominis, internal and external oblique, rectus abdominis, and lumbar multifidus muscles. Additionally, the cross-sectional area of the rectus abdominis was assessed.

RESULTS

Although males had significantly thicker muscles than females (P < .05), the relative change in thickness during specified tasks was equivalent. Overall, relative muscle thickness and symmetry were similar to previous studies using smaller sample sizes.

CONCLUSIONS

These findings provide a robust data set of muscle thickness values measured by ultrasound imaging and can be used for comparison to those with pain, abnormal function, and pathologic conditions.