Reliability of Ultrasound Imaging Measures of Transverse Abdominis and Lumbar Multifidus in Various Positions

Association between running biomechanics and lower limb musculotendinous changes over an adolescent marathon training program

BACKGROUND

Prospective musculotendinous changes have been observed among adolescents completing marathon training programs. However, examinations of potential factors influencing musculotendinous characteristics do not currently exist. Evaluations of biomechanical parameters and the influence on musculotendinous features and changes over time are warranted.

RESEARCH QUESTION

What are the relationships between adolescent running biomechanics and 1) lower extremity musculotendinous characteristics cross-sectionally, and 2) changes in musculotendinous properties over 6-months?

METHODS

Thirty-three adolescent runners participated in this study (19 F, 14 M; 15.8 ± 1.6 years). Ultrasound images of lower extremity musculotendinous structures were obtained to determine thickness and echogenicity. Following ultrasound measures, outdoor running biomechanics were assessed using wearable sensors to collect spatiotemporal, kinetic, and kinematic measures. A subset of participants had repeat ultrasound evaluations following a 6-month running program (n = 11; 6 F, 5 M). Hierarchical linear models were used to assess the relationships between biomechanics and ultrasound measures. Pearson's correlations were used to assess the relationship between biomechanics the change in musculotendinous characteristics (baseline to 6-months).

RESULTS

The strongest relationships between measures were for the Achilles tendon (R2=0.39, F=0.85, p = 0.10), and flexor digitorum brevis (R2=0.38, F=2.38, p = 0.06). The interaction between pronation excursion and velocity was a significant predictor for Achilles tendon thickness (p = 0.03), and medial gastrocnemius thickness (p = 0.05). Contact time was a significant predictor for intrinsic foot muscle thickness (p = 0.01). There were moderate correlations across biomechanical measures and changes in musculotendinous thickness and echogenicity.

SIGNIFICANCE

Biomechanical characteristics often noted with running-related injuries were moderately related to tissue-level characteristics, and changes during running training.

Learning Transversus Abdominis Activation in Older Adults with Chronic Low Back Pain Using an Ultrasound-Based Wearable: A Randomized Controlled Pilot Study

Background/Objectives: Chronic low back pain (CLBP) is prevalent among older adults and leads to significant functional limitations and reduced quality of life. Segmental stabilization exercises (SSEs) are commonly used to treat CLBP, but the selective activation of deep abdominal muscles during these exercises can be challenging for patients. To support muscle activation, physiotherapists use biofeedback methods such as palpation and ultrasound imaging. This randomized controlled pilot study aimed to compare the effectiveness of these two biofeedback techniques in older adults with CLBP. Methods: A total of 24 participants aged 65 years or older with CLBP were randomly assigned to one of two groups: one group performed self-palpation biofeedback, while the other group used real-time ultrasound imaging to visualize abdominal muscle activation. Muscle activation and thickness were continuously tracked using a semi-automated algorithm. The preferential activation ratio (PAR) was calculated to measure muscle activation, and statistical comparisons between groups were made using ANOVA. Results: Both groups achieved positive PAR values during all repetitions of the abdominal-draw-in maneuver (ADIM) and abdominal bracing (AB). Statistical analysis revealed no significant differences between the groups in terms of PAR during ADIM (F(2, 42) = 0.548, p = 0.58, partial η2 = 0.025) or AB (F(2, 36) = 0.812, p = 0.45, partial η2 = 0.043). Both groups reported high levels of exercise enjoyment and low task load. Conclusions: In conclusion, both palpation and ultrasound biofeedback appear to be effective for guiding older adults with CLBP during SSE. Larger studies are needed to confirm these results and examine the long-term effectiveness of these biofeedback methods.

Innovations in the Assessment of Skeletal Muscle Health: A Glimpse into the Future

Skeletal muscle is the largest organ system in the human body and plays critical roles in athletic performance, mobility, and disease pathogenesis. Despite growing recognition of its importance by major health organizations, significant knowledge gaps remain regarding skeletal muscle health and its crosstalk with nearly every physiological system. Relevant public health challenges like pain, injury, obesity, and sarcopenia underscore the need to accurately assess skeletal muscle health and function. Feasible, non-invasive techniques that reliably evaluate metrics including muscle pain, dynamic structure, contractility, circulatory function, body composition, and emerging biomarkers are imperative to unraveling the complexities of skeletal muscle. Our concise review highlights innovative or overlooked approaches for comprehensively assessing skeletal muscle in vivo. We summarize recent advances in leveraging dynamic ultrasound imaging, muscle echogenicity, tensiomyography, blood flow restriction protocols, molecular techniques, body composition, and pain assessments to gain novel insight into muscle physiology from cellular to whole-body perspectives. Continued development of precise, non-invasive tools to investigate skeletal muscle are critical in informing impactful discoveries in exercise and rehabilitation science.

Ultrasound Biofeedback Increases Abdominal Muscle Activation in Golfers With a History of Low Back Pain

OBJECTIVES

To compare activation ratios of the transverse abdominis (TrA) during an abdominal draw-in maneuver (ADIM) and abdominal obliques during a golf swing, with and without ultrasound biofeedback, and to determine intrarater reliability of these ultrasound thickness measures.

DESIGN

Single-session crossover study.

SETTING

Laboratory.

PARTICIPANTS

Sixteen adult golfers with 2 or more episodes of low back pain (LBP) in the past year.

INTERVENTIONS

Verbal cueing alone and verbal cueing with ultrasound biofeedback.

MAIN OUTCOME MEASURES

Bilateral TrA activation ratios were calculated during an ADIM with and without ultrasound biofeedback. Activation ratios of the abdominal obliques were calculated bilaterally during golf swings with and without ultrasound biofeedback. Intraclass correlation coefficients (ICCs) were calculated for average thickness across all muscles and conditions for the nonbiofeedback trials.

RESULTS

Transverse abdominis activation ratios were significantly higher when ultrasound biofeedback was provided bilaterally ( P < 0.001). Abdominal oblique activation ratios during the golf swing were also significantly higher with ultrasound biofeedback for the lead ( P = 0.014) and trail ( P < 0.001) sides. Intraclass correlation coefficient values ranged from 0.92 to 0.97 ( P < 0.001).

CONCLUSIONS

Ultrasound biofeedback can increase activation ratios of the TrA during a supine ADIM in adult golfers with a history of LBP. Postswing ultrasound biofeedback increases activation of the abdominal obliques during a golf swing in golfers with a history of LBP. Ultrasound thickness measures of the TrA and obliques have excellent intrarater reliability.

Comparison of Muscle Activity and Muscle Thickness According to Knee Flexion Angle during Supine Bridge Exercises using the Abdominal Drawing-in Maneuver on an Unstable Surface

This study evaluated changes in deep trunk muscle thickness and lower extremity muscle activities during bridge exercises with the abdominal drawing-in maneuver. Bridge exercises were conducted on an unstable surface at different knee flexion angles (60º, 90º and 120º), with the aim of identifying more effective angles for bridge exercises. This study included 21 healthy adults, aged 20-27 years. Biceps femoris (BF), rectus abdominis, and rectus femoris activity was measured using surface electromyography. The thicknesses of the transverse abdominis (TrA), external oblique (EO) and internal oblique (IO) muscles were measured. BF (p = 0.000, partial η2 = 0.670) activity increased considerably as the knee flexion angle decreased. TrA (p = 0.000, partial η2 = 0.883) and IO (p = 0.000, partial η2 = 0.892) thickness significantly increased, while EO (p = 0.000, partial η2 = 0.893) thickness decreased as the knee flexion angle decreased. When performing bridge exercises using the abdominal drawing-in maneuver on an unstable surface, the knee flexion angles should be at 120º and 60º to increase trunk stability and lower extremity muscle activity, respectively.

Binary classification of non-specific low back pain condition based on the combination of B-mode ultrasound and shear wave elastography at multiple sites

Introduction: Low back pain (LBP) is a prevalent and complex condition that poses significant medical, social, and economic burdens worldwide. The accurate and timely assessment and diagnosis of LBP, particularly non-specific LBP (NSLBP), are crucial to developing effective interventions and treatments for LBP patients. In this study, we aimed to investigate the potential of combining B-mode ultrasound image features with shear wave elastography (SWE) features to improve the classification of NSLBP patients. Methods: We recruited 52 subjects with NSLBP from the University of Hong Kong-Shenzhen Hospital and collected B-mode ultrasound images and SWE data from multiple sites. The Visual Analogue Scale (VAS) was used as the ground truth to classify NSLBP patients. We extracted and selected features from the data and employed a support vector machine (SVM) model to classify NSLBP patients. The performance of the SVM model was evaluated using five-fold cross-validation and the accuracy, precision, and sensitivity were calculated. Results: We obtained an optimal feature set of 48 features, among which the SWE elasticity feature had the most significant contribution to the classification task. The SVM model achieved an accuracy, precision, and sensitivity of 0.85, 0.89, and 0.86, respectively, which were higher than the previously reported values of MRI. Discussion: In this study, we aimed to investigate the potential of combining B-mode ultrasound image features with shear wave elastography (SWE) features to improve the classification of non-specific low back pain (NSLBP) patients. Our results showed that combining B-mode ultrasound image features with SWE features and employing an SVM model can improve the automatic classification of NSLBP patients. Our findings also suggest that the SWE elasticity feature is a crucial factor in classifying NSLBP patients, and the proposed method can identify the important site and position of the muscle in the NSLBP classification task.

RUNNERS SPORTS INJURIES AND REHABILITATION

ABSTRACT Introduction Independent athletes and sports enthusiasts are subject to injuries due to several factors, such as neglect of physical preparation, lack of knowledge of the evolutionary progression of load intensity, and deficient stretching. Running is a popular sport in China, and the knowledge of the injuries caused by this group of fans may guide awareness behaviors to prevent accidents in sports practice. Objective Evaluate the injuries and rehabilitation of runners. Methods A total of 265 ordinary chinese runners (166 men) were selected as research subjects. Information on running sports injury characteristics, subjective perception of the causes of runners’ injuries, prevention and rehabilitation methods in runners’ injuries were evaluated. Results The knee joint has the highest proportion of injuries (26.73%), followed by foot injuries (13.11%) and ankle injuries (10.65%). Pain after exercise was reported by 38.12% of the runners, while 21.89% felt pain during the race. Conclusion Warm-up exercises are recommended before sports practice. Protective equipment can reduce the probability of injuries. Such equipment is considered a method of treatment and prevention with greater satisfaction and better adherence among runners. Evidence Level II; Therapeutic Studies - Investigating the result.

The effect of activation of thoracolumbar fascia on the thickness of abdominal muscles: An ultrasonographic study

Objectives

This study aims to evaluate the changes in the ultrasonographic thickness of transversus abdominis and internal oblique muscles during bridge with arm extension compared to bridge and abdominal hollowing.

Patients and methods

Between March 1^st, 2019 and March 29^th, 2019, a total of 30 healthy individuals (15 males, 15 females; mean age: 28.8±8.1 years; range, 21 to 52 years) among hospital staff were included. Thickness of transversus abdominis, internal, and external oblique muscles of the participants were evaluated using ultrasound during four positions (rest, abdominal hollowing, bridge, and bridge with arm extension).

Results

The mean body mass index was 23.8±4.1 kg/m². The thickness of transversus abdominis and internal oblique muscles increased during all positions (p<0.001), compared to rest. The thickness during bridge with arm extension was greater than abdominal hollowing and bridge.

Conclusion

Co-activation of latissimus dorsi and gluteus maximus muscles during abdominal contraction increases the thickness of internal oblique and transversus abdominis muscles greater than abdominal contraction alone or co-activation of gluteus maximus alone. Simultaneous isometric contraction of latissimus dorsi muscle may enhance abdominal muscle function.

Reliability of lumbar multifidus ultrasound assessment during the active straight leg raise test

BACKGROUND

Previous evidence showed altered lumbar multifidus (LM) activation in populations with chronic nonspecific low back pain (LBP). We aimed to investigate the test-retest and inter-examiner reliability of ultrasound imaging (US) for assessing LM thickness at rest and activation during the active straight leg raise test (ASLR) and the association between thickness changes with clinical outcomes.

METHODS

Fifty-two patients with LBP and two examiners (one experienced and one novice) participated in this study. A total of 18 B-mode images at L4-L5 or L5-S1 level (both sides, 3 at rest and 6 during ASLR) were collected. For assessing test-retest reliability, the experienced examiner repeated the procedure after 7 days. Intraclass correlation coefficients (ICC), standard error of measurements (SEM) and minimal detectable changes (MDC) were calculated.

RESULTS

Inter-examiner agreement was good to excellent (ICC3,2 = 0.71-0.92) and test-retest reliability was excellent (ICC3,1 = 0.91-0.98). Mean average of multiple measurements improved the agreement. Greater LM thickness at rest (p < .05) and greater thickness change after 3 s (p < .01) and 10 s (homolateral side, p < .01; contralateral side, p < .05) were associated with less pain intensity.

CONCLUSIONS

US is a reliable method to assess the LM thickness at rest and contracted during the ASLR in patients with LBP. The measurement at 3 s after maintaining ASLR, as well as the use of the mean of three measurements, has been shown to be the most reliable method for measuring LM muscle thickness during ASLR.

Ultrasonographic Changes of Abdominal Muscles in Subjects with and without Chronic Low Back Pain

Chronic low back pain (CLBP) is a prevalent disfunction in the spine, affecting both women and men. The implication of the abdominal muscles in this disfunction has been studied, including wrong breathing patterns or inactivity of this area. However, there is a lack of studies examining changes in thickness of abdominal with ultrasonography. Thus, the aim of this study is to analyze the differences in the thickness of abdominal muscles at rest and during breathing between subjects with and without CLBP. A total of 72 subjects were divided in two groups: participants with CLBP (n = 36) and participants without CLBP (n = 36). In both groups, the thickness of the four abdominal muscles was measured and compared at rest and during breathing with ultrasonography. In TrA and IO there were no significant differences between groups, but those subjects with CLBP increased the muscle thickness more than participants without pain during breathing. In EO there were no differences in muscle thickness between groups and between rest and breathing. In RA, subjects with CLBP showed less muscle thickness than subjects without pain during breathing, but no changes were found at rest. In conclusion, the deepest abdominal muscles, TrA and IO, appear to increase their thickness and RA appear to decrease more in subjects with CLBP, in comparison with healthy participants.

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.

An Investigation of the Association between Transversus Abdominis Myofascial Structure and Activation with Age in Healthy Adults using Ultrasound Imaging

BACKGROUND

Because of their importance in core stability, training the deep abdominal muscles, fascial structures and particularly the transversus abdominis, is a key component of many sport and physical therapy programs. However, there are gaps in knowledge about age-related changes in the structure and activation capacity of these muscles.

HYPOTHESIS/PURPOSE

This study investigated the association between deep abdominal muscles and fascial structures and transversus abdominis activation with age in healthy adults.

STUDY DESIGN

A cross-sectional study.

METHODS

Eighty-six adults aged 18 to 77 participated in this study. An ultrasound image of their transversus abdominis, internal oblique, external oblique and associated fasciae was first captured at rest, then during a contraction of the transversus abdominis. Bivariate correlation analyses and hierarchical analyses were performed (significance level: p < 0.05).

RESULTS

The thickness of these three muscles decreases with age ( ρ = -0.66 for external oblique, -0.51 for internal oblique and -0.58 for transversus abdominis), whereas the thickness of their fasciae increases ( ρ = 0.39 for the fascia of external oblique, 0.54 for the fascia between internal oblique and external oblique, and 0.74 for the fascia between internal oblique and transversus abdominis). Transversus abdominis activation decreases with age (r =-0.44). Age accounts for 19.5% of the variance in transversus abdominis activation.

CONCLUSION

These results demonstrate that normal aging is associated with changes in deep abdominal myofascial structures and transversus abdominis activation. Assessment of these metrics can provide valuable baseline information for physical therapists involved in rehabilitation and strengthening programs targeting older individuals.

LEVEL OF EVIDENCE

Level 2.

Changes in abdominal muscles architecture induced by different types of breathing

BACKGROUND: The underlying morphology and behavior of abdominal muscles during breathing are still lacking in knowledge in healthy population. OBJECTIVE: To analyze the effects of three different types of breathing on the architectural characteristics of abdominal muscles. METHODS: Ninety-eight healthy subjects were measured to assess the effects of breathing on the abdominal muscles, subjects performed three different types of breathing and the muscular thickness was measured with ultrasound imaging, analyzing also the differences between sexes. RESULTS: During the three different types of breathing and in comparison with the resting state, an increase of the thickness has been reported in the transversus abdominis (p< 0.001; effect size = 2.44, very large) and internal oblique (p< 0.001; effect size = 1.04, moderate) in both sexes, but with a higher increase in men. External oblique and rectus abdominis increased their thickness through breathing only while the lips were with pursed (p< 0.05) with trivial effect sizes and only differences between sexes were found in rectus abdominis. CONCLUSIONS: All breathings activated the deepest abdominal muscles, but the most superficial were only activated with lips pursed. Moreover, men appeared to activate more the deepest abdominal muscles but also the rectus abdominis. Findings in this study support the use of different types of breathing depending on the muscle to be activated or the sex, helping health care professionals to address their interventions on the abdominal muscles with a more focused approach.

Abdominal Expansion versus Abdominal Drawing-In Strategy on Thickness and Electromyography of Lumbar Stabilizers in People with Nonspecific Low Back Pain: A Cross-Sectional Study

The abdominal expansion (AE) strategy, involving eccentric contraction of the abdominal muscles, has been increasingly used in clinical practices; however, its effects have not been rigorously investigated. This study aimed to investigate the immediate effects of the AE versus abdominal drawing-in (AD) strategy on lumbar stabilization muscles in people with nonspecific low back pain (LBP). Thirty adults with nonspecific LBP performed the AE, AD, and natural breathing (NB) strategies in three different body positions. Ultrasonography and surface electromyography (EMG) were, respectively, used to measure the thickness and activity of the lumbar multifidus and lateral abdominal wall muscles. The AE and AD strategies showed similar effects, producing higher EMG activity in the lumbar multifidus and lateral abdominal wall muscles when compared with the NB strategy. All muscles showed higher EMG activity in the quiet and single leg standing positions than in the lying position. Although the AE and AD strategies had similar effects on the thickness change of the lumbar multifidus muscle, the results of thickness changes of the lateral abdominal muscles were relatively inconsistent. The AE strategy may be used as an alternative method to facilitate co-contraction of lumbar stabilization muscles and improve spinal stability in people with nonspecific LBP.

Clinical Assessment and Thickness Changes of the Oblique and Multifidus Muscles Using a Novel Screening Tool and Exercise Program: A Randomized Controlled Trial

CONTEXT

Training and assessment of the abdominal and trunk muscles are widely used in the clinical setting. However, it is unknown what types of exercises are most effective in activation of both the global and local stabilizers in these regions.

OBJECTIVE

The purpose of this study was to establish the reliability of a novel clinical screening tool (sling screen) to assess the muscles of the abdomen and trunk. The second aim was to use the clinical screening tool and musculoskeletal ultrasound to compare the effects of a rotary-based exercise program that targets both the global and local muscles to the effects of a traditional exercise program on the activation of the abdominal and trunk muscles.

DESIGN

Double-blind, randomized controlled trial.

SETTING

Sports medicine facility.

PARTICIPANTS AND INTERVENTIONS

Thirty-one healthy participants were randomly allocated to receive a single-session rotary-based or traditional "core" exercise program.

MAIN OUTCOME MEASURES

The participants were assessed at the baseline and immediately postintervention. The primary outcome measures were muscle thickness examined by musculoskeletal ultrasound and clinical examination of muscle activation using a screening tool. The data were collected by blind assessors. Reliability and validity of a clinical screening tool (sling screen) were also assessed.

RESULTS

The analysis of the covariance tests showed a significant increase in oblique thickness for the rotary exercise group. All participants displayed a significant increase in multifidus thickness. The Wilcoxon signed-rank tests revealed a significant increase in clinical assessment scores in the rotary exercise group but not the traditional exercise group. Reliability of the sling screen ranged from moderate to good.

CONCLUSION

This clinical trial provides evidence that a rotary-based exercise program may be more effective in producing increases in oblique muscle thickness than traditional "core" exercises in young, healthy adults. The sling screen tool was able to identify these muscle thickness changes. Future studies should investigate how these results correlate to injury risk, other populations, and also how to implement the sling screen into clinical practice.

Role of Ultrasound in Low Back Pain: A Review

Low back pain is one of most common musculoskeletal disorders around the world. One major problem clinicians face is the lack of objective assessment modalities. Computed tomography and magnetic resonance imaging are commonly utilized but are unable to clearly distinguish patients with low back pain from healthy patients with respect to abnormalities. The reason may be the anisotropic nature of muscles, which is altered in function, and the scans provide only structural assessment. In view of this, ultrasound may be helpful in understanding the disease as it is performed in real-time and comprises different modes that measure thickness, blood flow and stiffness. By the use of ultrasound, patients with low back pain have been found to differ from healthy patients with respect to the thickness and stiffness of the transversus abdominis, thoracolumbar fascia and multifidus. The study results are currently still not conclusive, and further study is necessary to validate. Future work should focus on quantitative assessment of these tissues to provide textural, structural, hemodynamic and mechanical studies of low back pain. This review highlights the current understanding of how medical ultrasound has been used for diagnosis and study of low back pain and discusses potential new applications.

Inconsistent descriptions of lumbar multifidus morphology: A scoping review

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSIONS

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

Comparison of the recruitment of transverse abdominis through drawing-in and bracing in different core stability training positions

There are many proposed core stability exercises in a variety of positions; however, it is not clear that in which position, activation of transverse abdominis muscle is utmost. We aimed to compare the activation of transverse abdominis muscle in different core stability exercise positions through ultrasound imaging. in a 20 subjects' study we compared the effectiveness of drawing-in and bracing maneuvers on transverse abdominis in different core stability exercise positions (supine, hook lying, supine with 90° flexed knee and hip, supine with stretched knees and 90° flexed hips, bridge, bridge with one stretched knee and Bird dog). We used activation ratio and preferential activation ratio as measurements of transverse abdominis activation. Abdominal Bracing in the bridge position showed the highest activation of transverse abdominis (P<0.05). The results showed significantly higher activation of transverse abdominis, measured by preferential activation ratio, in bridge position during abdominal bracing.

Effect of Core Stability Training Monitored by Rehabilitative Ultrasound Image and Surface Electromyogram in Local Core Muscles of Healthy People

Background

The purpose of this study is to investigate the influence of transverses abdominis and lumbar multifidus thickness activation and electromyogram signal characteristics after core stability training monitored by rehabilitative ultrasound imaging and surface electromyogram.

Methods

60 healthy volunteers were allocated randomly into two groups, one of which received monitoring training and the other participated identical training without monitoring. Ultrasound image and surface electromyogram signal were collected at 0, 4, and 8 weeks during training. The muscle thickness activation ratio value and integrated electromyogram value were then extracted. During the training, the monitoring group was monitored by real-time rehabilitative ultrasound imaging and surface electromyogram while the control group was not.

Results

There are no differences in performance of local core muscles between both groups before training (p > 0.05). Compared with the control group, the thickness contraction ratio value and integrated electromyogram value of core muscles in the monitoring group were higher after 8 weeks' training (p < 0.05).

Conclusion

Together, the core stability training monitored by rehabilitative ultrasound imaging and surface electromyogram can markedly activate and enhance local core muscles in healthy people, providing a potential strategy to treat low back pain more effectively.

Gluteus medius activity during gait is altered in individuals with chronic ankle instability: An ultrasound imaging study

BACKGROUND

Altered gait mechanics are frequently reported in individuals with chronic ankle instability (CAI), and increasing information suggests proximal muscle adaptations occur in this population. Ultrasound imaging (USI) offers a visual means to evaluate muscle activity during movement, and overcomes limitations of electromyography (EMG) to detect hip muscle activity.

RESEARCH QUESTION

A descriptive laboratory study was conducted to determine if gluteus maximus (GMAX) and medius (GMED) muscle activity differed throughout gait in patients with CAI compared to healthy counterparts.

METHODS

Twenty young adults with CAI (21.6 ± 2.4 years, 10 males) and 20 healthy participants (21.2 ± 2.8 years, 10 males) walked on a treadmill at 1.35 m/s while researchers obtained 10-second clips of bilateral USI of the GMAX and GMED. USI clips were reduced to 55 frames consisting of 11 points over five full gait cycles. Muscle thickness values during walking were normalized to quiet bipedal standing USI images to obtain functional activity ratios (FARs). FARs with 90% confidence intervals (CI) were plotted as 10% interludes from 0 to 100% of the gait cycle to compare groups and limbs. Mean differences and Cohen's d effect sizes were used to assess the extent of differences. The CAI group had decreased GMED activity bilaterally from 0 to 40% of walking gait compared to healthy counterparts with large effect sizes (d≥0.60). CAI group FARs were below quiet stance levels (FARs<1.0) throughout the entire gait cycle. There were no differences noted between groups or limbs for GMAX measures.

SIGNIFICANCE

Proximal stabilizing musculature was altered bilaterally in CAI individuals compared to healthy counterparts, which may contribute to movement dysfunction. Previous studies using EMG have not detected this extent of bilateral gluteal muscle alterations in CAI groups during gait, however our findings suggest USI was able to detect significant proximal alterations during walking in this population.

Effects of a 4-Week Intrinsic Foot Muscle Exercise Program on Motor Function: A Preliminary Randomized Control Trial

Context: Intrinsic foot muscle (IFM) exercises are utilized clinically in the treatment of foot and ankle conditions. However, the effectiveness of training on IFM motor function is unknown. Objective: To study the effects of a 4-week IFM exercise program on motor function, perceived difficulty, and IFM motor activation measured using ultrasound imaging (USI) during 3 IFM exercises. Design: Single-blinded randomized control trial. Setting: Laboratory. Participants: A total of 24 healthy, recreationally active young adults without history of ankle-foot injury who have never performed IFM exercises participated (12 males and 12 females; mean age = 21.5 [4.8] y; body mass index = 23.5 [2.9] kg/m²) Intervention: Following randomization, participants allocated to the intervention group received a 4-week progressive home IFM exercise program performed daily. Participants in the control group did not receive any intervention. Main Outcome Measures: Clinician-assessed motor performance (4-point scale: 0 = does not initiate movement and 3 = performs exercise in standard pattern), participant-perceived difficulty (5-point Likert scale: 1 = very easy and 5 = very difficult), and USI motor activation measures (contracted measurementresting measurement) of the abductor hallucis, flexor digitorum brevis, quadratus plantae, and flexor hallucis brevis were assessed during toe-spread-out, hallux-extension, and lesser-toe-extension exercises. Results: The intervention group demonstrated significant improvement in motor performance in the toe-spread-out exercise (pre = 1.9 [0.5], post = 2.6 [0.5], P = .008) and less perceived difficulty in the toe-spread-out (pre = 3.1 [1.3], post = 2.3 [1.2], P = .01), hallux-extension (pre = 3.2 [1.5], post = 2.0 [1.2], P = .005), and lesser-toe-extension (pre = 1.9 [0.7], post = 1.2 [0.4], P = .03) exercises. Both groups demonstrated increased USI motor activation in the abductor hallucis during the toe-spread-out exercise (intervention: pre = 1.07 [0.06], post = 1.11 [0.08] and control: pre = 1.08 [0.06], post = 1.11 [0.06]; P = .05). No other significant main effects or group by time interactions were observed. Conclusion: A 4-week IFM exercise intervention resulted in improved motor performance and decreased perceived difficulty when performing the exercises, but not changes in USI measures of IFM activation compared with a control group.

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.

Ultrasound Assessment of the Transverse Abdominis During Functional Movement

OBJECTIVES

The traditional activation ratio divides contracted muscle thickness by resting muscle thickness while an abdominal draw-in maneuver is performed during hook lying. Ultrasound imaging during function, such as standing or gait, or peak knee flexion in a single-leg squat allows for further visualization of muscle activity. The goal of this study was to examine activation ratio calculations for transverse abdominis function in supine versus loaded conditions to determine the most informative normalization strategy for muscle activity based on thickness values.

METHODS

Transverse abdominis thickness was measured via ultrasound in 35 healthy participants under 4 different conditions. Comparisons were made between the traditional activation ratio tabletop, standing activation ratio (standing abdominal draw-in maneuver thickness/quiet standing thickness), and functional activation ratio (single-leg squat thickness/quiet standing thickness). Additionally, a cued activation ratio (single-leg squat with cued abdominal draw-in maneuver thickness/single-leg squat thickness) during the single-leg squat was obtained. Activation ratios of greater than 1.0 indicated that participants could activate the muscle during activity, and values were compared by analysis of variance.

RESULTS

The participants included 23 women and 12 men with a mean age ± SD of 21.3 ± 2.7 years, mass of 66.1 ± 14.4 kg, and height of 168.5 ± 10.1 cm. Activation ratios exceeded 1.0 in 94.3% for the traditional activation ratio, 85.7% for the standing activation ratio, 82.9% for the cued activation ratio, and 82.9% for the functional activation ratio. With groups defined as tabletop activated or not, the standing, cued, and functional activation ratios were all significantly different (all P < .05).

CONCLUSIONS

Normalizing muscle thickness to the corresponding functional position quiet value provides a useful functional activation ratio and may help clinicians better understand the transverse abdominis role during complex functional tasks. Assessment techniques using various formulas for activation ratios reveal that the muscle functions differently during weight bearing compared to traditional measures.

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.

Reliability and Precision of Sonography of the Lumbar Multifidus and Transversus Abdominis During Dynamic Activities

OBJECTIVES

To determine the intrarater reliability and precision of lumbar multifidus and transversus abdominis thickness measurements using freehand sonography in a range of static and dynamic conditions.

METHODS

Fifteen asymptomatic participants performed a range of exercises while sonography was used to measure absolute muscle thickness and changes in muscle thickness from rest. Exercise conditions included the abdominal drawing-in maneuver, active straight leg raise, contralateral arm lift, both unloaded and loaded, treadmill walking, and using the Functional Readaptive Exercise Device. Intraday and interday reliability was assessed by intraclass correlation coefficients, and the standard error of measurement was used to assess measurement precision.

RESULTS

Good to excellent reliability was achieved for absolute transversus abdominis and lumbar multifidus thickness in all conditions. Measurement precision for absolute lumbar multifidus thickness was ≤2.8 mm for the unloaded contralateral arm lift, ≤1.8 mm for the loaded contralateral arm lift, ≤3.1 mm for treadmill walking, and ≤3.8 mm for the Functional Readaptive Exercise Device; for absolute transversus abdominis thickness, precision was ≤0.6 mm for the abdominal drawing-in maneuver, ≤0.5 mm for the active straight leg raise, ≤0.7 mm for treadmill walking, and ≤0.5 mm for the Functional Readaptive Exercise Device. Good to excellent reliability was achieved for relative transversus abdominis and lumbar multifidus thickness in all conditions. Measurement precision for relative lumbar multifidus thickness was ≤3.7% for the unloaded contralateral arm lift, ≤3.8% for the loaded contralateral arm lift, ≤6.3% for treadmill walking, and ≤7.6% for the Functional Readaptive Exercise Device; for relative transversus abdominis thickness, precision was ≤13.6% for the abdominal drawing-in maneuver, ≤6.9% for the active straight leg raise, ≤11.1% for treadmill walking, and ≤7.2% for the Functional Readaptive Exercise Device.

CONCLUSIONS

Acceptable reliability and precision of measurement is achieved for absolute and relative measures of deep spinal muscle thickness using freehand sonography in relatively static and dynamic exercises.