A dose response analysis of exercise prescription variables for lateral abdominal muscle thickness and activation: A systematic review.

BACKGROUND: Various exercise programs are used to treat lateral abdominal muscle (LAM) impairments in people with low back pain. Factors comprising these programs include exercise type, session time, frequency, and program duration. However, specific clinical guidance about optimal exercise prescription is lacking. OBJECTIVES: To perform a dose-response analysis on exercise prescription variables for LAM thickness and activation as measured by ultrasound imaging. DESIGN: Systematic review METHOD: Databases were searched from their inception for studies examining the association between exercise interventions and LAM thickness/activation measured by ultrasound imaging in healthy individuals. Risk of bias was assessed using the Joanna Brigg's Institute critical appraisal tools. For each muscle, subgroup analyses were performed to determine the dose response of exercise prescription variables for LAM thickness and activation. Where there was insufficient data for subgroup analyses, data was narratively synthesised. RESULTS: Fourteen studies comprising 395 participants were included. Statistical and narrative synthesis revealed specific local abdominal exercises, programs from four weeks duration, three sessions per week and sessions of ≥30 min were associated with greatest improvements to LAM thickness. Only the variables exercise type, program duration and session frequency showed a significant between groups difference for the subgroup analysis. The main limitation was inability to perform subgroup analyses for all variables across all muscles measured at rest and during contraction, due to non-reporting of data. CONCLUSION: This review provides preliminary guidance to practitioners on how the LAM respond to different exercise dosages. Future research should trial these findings.

A Deep Learning Localization Method for Measuring Abdominal Muscle Dimensions in Ultrasound Images.

Health professionals extensively use Two-Dimensional (2D) Ultrasound (US) videos and images to visualize and measure internal organs for various purposes including evaluation of muscle architectural changes. US images can be used to measure abdominal muscles dimensions for the diagnosis and creation of customized treatment plans for patients with Low Back Pain (LBP), however, they are difficult to interpret. Due to high variability, skilled professionals with specialized training are required to take measurements to avoid low intra-observer reliability. This variability stems from the challenging nature of accurately finding the correct spatial location of measurement endpoints in abdominal US images. In this paper, we use a Deep Learning (DL) approach to automate the measurement of the abdominal muscle thickness in 2D US images. By treating the problem as a localization task, we develop a modified Fully Convolutional Network (FCN) architecture to generate blobs of coordinate locations of measurement endpoints, similar to what a human operator does. We demonstrate that using the TrA400 US image dataset, our network achieves a Mean Absolute Error (MAE) of 0.3125 on the test set, which almost matches the performance of skilled ultrasound technicians. Our approach can facilitate next steps for automating the process of measurements in 2D US images, while reducing inter-observer as well as intra-observer variability for more effective clinical outcomes.

Measurement of transversus abdominis activation in chronic low back pain patients using a novel standardized real-time ultrasound imaging method.

Real-time ultrasound imaging (US) to measure abdominal muscle dimensions has aided low back pain rehabilitation and research. Notwithstanding, ultrasound imaging measurement of transversus abdominis muscle activation in chronic low back pain populations has been characterized by variable and generally suboptimal intra-observer reliability. Methodological deficiencies of 'freehand' ultrasound imaging are uncontrolled probe-skin pressure, inclination and roll of the probe. Despite previous attempts to standardize these parameters, intra-observer reliability in chronic low back pain was poor to moderate (0.32-0.62). Therefore, a standardized method that controls and records probe force, inclination and roll during ultrasound imaging may optimize measurement reliability in chronic low back pain. This pilot study investigated utility, standardization and intra-observer reliability of ultrasound imaging transversus abdominis thickness measurement in chronic low back pain patients (n = 17). Transversus abdominis imaging over two separate measurement sessions was conducted using a novel method to standardize probe parameters. Resting and contracted transversus abdominis thickness, and transversus abdominis activation measurements were obtained from duplicate paired images (n = 68). Intra-class correlation coefficients were reported with 95% confidence intervals. Transversus abdominis thickness at rest (intra-class correlation coefficient = 0.97 confidence interval: 0.93, 0.99), when contracted (intra-class correlation coefficient = 0.99 confidence interval: 0.97, 0.99) and transversus abdominis activation (intra-class correlation coefficient = 0.93 confidence interval: 0.81, 0.97) measurements were highly reliable. Ultrasound imaging of transversus abdominis using the novel standardized ultrasound imaging method produced highly reliable intra-observer transversus abdominis measurements, superior to 'freehand' ultrasound imaging, despite the physical limitations typically associated with a chronic low back pain population. Unique standardizing ranges for 'probe force device' probe parameters were obtained. This novel standardized ultrasound imaging method may optimize transversus abdominis activation assessment in chronic low back pain and other populations, aiding future research.

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

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

Mechanisms for triceps surae injury in high performance front row rugby union players: a kinematic analysis of scrummaging drills.

The front row of a rugby union scrum consists of three players. The loose head prop, hooker and tight head prop. The objective of this study was to determine if known biomechanical risk factors for triceps surae muscle injury are exhibited in the lower limb of front row players during contested scrummaging. Eleven high performance front row rugby union players were landmarked bilaterally at the posterior superior iliac spine (PSIS), greater trochanter, lateral femoral epicondyle, midline of the calcaneus above the plantar aspect of the heel, midline lower leg 5cm and 20cm proximal to the lateral malleolus, at the axis of subtalar joint, lateral malleolus, and head of the fifth metatarsal. Players were video recorded during a series of 2 on 1 live scrummaging drills. Biomechanical three dimensional analysis identified large angular displacements, and increased peak velocities and accelerations at the ankle joint during attacking scrummaging drill techniques when in the stance phase of gait. This places the triceps surae as increased risk of injury and provides valuable information for training staff regarding injury prevention and scrum training practices for front row players. Key pointsFront rowers exhibited patterns of single leg weight bearing, in a position of greater ankle plantar flexion and knee extension at toe off during scrummaging, which is a risk position for TS injury.Front rowers also exhibited greater acceleration at the ankle, knee, and hip joints, and greater changes in ankle ROM from toe strike to toe off during attacking scrum drills.These reported accelerations and joint displacements may be risk factors for TS injury, as the ankle is accelerating into plantar flexion at final push off and the muscle is shortening from an elongated state.