Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise

This protocol uses motion mode ultrasound and surface electromyography simultaneously to measure muscle function of the core. Muscle thickness and activation of the local stabilizers (e.g., transverse abdominis, internal oblique) and global movers (e.g., external oblique) is achievable during specific time points of the side plank and dead bug exercises.

Motion mode (M-mode) ultrasound allows researchers and clinicians to measure the change of muscle thickness across time. Muscle thickness can be measured between fascial borders at a given time point during an exercise. This selected time point produces a one-dimensional image resulting in real-time, live observation of anatomy. Ultrasound used during functional movement can be referred to as dynamic ultrasound; this is feasible and reliable with the use of a linear transducer, elastic belt, and foam block to secure consistent transducer placement. The lateral abdominal wall is commonly investigated using ultrasound due to the overlapping nature of the muscles. Surface electromyography (sEMG) can complement M-mode ultrasound imaging because it measures the electrical representation of muscle activation. There is minimal evidence using M-mode ultrasound and sEMG simultaneously during core exercise. Exercises that challenge the core musculature involve both isometric holds (e.g., side plank), as well as oscillatory extremity movements (e.g., dead bug). In this study, both instruments will be used simultaneously to measure core muscle function during exercise. Ultrasound measurements will be obtained using a linear transducer and ultrasound unit, and sEMG measurements will be acquired from a wireless sEMG system. To make comparisons between participants and exercises, normalization methods using static, exercise starting positions for both instruments will be used. An activation ratio will be used for ultrasound and calculated by dividing the contracted thickness (thickness during a time point of exercise) by the rested (starting position) thickness. Muscle thickness will be measured in centimeters from the superior inferior fascial border to inferior superior fascial border. These methods aim to offer an innovative and practical measurement of muscle function with M-mode ultrasound and sEMG during core endurance exercises.

The lateral abdominal wall is made up of the transverse abdominis, internal oblique, and external oblique¹. The lateral abdominal wall contracts concentrically, eccentrically, and isometrically to withstand the forces placed on the body¹. The co-contraction of this muscle group provides stabilization of the center of the human body^2,3. These muscles are important during the prevention and rehabilitation of lower extremity injuries because poor trunk function is associated with increased hip adduction and knee valgus, which are risk factors for lower extremity inj....

All human participants provided informed consent. The protocol was part of a study approved by the Institutional Review Board of the University of Central Florida. Inclusion criteria included ages 18 -45 and physically active according to ACSM guidelines (30 min of moderate to vigorous activity 5 days per week)¹⁹. Exclusion criteria included low back pain within the past year, current hip, upper, or lower extremity pain or injury, a year history of low back surgery or lower extremity surgery, self.......

The measurements of both ultrasound and sEMG during the static, exercise starting position are represented in Table 2. These numbers will be used as the denominator when calculating the activation ratio. The thickness values of external oblique, internal oblique, and transverse abdominis during the first 5 s, last 5 s, and total duration (60 s) are in Table 3. These numbers are divided by the numbers in Table 2. The sEMG values normalized to static, exercise starting pos.......

M-mode ultrasound provides onset of muscle tissue movement and muscle thickness change during real time observation of anatomy over a selected time²¹. M-mode ultrasound combined with sEMG provides an overall understanding of muscle function, including electrical representation and visual observation. These instruments can be used in tandem during exercise to provide researchers with a global understanding of muscle function.

Specific training of ultrasound and sEMG tech.......

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