Muscle Activity "Onset" in the Transversus Abdominis - Simultaneous Recordings by Intramuscular Electromyography and High Frame Rate Ultrasound Imaging.

Delayed anticipatory muscle activity response in deep low back and abdominal muscles has been observed in patients with low back pain, indicative of a pathological condition. Muscle activity onset is traditionally recorded by intramuscular electromyography, but there is a need for a less cumbersome recording method in large clinical studies. The purpose of this experimental study is to explore whether high-frame rate m-mode ultrasound and tissue velocity imaging could measure anticipatory muscle responses ("onset") in the abdominal muscles reliably and comparably accurate to intramuscular EMG.