Portable acoustic myography - a realistic noninvasive method for assessment of muscle activity and coordination in human subjects in most home and sports settings

Abstract

Muscle sound gives a local picture of muscles involved in a particular movement and is independent of electrical signals between nerve and muscle. Sound recording (acoustic myography) is a well-known noninvasive technique that has suffered from not being easily applicable, as well as not being able to register at sufficient sampling speed. With modern amplifiers and digital sound recording this has changed, and such assessment during movement outside a laboratory setting may be possible. Our aim was to develop a setup for muscle-sound assessment, which could be reliably applied in any local setting. A group of healthy subjects were assessed during standing, stair climbing, walking, and running. Piezoelectric microphones were applied to the skin using contact gel. A digital sound recorder enabled sampling speeds of around 96,000 Hz. Surface electromyography was measured in parallel as a comparison. The recorded signals were assessed and described in terms of signal frequency (Hz) and peak-to-peak amplitude (mV) using Chart software. Bioimpedance of the involved muscles was measured. Sound recording was shown to be an easy noninvasive method for assessment of muscle function during movement with the possibility of being applied in most clinical, sports, and home settings. Muscle sound gives a representation of the work of each muscle group during a complex movement, illustrated here by a step test, which revealed both concentric and eccentric activity. The method in the presented new setup has great potential for assessment of function in patients with musculoskeletal complaints in out-of-clinic settings, as well as in sports.

A more precise, repeatable and diagnostic alternative to surface electromyography – an appraisal of the clinical utility of acoustic myography

“…Recent advances have led to the development of a set-up for muscle-sound assessment which can be reliably applied without discomfort for the subject and which does not require specialist technical knowledge of the person carrying out the recordings (www.myodynamik.com; Harrison et al, 2013). The CURO (MyoDynamik ApS) uses thin piezoelectric sensors with an acoustic gel, so extraneous noise and interference are almost negligible and a full working muscle frequency range is recorded (2-500 Hz), and the raw analogue signal is rapidly converted to a digital signal by a built in A/D converter for subsequent processing by an iPad using a specially designed App.…”

“…Indeed, such a wireless, stable and quick and easy to use technique lends itself to the assessment of patients with musculoskeletal complaints during daily activities, or assessment of athletes in terms of their efficiency of muscle use (Harrison et al, 2013). These new possibilities have paved the way for a useable and accurate clinical tool in the form of acoustic myography (AMG).…”

“…These new possibilities have paved the way for a useable and accurate clinical tool in the form of acoustic myography (AMG). Indeed, such a wireless, stable and quick and easy to use technique lends itself to the assessment of patients with musculoskeletal complaints during daily activities, or assessment of athletes in terms of their efficiency of muscle use (Harrison et al, 2013).…”

Muscle assessment using multi‐frequency bioimpedance in a healthy Danish population aged 20–69 years: a powerful non‐invasive tool in sports and in the clinic

“…; Harrison et al. , ; Lukaski ). mfBIA has been shown to characterize the relative changes in hydration as well as monitor changes in cellular function in a noninvasive way (Nescolarde et al.…”

“…In other movements like bending of the elbow, the condition of the agonist and antagonist muscles likewise influences movement. For the purpose of assessing muscle condition prior to movement, multi-frequency bioimpedance (mfBIA) (de Luca 1997;Hermens et al 1999) which is a well-known, validated, and much used method in both sports clubs and in the clinic, may be used (Gerdle et al 1997;Bernardi et al 1999;Karlsson and Gerdle 2001;Bajaj et al 2002;Larsson et al 2006;Moon et al 2008;Harrison et al 2012Harrison et al , 2013Lukaski 2013). mfBIA has been shown to characterize the relative changes in hydration as well as monitor changes in cellular function in a noninvasive way (Nescolarde et al 2013a,b).…”