Acoustic myography (AMG) measures the low-frequency mechanical pressure waves (sounds or infrasound, typically in the range of roughly a few Hz to a few hundred Hz) produced by contracting skeletal muscle fibers. This differs from electromyography (EMG), which records electrical activity from nerves and muscles. AMG captures the mechanical side of muscle function—fiber recruitment, coordination, and efficiency—often during actual movement rather than only in a static lab setting.
Primary Commercial Devices: SOFi / SOFi M² (and CURO lineage)
The main commercial medical devices using AMG are the SOFi™ and SOFi M²™ systems from Advanced Myographic Technologies (AMT), based in Florida. These (and the earlier CURO systems from CURO Diagnostics ApS / MyoDynamik, developed with involvement of Dr. Adrian P. Harrison) are widely described as the only commercial, portable, clinical-grade AMG platforms providing real-time spatial, temporal, and efficiency scoring of muscle fiber recruitment via acoustic signals. AMT holds the relevant IP and is the manufacturer/distributor.
Key features include:
- Lightweight (~10 g) wireless piezoelectric sensors that record pressure waves from active muscles (and related structures such as ligaments/suspensory tissues).
- Real-time analysis with scores such as E (efficiency/coordination), S (spatial summation/fiber recruitment), and T/O (temporal activity/frequency), often integrated into an ESTi™ or SOFi™ score, plus BSP (Balance, Strength, Performance) metrics.
- Cloud analytics, mobile/tablet apps, and reports viewable on phones, tablets, or computers.
- FDA 510(k)-exempt classification (e.g., under 21 CFR 890.5360 in marketing materials).
- Non-invasive use with acoustic gel; no need to shave in many cases; suitable for humans, equines, and canines during motion.
Typical applications cover sports medicine and rehabilitation (detecting imbalances, early injury signs, fatigue, hydration changes via acoustic signals, monitoring recovery and training efficacy), veterinary use (especially equine suspensory ligaments, muscle performance, and lameness-related issues), and research in areas such as Parkinson’s disease motor dynamics, age-related changes in muscle control, and post-injury rehabilitation. Baseline tests and comprehensive reports are offered; systems are marketed to licensed medical, veterinary, sports medicine, and training professionals. Pricing for full SOFi M² packages has been listed in the tens of thousands of dollars (with introductory discounts noted in materials). Official site: myographytech.com.
Peer-reviewed work (including studies by Harrison and collaborators) supports use for assessing muscle function, coordination, and changes with aging or disease, with advantages cited over surface EMG in simplicity, repeatability, and the ability to distinguish concentric/eccentric activity in some contexts.
Related and Research-Stage Acoustic / Mechanomyographic Approaches
AMG is closely related to mechanomyography (MMG), which also records muscle vibrations/oscillations. Research and prototype devices include:
- Dual-modal stretchable sensing patches that combine multi-channel EMG electrodes with AMG sensors for simultaneous monitoring during dynamic motion (e.g., high-strain applications).
- Systems such as M-MARK using MMG sensors (miniature microphones in acoustic chambers) for stroke upper-limb rehabilitation home devices.
- Broader wireless broadband acousto-mechanical sensing networks for continuous monitoring of cardiorespiratory, gastrointestinal, and other physiological signals (demonstrated in clinical settings like NICUs and thoracic surgery patients), though these are not muscle-specific AMG in the SOFi/CURO sense.
- Historical and patent work on acoustic myography transducers (piezoelectric or microphone-based) for force estimation, fatigue assessment, or prosthetic control.
In short, commercial clinical-grade AMG devices for real-time muscle analysis during activity are currently dominated by the AMT SOFi/SOFi M² (CURO) platform, with supporting research literature and emerging related acoustic sensing technologies for broader physiological or hybrid EMG/AMG monitoring. For the latest specifications, regulatory status, or availability, check the manufacturer site or peer-reviewed papers, as commercial offerings and claims evolve.
