EMG muscle scanning: stability of hand-held surface electrodes.
Electromyographic (EMG) muscle scanning measures 2-second samples of integrated muscle action potentials from individual neck and back muscles using a hand-held scanner with post-style surface electrodes separated by a fixed distance. This "scanning" technique is widely used to expeditiously assess muscle activity in the diagnosis of musculoskeletal disorders. In order to determine if the 2-second sample is sufficiently representative of electrical activity at a specific muscle site, the stability of the signal received by the hand-held scanner was measured bilaterally at six neck and back muscle sites over 40 seconds (20 2-second integration periods) in five seated subjects. Taking the overall average EMG activity as the "true" value, the mean number of 2-second integration periods required to achieve less than 5% standard error was calculated to be 1.47 for the 60 muscles tested. Only three sites required more than five integration periods. The validity of EMG scanning as a diagnostic tool is enhanced by longer integration periods.
Thompson
J M
JM
Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota 55905.
Erickson
R P
RP
Offord
K P
KP
D000200:Action Potentials; D000328:Adult; D001415:Back; D004566:Electrodes; D004576:Electromyography / Q000379:methods*; D006801:Humans; D009132:Muscles / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology; D013997:Time Factors