muscles contract, microvolt level electrical signals are created within the
muscle that may be measured from the surface of the body. A procedure that measures
muscle activity from the skin is referred to as surface electromyography (SEMG).
Researchers and clinicians use SEMG to evaluate the functional status of skeletal
muscles and assist in neuromuscular training and rehabilitation. The small electrical
current, or signal, which comes from active muscles, is detected by sensors
placed on the skin directly above the muscles. The strength and pattern of the
signal is displayed onto a computer screen and the data is collected in a software
program that is able to run various analyses of the data to create useful reports
regarding muscle function.
Because SEMG signals are small, their measurement is susceptible to interference
– for example, from electrical equipment, lights or movement of cables
that carry signals from the body to the measuring instrument. Evaluations require
the subject to perform a full range of movement exercises and interference from
movement of lead wires has been a problem.
Lower cost instruments attempt to eliminate artifact by electrode site pre-amplification
and by “notching out” or filtering the frequencies at which interference
occurs. Unfortunately, these frequencies are also where most SEMG signals are
located. Devices that use “notch-filtering” lose essential data.
That is why accurate, reliable SEMG measurement was impossible - until Noraxon.
Noraxon's breakthrough amplifier technology actually distinguishes between
SEMG signals and artifact. The result is reliable, repeatable and pure SEMG
data that enables professionals to make more precise evaluations of muscle activity
and performance. This is the secret behind all Noraxon systems.