Electromyography (EMG) Definition of EMG: - Electromyography is the study of muscle function through the inquiry of the electrical signal that the muscle emanates
Benefits of EMG:
- Allows us to directly look into the muscle
- Allows measurement of muscular performance
- Helps in decision making both before and after surgery
- Documents treatment and training regimes
- Helps patients to ”find” and train their muscles
- Allows analysis to improve sports activities
- Detects muscle response in ergonomic studies
Some Questions
Question - Is the muscle active ?
Answer – Yes/No and On/Off
Question is answered by observing raw EMG trace of any activity.
- A healthy well organized muscle in regular conditions turns off if it is not needed anymore
- If it still stays on, it is an indicator for active muscle spasm, reflex induced (e.g. pain), hyper tonus, joint instability or behavioral disuse
Question - How much is the muscle active?
- On this question the EMG amplitude has to be calculated on a metric scale
- Muscle Voluntary Contraction (MVC) must be determined
- Can only be performed on a healthy structure
- Performed against static resistance
- This kind of evaluation is important to understand the effect of treatment and training exercises
- Ergonomics may need to understand the neuromuscular demand of a given work activity
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