This Application note describes how to normalize EMG data to Maximal Voluntary Contraction (MVC), using LabScribe.
- Acquire the EMG data on a subject performing MVC.
- Place the 2 cursors around the EMG signal you want to normalize.
- On the recorded EMG channel, select the function button (fx).
- Select “…”
- Select “EMG”
- Select “Maximum Voluntary Contraction”
7. Set parameters in the EMG Analysis Dialog.
Window Length: Refers to the segment of time the software uses to analyze EMG data. Breaks the continuous signal into smaller slices or chunks. Each slice represents a fixed window of time.
Use first __ sec as zero: Sets a baseline using the first seconds of the recording, when there’s no muscle activity. This removes any offset, so the analysis focuses only on the actual muscle signals.
Moving Average: Smooths EMG signal by averaging a set number of data points. This helps reduce noise, making it easier to see trends in the muscle activity.
Higher number = more smoothing.
8. Select “Preview”
9. Select “Calculate MVC from current data”
Note: Any time any parameters are changed, (Window Length, Use first __ sec as zero, Moving Average) select “Calculate MVC from current data” again to recalculate RMS value for MVC.
10. Once “OK” is selected, a new channel will be created. This is the MVC channel.
8. Set the Channel Function to Max (at the right hand top of the MVC Channel Bar). The EMG channel is now in % MVC.
