You can use the 2-channel EMG preset settings together with a PowerLab with an inbuilt Bio Amp to record a surface electromyogram (EMG) from two groups of muscles. An RMS channel calculation allows you to quantify the muscle activity in each muscle group.
Exercises you can do with these settings
- Record a surface electromyogram (EMG) from a volunteer.
- Observe coactivation of a pair of "antagonistic" muscles, such as the biceps and triceps, using a dual Bio Amp recording of EMG activity, and root mean square (RMS) analysis to allow quantification of muscle activity.
The following instructions may be useful for you to copy and paste for your students:
Electromyography (EMG) equipment setup
- Remove any jewelry from the volunteer's wrist.
- Connect the five-lead Bio Amp cable to the Bio Amp socket on the PowerLab.
- Connect the five color-coded lead wires to the Bio Amp cable, as shown.
- Make sure the PowerLab is connected to the computer and turned on.
- Attach the green lead wire to the dry earth strap. If the dry earth strap has a single connector lead wire it should be inserted onto the pin nearest the Earth label.
- Firmly attach the dry earth strap around the volunteer's wrist. The fuzzy side of the dry earth strap needs to make full contact with the skin.
- Lightly mark two small crosses on the skin overlying the volunteer's biceps muscle, and two crosses over the triceps muscle. The crosses should be 2–5 cm apart and aligned with the long axis of the arm. Lightly abrade the skin over the crosses with abrasive gel, then clean with an alcohol swab.
- Snap the CH1 and CH2 lead wires onto some disposable ECG electrodes.
- Place the CH1 electrodes over the crosses on the volunteer's biceps, and CH2 electrodes over the crosses on the volunteer's triceps. Press firmly so they adhere well. It does not matter which is positive and which is negative.
- Check that all four electrodes and the dry earth strap are properly connected to the volunteer and the Bio Amp cable before proceeding.