Electromyography
- EMG – Karen Lonsdale
Electromyography (EMG) is “the recording of electrical changes occurring in muscles during contraction” (Karpovich & Sinning)
Here is how it works:
First, the skin needs to be cleaned, overlying the muscle to be assessed. Cleaning is by initial swabbing with an alcohol wipe and light surface abrasion with a proprietary agent to reduce skin impedance and aid in detection of the EMG signal.
- Cleaning skin for EMG
Self adhesive, disposable electrodes are applied to the cleaned skin
- Electrodes
Two electrodes are positioned in the middle of the muscle belly where accessible superficially (in other words, the muscle layer closest to the skin). A third (ground) electrode is placed at a site distant to the muscle of interest. Electrode leads are connected to the electrodes. These snap on easily.
- Leads connect to the electrodes
The electrode leads connect to an EMG device, so the electrical signal from the muscles can be converted into a digital signal for the electronic database.
- EMG Device
The electrodes are interfaced to a computer using EMG software.
- Computer with EMG Software
Video footage of the EMG study is taken as it helps to later compare the EMG findings with the original musical performance during the study.
- Video
So, the full EMG set up looks something like this:
- Full EMG Set Up
The EMG data obtained from the particular musical works is compared directly against the maximum voluntary contractions (MVCs) of the flute player analysed, in order to gain information about the percentage activity in each muscle group during playing of the works. Percentage outputs of EMG give some indication of the amount of work required by the major muscle groups for playing flute pieces of varying complexity. This data will provide a baseline against which to assess any later research which might compare different body positions, or flautist experience. Here is an EMG of a readout, where each line represents a different muscle group for one player:
- EMG Readout
The EMG results were compared with the results of the International Survey on Injury Prevention and Management for Flute Players (2007), which involved over 400 flute playing respondents. The survey has provided valuable information about what types of injuries flute players suffer from, as well as how teaching, rehearsal practices, instrument choices, lifestyle factors such as stress and so on might impact on physical aspects of playing. Flutists also commented on which activities and treatments were most effective in preventing and managing playing related discomfort, tension and injuries.
The outcomes of EMG analysis demonstrated that there are individual differences in flutists and that some muscles work harder on one side of the body compared to the other. While such differences may be significant for some players and not others, these findings need to be tested using a bigger sample, which may also look at muscular response rates over longer durations than were included in this study.
The EMG study highlighted the additional upper body muscular activity that is required by a small player where the left hand cannot reach the keys of the flute comfortably. Ergonomic modifications such as key extensions were suggested as a way of reducing the left hand stretch for a physically smaller player. The study may, therefore, have implications for teaching children, or other physically small players, who may find this stretch to the keys more difficult than adults, or larger players generally. Performing arts medicine authors recommend that suitably sized musical instruments are matched to the physical size of the player. Another way the smaller player in this study could have decreased the load on her body would have been to choose a lighter flute, such as a sterling silver, rather than a platinum clad model.
Where playing-related discomfort or pain is an issue, there are certainly ways in which flutists can optimize their set-up, so that loading on the body is reduced.
