View Full Version : Recording Time for Occupational EMG

Richard Wells
11-24-1998, 12:47 AM
EMG can be used for a number of purposes in occupational settings
including determining the activation (RMS) distibution of activation
(APDF), rest time (EMG "Gaps") or fatigue (MnPF/MdPF or its change over
time). My question is:

"How long need one record surface EMG for a given measurement precision"?

The literature seems to indicate three types of study;
1)Isometric, isotonic contractions. Time needed < 1sec?
2)Cyclic "stereotypic motion", e.g. gait, grasp. Time needed eg. 1-10
cycles, strides or repetitions?
3)"Real work" with multiple activities and tasks. Time defined
using sampling methodology or full day recording?

Situation 2) probably corresponds to many laboratory simulations of
occuaptional activity, often with multiple conditions. The answer
also seems to depend on the EMG variable of interest.

Our review of literature found that very few reserchers give reasons for
the time of recording and/or the number of trials used. The few exceptions
are in the gait literature. What is your experience and what documentation
are you aware of?
Thank you

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Richard Wells | Of the butchers and floorsmen...
Department of Kinesiology | their knuckles were swollen so that
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University of Waterloo, Waterloo, | There were the beef luggers,... and
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