Comparison of electromyographic (EMG) activity of selected forearm
muscles during low grade resistance therapeutic exercises in individuals
diagnosed with lateral epicondylitis
Issue title: Work Occupations and Outcomes Internationally
and Across the Lifespan
Affiliations: Cleveland State University, Cleveland, OH, USA
Note: [] Address for correspondence: CSU Department of Health Sciences
and Department of Psychology, 2121 Euclid Avenue, Cleveland, OH 44115, USA.
Tel.: +1 216 523 7353; Fax: +1 216 687 9316; E-mail: [email protected]
Abstract: Background and purpose: This was a descriptive and exploratory study
of electromyographic (EMG) activity of wrist extensor musculature specific to
the extensor digitorum (ED), extensor carpi radialis brevis (ECRB) and flexor
carpi radialis (FCR) in individuals with a medical diagnosis of the common work
associated complaint of lateral epicondylitis (LE). The purpose was to evaluate
and compare the EMG activity of the selected forearm muscles during three
different types of resistive (strengthening) therapeutic exercises (rubber
ball, theraputty, and "make-it-disappear" (MID) sponge) in participants with
LE. Participants: Five individuals between the ages of 44 and 55 years
of age diagnosed with lateral epicondylitis by a physician were recruited on a
voluntary basis from a local outpatient clinic. Methods: The participants completed 1 min. of each of the resistive
exercises, which were assigned randomly. Muscle activity was collected
simultaneously by 3 surface electrodes (4/18/16 DE -2.3 silver surface EMG
electrodes, Delsys Inc, Boston, MA) and recorded on an EMG Myomonitor-4 (Delsys
Inc, Boston, MA) utilizing EmgCE software (Delsys Inc, Boston, MA). The raw EMG
signal was converted to a root mean square (RMS) at each 0.0625 second interval
during the full 60 second recording using EMGWorks, (Delsys, Inc, Boston, MA).
The data were pooled, and the mean RMS was then determined as an overall
measure of activity for each muscle during the 60 recording. Results: A 1-way ANOVA with Tukey's post-test was completed using
Prizm Software (Graph Pad Software, Inc, San Diego, CA) for a comparison of the
mean RMS values of each muscle during each activity. Statistically significant
between group differences were noted for all muscles, among all exercises.
Relative activity was noted to be greatest for ED and FCR during MID exercise,
and for ECRB during putty exercise. Conclusion: All three exercises represent different patterns of
muscle activity, for the muscles observed. The possible differences in the
recorded activity may be consequent to the specific positioning and movement
requirements involved in the performance of the distinct exercises.
Practitioners may find the evidence of this study helpful in designing
rehabilitation programs for those affected with lateral epicondylitis.
