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Jenni Bridges
04-06-1998, 10:54 AM
I am seeking experience, opinions, and further references regarding EMG
amplitude of concentric vs. eccentric muscle contractions.

I have found conflicting information from my own experience (which tends
to show eccentric muscle contractions having LOWER EMG amplitudes
compared to concentric muscle contractions moving through a controlled
rate of elbow flexion/extension through an entire ROM) compared to the
information presented in "Selected Topics in Surface EMG for Use in the
Occupational Setting: Expert Perspectives" (1992) CDC Publications. On
p. 107 of the CDC "Topics" it states that: ..."The results for eccentric
contractions are quite different. Asmussen found that the IEMG of
muscles under concentric and eccentric contractions with the same tension
levels were different: eccentric contractions evoked GREATER EMG levels
than the concentric contractions (note: this was in the velocity-tension
effect discussion...).

So the conflict for me is whether eccentric EMG amplitudes are SMALLER or
LARGER than concentric amplitudes when velocity is constant. Any input
would be greatly appreciated. Thanks!

Dr. Jennifer Bridges, PhD
Saginaw Valley State University
University Center, MI 48710