Reexamination of the relationship between the surface integrated electromyogram (IEMG) and force of isometric contraction.

The integrated electromyogram (IEMG)--force relationships were studied in 26 physically active young men across the entire domain of forces in the elbow flexor group. All possible error factors (fatigue, muscle length, and co-contraction) were controlled to the greatest extent possible. The experimental conditions were more clearly defined than in previous experiments. The results confirm earlier observations of a linear relationship between IEMG and isometric force, under these experimental conditions and using a unipolar lead system. Highly significant correlations were found. Possible methodological error factors were studied. Bipolar recording produced a curvilinear, relationship which may explain some of the discrepancies of results reported in the literature.