Reliability of electromyographic measurements after surface electrode removal and replacement.

The purpose of this study was to determine the reliability of electromyographic measurements after surface electrode removal and replacement. Eight male subjects performed an isometric exercise with the left triceps brachii at loads equivalent to 50, 40, and 30% of their maximum voluntary contractile strength (MVC). Surface electrodes were utilized and the integrated action potentials recorded electromyographically as the muscle contracted. The muscle was tested first in a rested condition and then again after a sustained 30% maximum voluntary contraction. Each one of the subjects was tested three different times with a range of from 2 to 16 days between testing sessions. The electrodes were removed after each testing session. The data were means in centimeters of integrated action potentials over specified time periods. The test-retest correlations for the three testing periods resulted in coefficients ranging from .87 to .99. This was true under all loads and with the muscle either rested or fatigued.