REFERENCE VALUES OF MOTOR UNIT ACTION-POTENTIALS OBTAINED WITH MULTI-MUAP ANALYSIS

We collected reference values of motor unit action potentials (MUAPs) from healthy deltoid, brachial biceps, first dorsal interosseous, late ral vastus, and anterior tibial muscles in 105 subjects between 15 and 86 years. The MUAPs were recorded with a concentric needle electrode and extracted with a decomposition method we call multi-MUAP analysis. The main goal is to identify and extract MUAPs. Also, the firing patt ern of the motor units can be followed. No significant changes with ag e were found for duration, spike duration, thickness, amplitude, area, size index, or number of phases in all muscles studied. We did not fi nd any influence of gender or height. We found higher amplitudes and s horter durations compared with previous studies. This may be due to a higher contraction level that can be used with a decomposition techniq ue. No right-left side differences were found. The coefficient of vari ation of the parameters in repeated examinations was small, which impl ies a good reliability of the measurements. Interexaminer variability of four investigators was not greater than in repeated studies. (C) 19 94 John Wiley & Sons, Inc.