EFFECTS OF TEMPERATURE ON MOTOR UNIT ACTION-POTENTIALS DURING ISOMETRIC CONTRACTION

The effect of temperature on motor unit action potential (MUAP) config uration and recruitment was studied using automatic decomposition elec tromyography (ADEMG) recordings from a concentric needle electrode pla ced in the first dorsal interosseous (FDI) muscle of 10 normal adult s ubjects during isometric contraction. Focally cooling the FDI resulted in prolonged MUAP duration (P < 0.001, ANOVA), a finding congruent wi th those of Buchthal. Focal ulnar cooling at the elbow resulted in the increased MUAP frequency, In contrast to previous studies, there were no significant differences in amplitude or turns, Greater understandi ng of normal motor unit electrophysiology is necessary to improve diag nostic accuracy of EMG testing. (C) 1995 John Wiley & Sons, Inc.