Mecanomiografia triaxial e análise de torque isocinético: Resultados preliminares

Abstract

In mechanomyography (MMG), there seems to be more studies in isometric contractions than isokinetic ones. MMG amplitude can be used to track torque decline in fatiguing isokinetic contractions. This study aims to determine good MMG/torque correlation indicators. Three volunteers performed 50 isokinetic contractions at 300°s-1. The MMG acquisition system is based on a triaxial accelerometer sensor. It was positioned on the belly of the rectus femoris muscle. The acquired RMS and derived signals were first analyzed for determining whether they have normal distribution. Then, the linear correlation coefficients were calculated. Sensor's axis 1 presented weaker correlation with torque variables than axis 2 and 3. The modulus of the three signals (axes 1, 2, and 3) had the highest correlation values. The RMS MMG amplitude had better correlation with RMS torque than peak torque. However, with the averaged values, correlation coefficients were R=0.89 and R=0.89 (p<0.01) for peak torque and RMS value, respectively. Two main conclusions were drawn: the modulus is a good indicator of torque amplitude in isokinetic contractions at 300°s-1, and peak torque and maximum RMS torque values occur after the first extension. However, tests with more volunteers are needed in order to precisely assess these results. © Springer-Verlag Berlin Heidelberg 2007.