L'EMG di superficie durante la flesso-estensione di ginocchio isocinetica in pazienti emiparetici

In the present study the authors studied surface EMG activity of the vastus medialis, vastus lateralis, semitendinous and femoral biceps muscles during isokinetic flexion-extension of the knee in a group of 30 patients affected by normotonic hemiparesis. Twenty healthy subjects matched to the patients as closely as possible for age served as the control group. Each subject underwent two tests of 5 flexion-extensions of the knee at 60 and 120 degrees/second. The hemiparetic patients performed the tests, first on the healthy and then on the paretic side. Isokinetic and surface EMG signals were recorded simultaneously using a customized programme. The time lapse between the appearance of EMG activity and the torque zero was analyzed. The data we obtained showed two trends of EMG activity: in the healthy subjects and in both the healthy and paretic side of 12 hemiparetic subjects we observed the characteristic changing of agonistic-antagonist activity; in a largest group (18 patients) EMG activity persisted in the flexor muscles even during extensor contraction. The temporal numerical data showed a high statistical difference between healthy and hemiparetic subjects both on the healthy and particularly on the paretic side. The presence of EMG activity in the flexor muscles could represent co-activation and/or persistence of changed motor schemes after stroke.