Repeated maximum reciprocal knee movements in patients with minimal overt symptoms after ischaemic stroke: an evaluation of mechanical performance and EMG.

The ability to perform reciprocal knee flexions and knee extensions was investigated in patients with minimal or no overt motor symptoms after stroke. Ten patients and 22 controls performed 10 maximal reciprocal knee extensions and knee flexions without intervening rest period using an isokinetic dynamometer (Cybex II). Peak torque (PT; Nm), signal amplitude (RMS) and mean frequency (fmean) of the electromyography were registered for each extension and flexion separately and as the ratio extension/flexion. The patients exhibited pronounced motor deficit despite no or minimal overt clinical symptoms. The reduced motor capacity in the knee muscles was shown as a decrease in the PT and in a different electromyographic pattern compared with the controls. A bilateral affection was found with the formerly hemiparetic side mostly affected. Repeated reciprocal contractions influenced the motor performance, shown as an increase of the PT ratio in the patients, which was especially pronounced with an increasing number of contractions.