title: Effect of passive motions on the initiation of fast knee extension in patients with paraparesis.
abstract: Using reaction time paradigm, the effect of repetitive passive motion (RPM) on the initiation of fast knee extension was analyzed in seven normal subjects and 10 patients with paraparesis. Before and after 5 min RPM of the responding lower extremity, i.e., alternate flexion and extension of the knee and the hip with frequency of 0.5 Hz, the following five variables were examined: premotor time (PMT), latency from sound stimulus to initiation of EMG activities of the rectus femoris; tension lag time (TLT), period between onset of EMG activities and rise of tension; contraction time (FTmax); maximum tension (Tmax); and rate of tension development (RTD, Fmax/FTmax). In the normal group, PMT decreased significantly after RPM, whereas the other four variables did not show any change due to RPM. In the patient group, shortening of both PMT and FTmax after RPM was significant and Fmax tended to be small. These results suggested that RPM of an extremity induces behavioral alertness when the afferent pathway from moving parts to the higher center is not interrupted and also that RPM modulates abnormal pattern of motor neuron activities at the spinal level.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D006615:Hip; D006801:Humans; D007717:Knee; D008875:Middle Aged; D009038:Motion; D009046:Motor Neurons / Q000503:physiopathology; D009128:Muscle Spasticity / Q000503:physiopathology* / Q000628:therapy; D009132:Muscles / Q000503:physiopathology; D010291:Paresis / Q000503:physiopathology* / Q000628:therapy; D013997:Time Factors