DOES A SINGLE CONTROL MECHANISM EXIST FOR BOTH FORWARD AND BACKWARD WALKING

It has been proposed that the highly reproducible forward walking (FW) locomotor pattern is generated by a central neuronal program or centr al pattern generator (CPG) which provides the underlying mechanism whi ch produces the coordinated walking movement. The purpose of this stud y was to quantify the differences in the muscular activation patterns during FW and backward walking (BW) at a constant step frequency and t o determine if common features exist across both locomotor conditions. The hypothesis was that FW and BW are both mediated by the same CPG; therefore, only small modifications in the CPG are required in order t o produce the different characteristics of each walking mode. The resu lts noted kinematically reversed patterns at the hip and ankle joints between FW and BW. The knee joint movement pattern was similar between conditions, however, a phase shift of 14.3% of the gait cycle occurre d. An approximately 25% phase shift in the muscle activation patterns existed between FW and BW in four of the six muscles studied. Addition ally, a pattern recognition technique was applied to the combined EMG signals to determine the minimum number of features required to genera te the measured muscular output. Only two main features were necessary to produce the EMG patterns for both the FW and BW condition. The mai n features in FW were more consistent than noted in BW. The results su pport the notion that a single spinal mechanism such as a CPG with two main features appears to be in control during both FW and BW. (C) 199 8 Elsevier Science B.V. All rights reserved.