The Initiation of Locomotion in Man

The command to “start walking” demands a solution which protects postural stability while providing sufficient destabilization to permit lifting of one limb from the ground. Moreover, the solution should be sufficiently generalized so that a uniform principle (e.g., biomechanical) may be applied in the presence of flexible and modifiable neural networks contending with varying environmental problems such as those encountered by uphill or downhill, and forward or backward forms of walking (Grillner, 1981). Stein (1984) points out that with multiple forms of motor behavior (e.g., turtle scratch reflex), the transition between motor programs is smooth, suggesting considerable “overlap or interaction” between the networks.