The Contribution of Dynamic Electromyography to Gait Analysis

The Functional Challenge Walking relies on selective timing and intensity of appropriate muscles at each joint to provide weightbearing stability, shock absorption, and progression over the supporting foot during stance and to advance the limb in swing. Energy is conserved by activating only the muscles optimally aligned for each task and by substituting momentum and passive tissue tension for direct muscle activity wherever possible. Throughout this sequence of functions, the muscles perform in groups, as shown in Figure 1 (1) . While the dominant motions of the lower limb occur in the sagittal plane (i .e ., flexion and extension for the demands of progression), there also are significant actions in the other two planes (coronal and transverse) to enhance single limb balance and body rotations. Each muscle has a unique three-dimensional (3D) effect determined by its alignment across the joint or joints it crosses . In addition, most muscles are members of two or more HIP (hamstrings)