I’ve looked deep into spinal engine theory and came to the following conclusions; The spine’s twisting and bending during walking are passive responses to forces generated elsewhere, not the origin of those forces. EMG studies show that spinal muscles stabilise posture rather than initiate movement. The pelvis and hips, driven by leg muscles like the gluteals, initiate rotation, which the spine then accommodates. The spinal engine theory reverses this cause-and-effect relationship. Gracovetsky’s work relies heavily on theoretical modeling and lacks large-scale, peer-reviewed clinical or experimental studies to confirm its predictions. Mainstream biomechanics, supported by motion capture, force plate data, and muscle activation studies, prioritizes the role of the musculoskeletal system as a whole, not the spine in isolation. The spine does play a role in locomotion—it helps coordinate movement, maintain balance, and transfer forces between the upper and lower body. Its flexibility and curvature contribute to the smoothness and efficiency of gait. However, calling it the “engine” is a misnomer; it’s more like a transmission or stabilizer than the power source.