Preparatory motion to move the hip through the sagittal and transverse plane while maintaining a neutral spine.

Assume a midstance position, put a small weight underneath your big toe joint. This puts further emphasis on the pronation of your foot, which is an integral part of force transmission through your foot in dorsiflexion.

Glut max activity should be the prime driver of hip extension, not the muscles of the trunk.

As bipedal creatures the glut max in humans developed to stabilize the torso on the stance leg. This is crucial for pelvic and spinal stability, especially in running.