Gravity Drive - The left foot is pronating (orange-red arrow) as the left hip is externally rotating.
Hip Drive Pronation - Timing of the foot's Pronation/Supination is determined by the transverse plane (internal/external) rotations of the pelvis (See Animation below)
Gravity Drive: Gravity pulls the foot inward and downward (pronates the foot) until the entire foot rests on the ground.
Rothbarts (Primus Metatarsus Supinatus) Foot:
Left Hip Drive - Internal (clockwise) rotation of the left hip, internally rotates the left femur and tibia, which in turn, pronates the left foot.
Hip Drive Pronation and Normal Foot Pronation are synonymous terms
Gravity Drive Pronation and Abnormal Foot Pronation are synonymous terms
Gravity Drive Pronation - Timing of the foot's Pronation/Supination is determined by gravity acting on the foot's structure (See Animation below)