A biomechanical analysis and validation system and method suitable for clinical diagnosis while providing accurate measurements of the angles of lower body segments and joints (i.e. without undue drift error and gravity vector estimation error). The system and method use inertial sensors configured to be positioned at the pelvis, the right and left thigh, the right and left shank and the right and left foot, and, optionally plantar pressure sensors to be positioned under the right and left foot of a subject. Biomechanical information of the subject is provided by expressing the orientation of the inertial sensors with respect to the orientation of the lower body segments of the subject.
