Researchers used real-time X-ray imaging (called fluoroscopy) to watch the spines of elite powerlifters while they fully flexed their spines with no weights and while they deadlifted more than 400 pounds. With the exception of one trial of one subject, all men completed their deadlifts within the normal range of motion they displayed during full flexion. Ligament lengths were unaffected, indicating that they don’t help support the load but instead limit the range of motion.
