Medical researchers apparently unaware that one should never reveal a magician's trick have pulled back the veil on a seemingly impossible dance move by Michael Jackson. The singer's gravity-defying 45-degree tilt, in which he leaned forward while keeping his body straight and shoes flat on the floor, first left viewers dumbfounded when it debuted in the 1988 music video for "Smooth Criminal." As noted in a release, "That is not how the human body works!" But though a patented shoe was later revealed to play a key role in the maneuver, neurosurgeons at India's Postgraduate Institute of Medical Education and Research say it wouldn't permit any Average Joe to complete the move "that seems unearthly to any witness," per the BBC. Ankle support and solid core strength are also required, according to the study in the Journal of Neurosurgery: Spine.
Jackson's dance background meant he had core strength in abundance. But as even the strongest dancers can only achieve a 25- to 30-degree tilt on their own—the calf and Achilles tendon taking strain they weren’t designed for, per CNN—Jackson had to be helped by a special shoe inspired by astronaut boots, which can be fixed to a rail in zero gravity. In addition to providing the necessary ankle support, Jackson's shoes, patented in 1993, could attach to a nail or other anchor in the floor using a v-shaped slit in the heel. "Very inventive idea of him," study author Manjul Tripathi tells CNN, adding that "even with that shoe, I am not able to do 45 degrees." The neurosurgeons also say that Jackson has inspired new forms of dancing that "have begun to challenge our understanding of the modes and mechanisms of spinal injury." (This famous dance move is also best avoided.)