In 1987, Michael Jackson dropped jaws by performing a seemingly impossible dance move in his "Smooth Criminal" music video: the antigravity tilt. The move required Mr. Jackson to tilt his body forward at a 45-degree angle with feet flat on the ground and spine straight.
Researchers from Chandigarh, India-based Postgraduate Institute of Medical Education and Research sought to analyze spinal biomechanics in relation to this innovative dance move. Journal of Neurosurgery: Spine published the article.
Here are four observations.
1. When the human body stands erect, the center of gravity is in front of the second sacral vertebra. The ankle joints allow a limited degree of forward bending with a straight posture to prevent the body from falling forward. Highly trained dancers can only maintain a 25- to 30-degree forward tilt from the ankle with a straight torso.
2. The researchers found a patent registered under Mr. Jackson's name that allowed him to perform this move. He wore a shoe with a heel slot that could "engage a hitch member (a metallic peg, which emerged from the stage floor at just the right time), allowing the dancer to obtain the right amount of extra support to be able to lean forward beyond physiological limits."
3. Although Mr. Jackson did not defy the laws of physiology and physics, he did change the landscape of dancing. Consequently, the researchers warn of the danger of dancers developing new spinal injuries if they push their limits too far.
4. The study authors concluded: "The art of movement is life itself for many dancers, and it remains to be seen how surgical implants will hold up to the stresses of dance. While many new questions need answering, what is certain is that all this is owed to the ever-fresh inventiveness and style of 'The King of Pop.'"