Michael Jackson’s gravity-defying Smooth Criminal dance move, which wowed live audiences and inspired new forms of dancing, was down to core strength and an illusion, neurosurgeons write in The Journal of Neurosurgery: Spine.
Dubbed the anti-gravity tilt, the seemingly impossible dance move was first showcased in the 1987 music video for Smooth Criminal. The “mind-boggling” dance move required Jackson to lean forward at a 45° angle while keeping his spine straight, and his feet flat on the ground. Due to strain on the Achilles tendon, most trained dancers with strong core strength will only reach a maximum of 25° to 30° of forward bending while attempting this tilt.
Nishant Yagnick (Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India) and colleagues write, “Several MJ fans, including the authors, have tried to copy this move and failed, often injuring themselves in their endeavours.”
When the human body stands erect, its centre of gravity lies in front of the second sacral vertebra. When bending forward with a straight torso, keeping the hip joint as the fulcrum, the erector spinae muscles support the suspended spinal column during the forward shift of the centre of gravity by acting like cables, according to biomechanics and kinesiology studies. This prevents the body from falling forward.
However, when the fulcrum for forward bending is shifted to the ankle joints, as in Jackson’s famous antigravity tilt, the erector spinae lose their ability to maintain the centre of gravity, and strain is shifted to the Achilles tendon. This allows for a very limited degree of forward bending from the ankle joints, while keeping a stiff straight posture—unless you are Jackson.
Yagnick and colleagues revealed that Jackson (along with inventors Michael Bush and Dennis Tompkins) designed a special shoe for live performances. This had a triangular slot in the heel that hooked onto a hitch member (a metallic peg) that came up from the stage floor at the right moment, thus allowing Jackson to lean forward beyond physiological limits without collapsing.
A 1992 patent registered under the performer’s name reads, “In the past, a professional entertainer, one of the inventors herein, has incorporated dance steps in his recorded video performances, wherein he and other dancers would lean forward beyond their centre of gravity, thereby creating an impressive visual effect. This effect was accomplished by the use of cables connecting a harness around the dancer’s waist with hooks on a stage, thereby allowing the dancer to lean forward at the required degree. However, since this requires stagehands to connect and then disconnect the cables, it has not been possible to use this system in live performances. Moreover, the cables obviously restricted arm and body movements.”
“The present invention overcomes the above noted deficiencies of the previously employed cable system by providing specialised footwear and a moveable hitch or post to which the specialised footwear can be detachably engaged to allow the footwear wearer to lean forward on the stage, with his or her centre of gravity well beyond the front of the shoes, thereby creating the desired visual effect.”
Yagnick et al write, “But even with specially designed footwear and the support of the hitch member, the move is incredibly hard to pull off, requiring athletic core strength from strengthened spinal muscles and lower-limb antigravity muscles.”
“Trick or not, new forms of dancing inspired by Michael Jackson have begun to challenge our understanding of the modes and mechanisms of spinal injury. Ever since Michael Jackson entertained us with his fabulous moves, throughout the world dancers have tried to jump higher, stretch farther, and turn faster than ever before.”
“The hip-hop style of dancing and, particularly its offshoot, b-boying/b-girling are two styles that include significant elements of acrobatics. Stresses on the spinal column experienced by dancers of those styles are very high and frankly a bit odd. The rapid rise in popularity of dance as an art and exercise the world over is bound to produce new forms of injuries that may perplex the neurosurgeon. The situation will become more complicated when a dancer, who has received a surgical construct for fixation, wants to continue dancing.”
“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’.”