In 1987, Michael Jackson seemingly defied gravity in the video of his song Smooth Criminal, when he leant 45° forward, his spine straight, with only his feet preventing him from falling over. Three decades later, three neurosurgeons from the Postgraduate Institute of Medical Education and Research (PGIMER) in Chandigarh have deciphered the biomechanics that enabled Jackson to perform a move that not many other dancers could be expected to match.
The study, ‘How did Michael Jackson challenge our understanding of spine biomechanics?’ by Nishant S Yagnick, Manjul Tripathi, and Sandeep Mohindra, was published online in the Journal of Neurosurgery Tuesday.
So, how did Jackson manage it? With a combination of two factors, the doctors say. One was a specially designed shoe, patented by Jackson’s team, that supported him in that position by hitching him to the stage. Two, the sheer strength in Jackson’s tendons. Otherwise, the doctors believe, even the strongest and best trained dancers can go up to a maximum of only 25° to 30° while bending forward.
When a person stands with his or her back straight, the centre of gravity is in front of the second sacral vertebra (lower part of the spine). When the person bends forward with the back straight, the hip joints act as a fulcrum, on which the body moves forward. The muscles of the back support the spine and act as a cable while the body makes its movements. This helps in maintaining balance without the body falling forward.
“However, when the fulcrum for forward bending is shifted to the ankle joints, the erector spinae (muscles supporting the back and vertebral column) lose their ability to maintain the centre of gravity, and strain is shifted to the Achilles tendon,” the doctors said in the study.
In Jackson’s case, the authors said, his special shoes “had a slot in the heel”. “The triangular slot 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,” the study says.
Yet, even with the special footwear, the move would be possible only with “athletic core strength from strengthened spinal muscles and lower-limb antigravity muscles”. Dr Tripathi told The Indian Express from the UK that they have concluded that the secret lies “in the inventiveness and core muscle strength”.
“It is actually a mix of both. His patented shoe and strength in tendons,” Dr Tripathi said. “It might not have been possible even for Michael Jackson if he had no such specialised shoes.”
Dr Mohindra said even with special shoes, no one else could perform the same moves. “His tendons were developed so strong that he could bend up to 45° forward while keeping his spine straight.”
The authors have advised dancers to exercise extreme caution if they try to copy Jackson’s moves, as it could result in injuries. In fact, Dr Mohindra said, dancers should preferably avoid copying such moves.
“After dancers try to perform the MJ moves, we have been witnessing dancers visiting our hospital with different kinds of spine injuries. In many patients, we have a treatment line as severe as artificial implants,” he said.
It took the three doctors one-and-a-half-years to complete the study. Dr Tripathi said they examined videos, performed the moves themselves, and took the help of a professional choreographer before reaching their conclusion.
“I am a fan of MJ and I tried these moves in my childhood, but I could never do it,” Dr Tripathi said.