How Michael Jackson Defied Biomechanics

Michael Jackson’s 1987 music video “Smooth Criminal” is a classic. In a scene, he was able to lean forward to about 45 degrees while maintaining a straight spine, defying gravity. Many tried to replicate it, but this move is impossible from a biomechanical point of view.

Nishant Yagnick and colleagues from Postgraduate Institute of Medical Education and Research, Chandigarh, India analysed Michael’s biomechanics in an article published in Journal of Neurosurgery: Spine.

The authors explained: “When the human body stands erect, its center of gravity (COG) lies in front of the second sacral vertebra. Studies of biomechanics and kinesiology suggest that, as we bend forward with a straight torso, keeping our hip joints as the fulcrum, the erector spinae muscles act like cables to support the suspended spinal column during the forward shift of the COG, preventing the body from falling forward. However, when the fulcrum for forward bending is shifted to the ankle joints, the erector spinae lose their ability to maintain the COG, 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.”

Comment by Joe Muscolino

ANTERIOR TILT OF THE PELVIS AND POSTERIOR TILT OF THE PELVIS AT THE HIP JOINT. THE TILT OF THE PELVIS CAN BE LOOKED AT AS WHERE WATER WOULD SPILL (“PELVIS” COMES FROM THE LATIN WORD FOR BASIN). PERMISSION JOSEPH E. MUSCOLINO. KINESIOLOGY – THE SKELETAL SYSTEM AND MUSCLE FUNCTION, 3RD EDITION (ELSEVIER, 2017).

Comment by Joseph Muscolino

When the authors of the study state: “…bend forward with a straight torso, keeping our hip joints as the fulcrum…”, they are referring to anterior tilt of the pelvis at the hip joints. Then when they state “…when the fulcrum for forward bending is shifted to the ankle joints…”, they are referring to the legs dorsiflexing at the ankle joints toward the dorsum of the feet (the closed-chain reverse action of dorsiflexion of the feet at the ankle joints relative to the legs, which is the typically thought of open-chain standard joint action of dorsiflexion at the ankle joint). Unfortunately, we cannot quite see the ankle joints in the accompanying photograph, but we can see that the bend in Michael Jackson’s body must be happening at the ankle joints.

DORSIFLEXION AND PLANTARFLEXION OF THE FOOT AT THE ANKLE JOINT (OPEN CHAIN – STANDARD JOINT ACTION). PERMISSION JOSEPH E. MUSCOLINO. KINESIOLOGY – THE SKELETAL SYSTEM AND MUSCLE FUNCTION, 3RD EDITION (ELSEVIER, 2017).

How did Michael do it?

Most trained dancers with strong core strength can only reach a maximum of 25° to 30° of forward bending while performing this action.

It has now been revealed that Michael was able to perform this move with the help of a specially designed footwear. This shoe has a V-shaped slit in the bottom of each heel, and was latched to a metal peg driven into the ground which allowed Michael to lean forward in a gravity-defying move. However, even with this patented footwear and the support of the hitch, the move is still difficult to perform. This move requires a good core strength from strengthened spinal muscles as well as the lower-limb muscles.

The authors said that MJ challenged our understanding of the modes and mechanisms of spinal injury. Dancers now tried to perform more challenging moves by jumping higher, or stretching farther, and turning faster than before. These new moves created stresses on the spine that can cause injury.

Comment by Joseph Muscolino

Pushing our bodies further and further in the interest of art with all the challenges and stresses to the body that accompany this pursuit, is a noble endeavour. However, nobility is one thing and creating an injury that may cause pain and affect our ability to function for the rest of our lives is another matter. Certainly, the best way to prevent myofascio-skeletal injury is to be as strong and as flexible as possible. But even when we optimize these aspects of our body, we still need to be mindful that there are limits to the physical stresses that our tissues can endure. So, let’s all be healthy and work hard toward our goals for our art or for our sport, but be attentive and listen to our body’s responses to the demands we place upon it, and prevent injury.