When Jacek Cholewicki imagines the human body, he sees the spine in the same way he sees a bridge or a telecommuncations tower — as a structure supported not by muscles, but rather by wires. A professor of biomedical and mechanical engineering, Cholewicki blueprints bone structures and muscle masses with the skill of an architect.
Cholewicki researches spine biomechanics in a temporary laboratory at the Yale School of Medicine. Envisioning the spine as a structure capable of supporting a 4,000 pound compressive force, Cholewicki, though not a medical doctor, applies engineering properties to the human body in an attempt to understand the spine’s seemingly impossible strength, assistant professor of orthopedics Jonathan Grauer said.
“Part of the reason for this resistance is that the spine cultivates living tissue which regenerates,” Cholewicki said. “But we still have unanswered questions about the role of pressure on the spine, or the role of weightlifting belts — there’s no explanation for why they work.”
Cholewicki, who was a power lifter as an undergraduate, is especially equipped to deal with research which often involves sports injuries, research assistant and graduate student Peter Reeves GRD ’10 said.
“A lot of people in research don’t know how the body works, so it’s strange for them to do research in an area like that,” Reeves said. “He’s a suitable person to see the big picture in the research.”
In what he called the “defining point” of his professional career, Cholewicki revolutionized the way physicians approach lower back pain prevention and rehabilitation. He created an anatomical three-dimensional model that incorporated over 90 muscles to describe muscle tension and stiffness, external forces’ impact on the lumbar vertebrae and the flexing of the tiny neighboring muscles and passive tissues.
“The problem is, people do prevention and rehabilitation, and they don’t really know how the spine works,” Reeves said. “Biomechanics is a tool to determine whether these myths are true.”
Cholewicki was one of the first scientists to develop a model of the spine that accounted for injury resulting from exceptionally small loads, Reeves said. The spine of the lower back is more vulnerable to damage when the body is at rest than during periods of physical exertion, Cholewicki said. He arrived at this conclusion after researching the relationship between the lower back’s motor control system and incidence of chronic lower back pain.
The concept of spine stability can be understood by conceiving the spine as a ball in a bowl, Cholewicki said. Placed against the side of the bowl, the ball rolls to bottom because it seeks the minimum energy position for the system. He said mathematical modeling can be used to determine the maximum applied force for which the ball remains in the bowl.
“The muscles act like walls for the bowl — the more you use the muscles, the deeper bowl or energy well, and the more stable it is,” Cholewicki said.
With funding from a recent research grant, Cholewicki said he plans to study the use of abdominal belts in industry and rehabilitation programs. Although one hypothesis is that the belts enhance proprioception — sensing body position without seeing — there is no explanation why the increased intra-abdominal pressure caused by wearing the belt would be beneficial to the lower spine. Cholewicki proposes stiffness from the belt enhances stability, allowing for a slight relaxation in the muscles.