Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
January 11, 1999
Oh my aching back! Professors research focuses on hazards of sitting....
DON'T JUST SIT THERE!
Jack Callaghan, Department of Human Biology and Nutritional Sciences, recorded stresses on muscles in 14 locations on the backs of subjects working while seated for two hours. The findings show that sitting is more stressful than you think, and your Grade 1 teacher's pat admonitions to "sit up straight" were somewhat off the mark.
"Slouching or slumping puts stress on your back, but sitting straight all the time isn't good either," Callaghan said. "Anytime you confine yourself to one fixed position, it's not healthy. The human body is designed to move, it needs movement to provide nutrition to the spine," he said.
Callaghan is interested in how seating posture either alleviates or aggravates back stresses, especially in the lumbar or lower back region, which is three times as likely to sustain injury as any other part of the back. Most biomechanists observe subjects seated more or less in a single, prescribed position, but Callaghan wanted to see what happened when subjects were free to move around on the chair.
Most people adopt a variety of postures, some so extreme as to resemble toe-touching, he said. Lower back stresses from inappropriate sitting habits cause a sizable proportion of employee days-lost in organizations. Back problems accounted for about one-third of the roughly 10 million days-lost in Canadian workplaces in 1990, and of days-lost that cost American companies about $50 billion last year.
The best strategy is perhaps the most common-sense one: vary your sitting posture and take frequent breaks, every 15 minutes or so. "By standing and by altering your posture, you redistribute stresses so you don't have a focal point where injury can occur," Callaghan said.
Callaghan plans to conduct a follow up study to investigate links between the seating posture of people with back pain and how much pain they experience.
Professor Jack Callaghan, Department of Human Biology and Nutritional Sciences
OH, MY ACHING BACK !
Dickey, from the Department of Human Biology and Nutritional Sciences, is studying lower back motion to determine how to predict tolerable loads (the way the body acts in terms of tension in ligaments and compression across discs while doing different tasks). "There's a need to understand loads and to be able to predict if tasks are risky," Dickey said. "The number of people needing multiple operations on their backs is evidence that we don't know what's going wrong and how to fix it."
Dickey is studying human and pig lumbar spines, which are comparable in structure, to evaluate similarities and to understand the orientation and mechanics of ligaments.
Part of the research is being conducted with McMaster University and Hamilton General Hospital and includes studies of patients with chronic lower back pain and healthy individuals. The research uses x-rays, tools for measuring muscular activity and microscopic examination of organic tissues to predict loads.
Professor Jim Dickey, Department of Human Biology & Nutritional Science