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(March 21, 2002, Gazette)

Creating a healthier working environment

(L_R)  Angela Tate and Tracey Mills

Photo by Chris HammondEngineering grad student Angela Tate (R) demonstrates her research for the benefit of writer Tracey Mills.

Low back pain is the most common non-obstetrical problem that sends pregnant women to see their doctor, and about half of all women suffer from it. This problem can often become worse for women who are working while pregnant. Angela Tate, a graduate student in the Faculty of Engineering and Applied Science, was part of a research team at Queen’s University working to get a better idea of what tasks are problematic for pregnant women to perform. Using a biomechanical model that can accommodate the very unique parameters of a pregnant woman’s body, they are measuring the load on the low back while performing these tasks. This data will be used to determine how loads at the low back are a factor in the development of low back pain in working pregnant women.

Ms. Tate presented on her graduate research and spoke about the implications of her work for creating better working environments for pregnant women at the recent launch of the SafetyNet speaker’s series.

“When you look at the cost associated with pregnant women leaving work early and the cost of training someone else to replace them, it makes sense for employers to look at ways of keeping pregnant women in the workplace longer and safer,” says Ms. Tate.

Low back pain during pregnancy can occur at all stages and there are many physical and biomechanical changes that can cause it to occur, as Ms. Tate pointed out. “For starters there is a significant internal weight gain, which has a direct effect on the abdominal muscles, a major postural muscle. The muscles of the abdominal rectus (those typically thought of as the six-pack) are lengthened by 115 per cent during pregnancy.” As well, ligament laxity, which enables the baby to fit through the pelvis, could cause instability of the joints and compensation by the muscles, may lead to fatigue. The average pregnant woman also gains between eight and 13 kilograms and increases their abdominal depth, on average, by 0.38 cm per week.

“The weight gain, combined with the unique change in posture, has a tremendous effect on the loads on the low back during certain activities. It is interesting to see how women adapt to their ‘new’ shape and posture when performing routine activities such as getting into a car or washing dishes. Activities that involve bending or twisting are especially difficult since pregnant women no longer have that full range of motion in their torso,” added Ms. Tate.

As part of the research study, about 75 working pregnant women were surveyed on factors such as previous back pain history, lifestyle, how many children they had, and age. Each woman was also interviewed about her particular job and at-home demands and the tasks she finds difficult to perform. Using a biomechanical model created especially for the study, and a 3D tracking system that provided accurate information on the position and orientation of body segments, the motion of some pregnant women was studied. “In order to determine the forces on particular joints, you need to look at how a segment is moving, how much that segment weighs, and its center of mass location. And then you start to work backwards going from the wrist to the elbow to the shoulder, etc.” said Ms. Tate.

The women were asked to perform a lifting task while instrumented with the 3D tracking sys-tem, so that the loads at the low back could be estimated. The findings from the survey indicated that there are several tasks that women find hard to do at work including picking up objects from low locations, getting things out of file cabinets with drawers that are too low or high, and sitting or standing for long periods of time. The biomechanical model will be used to further study the relationship between low back loads and the difficulty associated with these tasks.

The benefits of a project such as this are many, said Ms. Tate. “We have a better understanding of the factors that increase the loads on the lower back and of what tasks are problematic for pregnant women to perform. This information is available to employers and can be used to increase the amount of on-the-job accommodation available to working pregnant women.” She went on to say, “Applied health research is a growing area and one that will become increasingly important for both employees and employers, who want to foster a safer, healthier workplace.”

Ms. Tate is now working on her PhD research in the area of biomechanical modeling of the upper body of snow crab processing workers, under the supervision of Drs. John Molgaard and Ray Gosine in the Faculty of Engineering and Applied Science. Her work is part of a SafetyNet project examining cumulative trauma disorders in snow crab processing workers. SafetyNet is a community research alliance on health and safety in marine and coastal work.