Working it Out

June 25th, 2010 by Andrea Bennett

At the Center for Physical Ergonomics, the focus is on how the work we do affects our bodies.

Brought to you by Liberty Mutual's
The Responsibility Project

In 2007, the Center for Physical Ergonomics evolved out of the former Center for Safety Research. Under the direction of Nils Fallentin, CPE research scientists investigate how job tasks tax human capacity . Using findings from lab and field studies in biomechanics, human machine systems, low back pain, repetitive work, tribology (the study of how surfaces in motion interact), and work physiology, they develop ways for companies to enhance safety on the job. Recent developments in the Ergonomics department are revealing some interesting results in the areas of slips, trips, and falls; overexertion; postural stability; and repetitive work.

And if it sounds like the work the Center for Physical Ergonomics does is all tireless number-crunching and data correlation, make no mistake: this is where you’ll find some of the most fascinating contraptions at the Research Institute. Real people—hundreds and up to thousands per year—serve as paid volunteers, hooked via electrodes to monitors and sophisticated devices (all built by the electricians and wood- and metalworkers within the Center) as the department tests real theories on real people. Over and over and over again.

Dr. Fallentin’s group has spent the past couple of years collaborating on joint research projects with the Faculty of Human Movement Sciences at VU University in the Netherlands, participating in international forums on work-related musculoskeletal disorders and publishing work on topics like using noninvasive methods to measure muscle blood flow and oxygenation during work tasks. We sat down with Dr. Fallentin to get more insight.

What are the most exciting things the Center for Physical Ergonomics has learned in the last year?

The Center deals with the workplace risk factors associated with the most costly and widespread occupational injuries and illnesses—for example, overexertion; slips, trips, and falls; and repetitive motion. For instance, in the area of overexertion, we have been studying the effect of back muscle training to prevent recurring low back pain, and raised some doubt on the common belief that training is an effective preventive measure.

Within the area of fall injuries, we have demonstrated how postural transitions—such as switching from kneeling to standing—in the construction industry increase the risk of a fall injury and formulated suggestions for ways to prevent them.

Our research in the last year has also led us to suggest eight-hour Maximum Acceptable Forces for repetitive hand movements for male industrial workers based on psychophysical criteria [what they think they can handle] and physiological criteria [capacity demonstrated in a lab] and we have been able to quantify the musculoskeletal disorder risk associated with using pneumatic hand tools.

Can you describe something you’re currently working on?

One thing we’re investigating now is the widespread belief that back injuries primarily occur when you lift too heavy a burden; it’s the classical overexertion injury. In reality, what we’ve found that is that it’s a cumulative trauma pathway that often creates the prerequisites for the events the lead to the injury. In other words, a chain of events—such as previous work activities— fatigues the back muscles, interfering with their ability to stabilize and protect the spine, making it more susceptible to injury.

So in order to understand the pathway, and suggest ways to prevent its development, we are conducting a series of lab studies. We have found healthy volunteers to perform different kinds of exercise to fatigue their back muscles, and are studying how fatigue influences the activation and coordination of the back muscles. A new technique has been developed that enables us to very precisely measure the stretch reflexes in the back muscles—think about the knee-jerk reflex that your general practitioner tests with a hammer, but relocated to the back muscles. This is important because well-functioning local stretch reflexes in the back muscles are the most important factor in maintaining a stable and well-protected spine. If we can identify the kind of workplace and individual factors that inhibit stretch reflex sensitivity, making the back unstable, we will have come a long way toward preventing a cumulative trauma pathway.

How many kinds of tests might the center be concurrently running on any given day?

If we are running lab experiments, we normally have from one to five subjects in the lab per day. (In some experiments the subjects have to be in the lab for several hours.) In some cases, we may have several of the labs doing experiments at the same time. To give you some context, we ran one lab experiment in which we recruited and screened 30 men and women to perform lateral load transfers under a variety of conditions. The volunteers reached 90 degrees to a box and transferred it the same distance 180 degrees to the opposite side. During each task, research scientists measured the volunteer’s center of mass using a 3-D motion capture system and collected the forces and moments of the feet in contact with the ground using force plates. They also used electromyography to measure the activation of critical body stabilizers on both sides of the body. They analyzed the data to assess the effects of load transfer, surface friction, and surface disparities on stability—and the risks of slipping and falling.

How quickly do you feel that understanding of ergonomics has evolved relative to other disciplines?

Ergonomics and work related musculoskeletal disorders (WMSD) has received a lot attention. This is not surprising since the economic and social consequences of WMSD are substantial, partly due to a close association with decreased quality of life, sickness absence, loss of productivity, and early retirement. Where a lot of other workplace exposures such as chemical and noise seem to be diminishing, the challenges associated with overexertion and repetitive motion continue to dominate the occupational safety and health agenda. And the problems are not disappearing by themselves. If we are not able to successfully identify and address workplace risk factors, and fail in initiating the required preventive efforts, the consequences of uncontrolled musculoskeletal disorders could become much worse in the coming years.