Narrator: This is Science Today. Often times in the workplace, both physical workload and job stress co-exist. That's why it's been hard to isolate if back injury may be solely stress-related. But Dr. Niklas Krause, of the University of California, Berkeley, was able to disentangle the two effects by studying San Francisco bus drivers.
Krause: We, for the first time with adequate methodology, proved that psychosocial job factors - job stress and physical workload - are both independent predictors of workplace injury - of low back injury - in that group of public transit operators.
Narrator: It's been thought stress is not an objective measure but rather a characteristic of one's personality.
Krause: It is important to note that you have a certain variation in personal dealings with stress, but if in the group of drivers nearly a third of them has injuries during a certain period, then that can not be easily attributed to the personality of these people because they are actually a highly selective group of very healthy people because they have a job that requires safety.
Narrator: For Science Today, I'm Larissa Branin.