Why obese workers get tired sooner

Workers who are obese may have significantly shorter endurance times when performing workplace tasks, compared with their non-obese counterparts, says a study.

Obesity is associated with physiological changes at the muscular level, including a decrease in blood flow, thereby limiting the supply of oxygen and energy sources.

When performing sustained contractions, these physiological changes may lead to a faster onset of muscle fatigue, the study said.

"Our findings indicated that on an average, approximately 40 percent shorter endurance times were found in the obese group, with the largest differences in the hand grip and simulated assembly tasks," said Lora Cavuoto, an assistant professor at University of Buffalo in the US.

For the study, researchers examined the endurance of 32 individuals in four categories (non-obese young, obese young, non-obese older, and obese older) who completed three distinct tasks that involved a range of upper extremity demands - hand grip, intermittent shoulder elevation, and a simulated assembly operation.

Each task involved periods of work and rest, and included pacing demands similar to those experienced by workers in manufacturing settings.

"Workers who are obese may need longer rest breaks to return to their initial state of muscle function," Cavuoto added.

"Based on the increased fatigue found among workers who are obese, workplace designers may need to consider adding fixtures and supports to minimise the amount of time that body mass segments need to be supported," Cavuoto said.

The study appeared in the Journal of Occupational and Environmental Hygiene.