None of the workers was diagnosed at the start of the study as having thickening of the arteries. Over three years, the scientists used ultrasound imaging to measure any thickening of the carotid arteries, which carry blood to the brain. Stress can raise clotting factors in the blood and may prompt the release of fat into the bloodstream, which can lead to clogging of the arteries. Physical activity, on the other hand, has been shown to reduce levels of these fatty acids. Digging deeper Researchers found, to their surprise, that people who got the most physical activity on the job had the greatest thickening of the arteries.
Conventional wisdom is that being active improves cardiovascular health.
And a separate part of the study supported the conventional wisdom. This section found that the people who were most physically active off the job had less progression toward the thickening, Nordstrom said. The researchers found that the people who worked the hardest, and who worked the most hours, reported the greatest job stress, Nordstrom said. And when the researchers did statistical analysis, it turned out that job stress was most closely associated with the increase in carotid thickening, she said. Another expert, however, has his doubts.