If you do heavy lifting at work, listen up.
Ohio State researchers looked at the oxygen levels of ten workers while they lifted heavy boxes onto conveyor belts.
Decreased oxygen means more muscle fatigue and that means a greater risk of back injury.
The study found workers who took a half-hour break in the middle of the day helped their muscles recover.
However, once they started back at work, muscle fatigue increased greatly.
To avoid back injuries, researchers suggest you should take longer or more breaks during the day.