06/09/2013 10:38 am ET

Chronic Stress Lowers Running Activity In Mice, Study Finds


If there's one thing that mice love to do, it's run. But a new study shows that chronic stress could actually affect mice by making them want to run less.

The West Virginia University study, recently presented at the American College of Sports Medicine and first reported by Runner's World magazine, investigated the spontaneous wheel running activity of mice to determine the effects of chronic stress. The researchers found that mice under chronic stress ran less than mice who were not under stress -- but once the stress was removed, their levels returned to normal. Because the findings have yet to be published in a peer-reviewed journal, they should be regarded as preliminary.

To put the mice under stressful conditions, the researchers gave them damp blankets, altered light patterns, and tilted and switched their cages (previous research has shown that changing environments increases mice's stress levels). For eight weeks, the mice were put under stress seven hours a day, Monday through Friday, and then were relieved of stress on the weekends. Runner's World reported that the stressed mice ran a full 73 percent less than the control group during the week, but on the weekends, they ran the same amount as non-stressed mice. But on Saturday and Sunday, their run time, distance, work, and caloric expenditure returned to higher levels.

Acute stress, however, has the opposite effect on mice, with a 2011 study in the journal Perceptual and Motor Skills showing that it could actually increase running activity in mice.

Past research shows that stress also seems to elicit depression-related symptoms in mice, TIME reported, as well as stop the creation of new brain cells.

And then of course, chronic stress is known to have effects on humans too -- in the form of decreased productivity, fatigue and burnout.



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