Benjamin Greenwood, an assistant research professor in University of Colorado at Boulder, said there was a question whether people reap the same mental benefits of exercise if they are forced to do -- as is common among high school, college and professional athletes, members of the military or those who have been prescribed an exercise regimen by their doctors.
Greenwood and colleagues, including Monika Fleshner, a professor in the same department, designed a lab experiment using rats. During a six-week period, some rats remained sedentary, while others exercised by running on a wheel.
The rats that exercised were divided into two groups that ran a roughly equal amount of time. One group ran whenever it chose to, while the other group ran on mechanized wheels that rotated according to a predetermined schedule. For the study, the motorized wheels turned on at speeds and for periods of time that mimicked the average pattern of exercise chosen by the rats that voluntarily exercised.
After six weeks, the rats were exposed to a laboratory stressor before testing their anxiety levels.
"Regardless of whether the rats chose to run or were forced to run they were protected against stress and anxiety," Greenwood said in a statement. "The implications are that humans who perceive exercise as being forced -- perhaps including those who feel like they have to exercise for health reasons -- are maybe still going to get the benefits in terms of reducing anxiety and depression."
The findings were published in the European Journal of Neuroscience.