Rat Study Suggests Even Mandatory Exercise Lessens Anxiety, Depression

New research using rats suggests that even when individuals are forced to exercise, they still benefit from reduced anxiety and depression.

Prior research has shown that voluntary exercise is a method to relieve stress, but experts were uncertain as to the mental benefit of exercise when exercise is mandated.

Specifically, researchers at the University of Colorado Boulder wanted to study whether a person who feels forced to exercise, eliminating the perception of control, would still reap the anxiety-fighting benefits of the exercise.

Examples of mandatory exercise include regimens placed on high school, college and professional athletes, members of the military or those who have been prescribed an exercise regimen by their doctors, said Benjamin Greenwood, Ph.D., an assistant research professor in CU-Boulder’s Department of Integrative Physiology.

"If exercise is forced, will it still produce mental health benefits?" he said. "It’s obvious that forced exercise will still produce peripheral physiological benefits. But will it produce benefits to anxiety and depression?"

To find an answer, Greenwood and colleagues 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 the following day. The anxiety was quantified by measuring how long the rats froze – a phenomenon similar to the proverbial deer in the headlights — when they were put in an environment they had been conditioned to fear.

The longer the freezing time, the greater the residual anxiety from being stressed the previous day, researchers said. For comparison, some rats were also tested for anxiety without being stressed the day before.

"Regardless of whether the rats chose to run or were forced to run they were protected against stress and anxiety," said Greenwood, lead author of the study appearing in the European Journal of Neuroscience.

The sedentary rats froze for longer periods of time than any of the active rats.

"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," he said.

Source: University of Colorado at Boulder