Rats Can Only Exercise So Much Before Getting All Stressy About It


Exercise is good for you, or so science has led us to believe. Regular exercise can confer such abstract, qualitative benefits as: stress reduction, anxiety easement, and optimism enhancement. It can also help you look more like your favorite member of the X-Men, minus powers. However, maybe science has deceived us. Maybe exercise doesn’t really help us cope with stress, anxiety, and depression. If the thought of strapping into your ill-fitting running shoes and staggering down the pavement of your neighborhood in winter spandex like a dazed fugitive who’s just broken out of a dystopian future prison stresses you out and you only do it because you’ve been guilt-tripped by every health blogger on the Internet, maybe, just maybe, dreading exercise can nullify the supposed stress-reducing benefits of actually exercising.

No study had directly compared the emotional effects of forced and voluntary exercise, according the New York Times‘ Well blogger Gretchen Reynolds, until recently when a group of scientists at the Center for Neuroscience at the University of Colorado at Boulder decided to gather some lab rats together for a good, old-fashioned coercive high school gym class. For rats. How would the rats respond to forced bouts of exercise? Would the super-fit rats excel, reveling in their athletic prowess like little rodent Adonnises, while the clumsier, uncoordinated rats merely dreaded the prospect of having a militaristic scientist stroll over to them and say, “If you can’t do a real push up, just put your knees on the ground, like the inferior physical specimen you are”? These were questions for science, and science, as it so often does, sort of answered them.

Reynolds offers a fairly concise account of the study. Scientists split healthy adult male rats into four groups: rats with free access to running wheels and the agency to exercise at their leisure, rats put on lockable wheels and forced to exercise at a varying pace controlled exclusively by scientists, rats put on mechanized treadmills that moved at a steady and unvaried pace, and, finally, sedentary rats.

All the rats exercised (or languished) for a period of six weeks, after which they were put into a stressful situation (a large, unfamiliar maze) “designed to determine their levels of anxiety or confidence.” The rats were evaluated based on how they reacted to being put into this terrifying new enclosure:

If they froze or scurried to the darkest corners of the cage and refused to explore, they were considered to be highly anxious and unsettled, by rodent standards.
The treadmill runners and the sedentary animals were, the results showed, extremely anxious. They froze or ran for the darkness at the first opportunity.
But the animals that had exercised on the running wheels, whether they could control their exercise regimens or not, proved to be quite resilient. They bounced back emotionally from the imposed stresses and were willing to explore the lighted regions of their new surroundings on the next day.
They were, by rodent standards, happy and well-adjusted guys.

Obviously, the phrase “by rodent standards” serves as a helpful reminder that no comparable experiment has been performed on people, although I think kids stuck in PE class at the mercy of a truculent, walrus-mustachioed, former police sergeant teacher would disagree. It’s interesting to note, however, that study leader Benjamin Greenwood and his team aren’t quite sure why the treadmill rats didn’t seem to experience any increased stress resistance.

Maybe it’s because those rats couldn’t control how they exercised, and got super-stressed from sprinting non-stop on an unfathomable mechanical device. Maybe scientists just need to take a closer look at the emotional benefits conferred by exercising in humans so we can have data once and for all that tells champion relaxizers that their mistrust of physical activity is well-founded. Basically, this study confirms what you’ve probably suspected already — treadmills are evil devices invented by a secret ruling cabal of machines to torture organic beings.

When Exercise Stresses You Out [NY Times]

Image via Jagodka /Shutterstock.

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