Friday, March 29, 2013

Science Friday: Stress-ercise

I've been a little stressed lately. There's work, wedding planning, and plenty of workouts, enough to make anyone a little crunched for free time. Some people's response to my hectic life is to suggest I give up running. I have to work of course, and the wedding will be the wedding of the century. (She says without a hint of Bridezilla in her voice.) But running, that's just for fun. Why add any unnecessary stress?

My response is always something along the lines of running is my stress release. Sure, as the Big Race gets closer it can seem quite the opposite, but in general, running keeps me sane. Even though it robs me of mornings spent sleeping in, late nights socializing, and lazy Sundays, I love it. I'd rather metaphorically run around a little hectically than literally not run around at all. 

But it has got me thinking, is there a point where the pressures of lots of miles, big races, and goals of PRs negate the stress release provided by a daily jog? What if it starts to feel like just another item on a long to-do list?

An interesting article came out recently about forced exercise--if you really hate exercising but your doctor or gym teacher is making you, do your stress levels still benefit? Or does the agony of it all just lead to more anxiety? To address this, the researchers used rats forced to run on treadmills and on running wheels. Previous research has shown that rats forced to run on treadmills don't have the same reduction in anxiety as rats that voluntarily run when they please on a wheel. (Rats: I totally understand your perspective here. Treadmills stink.) Was it the forced nature of the running? Or was the treadmill running just unnatural for rats? Rats tend to run in intermittent bursts, so the researchers rigged running wheels to do the same. (I.e. the wheels rotated quickly for a few minutes then stopped for a bit before starting again, uncontrolled by the rats.) Another group of rats ran on wheels whenever they wanted, a third group was forced to run continuously on a treadmill, and a final group did not exercise. After six weeks, the rats were stressed by a standard rat-stress-paradigm (shocks to their tails.) The rats’ behaviors following the stress showed the no exercise group and the treadmill group were the most anxious. The voluntary wheel runners had less stress (as expected), but interestingly, so did the forced wheel runners. Even though they were being told when and how to run, their anxiety levels still went down. The take-home: even forced exercise (doctor, gym teacher, or Jillian Michaels prescribed) is better for stress relief than no exercise. (Provided the exercise isn’t “unnatural” for humans.) Also, treadmills are the worst. (See previous comment about unnaturalness.) 

Of course I don't feel my running habit is forced upon me. I do it because I love it. But it’s nice to know that even on those days when it might feel like another chore, it is actually helping me relax. But if I was really pressed for time, would it help to give it up for a little while? 

A different study hints at the answer to that question. What happens if exercising mice stop exercising? Do they return to baseline (the same as non-exercising mice), or do things get worse? Here there were three groups of mice: mice that exercised for three weeks, mice that did nothing for three weeks, or mice that exercised for one and a half weeks and then did nothing for one and half weeks. Continuous exercise reduced some measures of anxiety, but the group that stopped exercising looked the same as mice that never exercised. On other measures, the exercise-quitters were worse than the ones who never exercised. The authors suggested these could be withdrawal symptoms; maybe the mice were addicted to running. Finally, the authors measured the number of new neurons in the hippocampus. (Exercise has been shown to increase neurons in the hippocampus, an important area for memory.) Once again, the mice that kept exercising had the most, while the non-exercisers and exercise-quitters looked the same. The take-home: Reducing exercise can increase anxiety, negating any benefits from previous exercising. So no, you shouldn't give it up even (especially!) if you're feeling stressed. 

Remember, these are rodents. But from my own human experience, I almost always feel better after a run. Maybe it's because I've already checked one item off my day’s to-do list, making the others seem do-able as well. Maybe it's because I’ve got new neurons in my hippocampus and endorphins in my bloodstream. Maybe it’s because I love running, even when it’s hard to fit in my schedule.

The take-home: I'll keep on running and not stressing about it.

Dream big,


  1. This is a great article to read at the start of a beautiful Spring day, perfect for getting off the treadmill and going outside! Your description of a treadmill that starts suddenly reminds me of parenting toddlers. Unexpected exercise is especially great when you get hugs at the end...

  2. Thank you for the research and the personal insight into why runners run... The moral: I need to get on my bicycle more.

    My calculator says your 951 miles/91 days of year = 10.45 miles avg/day! Whew, that's a lot of stress relief!

    Keep at it!