Lately, I’ve been doing a lot of thinking about what’s really going on inside my head when I go for a run. When you consider running in terms of the technology you utilize during a run–your MP3 player, heart rate monitor, GPS, etc.–your brain is likely the most advanced piece of equipment you take along with you. From controlling every movement you make, to determining your level of fatigue (and how to deal with it), to pumping out endorphins and other chemicals to stimulate your mind and body, running is converted from a seemingly simple task to a surprisingly complex one!

Steve and I are a little over halfway through our training for our first half-marathon, and the longer the distances get, the more I am learning about myself as a runner. Part of this learning process, as many long-distance runners will probably tell you, is discovering that running is just as much a mental exercise as a physical one. At this point, I can’t even tell you how many times I’ve had to fight through (or have succumbed to) the urge to slow down and walk for a minute or two because I might die if I don’t, even though factors like my heart rate and breathing pattern would indicate otherwise. I am finding, though, that training my brain to overcome the urge to stop, quit, walk, etc., is just as important as training my cardiovascular system and muscles to run 13.1 miles. Often, when I do make the decision to keep running, I’ll start to feel better and less tired within a few seconds.

Clearly, there’s a lot of crazy stuff going on up there! In his book, Eat and Run, Scott Jurek discusses the incredible number of calculations your brain is constantly engaged in during a run to determine if you can sustain your current pace without exceeding your physiological limits. If it decides you are pushing yourself too hard, you will start to feel a burning sensation in your muscles, your limbs will feel heavier, and you will have a strong desire to slow down. This is actually what’s known as muscle fatigue, and it was only recently that scientists began to recognize that it originated in the brain, and not from processes in the muscles themselves, such as lactic acid build-up and oxygen/glycogen depletion.

Researchers from the University of Zurich released a series of studies in 2011 in which they were able to observe the brain’s response to endurance activity. Amazingly, they found that the brain will actually start to shut down and/or regulate muscle activity, reducing the muscles’ capacity to perform and increasing the perceived level of exertion. This was, in part, determined by comparing muscle response and fatigue onset in the presence and absence of a spinal neural inhibitor. When the inhibitor was present, fatigue onset response was significantly weaker, thus indicating a strong link between the brain and muscle fatigue.

Luckily, there are some great ways to train your brain to delay or reduce those feelings of fatigue. These include exercises you can do during a run, such as counting your steps, listening to music as a distraction, or, as Ashley suggested in her hill-running post, choosing a specific object to focus on. There are also mental exercises you can do outside of a run, like taking the time to close your eyes and visualize your perfect race. For more tips on overcoming brain-triggered muscle fatigue, check out these great articles at RacingWeight.com, Runner’s World (here and here), and Competitor.

Of course, to further complicate matters, I recognize that keeping tabs on my fatigue level is not the only thing my brain does during a run. For many people, myself included, running can be a very therapeutic experience. Some people use running to clear their heads and forget about their problems for a little while. Others use their run as a chance to think through an issue and sort out their emotions. I’ve personally found that going for a run when I’m angry helps me process what I’m upset about. By the time I get back, I’m usually feeling better and ready to move on. Because running gives me a great place to focus my angry energy, I’ve also run some of my fastest times when I’m mad. On the opposite end of the emotional spectrum, there’s the elusive runner’s high, that magical feeling of euphoria experienced (and yearned for) by many a runner.

People who have been lucky enough to experience runner’s high describe it as a zen-like state, a running nirvana where pain, effort, and even time seems to slip away. Runner’s high was originally attributed to the release of endorphins into the bloodstream. Turns out, however, that endorphin molecules are too large to penetrate the blood-brain barrier, meaning that they could not get into the brain to create a feeling of being high. The actual culprit responsible for the runner’s high may be endocannabinoid molecules, specifically anandamide molecules, which are made up of lipids and are generated in the endocannabinoid system. These molecules are small enough to access receptors in the brain, and appear to have a similar effect on the nervous system as THC, the active ingredient in marijuana, making them a much better candidate for the cause of runner’s high than endorphins. For additional info, be sure to check out Amby Burfoot’s article linked below, and this more recent article from the New York Times.

As far as I know, I have yet to experience what others describe as a runner’s high, but I’m sure it will happen for me eventually. In an article in Runner’s World, Amby Burfoot reported that over his 108,000 miles of running at the time of printing, he had only experienced true runner’s high once, and only for about a 15 minute period. This is equivalent to 0.00185% of his total mileage, or one out of every 21,600 workouts! I haven’t even topped 1000 total miles of running, yet, and I’m still working my way up to what most runners would call “long” distances per run, so I think I might have a ways to go before I reach the apparent nirvana that is the runner’s high.

What it all comes down to is that you should definitely give your brain a big mental hug the next time you’re out for a run. Even when you feel like you are mentally “zoned out” on a run, your brain is working incredibly hard to create and sustain that feeling, which is pretty downright amazing. And, the next time you feel the overwhelming urge to walk or stop running, try using the tricks in the articles noted above and remember that you may only be a few more endocannabinoid molecules away from the mystical runner’s high, so keep going!

Images from ProCon.org, FreeDigitalPhotos.net, and TheKathleenShow.com.

Meagan is a geochemistry research lab manager, runner, Netflix binge-watcher, and Mom to a rescue dog, a bunny, and a human child. She started running in May 2011 and ran her first half marathon in October 2012, followed by her first marathon in October 2013. In July 2018, she joined the triathlon world and completed an Olympic-distance race. After an extended break (pregnancy/maternity leave), she is making a long-overdue return to running and is preparing for a high-elevation half marathon at Crater Lake National Park in August 2020.