the runner's high

As any good neuroscientist (in-training) knows, half of the battle to understanding the functional anatomy of the brain is understanding where things are and what they connect to (see my Paxinos rant, earlier) and the other half is understanding what neurochemicals are being squirted out and how they're being metabolized (i.e. their pharmacokinetics). Oh, and then figuring out how it all fits together to enable functionality. Of course.

Anyway, inspired by a new running path I found this weekend, I started wondering whether many studies had been done on runners' brains. We all hear about the runner's high, which is one of the continuous forces that's kept me self running for the past six years. But how's it work?

Unlike with dancers, I couldn't find any fMRI or structural studies in humans regarding changed neuroanatomy. But, runner's high has mostly definitely been linked to the latter half of the above - release of endocannabinoids, the naturally-occurring substances (reviewed here) that act on receptors more commonly associated with THC, one of the active substances in cannabis (hence leading to studies like this). This started coming into light in a 2003 study that found elevated levels of the endocannabinoid anandamide in college-aged males after running or biking with moderate intensity for 50min. Endorphins also contribute to a runner's minor analgesia during endurance runs, assumed to help runners run longer without processing aches and pains and, as a member of the opioid family, possibly contributing to the runner's high as well.

While one study associated runner's high with an ability to "use a cognitive style in which they cut themselves off from the sensory feedback they would normally receive from their body," I'd argue that any feelings of well-being and/or 'dissociation' stem from a combination of the above chemicals, plus dopamine release. While they may undoubtably induce a particular mental state, I certainly wouldn't argue that it's a conscious one.

This leads me to the gem of an article, discovered this morning. The researchers measured the changes in hormone and biochemical (NE, E, dopamine, cortisol, etc) levels in ultramarathoners running the 1000 km Westfield Ultramarathon that runs between Sydney and Melbourne, in order (get this), "to examine individual hormonal responses to extreme physical stress." Cripes. Excerpts from the abstract:

Before the race: "The baseline hormonal state of these highly trained athletes was quite different from normal" Resting serum conjugated catecholamines--epinephrine (E), norepinephrine (NE), dopamine (D), free E and free D--were significantly elevated above the normal mean (P less than 0.01). ACTH levels were
significantly elevated above the normal range...."

After the race: "The effect of the race on serum catecholamine levels was to elevate further free and conjugated NE...Other catecholamines, free and conjugated, remained significantly elevated above the normal mean...Adrenocorticotrophic hormone (ACTH) remained elevated, and IR-beta EP within the normal range, without significant change. A significant increase in GH...PRL...and cortisol...was
seen...."

Conclusion: "As a model of chronic physical stress, the ultramarathon runner demonstrates a significantly altered baseline hormonal state as reflected in the primary mediators of the stress response, the catecholamines and the hypothalamic-pituitary-adrenal axis. Their response to severe exercise is distinct from that of untrained individuals...[which] may represent hormonal adaptation to prolonged stress."

So, ultramarathoners have altered their basal levels of most major circulating hormones and thus, most likely, brain neurochemistry, and after extremely strenuous exercise will exhibit strong stress responsivity paired with an adaptive compensatory response that helps them return to their normal (elevated) state.

All while experiencing one hell of a runner's high.


See here for my brand allegiance, here for some future events that I hope to gear up for, here for good commute reading