Neon Runner

Does Leptin Explain a Runner’s High?

The notion of endorphins kicking in to produce a runner’s high at the end of a good run is an enduring legend taken as an absolute truth by most runners. The catch is that no real evidence exists to prove that’s how it works. But in the last week we’ve had a flurry of animal research suggesting that endocannabinoids and leptin — hormones involved in regulating hunger — may have more to do with a runner’s high than endorphins.

Endorphins are hormones produced by your body that have effects similar to opioids. For decades people have speculated that they were responsible for the euphoria that runners sometimes feel. That speculation has been repeated enough that it has been taken as an article of faith among runners.

But a new animal study in the Proceedings of the National Academy of Sciences finds evidence that cannabinoids may play a more important role. These are hormones that act on the same receptors that marijuana (cannabis) acts on. They regulate a variety of physiological processes, such as appetite, pain, mood, and memory. Their role in regulating appetite is interrelated with leptin, which is known as the hunger hormone.

Another new study, published in Cell Metabolism, found a role for leptin in the runner’s high. Maria Fernanda Fernandes and colleagues found that falling levels of leptin may increase the rewarding effects of running. They propose that this mechanism may serve to motivate the pursuit and acquisition of food, thus enhancing survival.

So, we’ve learned a lot about running rodents. And we’ve learned that “endorphins kicking in” might be an urban legend, even though the euphoria is real. Regardless, what’s important here is a deeper understanding of the relationship between physical activity, hunger, and reward systems that drive us to eat and perhaps run.

The more we know, the more likely it becomes that we can untangle the mess obesity makes of these systems that regulate our metabolic health.

Click here to read more in the Washington Post. Click here to read the study of cannabinoids. Click here to read the study of leptin.

Neon Runner, photograph © Markus Homann / flickr

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October 13, 2015

2 Responses to “Does Leptin Explain a Runner’s High?”

  1. October 14, 2015 at 9:12 am, Allen Browne said:

    Yup! Another piece for the puzzle.

  2. October 14, 2015 at 10:25 am, Ted said:

    It’s one of thos 5,000-piece jigsaws.