Your mid-run boost isn't about speed or distance; it's influenced instead by the presence of leptin, your body's hunger hormone
Anyone who's pushed through their first 5K is familiar with that euphoric mid-run boost: the runner's high. But you might have your prehistoric biology—not your training plan—to thank. According to a new study published in Cell Metabolism, the runner's high has less to do with your speed or your training and more to do with your body's level of satiety. Say what?
Researchers at the University of Montreal found that the occurrence of the runner's high is influenced by the presence of leptin, your body's hunger hormone. Mice who had lower leptin levels (meaning they felt hungry and less satisfied) ran twice as long as their sated counterparts.
Why? The low levels of leptin send a signal to your brain's pleasure center to increase the incentive for exercise (AKA hunting for food, as far as our primal biology is concerned). Researchers hypothesize that the less satisfied mice experienced greater satisfaction and a feeling of reward from exercise. And the more we associate pleasure with an activity, the more we start to crave it. Hello, marathon training. (Milk that "runner's high" for all it's worth: 7 Ways to Make Your Post-Workout High Last Longer.)
The best part about this effect? The more you exercise, the more you feel the low leptin effects. When you have less body fat, like a high performance runner does, your body has an overall lower amount of leptin. Previous studies have linked leptin to faster marathon times and increased athletic performance, but this new research points to that sweet runner's high as the reason why.
There can be a downside to these effects, though. The reward-leptin link has been evidenced in previous studies on exercise addiction, and the researchers from this study speculate that it could be the cause for the exercise addiction often associated with anorexia. If you're hungry, your body needs actual fuel, not just the high associated with working for it. (It’s a common disorder too. Learn How One Woman Overcame Her Exercise Addiction.)
Channel your inner huntress with a primal trail run to get your high on, then be sure to reward those hunger hormones with a post-run refuel.