This article was published in translated form in the Dutch edition of Runner's World, January 2017.
Ever noticed it's easier to run intervals with a group, rather than by yourself? To understand why, you need to be introduced to two heroes inside your head, the anterior cingulate and the prefrontal cortex. Be forewarned, though: after reading, you may never want to run alone again.
Not if you want to run faster.
Our first hero, the anterior cingulate cortex (ACC), is known as the source of "willpower." The ACC notices when actions don't match intentions. If you intend to run a demanding pace but begin to slow down, your ACC sounds the alarm and pushes you back to your target pace. The ACC has a limited amount of "willpower" each day. Like muscle, it too needs to recover.
When you're training hard or racing, you're also emotional. Physiologically, this makes sense. You're stressing your body towards its limits. Cortisol and noradrenaline flood your arteries. Your "fight or flight" nervous system is fully activated.
Time to meet our second hero, the prefrontal cortex (PFC). Located behind and above the eyes, the PFC helps us cope with emotions. Without a PFC, we would be prone to crying or screaming during difficult intervals or races, much as children do when they're emotional because their PFCs aren't developed. When you're running fast and feeling a bit desperate, your PFC hopefully whispers, "Everything's okay, you can do it, just relax." This calms you down.
But there's no such thing as a free lunch. Fueling the ACC and the PFC is expensive. Though only 2% of the body's mass, the brain consumes 20% of bloodstream glucose. Much of this glucose flows to the ACC and PFC. And there lies the rub: glucose, like money, can only be spent once. Glucose spent on the ACC or PFC can't be spent elsewhere, like in our muscles.
This makes sense individually. What happens when we add relationships? Solid relationships change the way we perceive challenges, altering the way the ACC and PFC work and making the brain work better.
In one experiment, participants had to carry a heavy backpack up a hill. Before climbing, they had to judge the weight of the backpack and the incline of the hill. Some participants were alone, while others had a friend. The results were astounding: participants with a friend estimated the backpack to be lighter and the hill to be less steep. Moreover, the stronger the friendship, the lighter the backpack felt and the shallower the hill appeared.
Translated to running, these findings suggest that racing with a supportive group will feel less demanding than doing so alone. The better the friendships, the less demanding the pace will seem. Why? Because less ACC willpower is needed. Energy gets saved. Moreover, your limited daily supply of ACC's willpower can be saved for later in the race.
But wait. It gets better.
Another study examined how relationships affect coping in the brain. Laying in an fMRI scanner, participants were told they might receive an electric shock if they saw a red "X." The moment the "X" appeared, activity in their prefrontal cortex (PFC) spiked because participants were coping with anxiety. However, if they held hands with their partner, and if the relationship with that partner was solid, then activity in the PFC subsided. In other words, in the presence of a supportive other, the brain behaves as if stress disappears.
Extrapolated again to running tough intervals or races, this likely means that our brains feel less stress when supportive others are nearby. Compare running a race in a foreign city by yourself with running the CPC with your friends, and you'll feel the difference. Social support means less coping from the PFC. Energy gets saved.
Why does social support calm our brains?
Evolutionarily speaking, being alone decreased our chances of survival. Parrot or primate, sticking together boosted the odds that a feathered or furry friend would notice danger if you didn't—and warn you. Our modern comforts may make this talk of survival seem rather abstract, but don't be mistaken. Our nervous systems remember these evolutionary rules.
Consider this: study after study confirms that those who enjoy good relationships outlive those who don't. Why? Because energy that doesn't have to be spent surviving can be spent living.
Just look at any large group of runners together, as opposed to individuals training alone. We're talking, smiling, laughing. We're not watching out for cars and bikes like we would on our own. We're like herds of Dutch teenagers biking to school! From within the safety of our group, our bodies trust that some other friend will notice danger if we don't. From within the safety of our group, we can turn down our ACCs and PFCs. We can relax and run.