You may recognize this common experience: You get nervous or scared, your heart races, and your stomach drops.
You can thank the vagus nerve for that.
But this isn’t all the vagus nerve, an important part of your nervous system, does. In fact, it’s one of the primary drivers behind the mind-body connection. Ahead, everything you need to know about the vagus nerve, from how it impacts your fitness to how to stimulate it for better health.
The vagus nerve is the 10th cranial nerve, connecting your brain stem to the rest of your body. “It travels from the brain toward the feet, and its nerve branches give innervation to many different structures along the way: your sense of taste, vocal cords, heart, lungs, blood vessels, and abdominal organs,” explains Dr. Taylor Graber, an anesthesiologist and founder of ASAP IVs.
Your digestive system is stimulated by the vagus nerve, which is why many people experience stomach upset in times of emotional distress.
The nervous system is divided into two main systems: the central nervous system and the autonomic nervous system. The vagus nerve is part of the autonomic nervous system, which is also made up of two components: the sympathetic nervous system and the parasympathetic nervous system.
“These two systems are always active, and strike an important balance so the body can react to different stimuli in the world,” Graber says. The vagus nerve is a major component of the parasympathetic nervous system.
Fun fact: Vagus means “wandering” in Latin. “The nerve was named accordingly because it courses such a long way,” Graber says. “In fact, it’s the longest nerve of the parasympathetic nervous system.”
The sympathetic and parasympathetic systems have very different functions.
The sympathetic nervous system is often called our fight-or-flight response. “It’s activated when dealing with an emergent stress, such as running from a lion,” Graber says. You might also feel it activate when you get scared, surprised or upset. “This leads to a release of catecholamines (dopamine, epinephrine [adrenalin], norepinephrine) in your body as well as cortisol, causing changes in multiple organs.” Your pupils constrict your eyes can see danger in the distance, your airways open increasing airflow and oxygen to the tissues, your heart rate rises to supply blood to the muscles. “All of these work together so that you can escape the danger,” Graber adds.
Conversely, the parasympathetic nervous system is referred to as our rest-and-digest state.
“When the parasympathetic system is activated, the vagus nerve tells the heart to slow down and conserve energy,” Graber explains. “Blood flow is shifted to the abdominal organs to help digest food after a meal. Cortisol levels decrease. Pupils become dilated, becoming easier to see what is close to you, rather than faraway dangers.”
You might think we don’t spend much time in a fight-or-flight state these days since we’re not exactly running away from lions regularly. Unfortunately, we actually spend a lot of time in a sympathetic state.
“In today’s speed-oriented world, we are constantly connected and switched on,” says Danny Lee James, a strength and conditioning coach. “We’re sleeping less, exercising less and under more strain and stress than any time before.” While some stress is good for us, too much shifts us into an overly sympathetic state.
It turns out, being in a fight-or-flight state frequently isn’t so great for our health. “Among many other medical problems, an imbalance of the autonomic nervous system can lead to fatigue, changes in heart rate variability and overall poor exercise performance,” Graber says.
What’s more, the autonomic nervous system is a primary regulator of inflammation throughout the body, James says. Some inflammation is normal, as in response to a workout or an injury. But chronic inflammation, caused by increased cortisol and other hormones, can be harmful to your health.
“The sympathetic response is pro-inflammatory, and the parasympathetic branch is anti-inflammatory,” James says. So how can you spend more time in the “rest and digest system?
One way to spend more time in the parasympathetic state is to stimulate the vagus nerve for a stronger response, also known as vagal tone. Better vagal tone means it’s easier to get into a rest-and-digest state. The most common way to measure vagal tone is via heart rate variability (HRV), which is increasingly becoming a metric used by newer fitness trackers.
HRV measures your heart’s ability to adjust the amount of time between beats. High HRV is associated with high vagal tone, whereas low HRV is associated with low vagal tone. That said, don’t worry if you don’t have access to your HRV. It’s safe to say most people can benefit from better vagal tone.
While you can’t exercise your vagus nerve the way you would a muscle, you can improve your vagal tone in a variety of ways.
Since intense exercise naturally puts us in a fight-or-flight mode, it’s especially important for fitness enthusiasts to focus on getting into the rest-and-digest state.
“We seem to have hit a trend where there is a disproportionate emphasis on exercise intensity, and that’s not necessarily a great thing,’ James says. “We need to ride that sympathetic wave during exercise only briefly, then shift back into a parasympathetic lull to maximize the adaption, performance and ultimately health across a range of systems.”
Here are some strategies to do exactly that:
- Deep breathing: “Because of its connection to the diaphragm, deep, slow breathing stimulates the vagus nerve,” explains Reece Mander, a personal trainer. “Methods such as inhaling for 5 seconds, holding for 5 seconds then exhaling for another 5 will work wonders for vagal tone. Be careful to breathe into your belly instead of into your upper traps to get real vagal stimulation.”
- Social connection: “Research has shown that having strong social connections and support, positive emotions and outlook and physical health are all connected and exert a synergistic influence on improving vagal tone,” James says. “And it’s not surprising: Who doesn’t love spending free time with people who care about you and with whom you feel completely at ease?”
- Low-intensity cardio: “One of the most robust interventions that we have for improving vagal tone and mitigating chronic inflammation is aerobic exercise,” James says. “Scientists are still not clear on how this works, but aerobically fit individuals seem to have developed an armor against chronic inflammation.” Instead of all that HIIT, try some low-intensity cardio.
- Proper workout cooldowns: If you’re going to do intense exercise, make sure you cool down afterward. “One of the best things you can do immediately upon finishing is to lay down somewhere in the corner and focus on slowing down your breathing and heart rate,” James says. Again, you want to focus on belly breathing here. “The sooner you can get into a parasympathetic state that facilitates recovery, the better.”