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What's All This Talk About the Vagus Nerve?

A brief look into the vagus nerve and its roles in athletic recovery, performance and wellbeing, followed by a short introduction to wearable non-invasive vagus nerve stimulators. 

Lucy Skipper, 06/10/25


As a fellow running enthusiast, (and guilty neuropsychology nerd) you may have been following along the incredible journey of Allie Ostrander on her youtube channel @allie_ostrander. In a recent video ‘Can I Win a Pro Race?’ (watch here: watch), Allie mentioned some of the interventions she was using to help her recover and prepare for her races. When Allie mentioned a vagus nerve stimulator, I was instantly hooked and thus came this article. 


What is the vagus nerve?


For those of you without a background  in neurobiology, the vagus nerve, also known as cranial nerve 10,  is actually ‘nerves’, with a main branch on either side of the body originating from the brainstem. 


‘Vagus’ is literally Latin for ‘wandering’, so you can think of the vagus nerves as long structures that run and branch out throughout the body. 


Without boring you with all the anatomy, the key point for the devices coming up is to know that the vagus nerves pass through key areas of the body that these devices intend to target. This includes the neck, chest, heart, lungs, abdomen and digestive tract. 


So What Does the Vagus Nerves Do and Why Do We Want to Stimulate Them for Athletic Recovery? 


The vagus nerves are like the background workers of your body keeping you ticking along without much of your conscious effort. The nerves originate from the medulla oblongata, a region of the brain highly responsible for most of our involuntary movements and functions (think your heart rate, breathing, swallowing, coughing etc.). The vagus nerves extend from the medulla oblongata and work as a part of the parasympathetic nervous system to perform functions that fall under the ‘rest and digest’ category. 


Rest and digest huh? That sounds like recovery…


Exactly! 


So now we know that the vagus nerves are involved in the body’s system of rest, let’s apply that to athletic performance. A very recent study by Blanco and Tyler (2025) acknowledges that human performance comes from a tightly regulated balance between our sympathetic ‘fight or flight’ and parasympathetic ‘rest and digest’ systems, a balance which, get this, is mostly regulated by the vagus nerve.


However, this ‘balance’ is more complex than it seems (like with most things in neurobiology), in fact the researchers state that it is the ability of the vagus nerve to be flexible with its sympathetic and parasympathetic switches that best influences our ability to recover well after periods of physical or psychological arousal. This basically means that the vagus nerve is capable of experiencing high periods of sympathetic stress, and responds quickly to reinstate parasympathetic control when such periods come to an end. 


It is important to note that many of these studies assess vagus nerve flexibility through heart rate variability, HRV. HRV is considered to reflect the balance between the sympathetic and parasympathetic nervous systems, making it a useful indicator of how well an athlete's body is recovering after physical exertion, though more research is needed in this area (Addleman et al., 2024).


To try and demonstrate this, let’s look at a study by de Souza et al. (2020), who took a group of professors and investigated the effect of various physiological measures on the recovery and reactivity of their HRV. One such measure was that of physical training during a cardiorespiratory test. The professors were evaluated based on the time, frequency and length of training, as well as their max, recovery and resting heart rates and HRV pre and post the training test. They found that HRV decreased during the test, (likely expected due to increased sympathetic activity during exercise to raise HR), and then gradually increased during the recovery phase, signaling a return of parasympathetic (vagal) activity (to return HR back to resting beat).  

Importantly, participants with higher heart rates during recovery, potentially indicative of slower recovery, showed reduced vagal (parasympathetic) activity after the test. In contrast, those with lower recovery heart rates, suggestive of faster recovery, showed greater parasympathetic (vagal) reactivation. These results suggest that the speed at which heart rate returns to baseline likely plays a role in vagus nerve activity and overall recovery quality. Notably, these effects were observed independently of gender.

Overall, the researchers demonstrated that greater fitness levels, reduced perceived stress, as well as more physiologically favorable anthropometric (body) measures, such as a lower waist circumference, were associated with greater vagal flexibility. Although, it is worth noting that this study only included a small sample of university professors, so please take these findings with a pinch of salt. 


Thus, generally being healthy, lower perceived stress levels and regularly partaking in cardiovascular activity, suggestively contributes to greater vagus flexibility and athletic recovery. 


Nothing much new there. But wait!...athletes generally fit these criteria (though stress levels may be questionable), so why the need for a stimulator and do they even work?


You may recall an inverted-U diagram that might have been shown to you at some point if you ever took a psychology class at school. This funny graph is actually the Yerkes-Dodson Law, based on the work of Yerkes and Dodson (1908). The law has been applied to many contexts, and more complex models developed from it, though at its most basic level the law states that as arousal (sympathetic activity) increases, performance will also increase up to the point that the inverted U then begins to decline again, and from this point increased arousal has a negative effect on performance. Many now agree that the vagus nerve is in part responsible for the tipping point of this curve. An athlete’s resting heart rate essentially reflects their baseline level of arousal (sympathetic activity), hence it is seen that having a lower resting heart rate is like having a greater vagal ‘brake’ to keep the body in a relaxed state during periods of recovery and allow for greater activation of the sympathetic nervous system during periods of intensity in training or competition (Blanco & Tyler, 2025). Therefore, an athlete with a chronically low HRV suggests a heightened baseline, and so even relatively small increases in sympathetic activity needed for performance can tip the athlete over the edge of the inverted U down its descending limb.  


I’d also just like to quickly add that if you wear a garmin or smart watch device, you may see a HRV status each morning and use this as a metric of training readiness. If you have found this useful for yourself, by all means that's amazing! However, current research shows that there is a greater context to HRV often missed by daily readings, and trends or using HRV as a part of a greater context of measures is often more preferable for long term outcomes. Similarly, too high HRV isn’t considered such a positive thing either, Blanco and Tyler (2025) highlight research suggesting that in some endurance athletes elevated HRV (to which they named ‘parasympathetic overreaching’) can result in symptoms such as reduced performance, ongoing fatigue and other signs warranted of poor recovery, opposed to the general assumption that a greater HRV is indicative of greater fitness. 


Back to the inverted-U…


Considering this law, an athlete then looking to improve their recovery, perhaps during a time of unforeseen stress, may seek out ways to invite their parasympathetic nervous system to have a bit more free rein, and in Allie’s case a sponsorship with a company that makes devices especially to target this need, makes the action a little more feasible. 


Vagus nerve stimulation (VNS) has been around for a while, with most methods however being invasive, and thus not suitable for the general population. However, more recently, wearable devices have been developed for people to wear casually in their own homes.  


The question of whether such stimulation could benefit the general healthy population came from reports of VNS therapy used to treat drug-resistant epilepsy and major depression, with seemingly positive side effects of improved attention, mood, cognition and balance  (Blanco & Tyler, 2025). It is only more recently these benefits have been questioned to improve sport performance. 


Blanco and Tyler (2025) essentially point out that whilst transcutaneous VNS is an emerging and promising tool for athletes seeking to support their performance under pressure,  recovery, skill development and stress, more rigorous and sport-specific research is needed to fully understand its effectiveness in elite performance settings. Nevertheless, early evidence points to tVNS as a powerful complementary technique, and if you've got the budget to spare it could be a fun tool to add to your recovery routine. 


Though, I would argue that if you are a casual enthusiast (like myself), such devices propose as more scientific curiosity than a serious purchase investment, as I think we all know by now as runners that the greatest improvements to our performances (that are not grabbing at the last  1-2%) have likely not yet been exhausted, unlike the professionals, and thus just an extra hour sleep or a small change to our nutrition would likely be a wiser (and cheaper) benefit to our performance and active lifestyles. 


Alternatively, if you’re looking for ways to help self-regulate without making a dent in your wallet, why not try investing some time into breathwork, mobility or mindfulness after a run?


Thank you for reading!


You can find more on my website @somastrengthperformance.com and if you're interested in this topic, why not let me know your thoughts or future article suggestions by emailing in at lucy@somastrengthperformance.com 


Don’t forget to check out Allie Ostrander’s YouTube at @allie_ostrander if you too love running and are interested in the lifestyle and adventures of a pro runner!


Sources/References:


Cleveland Clinic. (2022). Vagus nerve: Gastroparesis, vagus nerve stimulation & syncope. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22279-vagus-nerve 


Lopez Blanco, C., & Tyler, W. J. (2025). The vagus nerve: a cornerstone for mental health and performance optimization in recreation and elite sports. Frontiers in Psychology, 16. https://doi.org/10.3389/fpsyg.2025.1639866 


Martins, P., Samadi, N., Mauro, Poliana Elisa Assunção, Luiz, F., Bearzoti, E., & Guerra, G. (2020). Vagal Flexibility during Exercise: Impact of Training, Stress, Anthropometric Measures, and Gender. Rehabilitation Research and Practice, 2020, 1–8. https://doi.org/10.1155/2020/6387839 


Addleman, J. S., Lackey, N. S., DeBlauw, J. A., & Hajduczok, A. G. (2024). Heart Rate Variability Applications in Strength and Conditioning: A Narrative Review. Journal of Functional Morphology and Kinesiology, 9(2), 93. https://doi.org/10.3390/jfmk9020093 



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