Researchers found that tolerance of physical activity was improved by electrical stimulation of the vagus nerve, which runs from the brain to the chest.
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Gerry Gajadharsingh writes:
“I have blogged previously on the importance of the vagus nerve and its impact on the autonomic nervous system and our general health.
Many of the techniques that Osteopaths use as part of their repertoire of Osteopathic Manual Treatment (OMT) aim to influence the autonomic nervous system. In the majority of patients, this is usually to calm down sympathetic (stress) over activity and support/stimulate parasympathetic (relaxation) activity.
Specific techniques for stimulation of the vagus nerve have been used for a long time and is often a first-choice option for certain people whose heart rate is too fast. So called vagal manoeuvres are physical actions that make your vagus nerve act on your heart’s natural pacemaker, slow slowing down its electrical impulses.
There are various vagal manoeuvres including
Valsalva manoeuvre, bearing down like you’re having a bowel movement, take a deep breath and act like you are exhaling but with your nose and mouth closed for 10 to 30 seconds.
Diving reflex, while sitting you take several deep breaths, hold your breath and then quickly put your whole face into a container of water keeping your face submerged as long as you can.
Carotid sinus massage, usually done by a clinician who will use their thumb/fingers to push on the carotid sinus for 5 to 10 seconds when you’re lying on your back with your head turned to one side.
Gag reflex, a clinician may use a soft cotton bud to tickle the back of your throat and provoke a gag reflex, a variation of the Valsalva manoeuvre
Coughing, a variation of the Valsalva manoeuvre
Head stand for 30 seconds.
These manoeuvres are not appropriate on patients who have had a stroke or transit ischaemic attacks (TIA’s) have a carotid bruit a whooshing sound in the carotid artery have, had recent ventricular fibrillation or ventricular tachycardia, a recent heart attack or carotid artery disease.
The research below focuses on a Vagal stimulation device attached to the ear, and its impact on exercise. After using the vagus nerve stimulator device for seven days, participants’ oxygen uptake during exercise increased by 4 per cent. The researchers also analysed blood samples and found that those who used the device had lower levels of inflammation in their body. This suggests that much like exercise, the use of the device can help reduce inflammation — the overreaction of the immune system to things like stress, pollution and poor diet which can cause damage in the body over time.
As with many articles, it doesn’t detail the actual mechanism as to how vagal stimulation does this, for example, they suggest an increase in heart rate and breathing rate which does not fit in with the usual responses of vagal stimulation which generally decreases heart rate and breathing rate.
My thoughts are as follows.
Site and Nature of Stimulation
Auricular or transcutaneous vagus nerve stimulation (taVNS) often targets afferent fibres rather than efferent cardioinhibitory fibres.
These afferents project to the nucleus tractus solitarius (NTS) and higher brain centres, modulating autonomic balance and respiratory control networks.
The net effect may be enhanced central respiratory drive and improved autonomic coordination, even if direct bradycardia (low heart rate) is not observed.
Shift in Autonomic Balance
Exercise tolerance is limited partly by sympathetic dominance and stress-related cardiovascular strain.
Vagal stimulation can attenuate sympathetic overactivation, improving stroke volume, vascular compliance, and muscle perfusion.
The body can then tolerate a slightly higher heart rate (or maintain it longer) because overall cardiac efficiency is improved.
Respiratory-Circulatory Coupling
Vagal afferent input influences respiratory rhythm generators in the brainstem.
Some studies show improved ventilatory efficiency (lower dead-space ventilation, better alveolar ventilation/perfusion matching).
Even with an increase in breathing rate, the tidal volume and gas exchange efficiency may improve, resulting in better oxygen delivery.
Oxygen Utilization & Muscle Metabolism
Vagal stimulation may also shift muscle metabolism toward greater oxidative capacity, possibly via reduced lactate accumulation and improved mitochondrial function.
A small 4% increase in VO₂max or oxygen capacity is significant and may not be due to heart rate suppression but enhanced peripheral utilization.
Context Matters
At rest: Vagal stimulation → lower HR & BR.
During exercise: Vagal stimulation → enhanced regulation rather than suppression, leading to better autonomic flexibility and cardiorespiratory coupling.
Bottom line
The paradox dissolves when we consider afferent vs. efferent vagal effects and context-specific autonomic responses. The device isn’t simply increasing “vagal tone” in the classical sense but modulating autonomic integration, which during exercise can improve oxygen delivery and utilization, even if HR and BR are slightly elevated.
Outside of receiving Osteopathic Manual Technique (OMT) or indeed using some sort of vagal stimulation device why not adopt an improved breathing pattern consistently to achieve better autonomic nervous system balance?”
The Times
Kaya Burgess
Does exercise always feel like hard work, leaving you out of breath with your heart racing? Applying an electric current to your ear for 30 minutes a day could make it feel much easier, scientists have said researchers at Queen Mary University and University College London have found that electrically stimulating the vagus nerve, which runs from the brain down through the neck and into the chest and abdomen, could make people’s bodies much more efficient during exercise.
They tested a device that clips to the outer ear to deliver gentle electrical stimulation to the nerve, which has been found to play a role in regulating the function of the heart and other systems in the body.
The study, published in the European Heart Journal, found that the device could “offer an inexpensive, safe and scalable approach to improve exercise capacity”. It could be used to “improve exercise tolerance and promote cardiovascular health”.
For the research, 28 people were asked to wear the stimulator for half an hour a day for a week, while the other half wore a dummy device. They then switched for another week, taking part in regular exercise testing.
“After using the vagus nerve stimulator device for seven days, participants’ oxygen uptake during exercise increased by 4 per cent,” researchers found.
“This was accompanied by improvements in key functional exercise measures, such as their maximum breathing rate, which increased by an average of four breaths per minute, and maximum heart rate, which increased by four beats per minute during exercise. “As a result, those wearing the stimulator devices were able to exercise more intensely compared to when using the dummy device.”
They also analysed blood samples and found that those who used the device had lower levels of inflammation in their body.
“This suggests that much like exercise, the use of the device can help reduce inflammation — the overreaction of the immune system to things like stress, pollution and poor diet which can cause damage in the body over time,” the research found.
Professor Bryan Williams, the chief scientific and medical officer at the British Heart Foundation, which funded the study, said: “This early study suggests that a simple technology, which harnesses the connection between the heart and the brain, can lead to improvements in fitness and exercise tolerance. While more research is needed involving people with cardiovascular disease, this could one day be used as a tool to improve wellbeing and quality of life for people with heart failure.”
Professor Gareth Ackland, at Queen Mary, who led the study, said: “Maintaining physical activity is essential for every aspect of cardiovascular, emotional and cognitive health. The outcome of the trial is consistent with the significant body of evidence pointing to an important role of the brain in optimising exercise performance and regulating the activity of the immune system, helped by the vagus nerve.
“We will need to carry out larger trials to confirm our findings, but the results of this study in healthy volunteers suggest that increasing vagus nerve activity can improve fitness and reduce inflammation, potentially offering new approaches to improve heart health.”