Take It Easy: Too Much Exercise Frazzles the Vagus Nerve

Take It Simple: Too A lot Train Frazzles the Vagus Nerve


Bettering bodily health requires placing stress in your system throughout vigorous exercises. However the quest for peak efficiency usually backfires—the psychophysiological misery attributable to extreme train is not good for you. Discovering a “Goldilocks zone” the place your day by day exercises put sufficient stress in your physique to enhance health with out overdoing it may be tough.

Source: Chris Bergland

Chris Bergland ending a Triple Ironman within the early 2000s.

Supply: Chris Bergland

For instance, after I was making an attempt to get in form for excessive occasions just like the Triple Ironman (7.2-mile swim, 336-mile bike, 78.6-mile run), the danger of damage and burnout was extraordinarily excessive. Monitoring fluctuations in my coronary heart price variability (HRV) was a manner to verify I wasn’t overtraining.

The vagus nerve‘s capability to counteract the sympathetic nervous system‘s fight-or-flight stress response is mirrored by increased HRV.

Along with conserving tabs on how my nervous system responded to the day past’s stress load through the use of HRV, I additionally saved tabs on day-to-day temper adjustments. By way of trial and error, it grew to become clear that if I used to be actually cranky and in a foul temper the morning after an intense coaching session, it meant I used to be on the verge of getting burned out from overtraining and wanted to take it simple for a day or two.

As a retired extreme-distance athlete, I do know from lived expertise that doing an excessive amount of train will be dangerous to your psychological and bodily well-being. Overtraining is each endurance athlete’s Achilles’ heel. It is really easy for one’s ardour for sports activities and competitors to grow to be train fanaticism, which regularly results in accidents or overwhelming psychological misery.

Overtraining, Low HRV, and Detrimental Moods Go Hand in Hand

New analysis (Alfonso and Capdevila, 2022) from the Universitat Autònoma de Barcelona (UAB) in Spain provides us contemporary insights into the hyperlink between HRV, overtraining, and temper states. Their peer-reviewed findings have been revealed on March 30 within the PeerJ journal.

Carla Alfonso and Lluis Capdevila of UAB’s Laboratory of Sport Psychology discovered that if a motorcycle exercise was very intense and put an excessive amount of stress on a bicycle owner’s physique, HRV plummeted the next morning. Alfonso and Capdevila additionally found that HRV ranges correlated with cyclists’ moods. Low HRV was correlated with destructive temper states; increased HRV was related to higher temper states.

“The target of the analysis was to discover the relation amongst three facets: coaching, coronary heart price variability, and temper,” Alfonso stated in a information launch. “With this research, we aimed to know when an athlete should relaxation, as a result of their system is saturated, and when an athlete can practice, with roughly depth, as a result of their physique is able to assimilate the coaching load.”

The principle takeaway from this pilot research is that HRV and temper states appear to rise and fall in tandem. For instance, if a “weekend warrior” overdoes it on Sunday, odds are that they will be cranky or in a nasty temper Monday morning. Detrimental temper states the day after placing an excessive amount of stress in your physique by overtraining correlate with decrease HRV.


This illustration reveals the human mind and “wandering” vagus nerve. Within the Nineteen Twenties, a German-born researcher named Otto Loewi found that electrically stimulating the vagus nerve launched a parasympathetic substance that slows heartbeats and calms the nervous system. Right this moment, we consult with this vagus substance as acetylcholine. Loewi known as it “vagusstoff.”

Supply: Axel_Kock/Shutterstock

Coronary heart Fee Variability Displays the Vagus Nerve’s Response to Stress

The vagus nerve secretes an inhibitory substance immediately onto the center, slowing it down. Coronary heart price variability measures how successfully vagus nerve exercise is creating wholesome fluctuations between heartbeats. Increased HRV signifies that the physique has a sturdy capability to tolerate and get well from stress. Conversely, decrease HRV implies that the vagus nerve is “frazzled” and is not successfully inhibiting the sympathetic nervous system’s fight-or-flight response, which revs up heartbeats and displays a decrease stress tolerance.

Otto Loewi gained a Nobel Prize in 1936 for his discovery that stimulating the vagus nerve releases an inhibitory substance that slows heartbeats and calms the nervous system.

Within the Nineteen Seventies, my neurosurgeon father taught me about Loewi’s vagus nerve analysis within the context of sustaining grace underneath strain. My dad knew that “vagusstoff” was launched through the exhalation part of the respiratory cycle. So, he used respiratory workout routines to remain calm throughout mind surgical procedure and on the tennis courtroom. (See “How ‘Vagusstoff’ (Vagus Nerve Substance) Calms Us Down.”)

After I was a younger tennis participant, Dad coached me to take a fast inhalation by my nostril adopted by a protracted, sluggish exhalation by pursed lips to calm my nerves earlier than each serve. A latest research discovered that one five-minute session of deep, slow-breathing train (4 seconds in, six seconds out) will increase vagal tone and reduces anxiousness. Personally, I desire an inhale–exhale ratio of four-second inhalations adopted by eight-second exhalations.

On the idea of evidence-based analysis and lived expertise, I do know that longer exhalations are a straightforward option to hack your vagus nerve by triggering the discharge of vagusstoff. However, I additionally perceive that the calming impact of those respiratory workout routines tends to be short-lived.

When the sympathetic nervous system is overstimulated by an excessive amount of train, diaphragmatic respiratory is only a bandage that offers you short-term aid. Relaxation is the very best treatment for giving your vagus nerve and parasympathetic system an opportunity to bounce again.

To Sum Up: Extreme Train Reduces Vagus Nerve Tone as Listed by Low HRV

HRV is an indispensable software for conserving tabs on how your vagus nerve responds to exercise-induced stress and guaranteeing that you do not overtrain. Low HRV signifies that the fight-or-flight mechanisms of your sympathetic nervous system are in hyperdrive and that vagal tone is weak. Conversely, increased HRV reveals that vagus nerve exercise is powerful and that your parasympathetic nervous system is dealing with stress effectively.

The newest analysis (2022) on HRV and overtraining reaffirms that low HRV is a warning signal that your vagus nerve could also be “frazzled” from an excessive amount of psychophysiological misery. If you do not have entry to an HRV monitor, experiencing destructive moods the day after exercising vigorously could also be an indication that you must take it simple for the subsequent 24 hours and provides your system time to recuperate.


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