Take it easy: Too much exercise can weaken the vagus nerve

Improving fitness requires putting pressure on your system during intense workouts.but pursue peak performance Often it backfires – the psychophysical distress caused by excessive exercise is not good for you. Finding a “Goldilocks zone” where your exercise routine puts enough stress on your body to improve your health without overdoing it can be tricky.

    Chris Bergland

Chris Bergland completed the Triple Ironman in the early 2000s.

Source: Chris Bergland

For example, when I try to get in shape for extreme events like a triple (7.2-mile swim, 336-mile bike, 78.6-mile run), the risk of injury and burnout is very high. Monitoring heart rate variability (HRV) fluctuations is one way to make sure I’m not overtraining.

this vagus nerveAbility to resist empathy nervous systemA higher HRV reflects his fight-or-flight stress response.

In addition to using HRV to keep tabs on how my nervous system responds to the stressful load of the previous day, I also keep tabs on daily mood changes.Through trial and error, it became clear that if I was really grumpy and in a bad mood the morning after an intense workout, it meant I was about to get exhausted Overtraining and need to relax for a day or two.

As a retired ultra-distance runner, I know from life experience that doing too much exercise can damage your mental and physical health. Overtraining is the Achilles heel of every endurance athlete. A person’s passion for sports and competition can easily turn into a sports frenzy, which often leads to injury or overwhelming psychological distress.

Overtraining, low HRV and negativity go hand in hand

New research (Alfonso and Capdevila, 2022) from the Autonomous University of Barcelona (UAB) in Spain, for a new understanding of the link between HRV, overtraining and emotional states.Their peer review results were published on March 30 in Peer J Magazine.

Carla Alfonso and Lluis Capdevila of UAB’s Exercise Psychology Laboratory found that if a cycling workout was very intense and put too much stress on a cyclist’s body, HRV dropped dramatically the next morning. Alfonso and Capdevila also found that HRV levels correlated with cyclists’ mood. Low HRV correlates with negative emotional state; higher HRV correlates with better emotional state.

“The purpose of this study was to explore the relationship between three dimensions: training, heart rate variability and mood,” Alfonso said in an article Press Releases“With this study, we aimed to understand when athletes must rest because their systems are saturated, and when athletes can train at more or less intensity because their bodies are ready to absorb the training load. “

The main takeaway from this pilot study is that HRV and emotional state appear to rise and fall simultaneously. For example, if a “weekend warrior” overuses on Sunday, they are likely to be grumpy or in a bad mood on Monday morning. Negative emotional states were associated with lower HRV the day after stressing the body too much through overtraining.


This image shows the human brain and the “wandering” vagus nerve. In the 1920s, a German-born researcher named Otto Loewi discovered that electrical stimulation of the vagus nerve releases a parasympathetic substance that slows the heartbeat and calms the nervous system. Today, we refer to this vagal substance as acetylcholine. Loewi calls it “vagusstoff.”

Source: Axel_Kock/Shutterstock

Heart rate variability reflects vagal response to stress

The vagus nerve secretes an inhibitory substance directly to the heart, causing it to slow down. Heart rate variability measures the effectiveness of vagal nerve activity in generating healthy fluctuations between heartbeats. A high HRV indicates that the body has a strong ability to withstand and recover from stress. Conversely, a lower HRV means the vagus nerve is “tired” and unable to effectively suppress the sympathetic nervous system’s fight-or-flight response, which increases the heart rate and reflects lower stress tolerance.

Otto Lowe He won the Nobel Prize in 1936 for the discovery that stimulating the vagus nerve releases an inhibitory substance that slows the heartbeat and calms the nervous system.

In the 1970s, my neurosurgeon father taught me Loewi’s vagus nerve research to maintain grace under pressure. My dad knows that “vagusstoff” is released during the expiratory phase of the breathing cycle. So he uses breathing exercises on the brain surgery and tennis court to stay calm. (Look”How ‘Vagusstoff’ (vagus substance) calms us down.”)

When I was a young tennis player, my dad taught me to inhale quickly through my nose before each serve, and then exhale slowly and long through pursed lips to calm my nerves.recent study A five-minute deep breathing exercise (four seconds in, six seconds out) was found to increase vagal tone and decrease it anxiety. Personally, I prefer an inhale-exhale ratio of four seconds to inhale and eight seconds to exhale.

Based on evidence-based research and life experience, I know longer exhalation is a simple way to destroy the vagus nerve by triggering the release of vagusstoff. However, I also understand that the calming effects of these breathing exercises are often short-lived.

When the sympathetic nervous system is overstimulated by excessive exercise, diaphragmatic breathing Just a bandage to give you temporary relief. Rest is the best way to give the vagus and parasympathetic nervous systems a chance to recover.

Summary: Excessive exercise reduces vagal tone, as measured by low HRV

HRV is an indispensable tool for keeping an eye on the vagus nerve’s response to exercise-induced stress and making sure you don’t overtrain. A low HRV indicates that your sympathetic nervous system’s fight-or-flight mechanism is in overdrive and your vagal tone is weak. Conversely, a higher HRV indicates strong vagal activity and that your parasympathetic nervous system handles stress well.

The latest research on HRV and overtraining (2022) reiterates that a low HRV is a warning sign that your vagus nerve may be “wearing out” from too much psychophysiological distress. If you don’t have access to an HRV monitor, having a negative mood the day after a strenuous workout may indicate that you should take the next 24 hours to relax and give your system time to recover.

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