The Impact of the Autonomic Nervous System (ANS) on recovery from injury and disease

by Adam Brown  BScPT, MClScPT
updated April 8, 2024

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The autonomic nervous system (ANS) is an often overlooked, but crucially important system when considering how to promote recovery from injury or disease. In a healthy individual with a balanced ANS the system simply runs in the background maintaining homeostasis in all of our bodies systems. The ANS has direct control over heart rate, blood pressure, digestion, thermoregulation, inflammatory pathways, hormonal balance and metabolic control. It is responsible for every system in the body that we do not consciously manage.

It goes without saying that this is a critical system that must be working well for the body to function optimally.

 

The Autonomic Nervous System: A Brief Overview

The ANS has two main components, the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).

1. Sympathetic Nervous System (SNS):

The SNS is often referred to as the “fight or flight” system. It prepares the body for stressful situations by increasing heart rate, dilating airways, and redirecting blood flow to essential organs and muscles. This response is crucial in emergencies, enabling rapid, coordinated action.

Key Aspects of the Sympathetic Nervous System:

• Stress Response: Activated during stress, fear, or danger.
• Neurotransmitter: Releases norepinephrine (noradrenaline).
• Effects: Increases heart rate, dilates pupils, inhibits digestion, promotes glucose release from the liver, and redirects blood flow to muscles.

2. Parasympathetic Nervous System (PNS):

The PNS is often called the “rest and digest” system. It promotes relaxation and helps the body conserve energy. When active, it slows the heart rate, stimulates digestion, and facilitates bodily functions that occur during restful periods.

Key Aspects of the Parasympathetic Nervous System:

• Restful State: Dominant during periods of relaxation and rest.
• Neurotransmitter: Releases acetylcholine.
• Effects: Slows heart rate, constricts pupils, stimulates digestion, and promotes nutrient absorption.

 

Autonomic Dysregulation

Dysregulation of the autonomic nervous system (ANS) can occur due to various factors, including chronic stress, trauma, certain medical conditions, and genetic predisposition. When dysregulated, the ANS can lead to a range of health issues, such as anxiety disorders, cardiovascular problems, and gastrointestinal disorders.

ANS dysregulation related to a medical condition is a complex topic with wide ranging implications. It is sometimes unclear whether ANS dysregulation is a consequence or a contributing factor to various diseases. For the purposes of this article we will focus on the impact of chronic stress.

Stress management is a critical part of good mental health. Unfortunately our modern lives tend to produce chronic stress that, if not managed well, can impact our health negatively. One study from the American Psychological Association reported that up to 78% of the US population reports feeling chronically stressed.

 

ANS and Injury Recovery

The autonomic nervous system (ANS) plays a pivotal role in the body’s recovery from injury by regulating vital physiological processes. During the healing process, the balanced activity of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS) is crucial. The SNS, activated in response to stress, mobilizes resources by increasing heart rate and redirecting blood flow, aiding in immediate responses to injury.

On the other hand, the PNS promotes relaxation and conserves energy, allowing the body to allocate resources for tissue repair and recovery. By modulating inflammation, pain perception, and immune responses, the ANS influences the overall healing trajectory. Chronic stress, which dysregulates the ANS, can impede recovery by disrupting these processes. Techniques that promote relaxation and stress reduction, such as meditation, deep breathing, HRV biofeedback and vagus nerve stimulation can positively impact the ANS and support the body’s healing mechanisms.

In a nutshell, a chronically stressed individual will heal more slowly than someone who manages their stress well.

 

How Can You Support a Balanced ANS

There are several well established methods of promoting a balanced autonomic nervous system. Here are a few ways that you can begin to improve your ANS function and in turn promote recovery from injury or disease.

Mindfulness Meditation: Mindfulness practices, such as meditation and mindful breathing, have been found to activate the parasympathetic nervous system, promoting relaxation and reducing stress. Studies have shown that regular mindfulness meditation can improve ANS balance and reduce symptoms of anxiety and depression. (3)

Yoga: Yoga combines physical postures, breathing exercises, and meditation. It has been shown to enhance parasympathetic activity and improve ANS balance. Regular yoga practice has been associated with reduced stress and improved cardiovascular health. (4)

Heart Rate Variability (HRV) Biofeedback: HRV biofeedback is a technique that helps individuals regulate their ANS by providing real-time feedback on heart rate variability patterns. Training with HRV biofeedback has been shown to improve ANS balance, reduce stress, and enhance emotional well-being (5).

Aerobic Exercise: Regular aerobic exercise, such as walking, jogging, or swimming, has been linked to improved ANS balance. Exercise stimulates the release of endorphins and enhances parasympathetic activity, promoting relaxation and reducing stress. (6)

Deep Breathing Exercises: Deep breathing techniques, such as diaphragmatic breathing and coherent breathing, can activate the parasympathetic nervous system, leading to relaxation. These exercises are simple, can be practiced anywhere, and are effective in reducing stress and improving ANS balance. (7)

 

At Cornerstone Physiotherapy, we have been studying and practicing ANS regulation for several years as a part of our Long COVID treatment program. We have come to realize that a wide variety of our patients can benefit from these techniques. We have found that patients find HRV biofeedback is a powerful tool to help regulate the ANS and it provides the advantage of having real-time feedback on your sessions. If you are interested in discussing ANS regulation with one of our Long COVID trained physiotherapists to promote healing or recovery from a complex condition, please reach out to us, We would be happy to help.

 

 

References:

1)  Guyton AC, Hall JE. Textbook of Medical Physiology. 13th edition. Philadelphia, PA: Elsevier; 2015.
2)  Kandel ER, Schwartz JH, Jessell TM, Siegelbaum SA, Hudspeth AJ. Principles of Neural Science. 5th edition. New York, NY: McGraw-Hill; 2012.
3)  Tang, Y. Y., et al. (2009). Central and autonomic nervous system interaction is altered by short-term meditation. Proceedings of the National Academy of Sciences, 106(22), 8865-8870.
4)  Bernardi, L., et al. (2001). Effect of breathing rate on oxygen saturation and exercise performance in chronic heart failure. The Lancet, 357(9257), 1748-1749.
5)  Lehrer, P. M., & Gevirtz, R. (2014). Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology, 5, 756.
6)  Sothmann, M. S. (1995). The Cross-Stressor Adaptation Hypothesis and Exercise Training. In Stress, Exercise, and Dietary Adaptations (pp. 209-237). CRC Press.
7)  Zaccaro, A., Piarulli, A., Laurino, M., Garbella, E., Menicucci, D., Neri, B., … & Gemignani, A. (2018). How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Frontiers in Human Neuroscience, 12, 353.