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Melissa Seifried   MScPT
Registered Physiotherapist
Director of Long COVID Rehabilitation
updated Apr 3, 2024

You may be wondering why your Physiotherapist has recommended you “train” your Heart Rate Variability. Perhaps you’ve been told yours is low and that it correlates with the symptoms you are experiencing in Long COVID. What does this mean exactly? And what can we do about it? Read on to learn more!


What is Heart Rate Variability?

Contrary to the once-held belief that the heart beats steadily like a metronome, we now know that a heart’s rhythm is surprisingly nonuniform. This is known as Heart Rate Variability (HRV). HRV refers to the variation in time between consecutive heartbeats. HRV differs from heart rate, which is a measure of the number of heartbeats per minute (bpm). HRV reflects the fluctuation in timing between heartbeats and is measured in milliseconds (ms).

This variability is regulated by something called the Autonomic Nervous System (ANS). The ANS is the part of the nervous system that regulates most of the body’s internal functions – things like heart rate, breathing rate, blood pressure and digestion (to name a few). The sympathetic branch of the ANS serves to accelerate heart rate, while the parasympathetic branch slows it down.

hrv heart rate variability graph(Source:

This diagram above shows three heartbeats recorded on an electrocardiogram (ECG). See the variation in the time interval between consecutive heartbeats, giving a different heart rate (in bpm) for each interbeat interval.

HRV is commonly utilized to assess the status of the ANS and our body’s ability to manage stress. An imbalanced or dysregulated ANS can lead to various health challenges. A low HRV, indicating minimal variability between heartbeats, is associated with heightened stress and a diminished capacity to adapt to environmental changes. Conversely, a high HRV, characterized by increased variability between heartbeats, is linked to a greater ability to cope with and recover from stress. Enhancing HRV has proven particularly advantageous for conditions impacting the ANS like Long COVID.


What is “Normal” HRV?

Numerous factors influence HRV including age, gender, physical fitness level, quality of sleep, stress levels, and overall health. Generally, younger individuals typically exhibit higher HRV compared to their older counterparts, and men generally have higher HRV than women.(1)  Engaging in physical activity has been shown to elevate HRV, while insufficient sleep quality and heightened stress levels may contribute to decreased HRV. Specific health conditions, including heart disease, diabetes, and more recently, Long COVID, can also have an impact on HRV.(2)

It’s crucial to recognize that HRV is a dynamic metric, subject to change over time and susceptible to various influences. By taking measures to enhance overall health and effectively manage stress, individuals have the opportunity to improve their HRV trends.

The “normal” range for HRV is not universally defined, given its significant variability among individuals and susceptibility to the influences mentioned above. In broad terms, a higher HRV is generally regarded as favorable, indicating the body’s enhanced capacity to handle stress and uphold homeostasis. For a personalized understanding of what is normal for you, it is advisable to seek guidance from your Physiotherapist and use a reliable method for continuous monitoring and assessment of your HRV trends over time.


How Does Long COVID Affect HRV?

While research is inching closer to a universally understood mechanism of the pathophysiology of Long COVID, we do know that the virus will impact the autonomic nervous system in those individuals who experience symptoms beyond 12 weeks.(2)(3)(4)

Studies have revealed that many Long COVID patients develop dysautonomia, which is broadly defined as a dysfunction in the autonomic nervous system. A common condition we see in Long COVID is Postural Orthostatic Tachycardia Syndrome (POTS). POTS affects the body’s ability to regulate heart rate and blood pressure due to positional stress. It is also possible to have dysautonomia that is non-positional in nature and is characterized by an ANS that favors the sympathetic branch or “fight or flight” response. This manifests as highly exaggerated stress responses to low-level stimuli and is often associated with lower HRV.


How is HRV Monitored?

In our program, most individuals use some kind of wearable device (i.e. Apple Watch) that measures and displays daily heart rate and HRV readings. Most often these daily HRV measurements are provided as an average over a period of time (typically overnight while sleeping). Various devices are available, including chest straps and wristbands, with some providing more accurate data than others. You can find more information about choosing an appropriate monitoring device in this article.

HRV measurement can also be carried out using a smartphone app utilizing the phone’s camera to detect blood flow changes. Common apps we see individuals use to take real time HRV recordings include:

When conducting purposeful HRV measurements, it’s important to try and measure it at the same time every day to control for environmental factors. Typically it is recommended to do a reading first thing in the morning after waking up. It is also crucial to recognize that a single numerical value isn’t the sole focus; rather, more attention should be paid to the trends over a period of time. For a more accurate understanding of HRV, measurements should be taken consistently over at least a week or two. This continuous monitoring allows individuals to glean insights into their body’s response to their daily activity and stress and adjust their lifestyle for optimal recovery from Long COVID. Consulting with a Long COVID Physiotherapist is also advisable for proper interpretation of HRV measurements and guidance on improving HRV.


How Will HRV Biofeedback Help My Recovery?

Given that Long COVID symptoms can stem from ANS dysregulation, recent research suggests that HRV biofeedback training can serve as a valuable tool for recovery.(5)(6)  HRV biofeedback training is, at its core, a technique that consists of providing an individual with real-time visual feedback on instantaneous heart rate and respiration changes while being instructed to breathe at specific intervals.

HRV feedback can contribute to Long COVID recovery in several ways:

  • ANS Regulation: Previous research in patients with coronary artery disease that HRV biofeedback contributes to increased ANS recovery after anger-inducing events.(7)  Other studies results show that increased HRV induced by HRV-biofeedback is accompanied by changes in functional brain connectivity during resting state.(8)  Another meta analysis suggests that HRV biofeedback carries no risk and can be be effective in managing patients with chronic diseases.(9)
  • Stress management: Long COVID often induces or increases stress and anxiety in an individual’s life. HRV biofeedback is a therapeutic technique that proves effective in stress and anxiety management.(10)
  • Enhancing cardiovascular health: Long COVID can negatively impact cardiovascular health. Enhancing HRV through appropriately dosed exercise and other interventions can mitigate cardiovascular risks, although caution is necessary with exercise due to the common symptom of post-exertional malaise (PEM) in Long COVID.
  • Improving cognitive function: Long COVID may adversely affect cognitive function, a symptom commonly known as “brain fog”. HRV biofeedback has been demonstrated to enhance cognitive function in individuals with chronic conditions. This technique improves attention, memory, and decision-making skills, ultimately enhancing overall quality of life.(9)


A Method of HRV Biofeedback

In this program, we have adopted the use of the Inner Balance Coherence+ HRV biofeedback device from HeartMath. There are options to both test out a device over a rental period or purchase a device through Cornerstone. Please reach out to your Long COVID Physiotherapist or [email protected] for more information.

smartmath hrv monitor

This device conveniently clips to your ear and takes real-time heart rate readings. You can then connect your device to one of the recommended apps on your smartphone to see visual representation of your HR and HRV and engage in breathing sessions with visual feedback.

The Inner Balance app is the first HRV biofeedback app by HeartMath that is free to download and use with any models of devices they sell.

The newer HeartMath app is free to download and use for 7 days but does require an annual subscription of $79 CAD after this trial period has elapsed. With the purchase of a new Coherence+device, you will unlock a lifetime subscription to the HeartMath app which includes hours of video content in “coherence training”.

Dr. Boon Lim is a Cardiologist and Electrophysiologist in London. In this video, he demonstrates how to use the Inner Balance device with the Inner Balance App.

In the below video, I demonstrate the use of the new Inner Balance Coherence+ device with the new HeartMath app. You will see the interface is different but the overall premise remains unchanged.


HRV Biofeedback Without A Device

The HeartMath app gives the user an option of performing HRV biofeedback using their smartphone’s camera sensor instead of the Coherence+ device. Please note that this function is part of the Premium subscription as described above. Another app that can be used is the HeartRate+ Coherence Pro. This app is free to download and costs $6.99 to use this feature for longer than 1.5 minutes at a time.

The Role of Breathing

Coherent breathing, also known as resonant or paced breathing, is a specific breathing technique aimed at achieving a harmonious and balanced rhythm in the breath cycle. The goal is to synchronize ones inhalation and exhalation with a specific respiratory rate, typically around five to six breaths per minute. In coherent breathing, individuals strive to achieve an equal duration for both the inhalation and exhalation phases. The emphasis is also placed on diaphragmatic or belly breathing, where the breath is drawn into the lungs, expanding the diaphragm, rather than more shallow chest breathing.

Enhancing “Coherence”

A crucial distinction highlighted by HeartMath researchers is that the state of “coherence” differs both psychologically and physiologically from the state achieved through typical relaxation techniques. Physiologically, relaxation is characterized by an overall decrease in autonomic outflow, leading to higher HRV and a shift in the Autonomic Nervous System (ANS) balance towards increased parasympathetic activity. Instead, it is primarily characterized by a shift in the heart rhythm pattern.

While breathing patterns influence HRV as described above, it is useful to focus on intentionally generating heartfelt positive emotions in addition to paced breathing. Positive emotions naturally induce coherence, synchronizing heart and breathing rhythms, offering broader benefits such as perceptual changes, improved creativity, cognitive enhancements, and favorable hormonal balance. Some positive emotions that have been shown to increase coherence include joy, appreciation, love, care and compassion.


In summary, the incorporation of HRV biofeedback in Long COVID rehabilitation holds significant promise for enhancing recovery. Understanding the connection between HRV and the Autonomic Nervous System (ANS), coupled with continuous monitoring through wearable devices and smartphone apps, allows for personalized insights that are specific to the individual. The adoption of HRV biofeedback devices, like the Inner Balance Coherence+ from HeartMath, along with coherent breathing techniques, provides a complement to the fundamentals of recovery you are already working on. By fostering “coherence” through rhythmic breathing and intentional mindfulness, individuals living with Long COVID can unlock broader physiological and psychological benefits.



About the author

Melissa Seifried

Physiotherapist Learn More about Melissa Seifried

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