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What Is Heart Rate Variability? How Can I Improve It?

Updated: Jul 31


You may have seen articles linking heart rate variability (HRV) to overall health—but what exactly is it, and why does it matter?


Your heart beats regularly, typically between 60 and 89 times per minute. A resting heart rate 90 or higher is considered tachycardic or higher. Heart rates of 59 and lower are considered bradycardic or lower. Even with a normal rhythm, there are micro-variations in the time between each heartbeat. These slight fluctuations—measured in milliseconds—are healthy and desirable. They reflect a balanced interplay between the sympathetic and parasympathetic branches of your autonomic nervous system.

Sinus arrhythmia is a normal and healthy sign of visible HRV during breathing. With sinus arrhythmia, there is a slight increase in the HR during inspiration and a slight decrease during expiration. Photo of Dale Dubin, MD's work.
Sinus arrhythmia is a normal and healthy sign of visible HRV during breathing. With sinus arrhythmia, there is a slight increase in the HR during inspiration and a slight decrease during expiration. Photo of Dale Dubin, MD's work.

The parasympathetic nervous system (your “rest and digest” mode) supports the heart via the vagus nerve, a large cranial nerve that runs from your brainstem, out of your skull, and through your neck along your carotid artery and jugular vein to your chest, and through your hiatus (where the esophagus attaches to the stomach) to the abdomen. The sympathetic nervous system is responsible for controlling your “fight, flight, or freeze” mode. It is located in a chain of nerve tissue along the spinal column on both sides and in the adrenal glands.


Ideally, your body spends most of its time in a parasympathetic state—relaxed and recovering—not on constant alert. In fact, HRV often increases during sleep, reflecting a dominance of parasympathetic tone and alignment with your circadian rhythm.



What Exactly Is Heart Rate Variability?



HRV is the measure of variation in time between heartbeats, commonly recorded as the R-R interval on an ECG (aka EKG), measuring the time between two R-waves. Some devices may use other points, such as P-P intervals, depending on the algorithm.


Rather than your heart beating like a metronome, a healthy heart shows slight fluctuations between beats. This is a sign that your nervous system is agile and responsive. Higher HRV typically indicates stronger parasympathetic (vagal) tone, improved recovery, and better overall resilience to physical and emotional stress. Lower HRV, on the other hand, can be a sign of:

  • Chronic stress

  • Fatigue

  • Illness

  • Overtraining in athletes

  • POTS (Postural Orthostatic Tachycardia Syndrome)

  • Depression

  • Inflammation

  • Poor sleep or recovery

  • Autonomic dysfunction



What’s a Good HRV?


HRV is highly individualized and varies based on age, genetics, fitness level, and stress. There’s no single “normal” or “ideal” number, but general ranges can be helpful:

  • Elite athletes: 80–150 ms

  • Fit adults (20s–30s): 50–100 ms

  • Middle-aged adults (40s–50s): 30–70 ms

  • Older adults (60+): 20–50 ms

HRV naturally declines with age. The most meaningful way to use your HRV data is to track your personal baseline over time and aim for gradual improvement.



How Do You Measure and Analyze HRV?


Popular tools include:

  • Oura Ring

  • WHOOP Strap

  • Garmin devices

  • Apple Watch

  • Apps like HRV4Training, which pair with these devices and provide more detailed analysis

That said, accurately measuring HRV can be challenging. These devices may pick up “artifact” (interference or noise), especially during movement. While the Apple Watch has been validated for manually collecting HRV data, it samples intermittently, especially at night, rather than continuously, which can limit the depth and context of the data. Devices may collect HRV data effectively, but struggle to analyze it due to artifact. This is overcome with apps like HRV4Training.



Getting an accurate HRV measurement:


There are a few things to consider when checking HRV. At the end of this post, I will have a link that describes data-supported best practices.

  • Measure at the same time daily, preferably first thing in the morning

  • Use the same conditions—ideally after waking but before caffeine or activity

  • During sleep, continuous overnight measurement is most helpful

  • For fitness tracking, assess HRV in response to specific exercises or stressors



How to Improve HRV


If your HRV is consistently low, take it as a signal to address stress. Simple strategies that can help include:

  • Deep breathing exercises

  • Mindfulness or meditation

  • Regular movement and exercise (without overtraining)

  • Prioritizing sleep

  • Cold exposure or contrast showers

  • Spending time in nature

  • Nutrition support (e.g., omega-3s)

  • Improving your posture


Poor posture is a common issue, especially involving the neck and upper back. When these areas are misaligned, they can compress the sympathetic nervous system, potentially contributing to various health concerns.



A simple way to assess your posture is to have a friend take a side-view photo of you while you're standing naturally. In the photo, imagine drawing a straight vertical line from your ear down towards the ground. The line from your ear downward should go through the center of your shoulder. If your ear is positioned in front of your shoulder, this indicates a forward head posture. Do either of the first two women above have good posture? Click on each image for the caption.


Next, examine your upper back. Is there a visible hump or exaggerated curve? If you notice either forward head posture or excessive upper back rounding, it's a sign that your posture needs attention—and correcting it may have significant health benefits.



Conclusion


In summary, heart rate variability is a powerful window into your nervous system and overall health. Track it over time, not in isolation, and use it as a tool to guide recovery, lifestyle choices, and stress management.



Sources:

For the HRV4Training app: https://www.hrv4training.com/

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