I wear a Whoop. And my Whoop measures a bunch of numbers, including something called Heart Rate Variability (HRV). Heart Rate Variability has become one of the most talked-about numbers in wellness, sports performance, and biofeedback. It’s often promoted as a direct measure of recovery, stress resilience, or nervous-system balance.

HRV is simply the time between heart beats. And the simple story goes:

Higher HRV = healthier, calmer, better recovered

Lower HRV = stress, fatigue, or dysfunction

Because it’s presumed that the more variable your heart rate is, the less stuck you are in a stressed sympathetic state, where your heart is beating at a constant stressed speed (and dominantly influence by the sympathetic nervous system).

The theory is almost believable. Almost.

However, if you happen to be like me, you may have a low HRV. And mine is really low. It averages 28. And even though I’m 58 years old and it decreases with age, that is still really low. But I’m super active and very healthy. And my resting heart rate average is 50. So I’m not stuck in some kind of stressed sympathetic pattern even though my HRV is low.

The Autonomic Nervous System Is Real, but Its Function Is Still Theory

The autonomic nervous system (ANS) unquestionably exists and governs heartbeat, breathing, digestion, and many other involuntary functions. It has two main branches:

• Sympathetic: mobilizes energy (“fight or flight”)

• Parasympathetic: restores balance (“rest and digest”)

HRV reflects their dynamic interplay. But while we can measure HRV precisely, what it truly means remains theoretical. Researchers continue to debate:

• How the sympathetic and parasympathetic branches interact in real time

• How emotions, hormones, and metabolism affect HRV

• Whether HRV patterns reliably indicate health across individuals

So, while the ANS is real, its operational model is still a best-fit theory.

HRV: Measurable Data, Context-Dependent Meaning

HRV measures the millisecond-to-millisecond variation between heartbeats. That variability can change due to countless influences:

• Sleep quality and circadian rhythm

• Hydration and electrolyte balance

• Breathing rate and depth

• Food, glucose, and gut inflammation

• Hormones, medications, or menstrual phase

• Fitness level, genetics, and even posture

In other words, HRV is real physiology—but not a single diagnostic truth. Its meaning depends on who you are, what your body is doing, and when you measure it.

Does Higher HRV Always Equal Better Health?

No. Many studies show that higher HRV often correlates with better recovery and adaptability. Yet research and clinical experience also reveal exceptions:

• Some people with chronic fatigue, autoimmune disease, or dysautonomia display high HRV from erratic or unstable signaling.

• A temporarily low HRV may appear during intense training, immune response, or healthy stress adaptation.

So HRV is best understood as one signal among many, not a universal scoreboard.

Common Assumption—and Its Limits

It’s tempting to think:

• High HRV = strong parasympathetic tone

• Low HRV = sympathetic dominance or stress

That’s sometimes true, but physiology isn’t that black-and-white.

Resting Heart Rate (RHR) and Parasympathetic Tone

A low resting heart rate usually indicates strong parasympathetic (vagal) influence and an efficient cardiovascular system. It’s typical among endurance athletes and well-conditioned individuals. Low RHR usually means the heart pumps effectively and doesn’t need to beat as often—a mark of efficiency, not fatigue.

Low HRV Doesn’t Always Mean Sympathetic Dominance

A low HRV can result from several different states:

• High sympathetic drive from stress or illness

• Stable efficiency, where beat-to-beat intervals simply don’t vary much

• Genetic or constitutional traits producing naturally steady rhythms

So a low HRV may reflect either strain or stability. Context is everything.

Different Athletic Profiles, Different HRV Patterns

🏃‍♂️ Endurance Athletes: Tend Toward Higher HRV

On average, endurance athletes tend to have higher HRV than the general population or strength athletes. Here’s why:

• Chronic aerobic training increases parasympathetic (vagal) tone, which promotes greater beat-to-beat variability.

• Their hearts become more efficient and responsive, able to shift easily between exertion and recovery.

• This adaptability shows up as higher HRV, especially during rest and sleep.

So in general, long-term endurance training (running, cycling, swimming, etc.) elevates HRV compared to untrained individuals.

🏋️ Strength / Power Athletes: Often Show Lower HRV

Speed, strength, and power athletes (e.g., CrossFit, martial arts, weightlifting) often display lower HRV, even when they’re in peak condition.

Reasons include:

• More emphasis on sympathetic activation for explosive performance

• Shorter training bouts with intense neuromuscular load rather than long aerobic effort

• A nervous system that favors stability and readiness, not fluctuation

They also commonly have low resting heart rates, reflecting efficient cardiac output, even if HRV is relatively low.

And guess what. That describes my athletic style. I do track workouts emphasizing speed, and I lift weights. I do NOT like to run long distances.

Both are healthy adaptations to different performance demands. One system favors endurance efficiency and fluid variability; the other favors rapid power output and autonomic steadiness.

Context Always Wins

• Low HRV + Low RHR can indicate calm, efficient physiology—or stress and exhaustion.

• The difference lies in symptoms, recovery, energy, and emotional stability.

If you sleep well, recover easily, digest smoothly, and feel energetic, then low HRV and low heart rate likely reflect your healthy normal.

The Body Is Smarter Than the Metrics

Wearables and dashboards can’t capture the full complexity of the nervous system. HRV and heart rate are valuable tools—but only in context.

Health is a pattern, not a number.

Trends, symptoms, and performance tell the real story.

Final Thoughts

The autonomic nervous system is real, but its function remains a theory in progress. HRV and resting heart rate are measurable facts—but their interpretation depends on physiology, genetics, and circumstance.  And my low HRV and low RHR are probably due to both genetic and the way I train.

You can absolutely be healthy, strong, and balanced with both low HRV and a low resting heart rate. The key is how your body performs, not what your tracker reports.

Instead of chasing a score, listen to your body’s signals—because your body always knows the truth long before your data does.

Thank you for reading. I would love to read your experience with HRV in the comments section below.

And remember to take good care of your body. It’s the only place that you have to live.

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