A Masterclass in Improving Your HRV - Dr Jay Wiles

Heart Rate Variability (HRV) has rapidly evolved from a niche clinical metric to the "new hot girl in school" of the wellness world. With the advent of wearable technology like Whoop, Oura, and Apple Watch, millions of people now have access to data that was previously restricted to specialized academic clinics utilizing expensive EKG machinery. However, this accessibility has created a significant knowledge gap: we have the ability to detect HRV, but very few people understand how to influence it. It is not merely a vanity metric or a high score to chase; it is a window into your autonomic nervous system’s ability to handle stress, recover, and adapt to the environment. Understanding the nuance between state changes and trait changes is the key to moving from passive tracking to active nervous system training.

Key Takeaways

• HRV is a proxy for adaptability: It measures the variance in time between heartbeats, serving as a window into how flexible and resilient your nervous system is in response to stress.
• Context is king: An "optimal" HRV is relative to your own baseline, not a comparison to others. Stability across time is often more important than a single high number.
• State vs. Trait change: Most breathwork offers a temporary "state" shift, but specific protocols like resonance breathing create lasting "trait" adaptations to the nervous system.
• Precision beats intention: To truly train the baroreflex mechanism and improve HRV, you must breathe at your specific resonance frequency (usually between 4.5 and 6.5 breaths per minute).
• The physiological protocol: Significant structural changes to the nervous system generally require 10–20 minutes of practice, 4–6 times per week, for at least 8–10 weeks.

Demystifying the Metric: What HRV Actually Measures

To understand HRV, we must first dismantle the misconception that the heart should beat like a metronome. If your heart rate is 60 beats per minute, it is not beating exactly once every second. A healthy heart functions with a degree of chaotic variance. As you inhale, the time between heartbeats shrinks (heart rate speeds up); as you exhale, that time elongates (heart rate slows down). This variance is Heart Rate Variability.

HRV is the single greatest non-invasive proxy we have for measuring the adaptations of the nervous system. It reflects the interplay between the two branches of the autonomic nervous system:

• The Sympathetic Nervous System: Often simplified as "fight or flight," this is better understood as the system that mobilizes energy. It prepares the body to evade threats or perform tasks.
• The Parasympathetic Nervous System: Often called "rest and digest," this system is about conserving energy. It is the "brake" that slows the system down.
• Homeostasis and Balance: These systems do not operate like a seesaw where one is on and the other is off. They work dynamically together. A higher HRV generally indicates a flexible system that can rapidly switch between mobilizing and conserving energy to maintain homeostasis.
• Allostatic Load: When the nervous system cannot keep up with the input—due to chronic stress, poor sleep, or illness—HRV decreases. This indicates the body is struggling to adapt to its environment.
• The Baroreflex: This is the body's cruise control for blood pressure. It bridges the gap between the autonomic nervous system and the cardiovascular system. High HRV correlates with high "baroreflex gain," meaning the body can smoothly adjust blood pressure without overshooting.
• Vagal Tone: High frequency power in HRV metrics is driven by the vagus nerve. Improving this tone allows for faster physiological recovery after stressors.

HRV is the single greatest non-invasive proxy that we have for measuring the adaptations of the nervous system.

Interpreting the Data: The Context Trap

A common pitfall for wearable users is biometric hypervigilance—stressing over the daily number. Is a high number always good? Is a low number always bad? The answer is nuanced. While a generally higher HRV suggests better fitness and recovery, the metric is highly individual. Comparing your HRV to a professional athlete's score is a recipe for anxiety, not improvement.

There are distinct factors that influence your baseline HRV, split into modifiable and non-modifiable categories:

Non-Modifiable Factors

• Age: There is a distinct negative slope in HRV as we age, particularly dropping in the 30s and 40s due to reduced autonomic efficiency and vascular stiffening. However, the "ceiling" for improvement remains accessible regardless of age.
• Genetics: Twin studies suggest a moderate to high genetic component. Some individuals, like certain NFL linemen, may naturally have HRVs in the 150s, while elite Olympic sprinters might sit in the 40s. Neither is necessarily "healthier" based solely on this number.
• Sex Differences: Men generally have higher average HRV than women. This is partly due to hormonal cycles; progesterone and estrogen fluctuations during the menstrual cycle can increase sympathetic drive and lower HRV.

Modifiable Factors

• Cardiorespiratory Fitness: Increasing VO2 max, stroke volume, and lowering resting heart rate creates a more efficient cardiovascular system, which typically raises HRV.
• Chronic Health Conditions: Diabetes, cardiovascular disease, and chronic pain significantly lower HRV. Managing these conditions is the first step to improvement.
• Stress Load: This is arguably the most critical factor. Chronic psychological stress creates a rigid, non-adaptive nervous system.
• Sleep Quality: Sleep is the foundation of recovery. Fragmentation and poor sleep efficiency are major suppressors of HRV.
• Alcohol Intake: Alcohol is a potent suppressor of the parasympathetic nervous system and will acutely crush HRV scores.
• Hydration and Nutrition: Blood volume impacts HRV, meaning dehydration can skew numbers. Conversely, over-hydration or excessive salt intake can also disrupt readings.

State Change vs. Trait Change: Training the Nervous System

There is a fundamental difference between doing something to feel better in the moment (State Change) and doing something to permanently upgrade your physiology (Trait Change). Many wellness practices, including generic breathwork or a glass of wine, may induce a temporary state of relaxation. However, they do not necessarily build a more robust nervous system over time.

To achieve trait change, you must view the nervous system like a muscle that requires progressive overload and consistency. You are effectively taking your nervous system to the gym.

• State Change (The Acute Shift): This is transient. For example, taking a deep breath before a meeting engages the parasympathetic nervous system to lower anxiety immediately. It signals safety to the brain, allowing for better mental acuity and emotional regulation in the moment.
• Trait Change (The Longitudinal Shift): This is the "fine-tuning of the engine." It occurs when consistent practice rewires the autonomic baseline. The thermostat of the nervous system is reset, making you naturally more resilient to stress without conscious effort.
• The Gym Analogy: A single workout provides a "pump" (state change), but you only get stronger muscles (trait change) if you show up consistently over months.
• The Research Gap: Many popular breathwork techniques (like cyclic sighing or box breathing) are excellent for state change but lack robust clinical evidence for long-term trait change.
• Resonance Frequency: The only breathing intervention with extensive literature supporting trait change is Resonance Frequency Breathing (Biofeedback).
• Timeline for Adaptation: Research indicates that consistent training takes about 8 to 10 weeks to manifest as a permanent shift in autonomic baseline.

Precision always beats effort and intention when it comes to breathing.

The Science of Resonance Breathing and Biofeedback

Resonance breathing is not just "slow breathing." It is a specific protocol designed to create physiological resonance—a state where the heart rate, respiration, and blood pressure systems oscillate at the same frequency. When these systems align, they maximize the efficiency of gas exchange and nervous system regulation.

This was originally discovered by researchers studying cosmonauts and later refined by Dr. Paul Lehrer. They found that humans have a specific "resonance frequency," typically between 4.5 and 6.5 breaths per minute.

Why Precision Matters

Unlike general meditation, resonance breathing relies on precision. Breathing at 6 breaths per minute when your ideal frequency is 5 breaths per minute will still induce relaxation, but it will not maximize the "exercise" effect on the baroreflex. To get the compounding interest of trait change, you need to be precise.

Historically, finding this frequency required expensive lab equipment. Today, technology is bridging the gap. Devices like Ohm use photoplethysmography (PPG) sensors to read HRV in real-time and use light or vibration to guide the user into their specific resonance pattern. This moves biofeedback from the clinic to the living room.

• Low Frequency Power: Resonance breathing increases power in the "low frequency" band of HRV analysis, which is associated with baroreflex activity.
• High Frequency Power: Over time, training the low frequency band results in a higher resting "high frequency" power, indicating a stronger vagal tone at rest.
• Dynamic Nature: Your resonance frequency can shift slightly day-to-day based on stress and physiology, which is why real-time biofeedback tools are superior to static pacing tapes.
• The "Ohm" Advantage: By using a handheld device that vibrates or lights up, users can close their eyes or disengage from phone screens, reducing the friction and digital stimulation often associated with app-based biofeedback.
• Subjective Feel: While the goal is physiological training, most users report a sense of calm or sleepiness as a byproduct of the alignment.
• Mental Focus: While you can do resonance breathing while watching a movie, layering mindfulness (paying attention to the breath) likely enhances the benefits by training the mind alongside the body.

Building Your Protocol: How to Optimize HRV

If your goal is to improve your HRV and nervous system resilience by the end of the year, you need a structured approach. Random acts of breathwork will yield random results. A dedicated protocol focuses on the two biggest levers: cardiorespiratory fitness and resonance breathing.

The "Nervous System Gym" Protocol:

1. Frequency: Aim for 4 to 6 sessions per week.
2. Duration: 10 to 20 minutes per session. (Research shows diminishing returns after 20 minutes).
3. Timing: The nervous system begins to make significant adaptations between minute 8 and minute 12 of a session. Short "micro-doses" (1-3 minutes) are great for acute stress relief, but the 10-20 minute window is required for trait change.
4. Pre-Sleep Integration: Performing resonance breathing 30 minutes before bed is highly effective. It acts as a "vagal brake," winding down the system and reducing sleep fragmentation.
5. Post-Exercise Recovery: High-performing athletes use biofeedback immediately after training to switch the body from a catabolic (breakdown) state to an anabolic (recovery) state.
6. Exercise Foundation: Combine this with 120–150 minutes of Zone 2 cardio per week and occasional high-intensity (Zone 5) work to build the "hardware" of the heart.

The Mind-Body Loop: Bottom-Up Regulation

We often try to solve psychological problems with psychological tools—thinking our way out of stress. This is "top-down" processing. However, emotions often move "bottom-up." The body detects a threat (or a perceived threat), the physiology shifts into a sympathetic state, and the brain then creates a narrative to explain why we feel anxious.

Resonance breathing offers a "bottom-up" intervention. By mechanically regulating the breath, you send a safety signal to the brain, which can dismantle the anxiety loop more effectively than logic alone. This is particularly powerful for those suffering from PTSD or chronic anxiety, where the body is stuck in a threat response regardless of the actual environment.

Trying to change the mind with the mind is a bit like tug of war.

Conclusion

HRV is a complex metric, but improving it doesn't have to be complicated. It requires shifting our mindset from passive monitoring to active training. We cannot simply "will" ourselves to be less stressed, nor can we rely solely on generic relaxation techniques to rewrite our physiology. By combining general fitness with the precision of resonance breathing biofeedback, we can physically restructure our nervous system's baseline.

Treat your breath practice with the same discipline you treat your gym workouts. It isn't just about feeling calm in the moment; it is about building a system that remains resilient, flexible, and robust in the face of life's inevitable stressors.