Heart Rate Variability refers to the constant variation in milliseconds between your heartbeats. As popular as the metaphor may be, a healthy heart doesn’t beat as regularly as a metronome—it changes its rhythm with each beat. Some situations increase variation (high HRV), while others cause the intervals between beats to remain constant (low HRV). 

You may be unaware of these subtle variations, but they reflect your heart’s ability to respond to different situations. HRV can react to stress and/or illness before resting heart rate (RHR), which makes it one of your body’s most powerful signals—providing useful insights into your stress levels, recovery status, and general well-being. As a rule of thumb, high HRV is associated with rest-and-digest, general fitness, and good recovery, while low HRV is associated with fight-or-flight, stress, illness, or overtraining.

While individual days may be lower after high-intensity exercise, a night out, or a stressful day, if your recent HRV is on par with or better than your average, it’s a sign of good recovery. Monitoring HRV trends shows whether you are adapting or not to the “load” you are exposed to. This load could be new medications or treatment plans, or an increase in training load. 

Finally, one person’s HRV should not be compared with another’s. HRV is very personal. The key is to track trends over time. The coefficient of variation of HRV is a great metric to focus on as it removes the daily variations and helps you focus on the bigger picture.

Moving the needle – How to increase HRV

1. HRV tends to decline with age. The most effective way to hedge this decline is cardiovascular exercise. No other lifestyle change comes close to cardio. 
2. Biofeedback, coupled with controlled breathing can affect both short and long term HRV. 
3. Poor sleep hygiene can negatively affect HRV over the short term. So try to avoid late exercise, meals, and dramatically reduce or eliminate alcohol, which is the single worst thing for HRV. 
4. Ice Baths speed up recovery and help push you into a more parasympathetic state (Rest and Relaxation). 
5. Meditation is another protocol that calms one’s mind and puts you into a parasympathetic state. Meditation has been shown to have a short term effect on HRV. 
6. It is well known that modern man does not drink enough water as we should. Sufficient hydration aids with thermoregulation and can help increase HRV at least temporarily. 

Resources

• Deep dive into HRV – https://medium.com/@altini_marco/the-ultimate-guide-to-heart-rate-variability-hrv-part-1-70a0a392fff4, https://medium.com/@altini_marco/the-ultimate-guide-to-heart-rate-variability-hrv-part-2-323a38213fbc, https://medium.com/@altini_marco/the-ultimate-guide-to-heart-rate-variability-hrv-part-3-5fe902f3d2b3, https://medium.com/@altini_marco/the-ultimate-guide-to-heart-rate-variability-hrv-part-4-909b52f71131
• Biofeedback and deep breathing – Long term effects of deep breathing on Heart Rate Variability