There is a very useful tool that has become accessible because of new consumer devices, smartphone apps, and the ability to record heart rate. It is the measurement of a phenomenon called heart rate variability, or HRV. Tracking, then managing, HRV, gives you a new way for achieving goals such as deep relaxation, reduction of blood pressure, control over recurrences of atrial fibrillation, even reduction of abnormally high cortisol levels. I have been applying HRV for around 20 years. Over this period, the consumer technologies have advanced considerably from clunky, non-real time, inconvenient, and expensive to accessible, easy-to-use, real-time, and at far lower cost (even free).
Heart rate is dictated by a balance of two nervous system inputs: the sympathetic (“fight or flight”) and parasympathetic (relaxation or calm), much as the gas and brake pedals govern the speed of your automobile. At rest, parasympathetic input dominates; if it did not, the resting heart rate would hover around 100 beats per minute (BPM). The stresses of modern life, the failure to reflect and enjoy quiet moments, and the use of stimulants to jog performance all contribute to excessive sympathetic effects that are reflected in higher heart rates and a dampening of parasympathetic input. In general, a resting heart rate of 40-60 beats per minute (bpm) is ideal, and is associated with a high level of variation in the time intervals between beats, so-called heart rate variability.
HRV is a measure of the variation in intervals between heart beats, in this case obtained via EKG:
There is a widely-held misconception that a healthy heart rate is perfectly regular and that irregular heart rates are unhealthy. This originates with the fact that some pathological heart rhythms, such as atrial fibrillation and premature atrial or ventricular contractions (early beats), are irregular. But the opposite is true: Health is reflected by increased levels of HRV, lack of HRV—perfect regularity—is associated with poor health.
Situations that have been associated with reduced HRV include:
- Worry, anxiety, stress, panic
- Heart disease with increased mortality
- Post-traumatic stress disorder (PTSD)
- Serious illness—such as congestive heart failure, sudden cardiac death, sepsis, liver failure, cancer
- Low testosterone levels
- Type 2 diabetes and metabolic syndrome
The healthiest heart rate pattern from beat-to-beat is variable. In general, the greater the HRV, the healthier you are; the lower the HRV, the less healthy you are. But HRV is ideally not random but in synchrony with respiration.
When you inhale, heart rate increases (due to increased intrathoracic pressure that impedes venous return of blood to the heart that, in turn, triggers heart rate to increase). When you exhale, heart rate decreases (due to reduced intrathoracic pressure that allows greater volume of venous blood flow return to the heart).
In an ideal situation, these two phenomena—heart rate and respiration—are in perfect synchrony. The degree of heart rate and respiratory synchrony is reflected by a measure called coherence, i.e., HRV cycles are in synchrony with respiration. Higher levels of coherence are associated with:
- Greater feelings of calm; reduced anger, fatigue, hostility
- Psychological resilience
- Improved cognitive performance
- Lower blood pressure
- Lower levels of cortisol
- Higher levels of sports performance and recovery
- Reduced pain perception
(From McCraty 2014. Summary of coherence effects summarized here.)
While spontaneously occurring higher coherence can yield such positive effects, so can purposeful generation. In other words, using devices that track HRV and respiration in real-time, the user can purposefully generate higher levels of coherence and obtain the above benefits.
For additional discussion, including how to track HRV, how to increase HRV to gain control over phenomena such as blood pressure and anxiety, and a review of the devices that can be used to measure HRV, see the extended discussion posted in our Undoctored Inner Circle.