Heart rate variability (HRV) is a noninvasive electrocardiographic method that can be used to measure your body’s adaption to stress and exercise. HRV is simply a measure of the variation in time between each heartbeat. This variation is controlled by a primitive part of the nervous system called the autonomic nervous system (ANS).
HRV can identify these variations and imbalances. If a person’s system is in more of a fight-or-flight mode, the variation between subsequent heartbeats is low. If one is in a more relaxed state, the variation between beats is high. In other words, the healthier the ANS the faster you are able to switch gears, showing more resilience and flexibility. Over the past few decades, research has shown a relationship between low HRV and worsening depression or anxiety. A low HRV is even associated with an increased risk of death and cardiovascular disease.
Research has shown a strong correlation between low HRV values and increase the risk for diabetes, coronary disease, depression, and anxiety. Low HRV scores are also associated with impaired regulatory and homeostatic ANS functions that reduce the body’s ability to cope with internal and external stressors. Higher HRV scores correlate with an increased human peak performance, fitness levels, and improved rest and recovery.
Recovery is more complicated than an isolated measurement and looking at daily HRV values does not indicate your level of recovery or how well you handle stress. It is difficult to determine how you are responding to stress and adaptation just by looking at individual HRV values. So it is important to first establish baseline HRV values over a minimum of one week to understand how your body’s response to stress and other stimuli.
The gold standard is to analyze a long strip of an electrocardiogram, the test we frequently do in the medical office where we attach wires to the chest. But Dr. Marco Altini has developed a clinically validated app called HRV4Training in the Apple and Android app store where you can use your phone/iPad camera to measure your heart rate variability.