By Dr Theron Hutton MD
Heart rate variability (HRV) refers to the fluctuation in the time interval between consecutive heartbeats. It is a measure of the autonomic nervous system (ANS) activity and reflects the balance between the sympathetic and parasympathetic branches of the ANS.
HRV has gained increasing attention in recent years due to its association with various physiological and psychological states. For instance, low HRV has been linked to a higher risk of cardiovascular disease, diabetes, and mortality (Thayer and Sternberg, 2006). On the other hand, higher HRV has been associated with better physical and mental health outcomes, including improved cognitive function, emotional regulation, and stress resilience (Porges, 1995).
HRV can be measured using various techniques, including electrocardiography (ECG), photoplethysmography (PPG), and respiratory sinus arrhythmia (RSA). The most common method is the analysis of the R-R interval in an ECG recording, which reflects the duration between consecutive R waves of the ECG trace (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, 1996). Many modern wearable health trackers measure HRV.
There are several factors that can influence HRV, such as age, sex, physical activity, and stress (Thayer and Sternberg, 2006). HRV tends to decrease with age and is generally higher in women than in men (Thayer and Sternberg, 2006). Physical activity has been found to increase HRV, while stress has been shown to decrease HRV (Thayer and Sternberg, 2006).
HRV has also been shown to be influenced by various psychological and social factors. For example, positive emotions, such as joy and gratitude, have been found to increase HRV, while negative emotions, such as anger and anxiety, have been found to decrease HRV (Thayer and Sternberg, 2006). Social support has also been found to be positively associated with HRV (Thayer and Sternberg, 2006).
In conclusion, HRV is a measure of ANS activity that reflects the balance between the sympathetic and parasympathetic branches. It has been linked to various physiological and psychological states and can be influenced by a range of factors, including age, sex, physical activity, stress, and social support. Further research is needed to fully understand the implications of HRV and its potential as a marker of health and well-being.
At Mulberry Clinics we often use HRV as a measure of the health of our patients. We consider it an important vital sign.
References:
Porges, S. W. (1995). Cardiac vagal tone: A physiological index of stress. Neuropsychobiology, 32(2), 76-80.
Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. (1996). Heart rate variability: Standards of measurement, physiological interpretation, and clinical use. European Heart Journal, 17(3), 354-381.
Thayer, J. F., & Sternberg, E. M. (2006). Beyond heart rate variability: Vagal regulation of allostatic systems. Annals of the New York Academy of Sciences, 1096(1), 72-78.