Studying the heart provides a vast amount of important information about our body as a person's heart rate and heart rate variability are continuously changing in a reactive manner to particular life events.
What is Heart Rate Variability?
Heart Rate Variability is the variance in time of the intervals between successive heart beats, typically measured in milliseconds.
HRV can be used to measure Autonomic Nervous System (ANS) activity, which is responsible for maintaining homeostasis - the maintenance of physiological processes such as heart rate (HR) hypertension and thermoregulation.
External or internal stimuli can elicit a measurable response from the ANS via the secretion of stress hormones (glucocorticoids) and the release of neurotransmitters.
The ANS is regulated by a region in the brain known as the hypothalamus which is ultimately responsible for ANS balance by stimulating or relaxing various systems throughout the body.
The ANS consists of two divisions, the sympathetic and parasympathetic nervous systems. Sympathetic and parasympathetic activity can be estimated from time and frequency domain parameters derived from an individual's HRV.
The sympathetic nervous system (SNS) is responsible for the traditional ‘fight or flight’ response, causing an increase in HR and blood pressure as well as elevated blood glucose levels and a decrease in HRV.
Conversely, the parasympathetic nervous system (PNS) is responsible for the traditional ‘rest and digest response’. This system which works in opposition to the SNS by decreasing HR and blood pressure, whilst stabilising blood glucose levels and increasing HRV; This is typically when recovery takes place.
These two systems are always active - it is the balance between the two that dictates if someone is in a predominantly stressed or recovery state.
Why Does Understanding HRV Matter?
Stress is a loosely defined term with many different interpretations, however B-Secur defines stress as a physiological response to an internal or external stimulus. This stimulus can be physical, emotional, societal or psychological.
By measuring HRV over time, individuals can gather information about how they are responding to everyday situations. With this information, the individual can gain insights into potential stressors and also determine if they need to spend more time prioritising recovery.
HRV has also been linked to several health conditions including diabetes, autoimmune disorders and cardiorespiratory conditions. Furthermore, there is strong evidence HRV can be used as an indicator of mortality.