Two college wrestlers square off on the mat awaiting the signal that will begin their match. To the casual observer, the outcome seems impossible to predict. Their coach, however, knows one competitor has a clear advantage—a heart rate variability level (HRV) that is higher than his opponent’s. Examining HRV data provides more than insight into athletic performance, it offers a window into a broad spectrum of functions that influence psychophysiological health.
In simple terms, HRV is the natural variation in the intervals between each heartbeat over time. Unlike a ticking clock, our hearts do not beat at a constant rate. As such, variations in heart rate can provide a wide range of valuable information on our bodily systems. This is because HRV represents a balancing act between our sympathetic and parasympathetic nervous systems, which together make up the autonomic nervous system. As we have discussed in previous posts, the autonomic nervous system controls nearly all the body’s involuntary functions.
The sympathetic nervous system is activated in times of stress or danger (i.e., the fight-or-flight response), during which our bodies sweat, our heart rates increase, and the interval between beats decreases. Conversely, the parasympathetic nervous system acts as a sort of switch, shutting down the sympathetic nervous system and activating a relaxed state (i.e., rest and digest). To do this, it releases acetylcholine, a neurotransmitter that makes the heart beat slower and at greater intervals.
When these two systems are in balance, they produce higher HRV through a more variable heart rate. Greater variability has been associated with the body’s ability to switch between these systems. Thus, HRV is used as a health marker, such that high HRV is associated with better cardiovascular health, mental focus, emotional health, stress management, and ability to recover from exercise, while low HRV is associated with inflammation, chronic fatigue, increased stress, depression, and chronic pain.
HRV has also been connected to willpower and is a predictor of persistence and self-control. HRV increases during periods of self-regulation sometimes called the “pause and plan response.” As such, HRV has been particularly useful in research into the mechanism associated with addiction. A 2019 study used HRV to explore how chronic pain patients treated with opioids could regulate drug cravings and depression through dispositional mindfulness. Electrocardiogram (ECG) data were sampled with a BIOPAC data acquisition unit while HRV was calculated with AcqKnowledge software.
Because HRV plays such a critical role in physical and psychological health, several studies have investigated how to self-regulate HRV, including examining how it is affected by posture. A 2020 study used a 2-channel BSL data acquisition unit to gather ECG data to calculate HRV for a variety of bodily positions to determine their impact.
A similar study examined the link between HRV and resilience, i.e., the individual’s ability to return to stable physical and psychological equilibrium after experiencing stress. HRV calculations were made from data gathered via a BIOPAC ECG100C ECG amplifier, RSP100C respiratory amplifier, and EDA/GSR amplifier. The study identified possible trends connecting resilience factors and HRV levels during specific stress-inducing simulations.
Calculating HRV with BIOPAC hardware and software solutions provides researchers with a myriad of psychophysiological insights for their lab work. Learn more about HRV from our Knowledge Base entry, as well as application notes on data preparation for analysis and statistical and geometric measures.
For additional information on how BIOPAC can assist you with a wide range of research and educational applications, contact your local sales representative.