What is LF/HF?
LF is an abbreviation for Low Frequency and refers to the wave measured based on the blood pressure fluctuations mentioned above. HF is an abbreviation for High Frequency and refers to the wave measured in synchronization with respiration, as described earlier. These two components are compared when estimating the balance of the autonomic nervous system from heart rate variability. LF appears in heart rate variability when either the sympathetic or parasympathetic nervous system is active. In contrast, HF appears in heart rate variability only when the parasympathetic nervous system is active.
What is the autonomic nervous system?
It plays a role in regulating bodily functions that cannot be consciously controlled, such as heart rate, blood pressure, digestive activity, and body temperature regulation. It is the counterpart to the motor nervous system, which controls muscle movement through conscious intent. The autonomic nervous system is divided into two branches: the sympathetic nervous system and the parasympathetic nervous system. When the balance between these two systems is disrupted, symptoms commonly referred to as autonomic nervous system dysfunction may occur.
What is the sympathetic nervous system?
It is a branch of the autonomic nervous system. The sympathetic nervous system becomes active during periods of activity and causes effects such as pupil dilation, facial pallor, sweating due to tension, and stimulation of respiration and cardiac activity. As a result, when the sympathetic nervous system is active, increases in heart rate and blood pressure are observed. Conversely, bodily functions not directly related to intense physical activity—such as gastrointestinal movement (intestinal peristalsis and digestive fluid secretion) and activity of the genitourinary system—are suppressed. In addition, activation of the sympathetic nervous system triggers the secretion of the hormone adrenaline. Adrenaline amplifies the excited state described above. The sympathetic nervous system is also activated during REM sleep, a state in which dreaming frequently occurs.
What is the parasympathetic nervous system?
It is the other branch of the autonomic nervous system.
The parasympathetic nervous system becomes active during restful, relaxed states, such as when sleeping. When the parasympathetic nervous system is dominant, pupil constriction occurs, heart activity is suppressed leading to a decrease in heart rate, and blood pressure is reduced.
In contrast, gastrointestinal peristalsis, secretion of digestive fluids, and activity of the genitourinary system are promoted.
Therefore, the parasympathetic nervous system can be described as the system that helps restore the body by creating conditions suitable for recovery after activity. However, even when the parasympathetic nervous system is dominant, the sympathetic nervous system continues to remain active at all times, sending stimuli to various organs.
Data analysis application
We have launched a web application that allows you to try calculating LF/HF, an index of autonomic nervous system balance.The link to the Web Application is here.If you would like to try using it, please contact us through the inquiry page. We will provide instructions on how to use the application. Additionally, feel free to send any requests or feedback regarding the application.
引用
Note 1: The Science of Stress and the Autonomic Nervous System – What is Heart Rate Variability? What are Heart Rate Fluctuations?
―(https://hclab.sakura.ne.jp/stress_novice_hartrate.html)
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