Your Autonomic Nervous System
Your nervous system is divided into nerves
that control voluntary movements (mainly muscles) and the Autonomic Nervous
System (ANS), which regulates individual organ function and homeostasis, and
for the most part is not subject to voluntary control. The ANS is divided into
two separate divisions called the Parasympathetic (PSNS) and Sympathetic
(SNS) Systems, on the basis of anatomical and functional differences.
Most of your organs are controlled by
both divisions of the ANS and the influence is usually opposing (e.g. the vagus
slows the heart, whilst the sympathetic nerves increase its rate and
contractility). In physiological terms,
the parasympathetic system conserves and restores energy as it causes a
reduction in heart rate and blood pressure, facilitates digestion and
absorption of nutrients, and consequently the excretion of waste products.
In contrast your sympathetic system
enables you to be prepared for fear, flight or fight. Sympathetic responses
include an increase in heart rate, blood pressure and cardiac output, a
diversion of blood flow from the skin and organs to those supplying skeletal
muscle, increased pupil size, bronchial dilation, contraction of sphincters and
metabolic changes such as the mobilization of fat and glycogen for immediate
energy.
It
is important to realize that the tissue between individual cells is where the
ANS ends. This connective issue bathes
every cell and regulates their function.
ANS messages travel both directions and become a dialogue
between tissues throughout the body and your central nervous system. Thus, your ANS controls immune support,
nutrient delivery, detoxication, blood flow, and oxygenation (via
vasodilation/constriction). Monitoring
the state of your ANS thus becomes a powerful tool that guides us toward
optimizing cellular function and thus your overall health, even when you seem
to “feel fine.”
Using Heart
Rate Variability (HRV) to measure your ANS
HRV analysis is based on measuring
variability in your heart beat. On an
EKG, one way to measure the heart beat rate is to count the R wave spikes. However, there are subtle differences in the
time between each beat and this is the basis for HRV, which measures the “R to
R intervals.” These RR intervals can be
analyzed into to a relationship between the two divisions of the Autonomic
Nervous System:
- The
Sympathetic Nervous System (the tone is represented on the vertical axis up
and down; higher is stronger)
- The
Parasympathetic (Vagal) Nervous System (the tone is represented on the
horizontal axis left or right; rightward is stronger)
Thus, HRV is a measurement of the
interaction between sympathetic (i.e., "fight or flight" energy
mobilization; much like the gas pedal on your car) and parasympathetic (i.e.,
the opposite of the sympathetic activity or "relaxation" response;
the brakes). Our Nerve-Express program
provides a “fingerprint” of your Autonomic Nervous System (ANS) based on Heart
Rate Variability (HRV) analysis.
Nerve-Express is the only system that enables precise recognition and
classification of 74 ANS states. The
algorithms used by Nerve-Express have been developed and tested for over twenty
years in studies involving more than twenty thousand patients.
A proper evaluation requires measurements
in at least two different situations.
Nerve Express uses a popular method to provoke an autonomic response –
stand upright from a lying (supine) position.
Any physical or mental dysfunction will reflect as an inadequate ANS
response. For example, introverts tend to have an increase in the vagal tone
upon standing. Those with an ANS
component to their GI distress will show a decrease in vagal tone from above 0
while lying down to an insufficient tone (< 0) when standing upright.
What use is
an HRV?
Measurement of heart rate variability
(HRV) provides a non-invasive way to obtain reliable and reproducible information on your autonomic nervous
system’s influence on the heart and has become an important tool for risk
assessment. Measurement of HRV may also be used to evaluate the effects of treatments.
Research has shown that emotions are reflected in our heart rhythm patterns. The analysis
of Heart Rate Variability (HRV), or heart rhythms, is recognized as a powerful
measure that reflects heart-brain interactions and autonomic nervous system
dynamics, which are particularly sensitive to changes in the emotional state.
Clinical research identifies HRV as a key indicator of preventable stress and
shows correlation with a broad range of related health problems. For example, studies have shown that smokers
have increased sympathetic and reduced vagal activity as measured by HRV
analysis. HRV is reduced following acute
ingestion of alcohol suggesting sympathetic activation and/or parasympathetic
withdrawal.
How Do I interpret my Nerve Express HRV and Physical
Fitness Evaluation?
The picture below is an
example of a HRV print-out showing a graphic representation of your Sympathetic
and Parasympathetic Nervous Systems. The
upper half of the page shows a Rhythmogram of the R-R intervals between 448
heart beats. From this graph of each R-R
interval, three main components are seen:
HF: all parasympathetic (PSNS)
LF1: sympathetic
& parasympathetic
LF2: mostly sympathetic (SNS)
The single row of numbers underneath the Rhythmogram
show the average heart rate (HR), the high frequency/parasympathetic tone (HF),
the combined sympathetic/parasympathetic tone (LF1), and the very low
frequency/mostly sympathetic tone (LF2).
The graph on the right lower shows the
Parasympathetic/Vagal system (PSNS) when lying down (supine; with an empty
circle) and when standing upright (solid black circle) on the X-axis (right and
left). The same information about the Sympathetic system (SNS) is shown on the
Y-axis (up and down). Using a scale of
-4 to +4, ANS balance would be represented as each axis having the same numbers
(for example 0.0, 1.1, 2.2, etc) as would be found in the gray box. However, in this example the SNS turned on too
much and the PSNS turned down too much when the patient stood up. This response to standing shows two features
of an unfavorable health status: