The term "stress level" can be interpreted in a variety of ways in the modern world. Actually, everything that happens to your body in a state other than rest may be considered stress. Since our body can adapt skillfully, a good part of external factors exert no negative effect on us.

Excessive physical exertion, strong or prolonged psychological (emotional) stress, ambient temperature (for example, a sauna), a sudden rise in body temperature, driving in traffic for a long time, etc.—all these things may affect your body. How do you conduct a stress level test?

One of the ways is to measure the stress index, also known as stress index of regulatory systems or the Baevsky index, which helps evaluate the heart rhythm variability. This parameter characterizes the status of the centers regulating the cardiovascular system, i.e., both the general functional state of the body and the baroreceptor apparatus, especially during orthostatic tests (changes in the body position). In simpler words, it helps you learn how well your body can adapt to changes in the environment.

In the human body, the pressure is constantly changing for a variety of reasons, but the pressure in the aorta must be constant. The body has the only way to regulate pressure—to manage the pulse rate. If the baroreceptor apparatus works well, i.e. the stress is low, the pulse rate will be constantly changing: at the first beat it will be, say, 58; at the next, it will bw 69, and so on. (Of course, you can find out the pulse rate from a single heartbeat by measuring the duration of a single pulse wave). When your body experiences stress, the pulse rate will remain constant over a long time.

AngioCode visualizes the stress index by means of the diagram where the vertical axis shows the number of beats (with a certain frequency) and the horizontal axis shows the frequency (or the time/length ratio of the pulse wave).

The example on the left indicates a satisfactory functional state of the patient. In the diagram you can see an express variability of the heart rate. At rest, the act of breathing "forces" the number of heartbeats—and therefore the duration of the pulse wave—to adapt.

The picture to the right is an example of a test protocol in a subject with a highly unsatisfactory general functional state of the body. Such a situationmay occur either in marked sympathicotonia or in impaired production of nitric monoxide. There is another way to evaluate the stress index: using a simple quantitative algorithm.

The table below gives the stress level values:

Note: This index is not applicable in arrhythmia, severe respiratory dysfunction, since the stress level in this case will be false-low.