Heart Rate Variability (HRV)

Tech Talk by Dave Siever

Heart Rate Variability (HRV) & Audio-Visual Entrainment (AVE)

The heart beats to several of its own rhythms: within its every beat, between consecutive beats, during breathing and with every thought. For instance, with every breath we take, our heart speeds up with our in-breath (inspiration) and slows down with our out-breath (expiration). The heart also has long, slow swings that span several breaths. These slow (low frequency) swings in heart rate reflect a degree of "flight-or-fight" response, anxiety, or sympathetic activation within our bodies in relation to fears, anger, and aggression (which are also forms of fear). Rapid, small (high frequency) variations and "spiking" that show up within the natural variations in heart frequency during breathing, reflect para-sympathetic activity as the heart tries to compensate for the reduced output caused by sympathetic activation.

Therefore, we can assess heart rate variability, process its spectral properties, and see how much heart activity is normal, sympathetic, and parasympathetic. We can see what thoughts, foods, and events can trigger unhealthy heart rhythms and we can use HRV feedback to teach ourselves how to relax.

There are several HRV systems available. Two systems that I know of are the Cardio-Pro, by Thought Technology and the Freezeframer now called emWave by HeartMath. The Cardio-Pro consists of an EKG sensor and software as an add-on to the Procomp from Thought Technology. It has advanced analysis software and is meant for professional and research use.

The emWave consists of software and an optical sensor that plugs into the USB port of a computer. The emWave2 and emWave Pro both cost under $300.00 US. The emWave Pro has fairly good analysis capability for use by both professionals and the general public.

The breathing rate that is considered to be optimal is based on a ten-second breathing cycle (breathe in for five seconds and breathe out for 5 seconds), making six breathing cycles per minute. However, smaller people typically breathe around 7 breaths per minute, while larger people can breathe as low as 4 breaths per minute.

How HRV Works 
Figures 1 to 4 show data from two women (recorded on the Freezeframer). The spectral analysis window is normally viewed from a separate selection but for the sake of space, we have dropped it into the HRV-heartbeat rate display. Figure 1 has two large sections (pre-AVE and post-AVE) within it. Each of these sections contains four smaller sections.

The upper left side of each profile (in green) shows the actual heart rate in beats per minute. It would normally span across the entire top area, but we placed the spectral results (blue "mountains") over top of some of it so we could see everything on one page. The spectral results show a peak at the breathing frequency of 0.1 Hz (ten-second breathing cycles). The "mountains" on the left represent sympathetic activity while the smaller "hills" to the right represent para-sympathetic activity. These ten-second breathing cycles are paced from a synthesized "ba-bump" heartbeat sound from a Paradise XL/Delight through a set of headphones. They are 24 beats per minute played through the headphones. The user inhales for two beats and exhales for two beats, which when divided by 4 beats per breath cycle = 6 breaths per minute (bpm).

Breathing entrainment (BE) is the measure of how smooth and flowing her heart rate variability is with her breathing. BE is shown on three bar graphs, where green is the best BE, blue is intermediate, and red is poor.

Client Results 
We've seen many anxious people on the Freezeframer and the results are always the same. When their breathing is paced at 6 bpm, their anxiety shows itself after about three minutes. Their heart rate becomes erratic ("jaggedy" green lines with red sections in it) and their performance score begins to erode (small window below). The woman in Figures 1 and 2 was crying by the end of the recording. Her average heart rate was 77 and her BE score (green, blue, and red bars) was quite poor.

We gave her a five-minute break to "collect herself" and put her back on the Paradise XL/Delight, and added AVE at 7.8 Hz in addition to the heart beats. In the right-hand section, you can see that as she began dissociating from her anxious thoughts, her breathing and heart rate became smooth and rhythmic as can be seen in the BE chart area. Spectral analysis shows one beautiful meditators peak at 0.1 Hz, her breathing frequency. All sympathetic and parasympathetic activity was gone. Her performance score went straight up and her heart slowed by 5 bpm to 73 bpm. Her BE was almost perfect at "93".

Figure 1


Figure 2 is a comparison of her three sessions. Her first was free breathing (charts not provided in this example). The second was the paced, ten-second breathing cycle from the Paradise XL, and the third was paced and 7.8 Hz AVE. You can see that her free breathing was so erratic that her BE score was 0 (all in red). Paced breathing was better with some green in the bar graph, but the challenge of paced breathing forced up her heart rate. AVE assisted breathing produced close to perfect results with a slowing in heart rate as well.

Figure 2


Figures 3 and 4 are recordings from a young woman with some very serious concerns in her life as indicated in the captions included with her charts. The left side of Figure 3 was recorded during negative thoughts, and she had plenty! During these thoughts her heart rate was all over the board. The spectral analysis was all over the board with ample sympathetic and parasympathetic activity. Even her paced (ten-second) breathing really didn’t show. Her performance score was a flat 0 and her BE ratio was 100 in the poor category (red). Her average heart rate was at 99 bpm. Just five minutes later, AVE was added to the paced heartbeat heard through headphones. Notice how smooth both her breathing and heart rate rhythms became. She had an abreaction at about two minutes (the green heart rate chart became flat, then spiky) when some negative, anxious thoughts entered her mind, but as she dissociated with the AVE. her mind once again cleared and her heart rate rhythms returned. Her performance score showed the anxiety with a down-turn in her score which recovered as she dissociated from her anxious thoughts. Her spectral analysis showed a nice meditators peak with a small bit of sympathetic activity as seen on the left side. Her BE score was 65% to the green while her heart slowed by 22 bpm to 77 bpm!

Figure 3


Figure 4, like Figure 2, is a quick summary of various sessions beginning with happy thoughts, followed by negative thoughts, then the AVE session, then 15 minutes later on her own where she showed she could control her breathing very well which demonstrates that AVE helped her learn to breathe in a relaxed manner.

Figure 4