Jul 182015

We have seen examples where the respiration rates for experienced meditators are lower than those for novices. What about patterns of inhalations and exhalations? Plotting the average respiration waveform for a novice (<200 hrs) and an expert meditator (>5,000 hrs), we see that the exhalation time is 50% longer than the inhalation time for novice and 70% longer for the expert.


comparison of respiration waveforms

Ratio of exhalation to inhalation time for novice is 1.5 while for expert is 1.7.

Furthermore, the expert breathes much more deeply than the novice, as indicated by the difference in pressure from the bottom of the exhalation to the top of the inhalation.


Jul 172015

The plots below show electrocardiogram and respiration signals for a 20-second segment of meditation.

Heartbeat and respiration

Heartbeat and Respiration during meditation. Note the increase in amplitude of the ECG signal during exhalations.

During exhalations, the amplitude of the waves in the upper plot (the sharp spikes in the electrocardiogram, known as R-waves) increase while they decrease during inhalations.

A comparison of ECG signals for a novice and an experienced meditator are shown below.

novice meditator

Heartbeat and respiration for Subject 8, a relatively inexperienced meditator. Amplitude of R-wave increases by ~10% during exhalations.


experienced meditotor

Heartbeat and respiration for a highly trained meditator. Amplitude of R-wave increases by ~50% during exhalations.


For novice meditators, this effect was small (roughly 10% change in R-wave amplitude, as shown in the upper figure, above). For highly trained meditators the effect was quite pronounced (roughly 50% as shown in the lower figure, above).

The amplitude of the R-wave is an indicator of the strength of the signal from the heart when the left ventricle is forcing blood out to the rest of the body. The electrical resistance of the body between the heart and the ECG electrode on the surface of the skin changes as the lungs fill with air and then collapse. After consulting with a cardiorespiratory expert (an anesthesiologist), I have concluded that this dramatic change in R-wave magnitude reflects the deeper breathing of the trained meditator—as the intrathoracic cavity collapses during exhalation, the gap between the heart and the outer surface of the body (where the ECG signal is measured) shrinks, thereby reducing electrical resistance and resulting in an increased amplitude of the R-wave.

Jul 162015

In the following plot of respiration during meditation, we see a regular repetition of inhalations and exhalations with a wave-like quality.

Recording of breath during Zazen meditation

My breath recorded on the 7th day of a meditation retreat.

Selecting a range of cycles, we can average the values centered around the peaks to extract a waveform that represents the entire range. Averaging over 12 cycles, we get the following:

Respiration waveform

Average waveform of the breath for subject S1 (myself) at the end of a 7-day meditation retreat

An interesting aspect of this waveform is that the exhalations are almost twice as long as the inhalations. Here, one complete cycle is 19 seconds long which corresponds to 3.2 breaths/minute. Compare this with the waveform for reading:

Reading waveform

Average waveform of the breath for subject S1 quietly reading

Jul 152015

To compare respiration rates for meditation and non-meditative activities, I recorded my breath using a Vernier LabQuest device connected to a gas pressure sensor and a respiration monitor belt. the first plot below shows my respiration sitting quietly and reading. The second plot is a recording of meditation during the 7th day of a meditation retreat.

Respiration while reading

Respiration while sitting quietly and reading. Breath rhythm was variable. Occasionally I took a deep breath. Average breathing rate was 14.6 breaths/min.


Recording of breath during Zazen meditation

Breath recorded on the 7th day of a meditation retreat. Breathing rate was 2.85 breaths per minute.

Below is a comparison of breathing rates for various other activities.

Respiration Rates

Comparison of respiration rates for various activities, including meditation.

Clearly my zazen practice is characterized by a slower breath rate compared to other activities during the day.


Jun 162015

In September 2014 I enrolled in an online course Exploring Neural Data offered by Brown University via coursera.org. The basic premise of the course was that students would be able to access data coming from various neuroscience labs around the country and learn techniques for analyzing that data, forming hypotheses and testing them. Participation in the course required learning the Python programming language. It sounded like an opportunity I couldn’t pass up. I had already completed two coursera online courses, Duke University’s Medical Neuroscience and Hebrew University of Jerusalem’s Synapses, Neurons and Brains, which gave me a bit of orientation to neuroscience (my background is physics and astronomy). I also discovered some good online tutorials on Python, so I could start familiarizing myself with a new language.

The final project for the Exploring Neural Data course was to apply some of our programming skills to a new data set. I chose to collect respiration and and electrocardiogram (ECG) data for subjects during meditation and reading. I chose to develop a new application I called the Cardiorespiratory Viewer. Written in Python, using the Anaconda Spyder programming environment, it imports program modules from the Tkinter, numpy, scipy and matplotlib libraries. The application reads data files generated by the LabQuest recorder, displays simultaneous plots of EKG voltage and breath pressure, and enables the user to specify time segments and signal threshold levels for analysis.

Cardiorespiratory Viewer

Program for displaying and analyzing ECG and respiration signals

PDF for final project, Exploratory Investigation of Cardiorespiratory System during Meditation


Jun 112015

For the past 15 years or so, I have maintained a daily meditation practice. My morning routine includes yoga stretching and 20-25 minutes of sitting meditation. During meditation, I usually start by counting my breaths. If and when my mind quiets down, I transition to following my inhalations and exhalations, and being aware of bodily sensations and sounds in the environment. Some days I’ll sit again just before bed. I find this routine is good for maintaining perspective on the concerns that come up during the day. It helps reduce frenetic mental activity and brings me to a place of calm.

In addition to daily practice, for several years I have participated in 7-day intensive meditation retreats, or sesshins, three or four times a year at the Tahoma Zen Monastery in Freeland, Washington. The daily schedule of sesshins includes about 7 hours of formal sitting zazen meditation plus “applied” zazen in activities such as chanting, silent meals, work, exercise and listening to a dharma talk by the Roshi, or Zen teacher. I find that after several days of meditation, such as during sesshin, my mind grows distinctly more calm. Generally, by the 3rd or 4th day, I experience periods of clarity in which the usual random jumping from one thought to another ceases and gives way to simple awareness free from internal dialog.

When I am not meditating, I tend to identify with my thoughts and feelings. The desire for a cup of coffee is MY desire. The insomnia is MY regret. The cramp in my leg is MY pain. Opinions about presidential politics are MY opinions. For me, counting breaths is a tool for disengaging from the identification process: desires, aversions, pain and opinions are what they are but the additional step of making them mine is optional. Meditation seems to reduce the feeling of drivenness of mental activity. If I find myself unable to maintain the count of breaths, it’s usually because I have become hooked on some random thought and caught on following a chain of connections from one thing to the next, far removed from the present moment. By gently returning to the awareness of the breath over and over again, these excursions gradually become less enticing.

Each day of a sesshin at Tahoma has a Golden Hour from 6:00 – 7:00 pm in which participants sit without changing posture for the full hour. Typically, I find that during Golden Hour the first 2-3 days, my practice is rather disrupted—I am pulled around by all kinds of thoughts. But by the 4th or 5th day, I can sometimes experience a clear mind. Occasionally I try to monitor this quality, by starting my count at the beginning of the hour and trying to maintain it for the full hour. Usually for the first few days of a sesshin, this is impossible—I frequently lose track of the count. But toward the end of a sesshin, I can sometimes count my breaths without interruption. The advantage of this technique is that I am less able to tell myself I am meditating when in fact I’m engaged in reverie.

I was surprised to find that I was having only 170-190 breaths in 60 minutes, or about 3 breaths per minute. It seemed much less than when I’m doing other things and not meditating.

One aspect of zazen instruction is deep breathing—on each exhalation to expel all the air from the lungs before taking an inhalation. Naturally, the inhalation brings in more air after a complete exhalation than it would during shallow breathing. I was interested in this experience of deep breathing at a slower rate and wanted to measure it with a recording device and see the data in a graph.