More Love for Baroreceptors: Supporting Your Head in Restorative Poses

by Nina

When I first starting taking yoga, I was confused about why my teachers were always rushing put to a folded blanket under my head when I was lying on my back. Something about the position of my head when I was lying on the floor was driving them crazy, but what was it? And why was it such a problem?

Later I learned that they were adding this support because, when my head was flat on the floor, due to tightness in my shoulders, my neck was arching up and back and my chin was tipping away from my chest. Putting the folded blanket under my head allowed me lie with my chin pointing toward my chest like this:

This was considered to be the proper--and healthy—position for the head in supine poses. So I went along with it. But secretly I continued to wonder why. In case you have already noticed, I'm like that—always wanting to know the whys as well as the hows, always wanting to dig a bit deeper. Which is probably why I ended up as a yoga blogger, but I digress.

Anyway, it was only when I learned about baroreceptors that I found a satisfactory explanation. As I mentioned yesterday (see Why You Should Love Your Baroreceptors), when your neck is slightly flexed (the position when your chin is pointing toward your chest), the position puts some pressure on the baroreceptors in your carotid arteries. And this pressure can cause the same response as an inverted pose does on your nervous system—switching you from fight or flight to the relaxation response. The opposite neck position with your neck in extension (a backbend position with your chin tipping away from your chest) can have the opposite effective, stimulating your nervous system.

Of course, this understanding of the role of baroreceptors in yoga poses is very recent. In fact, the understanding of the role in regulating blood pressure in general is pretty recent as well. So the yoga teachers, like B.K.S. Iyengar, who developed restorative yoga discovered the best position for the head through personal observation, not science. (That says a lot about personal observation, doesn't it?) Interestingly, the head position Jalandara Bandha, with neck flexed and chin pointing down toward the chest, used in seated poses for pranayama, which is much older than restorative yoga, was probably adopted for the same reasons. Yoga practitioners noticed that head position enhanced the quieting effect of the practice.

I thought I'd tell you all this not just because you might not have made this connection on your own, but because I also realized there might be some people out there who don't have teachers running to put a folded blanket under their heads every time they lie in a supine restorative pose. So that's both the how and why for you. The how is that when you lie on your back, if your chin does not easily point down toward your chest, always add some support under your head. The why is that having your chin pointing down toward your chest will enhance your relaxation due to slight pressure on your baroreceptors.

Long live head support!

Why You Should Love Your Baroreceptors: Stress Management Made Easy

by Nina

I found this nice little illustration of baroreceptors that I'm excited to share with you. Okay, I admit it, I'm a little obsessed with baroreceptors. But that's because ever since I found out how our baroreceptors help regulate our blood pressure and I understood how we can use this aspect of our anatomy to switch our nervous systems from fight or flight to relaxation mode, I've not only included supported inverted poses in my practice on a regular basis but I've been on a mission to spread the word. Using supported inverted poses for stress management is one of easiest ways—at least for me—to calm yourself down because all you have to do is set yourself in the pose and stay there for a while. The shape of the pose itself causes the baroreceptors to work their magic.

As I wrote in my post Just in Time for the Holidays: Inverted Poses, the reason that inverted poses trigger the relaxation response is due to the pressure sensors called baroreceptors that are connected to the nerves controlling your heart rate and blood pressure. Your baroreceptors are located in the wall of each internal carotid artery at your carotid sinus (the arteries on each side of your neck that carry blood from your heart to your brain).

And in the wall of your aortic arch (just above your heart).

Aortic Arch

These baroreceptors detect any changes in your blood pressure, stretching when your blood pressure is high and shrinking when your blood pressure is low. If your baroreceptors detect a fall in your blood pressure, they send signals via your nerves to increase your heart rate, constrict your blood vessels to raise your blood pressure, and switch your nervous system to fight or flight mode. Likewise, if your baroreceptors detect abnormally elevated blood pressure, they send signals to slow your heart rate, relax your blood vessels to lower your blood pressure, and switch your nervous system to relaxation mode. And now I have a picture to illustrate this!

In an inverted pose, your heart is higher than your head, the opposite of its position when you are upright. With your heart higher than your head, gravity causes more blood to flow in the direction of your head, creating more pressure than usual on your carotid sinus and aortic arch. As the arterial pressure is increased, your baroreceptors are stretched and signals are transmitted to your central nervous system as if your blood pressure was high throughout your body. Feedback signals are then sent back to your body to reduce the arterial pressure, slowing your heart rate, relaxing your blood vessels, and releasing hormones that decrease adrenaline production. This automatically switches your body to relaxation mode.

Because there are baroreceptors in your carotid sinus (the arteries on each side of your neck that carry blood from your heart to your brain) inverted or partially inverted poses where your neck is flexed (that is, your chin is pointing toward your chest), as in Shoulderstand, Plow pose, or Bridge pose, puts added stimulation on your baroreceptors, which may enhance the calming effects of the inversion.

Any yoga pose where your heart is above your head is considered to be an inversion. Inverted yoga poses include full inversions, such as Headstand and Shoulderstand, where your heart is directly over your head and the rest of your body is also fully inverted. Partial inversions, such as Downward-Facing Dog pose and Standing Forward Bend, where your heart is less directly over your head and your legs are either not fully or not at all inverted, are also considered inverted poses and will have similar calming effects. As long as you are warm, quiet, and comfortable in the inverted pose, all you have to do is let the baroreceptors work their magic. Naturally, supported versions of the poses (such as Shoulderstand with a chair or Bridge pose on blankets) are more relaxing than the versions of poses in which you must support yourself, so if you’re practicing inversions for stress reduction, choose the supported versions. See Just in Time for the Holidays: Inverted Poses for a complete list of the inverted poses.

I'm such a believer in these poses that I recently had a friend (thank you, Erin Collom) take photographs of me doing all the supported inversions, so I could write in detail about the individual poses. For now, here's a photograph of a Supported Standing Forward Bend, a surprisingly calming pose.

Caution: Inverted poses may be unsafe for those with certain medical conditions (see here).

9/11 Anxiety and Yoga

by Baxter

Some years ago, when Nina and I were working on a series of yoga classes for stress management, I read the book The Relaxation Response by Dr. Herbert Benson, and an interesting finding from the work he did has stuck with me. He noted that his blood pressure patients who meditated regularly not only saw improvements in their blood pressure readings, but they also had certain substances in the blood stream that increased or decreased.  One of those substances was lactate, or lactic acid, which is a byproduct of cells using sugar or glucose for fuel. It had already been noted back in the 60s that folks with anxiety disorders often had elevated levels of lactate in their bloodstream compared to individuals without anxiety. Since meditation seemed to lower lactate levels, it seemed like a great potential treatment.

More recently, an article in Scientific American looked at lactate and other markers in the body that could account for why some folks develop panic disorders, an extreme form of anxiety. Studies done in the last two years point to the pH in the brain as a possible causative factor in the experience of fear, and by extension, anxiety. It seems a more acidic pH in the brain is associated with more active trigger of the fear centers in the brain. In fact, there are receptors at individual synapses, the spaces between to nerve cells, that respond to elevated levels of acid. In the area of the brain strongly associated with the emotion of fear, the amygdala, this increase in local pH can trigger fear responses.

They also noted that carbon dioxide levels, when increased in the blood stream and the brain, lead to greater acidity. And other studies have demonstrated that patients with panic disorders are more likely to have an event if they inhale a higher concentration of CO2, compared to non-anxious individuals. These researchers also addressed the lactic acid phenomena that Dr. Benson noted years before: patients with panic disorder tend to generate excess lactic acid in their brains. We all generate lactic acid in our brains as sugars are burned as fuel, but in people with panic attacks, even normal mental activity to lead to an accumulation of lactic acid in the brain.

So if an increase in pH in the brain could be a trigger for anxiety and panic attacks, either due to a real or simply a perceived danger, whether due to CO2 build up or lactic acid build up in certain areas of the brain, how could yoga diffuse this situation? Well, way back in the 60s it was already observed that the “relaxation response” that arose from simple meditation practice could lower the pH in the blood stream. This might indicate that it could be lowered in the brain, too. So I’d give high marks to establishing a regular meditation practice, even if only for ten minutes at a time. Secondly, certain pranayama practices could theoretically lower blood CO2 levels slowly and gradually, especially those that favor a longer exhale over inhale ratio.  hat sounds like it would be worth a trial as well. And finally, the authors of the study noted that: “one of the many beneficial effects of aerobic exercise training (like running or cycling) is that metabolically active tissues (including the brain) become more efficient at consuming–removing—lactic acid.”  And although not all yoga asana practices are aerobic, some are to a certain degree. So, physiologically, your asana practice, especially if it is more vigorous, could be the third prong in your yoga tools approach to anxiety, panic attacks and fear.

Here is a link to the 2010 SA article here so you can get more details on the work I’ve alluded to: scientificamerican.com. And may you and yours be safe and anxiety free this 9/11 anniversary.