Last weekend I taught a Yoga Lab workshop on the anatomy of back bends. Yoga Lab is a monthly workshop at Blue Point Yoga Center that draws from the latest scientific research to understand the effects of movement and mindfulness. There are many good reasons to practice back bends, but improvement in cardiovascular health may be one of the most important, and one of the most overlooked. There are several ways that a regular practice of back bends can impact your heart and lung function. The back bends don’t even have to be deep. Moderate poses such as bridge pose or locust pose would work well.
How it works
When you practice a back bend, you are bringing your spine into extension. This is healthy for most people, especially those who sit for long periods of the day. Spinal extension stretches the muscles on the front of the body, including the diaphragm. The diaphragm, or breathing muscle, is a large, dome-shaped muscle that separates the thorax from the abdomen (Image 1). When the diaphragm contracts, the center of the dome draws down towards the abdomen and creates a vacuum in the lungs that allows air to rush in for the inhale. When the diaphragm relaxes, the air is pushed out of the lungs for the exhale. If the diaphragm is short and tight, the amount that it is able to contract will be inhibited, limiting the inhale. If the diaphragm is regularly stretched, then it will be able to contract a greater distance, maximizing the inhale. [Side note - muscles can get longer over time - future blog post coming on that topic]. Similarly, stretching all of the abdominal muscles on the front of the body during a back bend also allows these muscles tostretch to accommodate a bigger inhale.
A second way that back bends are good for cardiovascular health is the positive effect back bends have on arteries. A study in 2009 showed that individuals with greater trunk flexibility had less arterial stiffness. Arterial stiffness is linked to high blood pressure, organ failure, diabetes, renal failure and other health problems. As we age, the elastin in the walls of the arteries deteriorates and it is not replaced, leading to stiffening. However, the elastic properties of arteries are dependent on two factors - elastin and smooth muscle (see Image 2 for a schematic of an arterial wall). Once elastin degrades, the body does not repair it. But the body is capable of repairing smooth muscle, which is where stretching and yoga can help. Preserving arterial elasticity should be a priority for those wishing to maintain good health in an aging body.
The 2009 study looked at a forward fold, but there is no reason to suspect that a back bend would be any different. In fact, the major artery of your body, the aorta, lies just in front of the vertebral column. Every time you bring your back into extension, the artery, and the heart itself, are under gentle tension that can keep the smooth muscle and cardiac muscle supple and elastic. In another example, the femoral artery is a large artery that supplies the leg. As it passes from the pelvis into the thigh, it sits right on top of the psoas muscle, a deep hip flexor that lies on the front of the vertebral column (Image 3). The psoas is stretched during back bends, along with the femoral artery lying on top of it. These these relationships of muscles and arteries happen throughout the body. In many cases, when you stretch a muscle, you also stretch an artery.
There are several reasons why back bends can be considered the ‘wonder drug’ of your yoga practice. Their benefits are extensive and varied. Of course they promote healthy and strong muscles, but it is in their lesser known effects that the biggest benefits lie. Who wouldn’t want to improve cardiovascular health by adding a few more back bends into their daily practice?
Here are a few examples, from beginners to more advanced.
Thorin-Trescases N, Thorin E. 2016. Lifelong cyclic mechanical strain promotes large elastic artery stiffening: increased pulse pressure and old age-related organ failure. Canadian Journal of Cardiology 32:624-633.
Yamamoto K, Kawano H, Gando Y, Iemitsu M, Murakami H, Sanada K, Tanimoto M, Ohmori Y, Higuchi M, Tabata I and Miyachi M. 2009. Poor trunk flexibility is associated with arterial stiffening. Am J Physiol Heart Circ Physiol 297:H1314-H1318.