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Yoga and Heart Health by: Dr. Jess Goodman, iHeart Internal Age

Spinal flexibility is being recognized by medical science as an important heart health factor. Yoga has for many centuries promoted spinal stretching. It is said that you are only as young as your spine is flexible.
The Aorta is the body’s largest artery, carrying blood from the heart through the chest and abdomen. Published studies have shown that with increasing stiffness of the spine and trunk Aortic Stiffness increases. The Aorta runs immediately in front of the spine and Aortic Stiffness is a surrogate measure of spinal stiffness. 
Twenty years ago, Aortic Stiffness was discovered to predict risk of death from all causes and be a powerful heart health indicator. The relationship between Aortic Stiffness and heart health is well understood. The relationship between Yoga and heart health is real and needs to be better understood and promoted.
When the heart beats a pulse wave spreads out from the heart and travels along the walls of the body’s arterial tree. This pulse wave travels down the Aorta. Let’s call this pulse wave travelling down the Aorta the Primary Wave. Small reflections of the Primary Wave form as the Aorta sends branches off to the intestines (Celiac Artery), kidneys (Renal Artery) and when the Aorta divides to form the two Illiac arteries travelling to the legs. These reflections merge together to form a Reflected Wave travelling back up the Aorta to the heart. 
The Reflected Wave returns to the heart, in a young individual, just as the heart ends its contraction phase (Systole) and begins its relaxation phase (Diastole). The Reflected Wave maintains pressure in the Aorta allowing blood to flow into the arteries feeding the heart muscle (Coronary Arteries). This beautiful and subtle dance occurs with each heart beat.
Speed with which pulse wave travel is measured as Pulse Wave Velocity (PWV) and the speed a pulse wave travels down the Aorta is known as Aortic PWV. A basic principle of physics is that all waves travel faster in stiffer media. Increased stiffness of the spine leads to increased Aortic Stiffness and increased Aortic PWV. With increased Aortic PWV the Primary and Reflected Waves travel more quickly and return to the heart earlier and earlier as the spine becomes less flexible with aging, injury, illness and stress and Aortic Stiffness increases.
There are four particularly dangerous effects of increasing Aortic Stiffness on heart health.
1)    The Reflected Wave arriving early meets the outgoing Primary Wave and the two waves crash into one another. The pressures of the two waves add together, resulting in increased Blood Pressure. This is the main reason people develop Hypertension. Yoga promotes increased flexibility of the spine, lowers Aortic Stiffness and lowers Blood Pressure. Hypertension is a physical problem and medications should not be the only approach to lowering Blood Pressure. Yoga and other exercise are well known to reduce Blood Pressure but not enough doctors prescribe Yoga for their patients.
2)    When the Reflected Wave returns early, due to increased Aortic Stiffness, it creates higher pressure the heart has to pump against. This results in an increase in heart muscle thickness and in time can result in heart failure, with fluid backing up into the lungs. Regular Yoga practice will keep the heart muscle from overworking.
3)    During the heart’s relaxation period (Diastole) it is important for the Reflected Wave to help blood flow into the Coronary Arteries feeding the heart muscle. If the Reflected Wave arrives too early there will be decreased filling of the Coronary Arteries with ill effects on these arteries and the heart muscle. Yoga practice prevents heart attack.
4)    When there is increased Aortic Stiffness and Blood Pressure increases as a result of the Primary and Reflected Waves crashing into each other, the high Blood Pressure injures the walls of the very small and fragile blood vessels of the brain. Over time time this damage leads to areas of the brain being deprived of blood flow (Ischemia). On an MRI image of the brain these small but numerous areas show as pale spots and are called microangiopathic lesions. The biggest risk factor for development of Dementia is Hypertension. If you want to avoid cognitive decline and Dementia practice Yoga every day.
There is a new, simple and effective way to measure Aortic PWV and Aortic Stiffness. The iHeart Internal Age system uses a fingertip arterial pulse sensor to precisely identify the Aortic Reflected Wave in the pulse signal and calculate Aortic PWV. The age a person’s Aortic PWV corresponds to is displayed as their Internal Age. If a person has an Aortic PWV equal to the average Aortic PWV at age 30 they have an Internal Age of 30. Yoga and other exercise that mobilize the spine lowers Aortic PWV and Internal Age. The stiffer a person is when they start exercising, the more often they exercise and the more vigorously they exercise determines how quickly they will reduce their Aortic PWV.
Yoga is an art that maintains the body in a young and vigorous form. Spinal flexibility is a big part of Yoga’s benefit.


Poor trunk flexibility is associated with arterial stiffening.

Yamamoto K, et al. Am J Physiol Heart Circ Physiol. 2009. notes an association between decreased trunk flexibility and brachial-ankle pulse wave velocity, an index of Aortic Stiffness.
The review article, Human flexibility and arterial stiffness J Phys Fitness Sports Med, 6 (1): 1-5 (2017) DOI: 10.7600/jpfsm.6.1
JPFSM notes a relationship between Stiffness and Carotid-Femoral PWV, the good standard measure of Aortic Stiffness. A number of Yoga focused studies are mentioned in the article that showed little change in Aortic Stiffness with short term practice of Yoga. This is understandable in the context of Yoga causing improved flexibility through fibroblast mediated soft tissue changes occurring over several months to years.
2) ‘Twenty years ago, Aortic Stiffness was discovered to predict risk of death from all causes and be a powerful heart health indicator.’
The review article noted below is a good reference source.

Prediction of cardiovascular events and all-cause mortality with arterial stiffness: a systematic review and meta-analysis.

Vlachopoulos C, et al. J Am Coll Cardiol. 2010.

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