Yoga & Hypertension
Understanding how the heart functions
Blood is the carrier of Oxygen and nutrition in human body, prerequisites for us to survive. Heart pumps the carbon dioxide laden blood to the lungs and passes the oxygen rich blood from the lungs to the arteries. Arteries are part of a system called blood vessels – tube shaped structures that are semi-elastic in nature that help carry blood throughout the body. Our bodies are made up of a network of blood vessels: arteries, veins and capillaries, over 95000 kms long. Our heart pumps more than 7500 litres of blood every day through this network of blood vessels. Heart rate defines the number of times our heat beats per minute. When the human body is at rest it should beat between 60-100 times a minute, for an average healthy individual, while it goes down to even 40 a minute for an athlete. Blood pressure is the force with which the blood is pumped to the arteries as a result of the heart beat. Our heart has to work continuously to make sure we stay alive.
Heart is a muscle and like any other muscle if used well it will grow in strength. A strong heart is very important as its primary function is to pump hard enough to make sure blood reaches to the farthest corner of the body (even though it is aided by strategically placed valves throughout the body) and to beat enough times so that it can sufficiently oxygenate the blood.
If the heart is strong it can race up during heightened physical activity and return to a normal state very quickly and efficiently without causing any damage to other organs of the body. It needs to race up because during an increased physical activity muscles require more oxygen. Hence it pumps faster to oxygenate the toxic blood when needed. Once the oxygenation is done the fresh blood needs to travel throughout the body, so there has to be a certain force with which heart would pump the blood at every beat. When this force is more than normal (normal being measured in two parts – 120/80 mm-Hg) blood vessels experience increased pressure on its walls and that is what we know as high blood pressure or hypertension.
Why blood pressure goes up?
Many factors are responsible for our blood pressure to go up. Say for example age. With age the heart grows old and weak like other organs of the body. Or when we are on a high sodium/salt diet for a prolonged period, we damage the functioning of the kidney. Kidney starts retaining water instead of passing it out to the bladder as urine. This water mixes with blood and increase the volume of liquid passing through the blood vessels – this increases pressure on the blood vessels. Choked lungs due to smoking, or clogged arteries and veins due to cholesterol and other depositions again puts lot of stress on the heart. It has to work that much harder to get enough oxygenated blood in the system.
How does Yoga help ?
Practice of yoga has been regarded as an antidote to high blood pressure. The reason is yoga practice build up the muscles of our heart by using it in a controlled manner. During the cyclic movements such as Suryanamaskar the heart beat increases gradually, also while going into a new posture first few seconds when the muscle goes through extreme discomfort the heart beat increase while in middle of a pose - when we align the posture and breathe and hold the pose the heart rate wants to come down a little. Again as soon as we do a strength posture like Chaturangadandasana the heart would increase its activity as muscle of arms, shoulders are quite extensively used while if we go to Bhujangasana after Chaturangadandasana heart may relax a little. So this constant racing up and calming down of the heart strengthens its muscles. Strength in the muscularity of heart improves the ease with which it can push blood to the arteries and hence the blood pressure remains normal. Also body movements, up and down, side bindings, twists, binds and releases improves the blood circulation. So impacting the blood circulation in a positive manner eases the burden on the heart as well.
This continuous slow increase and drop in heart rate is very unique to Yoga as compared to other forms of physical exercises. Constant movement, holding, stretching and strengthening of muscles require the blood to be oxygenated at quick intervals hence aiding the oxygen levels in the blood.
Pranayama with its breathing patterns take in lot more oxygen into the system than a normal breath would do. Hence the lungs can provide more oxygen to the blood at one go. Since the blood is oxygenated in fewer pumps the heart rate drops; providing your heart with required rest.
However, those who already have high blood pressure should avoid sudden increase in heart rate by joining a yoga class in the middle or 10-15 min late. In the first 10-15 min you have slow movements, warm up, Suryanamaskar etc. and the body is slowly adjusting to the increased activity; to jump in when the whole class is at a different level of activity shocks the heart as well as the blood vessels.
Also one should be careful as to how you bend forward and go down in Yoga poses. Hasty movements should be avoided. Take time to do a forward bend by first holding the posture half way before going down. If the posture requires you to put the crown of the head or the forehead down, see if it is possible to use your chin to hold head straight. Inversions and downward movement should be done with caution because blood vessels of the eye and that of the brain are especially sensitive.
Now blood pressure has three stages one must be aware of the current pressure, how high is your high BP. If the systolic pressure is between 120–130 or a diastolic pressure between 80 and 89 it is still in the pre-hypertension zone. At Stage 1 Hypertension 140–159 movements to be done with extra caution and if it is Stage 2 - 160 and up then avoid headstand, Sarvangasana and other inversions; also consider going half way only in all forward movements.
Systematic changes in lifestyle by eating the right kind of food, reduced intake of nicotine and regular practice of Yoga will keep your heart in a good shape – regular practice is the key to reduce your dependence on medication.