The health and functioning of the human body depends primarily on the adequate supply of glucose and oxygen for energy production. We get glucose through the process of digestion in the digestive system and oxygen from the air we breath in through the respiratory system. The glucose and oxygen should reach all the distant body cells. This function is carried out by the circulating blood. The blood is continuously in motion, never static or stagnant. Proper blood flow to all body parts is essential as they are dependent on the blood for the supply of glucose and oxygen.
The heart carries out the vital function of pumping the blood in the arteries and keeping it in circulation. On the other hand blood from various body parts is collected through the venous circulation and returned back to the heart.
When the heart pumps the blood in the arteries it is under pressure, but as it circulates through the body the blood pressure gradually decreases. In the venous side the pressure goes as low as 40 mm of mercury. It is necessary that this blood is returned to the heart so as to maintain proper blood circulation. (as the same blood is circulated again and again )
The overall health of the human being is dependent on the optimum functioning of the body cells, which in turn are dependent on a proper blood supply.
In short one of the keys to good health is proper blood circulation in the body. It is said that yoga has an effect on the heart and blood circulation, it helps to keep the blood pressure normal. Let us consider some of the yoga techniques and their effects on circulation.
DEEP BREATHING: When we breath in the diaphragm is pulled down, due to this the pressure in the chest is reduced and on the other hand the pressure in the abdomen is increased. This causes the compression of veins in the abdomen and pushes the blood towards the chest and into the heart. During the process of breathing out the diaphragm goes up to the normal position. The pressure in the abdomen reduces. This reduction in pressure causes the blood from both the legs to be pulled towards the abdomen. In the next cycle of breathing the same blood is pushed towards the heart and the cycle continues. During the practice of deep breathing the above mentioned effect is enhanced and it improves the venous return to the heart.
KAPALBHATI: Practice of kapalbhati has a slightly different effect. It also increases the venous return to the heart but as it is practiced with a jerk there are chances of increasing the blood pressure. So practice of kapalbhati is contraindicated in those suffering from high blood pressure.
INVERSIONS: During the day we are standing or sitting and it causes some accumulation of blood in the lower parts of the body. The distance from the heart to the legs is more than any other body part. At the same time gravity always tries to pull the blood downwards away from the heart. Due to all these factors the venous return from the legs to the heart slows down. In the inverted postures like the shoulder stand and the headstand the legs are at a higher level and the heart at the lower level. So the blood flows towards the heart under the influence of gravity. Thus the venous return is increased, improving the circulation. On the other hand there are chances of increasing blood pressure. In the inverted position the heart has to pump blood against gravity, so the blood pressure can increase and inverted postures are contraindicated in those suffering from high blood pressure.
STANDING POSTURES: The warrior pose and triangle pose help in improving the muscle tone of the legs. The efficiency of the muscles is increased. It causes effective contraction and relaxation of the muscles. It causes compression and decompression of the veins in the legs. This produces a pump effect and the blood is pushed towards the heart. On the other hand the tree pose and the mountain pose increase the elasticity of the blood vessels which further improves the circulation. The stretch produced during a standing posture prevents the deposition of cholesterol and thus prevents the thickening of the blood vessels and maintains the blood pressure.
RELAXING POSTURES: In shavasana or any relaxing position the body is completely relaxed. The capillaries and the muscles are relaxed. It helps the flow of blood through the capillaries and maintains a proper circulation. Relaxation of mind and body in these positions helps to reduce the blood pressure.
In the end it is important to note that the practice of yoga can improve and maintain proper blood circulation without increasing the heart rate and the blood pressure. So if you want benefits without causing harm to yourself you have to follow the traditional style of yoga.