It has been rightly said that a healthy body contains a healthy mind and a healthy mind makes the body healthier. Yoga promises the same to its practitioners. By way of their actions musco-vascular and endocrine systems, yogic exercises act upon the Central Nervous System (CNS) rendering it more pliable and active. The help in curbing emotional upheavals such as anger, excitement, depression, etc.
According to sage Patanjali, Yoga has eight stages or limbs and that- is why it is known as Ashtanga – Yoga. These eight stages are Yama (moral values), Niyama (self purification), Asana (physical postures), Pranayama (control of breath), Pratyahara (withdrawal of senses), Dharana (concentration), Dhyana (meditation) and Samadhi (contemplation or state of super consciousness).
Observance of Yama and Niyama helps in controlling the emotions and passions. Asanas keep the body strong and healthy in a natural way. Pranayama, the fourth stage, teaches the aspirant to regulate the breathing through prescribed techniques which provide immense help in control of mind. Pratyahara enables one to control the senses and ensure freedom from worldly desires. The last three stages- viz Dharana, Dhyana and Samathi deal with mental faculties and help aspirant achieve the ultimate goal ie the realisation of the true self.
Yogic exercises provide the body with adequate action required for its natural development. Their action on the body is manifold. These, through their action on the musculo-vascular system provide necessary stimulation to the endocrine system (a ductless glandular system which secrets hormones required for the coordination and harmony of various body functions). In this away, they also help achieve coordinated functioning of the Central Nervous System (CNS).
As may be seen, all physical exercises are primarily designed to increase blood circulation and the oxygen intake. This purpose is served by any exercise, may it be moderate such as yogic exercises or violent like boxing or wrestling. The skeletal muscles go through a series of motions under any type of exercise.
These motions are constituted of stretching, contraction and relaxation in the given order. When muscle contracts during the exercise, the glycogen stored in the activated muscle breaks down to lactic acid causing an additional release of energy. It is then utilized for various chemical changes in the body. Yogic exercises cause metabolic changes in the muscles but owing to their moderate and scientific nature, they produce a small quantity of lactic acid in the muscles involved. The lactic acid which requires to be reconverted into the glycogen readily does so, for deep and rhythmic respiration supplies sufficient quantity of oxygen needed to oxidise it. It is for this reason that one does not feel fatigued or lethargic after practicing yogic exercises. Unlike violent exercises, they provide evenly distributed stretch to the muscle involved and activate them in a manner suitable to their proper development. Long before the scientists discovered the endocrine system, the yogis knew about the existence of certain secretions which were responsible for the regulation of various mental and physical functions of the man. These secretions have been discovered by modern scientists and are termed as Hormones. It is now scientifically established that the endocrine glands called Pituitary, Thyroid, Parathyroids, Pancreas, Adrenals and Gonads (ovaries in females and testes in males) secrete various hormones which are responsible for harmonious coordination for various bodily functions. For instance, hormones secreted by the Thyroid glands are responsible for the growth, that of Pancreas for maintaining the blood sugar level. These glands also function in coordination with each other and are interdependent and complimentary to each other. Any imbalance in the functions of one more of these glands leads to serious mental and physical disorders. Yogic exercise provide suitable mental and physical conditions required for normal functioning of these glands.