Anatomy and Physiology of Hatha Yoga
When you practice yoga, especially hatha yoga, you find yourself dealing with that same object which you met first when you were born and will leave last at the moment of departure. While practicing yoga process you learn to master this object and use it and transcend it… but first of all you have to know it. In hatha yoga you deal with the most familiar and yet most mysterious of all objects – you deal with your own body.
This gross body is the seat of the soul, its vehicle, and medium through which it interacts with the surrounding world. In the yogic tradition it is said that no liberation or self realization can be attained without having a gross body and experiencing the different states it allows us to go through. One can buy new clothes every day, change a car every month, move to a new house every year, but has this one and only one body during all lifespan. Despite being the first object to encounter and last to leave, our body and many of its parts, reflexes, and mechanisms remain enigmatic to many of us, even though we are this body’s everyday-users.
If for everyday ordinary life you need only the body’s users’ manual, yogis need a much more detailed one, a kind of developer’s manual. In this series of articles we’ll try to shed a light on these sides of our bodies’ anatomy and physiology that we need to know as yogis to enhance our practice.
1 origin 2.joint 3.insertion
Any conscious movement of the body involves at least 3 body systems: the nervous, the musculoskeletal and the cardiovascular`. The conscious order to move any part of the body is generated in the cortex of the brain; it is then transmitted by motor neurons that are a part of the spinal column and form the ventral root of the spinal nerves. These nerves deliver the order to the muscles and the muscles contract. Muscles are inserted in the skeleton in such a way that their contraction causes the body to move (pic. 1). They are usually attached from one side to a fixed bone (this place called origin) and from the other side to a movable end (point of insertion) with a joint between. But for the contraction to take place energy is needed, and this energy is supplied by the blood vessels in the form of oxygen and nutrients. But the job of the nerves is not completed yet. There are special sensory nerves that transmit data from the muscle to the brain to give it feedback about the state of the body and prevent any damage that might take place because of hyper-contraction or hyper stretching.
The proprioceptors allow the brain to know the exact place and state of our muscles and what they are doing, without having to consciously monitor their movement and position or look at them. The stretch receptors detect changes in the length of a muscle as it is stretched and give the nervous system feedback so that it prevents overstretching. Some reflexes are totally spinal reflexes, i.e. they end in the spinal cord and the reaction is generated there unconsciously. knowing about these reflexes enhances our ability to use our muscles rather than abuse them and to nourish our physical and spiritual growth rather than hinder them. That’s why it is always advised that yogis don’t push or force an asana so that the body systems don’t start working against them.
Muscles: agonists and antagonists
pic. 2
Agonist muscles are those that work (contract) together to perform a specific movement (ex. the arm flexors when flexing the arm). Antagonist muscles are responsible for performing the opposite movement. These muscles must relax for the agonists to perform properly (the extensor muscles of the arm must relax while flexing it). These pairs of muscles (flexors and extensors) are called antagonist pairs (i.e. working against one another).
Consider, as an example, extending the arm in the elbow joint. The triceps muscle is considered the agonist and the biceps muscle is the antagonist. The biceps and the triceps are a classical antagonist pair. So, if you are trying to extend your arm in the elbow after training your biceps in a session of body building, you wouldn’t be able to make an easy extension and straighten your arm. The contacted biceps will oppose the stretch needed to complete the movement. (pic. 2)
While practicing hatha yoga, we usually face some difficulties in stretching those muscles that are trained spontaneously during everyday life. An example would be those muscles that help us stand straight, walk and keep our gait firm.
Types of muscle contraction
When you lift an object with your hand with the arm resting on a table for example (as in pic.2) your flexors muscles contract to lift that weight up and their length diminishes. This is concentric shortening of the muscles. The contraction of the muscle with its shortening under a constant load is called isotonic contraction. All lifting exercises require isotonic contractions.
If you hold the lifted object in one place not allowing it to fall, your muscles (the arm flexors in our example) are contracted but they don’t shorten any more, their length remains the same. This is calledisometric contraction.
When you are returning the object down to its place, you don’t just drop from your hand. As you extend your elbow to put the object your flexor muscles remain tensed till the object reaches its destination. But in this case the tension is combined with the lengthening of the flexors. This is called eccentric lengthening. An example is the stretching of the tensed leg muscles when you are walking downhill or walking downstairs.
In hatha yoga the object you are lifting, holding and returning to place is nothing but parts of your body: your arm, your leg, etc.
(to be continued in the next issue)
Till then, think of examples from your own practice of different types of muscle contraction in different asanas.
