Astanga yoga:

The eight limbs of yoga are as follows:

“yamaniyamaasanapranayama pratyhara dharana dhyanasamadhayo-stavangani”

The eight rungs, limbs, or steps of Yoga are the codes of self-regulation or restraint (yamas), observances or practices of self-training (niyamas), postures (asana), expansion of breath and prana (pranayama), withdrawal of the senses (pratyahara), concentration (dharana), meditation (dhyana), and perfected concentration (samadhi).

1) Yama – Ethical and Moral Codes of Conduct

“ahimsa satya asteya brahmacharya aparigraha yama”

Non-injury or non-harming (ahimsa), truthfulness (satya), abstention from stealing (asteya), walking in awareness of the highest reality (brahmacharya), and non- possessiveness or non-grasping with the senses (aparigraha) are the five yamas, or codes of self-regulation or restraint, and are the first of the eight steps ofyoga.

2) Niyama – Personal Codes of Conduct

“shaucha santosha tapah svadhyaya ishvarapranidhana niyamah”

Cleanliness and purity of body and mind (shaucha), and attitude of contentment (santosha), ascesis or training of the senses (tapas), self-study and reflection on sacred words (svadhyaya), and an attitude of letting go into one‟s source (ishvarapranidhana) are the observances or practices of self-training (niyamas),and are the second rung on the ladder of yoga.

3) Asana – Body Posture

“sthira sukham asanam”

The posture (asana) for yoga meditation should be steady, stable and motionless, as well as comfortable, and this is the third of the eight rungs of yoga.

4) Pranayama – Breath Control

“tasmin sati shvasa prashvsayoh gati vichchhedah pranayamah”

Once that perfected posture has been achieved, the slowing or braking of the force behind, and of unregulated movement of inhalation and exhalation is called breath control and expansion of prana (pranayama), which leads to the absence of the awareness of both, and is the fourth of the eight rungs.

5) Pratyahara – Withdrawal of Senses

“sva vishaya asamprayoge chittasya avarupe anukarah iva indriyanam pratyaharah”

When the mental organs of senses and actions (indriyas) cease to be engaged with the corresponding objects in their mental realm, and assimilate or turn back into the mind-field from which they arose, this is called pratyahara, and is the fifth step.

6) Dharana – Concentration

“deshah bandhah chittasya dharana”

Concentration (dharana) is the process of holding or fixing the attention of mind onto one object or place, and is the sixth of the eight rungs.

7) Dhyana – Meditation

“tatra pratyaya ekatanata dhyanam”

The repeated continuation or uninterrupted stream of that one point of focus is called absorption in meditation (dhyana), and is the seventh of the eight steps.

8) Samadhi – Enlightenment

“tad eve artha matra nirbhasam svarupa shunyam iva samadhih”

When only the essence of that object, place, or point shines forth in the mind, as if devoid even of its own form, that state of deep absorption is called deep concentration or Samadhi, which is the eight rung.

Among these 8 limbs of yoga, the 3rd limb asana (posture) helps in keeping the physical body healthy and in good structure. Its acts at all the systems of the body, but predominantly on the musculoskeletal system. The 4th limb pranayama (breath control) helps in keeping the respiratory and circulatory system healthy. It also indirectly governs the nervous system and the brain function.