Sutra 2.50

बाह्याभ्यन्तरस्तम्भवृत्तिर्देशकालसंख्याभिः परिदृष्टो दीर्घसूक्ष्मः॥५०॥

bāhya-ābhyantara-sthambha vr̥ttiḥ deśa-kāla-sankhyābhiḥ paridr̥ṣṭo dīrgha-sūkṣmaḥ ॥

bāhya, external; ābhyantara, internal; stambha, restrained, suppressed; vṛttiḥ, movements; deśa, place; kāla, time; saṅkhyābhiḥ, and by number; paridṛṣṭaḥ, is manifest; dīrgha, long; sūkṣmaḥ, subtle

Sw. Satchidananda

“The modifications of the life-breath are either external, internal or stationary. They are to be regulated by space, time and number and are either long or short.”

Bryant

“[pranayama] manifests as external, internal, and restrained movements [of breath]. These are drawn out and subtle in accordance to place, time, and number.”

Taimni

“(It is in) external, internal or suppressed modifcation; is regulated by place, time and number, (and becomes progressively) prolonged and subtle.”

Discussion

As we know, in the yoga sutras, Patanjali does not describe any specific pranayama practices. However, in the current sutra, he offers some of the variables that can be used in developing different pranayama techniques. Three attributes of a breathing cycle are mentioned – inhalation (ābhyantara vr̥ttiḥ), exhalation (bāhya vr̥ttiḥ) and breath retention (stambha vr̥ttiḥ). The breath retention (stambha) can be applied after inhalation, or exhalation, or any time during the breathing cycle. As mentioned while discussing the previous sutra, the Sanskrit terms used for the four phases of breathing in the modern yoga literature are – pūraka (inhalation), rechaka (exhalation), antara-kumbhaka (retention after inhalation), bāhya-kumbhaka (retention after exhalation).  The term vritti is used in this sutra to imply the various attributes of breathing, as listed.

The variables that can be used in managing these attributes are given as desha (location), kāla (time duration) and samkhyā (number). As per the commentators, these three can have the following interpretation:

Desha (location)

• Maintaining awareness on some physical location in the body while practicing pranayama – e.g., one of the chakra locations (navel, heart, throat, third eye location etc.); tip of the nose, forehead; crown of the head etc.
• Breathing through one or both nostrils
• Awareness outside the body – how far the breath goes when you exhale
• Awareness inside the body – during inhalation, become aware of the flow through the nostrils, the bronchial cavity, all the way down to the lungs; during exhalation , feel the flow out from the lungs, through the bronchial cavity and out through the nostrils

Kāla (time) – duration of each inhalation, exhalation and retention. For example, in the practice of Kapalabhati, the duration of each breath is short (in my class, typically 70-80 breaths per minute). On the other hand, while practicing Nāḍī shuddhi (alternate nostril breathing), we try to make each breath as long as comfortable. Typically, with practice, while maintaining a ratio of 1:2, you can achieve a duration of about 8-10 seconds for inhalation and about 16-20 seconds for exhalation.

Samkhyā (number) – Number of repetitions for a given pranayama practice. For example, for Kapalabhati, you may start out with about 50 breaths per round and, over time, build up to about 120 breaths per round (or even higher).

When we can vary and control the inhalation, exhalation and retention with close attention (paridṛṣṭa) to the three variables – desha, kāla and samkhyā, the breath can become very long (dīrgha) and subtle (sūkshma). For example, when the breath becomes very subtle, you may not feel the flow of exhalation even a few mm away from the nostrils.

Based on the variables presented by Patanjali, a large number of pranayama practices have evolved over time. The most commonly referenced text for pranayama, and other yoga practices, is the Haṭha Yoga Pradīpikā. This text, which is believed to be about 600-800 years old, contains several basic pranayama techniques and some that are based on breath retention (kumbhaka). Some of the more recent books on pranayama available today are from BKS Iyengar, Bihar School of Yoga, Swami Sivananda, kaivalyadhama, to name a few.

In the classes that I teach, I offer the following set of six pranayama practices which I believe should form the basic core of your pranayama routine:

1. Kapālabhāti
2. Bhastrikā (bellows breath)
3. Ujjāyi pranayama
4. Nāḍī Sañcālana (rapid breathing)
5. Bhrāmarī (humming bee pranayama)
6. Nāḍī Shuddhi (a.k.a. Anuloma Viloma) (alternate nostril breathing)

In the pranayama programs that I offer, I teach several other techniques as well. Once you build your core practice, you can add many other techniques to your daily routine from time to time.