Pranayama is defined in Yoga Sutra II.49 as extension of inhalation and exhalation (for example Ujjayi during Ashtanga Vinyasa). Sutra II.50, however, gives a deeper meaning of pranayama as various breath retentions which are called internal, external and midway suspension. An even more advanced meaning is given in sutra II.51 that talks about spontaneous suspension (called chaturtah by Patanjali and Kevala Kumbhaka in Hatha Yoga Pradipika). These three meanings can only be experienced consecutively. This means: 1. Start pranayama by slowing down the breath. 2. Continue pranayama through formal practice of breath retentions sitting in Padmasana, Siddhasana, etc. 3. Once you have thus mastered prana through years of formal breath retentions, prana suspends and thus the mind, which is fan powered. Samadhi will thus be attained. This is of course very, very simplified. In my forthcoming pranayama book I have dedicated several hundred pages to this process. There is even a section called ‘why Ashtanga Vinyasa yogis need to go beyond Ujjayi’. This means that while it is correct to say that Ujjayi is pranayama, the reverse is incorrect. Meaning, yes you are practicing pranayama when you practice Ujjayi during vinyasa but pranayama is larger than Ujjayi. Shitali, Surya Bhedana, Bhastrika, kumbhakas etc also need to be practiced.