Prana is the vital life force that is present everywhere. Prana is Brahman. Brahman is prana. Prana pervades all.
To be the acharya (master) of Brahman, be the master of the life force. To have the mindful conscious awareness of the life force that is sustaining one and all, is to be in that consciousness where we acknowledge the Shakti present in us all in all forms.
The shakti that will cut through the delusions of the mind and take us to the real abode of Atman instead of disspating it in the outside world. That is what Brahmacharya is to me! To be conscious of the Brahman present in this seemingly limited body and be ever-present in that consciousness; in the sound of Pranava that will lead us beyond.
So again celibacy as its normally translated as, is not the cause but the effect. Not letting the vital energy dissipate through any of the nine portals will be natural for one who is in Brahman consciousness at all times.