Just as we know that the physical body is a flesh and blood concern. the subtle body may be realized as a sensation body. As there is bone, flesh, hair and liquids in the physical body, so there is sensation as the contents of the subtle one.
That subtle content is experienced as emotional energy or feelings in the physical system. To prepare for the hereafter one should become familiar with this energy content of the subtle body long before one is deprived of the physical system which serves for the time being as the cultural self.
During pranayama breath infusion practice, one may experience bursts and spreads of the sensations in the subtle body. One may pinch, squeeze, compress and experience absorption of that subtle energy. This will give insight into the format of the subtle form, as to if it has a membrane or diminishing edge, as to the quality of its energy, regarding if it is blissful, neutral or unpleasant.
While there are muscular contractions (bandhas) used in kundalini yoga. These relate to controlling the flow of physio-psychic energy in the physical body. In the subtle form, it is the control of sensations which are essential for practice. These are confined, compressed, squeezed and observed through absorption inner confined focus (samyama).
The value of this is the familiarly with the contents of the subtle body and the ability to gage which level one will shift to hereafter, where one can better prepare for being deprived of the physical form and one can target the self so that it acts as a transit to higher places of existence where yogaGurus and deities reside.
If now a yogi can during spiritual practice, transit to higher planes of consciousness and experience the subtle body as it would be if it was transferred to those level, he/she may be self-assured of reaching a desire destination hereafter. Otherwise it is likely that the hope for liberation will be frustrated resulting only in attaining a lower astral plane once the physical system is no longer accessible.