The advanced techniques consist of postures and cleaning methods. Without a perfect teacher nobody can attain the results. The hard postures help to develop the confidence and provide the capacity to bear and awake the power of Kundaleeni in the body.
The person who attains Hadoyogam will be able to sit or stand in a particular posture for an undetermined period of time and to visualize the chakras with their color, not only by imagination but also with the naked eye. From the end of Hadoyogam we can start Rajayogam. You can practice Hadoyogam until the middle of Rajayogam. It continues with the Kundaleeni techniques.
This branch of yoa does’t has any relation with spiritual activities. it consist only hard postures and hard techniques. Make the person confident and more flexible. The book Hadapradeepika is the one and only book about Hadayogam by swami Swalmaraman recently.