Srimad Bhagavatam Canto 02, Chapter 02, Text 20

SB 2.2.20

nabhyam sthitam hrdy adhiropya tasmad
udana-gatyorasi tam nayen munih
tato ’nusandhaya dhiya manasvi
sva-talu-mulam sanakair nayeta
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The meditative devotee should slowly push up the life air from the navel to the heart, from there to the chest, and from there to the root of the palate. He should search out the proper places with intelligence.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
There are six circles of the movement of the life air, and the intelligent bhakti-yogi should search out these places with intelligence and in a meditative mood. Among these, mentioned above is the svadhisthana-cakra, or the powerhouse of the life air, and above this, just below the abdomen and navel, is the mani-puraka-cakra. When upper space is further searched out in the heart, one reaches the anahata-cakra, and further up, when the life air is placed at the root of the palate, one reaches the visuddhi-cakra.
Srimad Bhagavatam Canto 02, Chapter 02, Text 19
Srimad Bhagavatam Canto 02, Chapter 02, Text 21