Kundalini
kuṇḍalinīThe coiled energy at the base of the spine, said to rise with practice. Also a modern practice style bearing the name.
In the Hatha Yoga Pradipika this is not a fringe idea; it is the foundation the whole system rests on:
As the chief of the snakes is the support of the earth with all the mountains and forests on it, so all the Tantras (Yoga practices) rest on the Kuṇḍalinî. (The Vertebral column.)
The original Sanskrit
sa-śaila-vana-dhātrīṇāṃ yathādhāro'hi-nāyakaḥ / sarveṣāṃ yoga-tantrāṇāṃ tathādhāro hi kuṇḍalī
When the sleeping Kuṇḍalinî awakens by favour of a guru, then all the lotuses (in the six chakras or centres) and all the knots are pierced through.
The original Sanskrit
suptā guru-prasādena yadā jāgarti kuṇḍalī / tadā sarvāṇi padmāni bhidyante granthayo'pi ca
A sleeping power, awakened with a teacher's help, opening the body's centers as it rises. Whether you read this as subtle physiology or as metaphor, this is the source the studio version traces to.