Tummo
Inner heat, generated through specific breath-holding exercises, helps vital winds enter the central channel, leading to blissful experiences.
[5] Scientific studies have explored the effects of tummo, demonstrating notable increases in body temperature, metabolism, and thermal power output among expert meditators.
While the practice's effects on body temperature have been investigated, its primary purpose within Tibetan Buddhism remains focused on spiritual development, combining visualization, breath, and meditation to harness the inner fire and achieve profound states of enlightenment.
[9][10] This practice works with the subtle body (also known as the vajra-body) system of channels (nadis), winds (lung, vayu), drops (bindus) and chakras.
[9] This practice is a kind of pranayama, that generally involves sitting with a straight back, visualizing the channels, holding the breath deep in the abdomen for extended periods (called "vase breath", kumbhaka), then applying visualization of a fiery short stroke AH syllable on the navel.
This practice leads the vital winds into the central channel, where they are said to melt the drops (bindus, which are tiny spheres of subtle energy) causing great bliss.
[14] Samding Dorje Phagmo Ulrich Timme Kragh outlines the progression of this practice from one of Gampopa's manuals, entitled Closely Stringed Pearls.
At the end of the practice, the practitioner stops visualizing (yid la mi byed) the channels, winds, and drops, and instead rests in an uncontrived state of Mahamudra (phyag rgya chen po ma bcos pa'i ngang).
[15] Another meditation manual by Gampopa also mentions a practice that relies on visualizing a drop (thig le, *bindu) between the eyebrows.
[17] Tsongkhapa's commentary The Three Inspirations, divides the practice of inner heat into three main components:[18] Tsongkhapa describes the outcome of the full method (with all three elements described above practiced at once) as follows: Then the energies residing in the chakra at the secret place cause the AH-stroke syllable at the navel chakra, which is in nature the inner fire, to blaze with light.
This light rises up the central channel avadhuti and melts the other three syllables, HAM, OM and HUM [respectively at the crown, throat and heart chakras].
Light from this flame rises up the central channel, where it melts the drop of white bodhimind substance abiding within the crown chakra.
When meditative stability has been achieved then the radiance of the light from the inner fire will illuminate the inside and outside of one's body, as well as one's dwelling place and so forth, rendering them as transparent as a piece of kyurura fruit held in the hand.
Tsongkhapa describes various signs that this has occurred, mainly that the breath flows smoothly and evenly through the nostrils, then it becomes increasingly subtle, and then it stops altogether.
"[28] Studies on Tibetan monks and a Western control group have demonstrated the effect of increased thermal power output using the forceful breath technique that depends in part on meditative visualization.
[30] In a 2002 experiment reported by the Harvard Gazette, conducted in Normandy, France, two monks from the Buddhist tradition wore sensors that recorded changes in heat production and metabolism.
"[29] A 2013 study by Kozhevnikov and colleagues showed increases in core body temperature in both expert meditators from eastern Tibet and Western non-meditators.
It was also discovered that when those in the traditional condition also applied their visualisation techniques, the rise in temperature could be sustained for a longer period of time.
These findings reveal that, when tummo is practiced in the right form, both experienced and newly-trained practitioners are able to raise their body temperature.
