What swara yoga says about the body
Swara yoga's advice about the body is almost entirely about timing. It does not prescribe exercises or foods so much as tell you when to do the ones you already do, and the clock it uses is the breath. Much of what follows is a traditional account of how the body works, and I have kept to what the texts assert rather than dressing it up as anything else. Here are eight concepts, each with its source.
The 72,000 Energetic Pathways (Dvisaptati Sahasra Nadi)
The subtle body is described as 72,000 channels radiating from a point below the navel, with the nostril breath as the master control among them. This is the map that the rest of the advice assumes.
Goraksha Samhita 1.14
The Nature of Chandra Swara — Cool, Receptive, Healing (Chandra Svara Swarupa)
Left-nostril flow is called the cooling, receptive side. It is where the tradition places rest, recovery and quiet work.
Shiva Svarodaya 1.55
The Nature of Surya Swara — Heat, Energy, Execution (Surya Svara Swarupa)
Right-nostril flow is the heating, active side, the phase for effort, appetite and getting things done. The two sides are not ranked against each other; they are shifts.
Shiva Svarodaya 1.95
The Breath as the Master Diagnostic Tool (Roga Nidana Svara)
A breath stuck on one side for long stretches is read as a warning, ahead of any symptom. This is the tradition using the breath as a reading rather than as a practice.
Shiva Svarodaya 3.12
Agni and Digestive Fire Peak in Surya Swara (Jathara Agni Dipana)
Main meals are to be eaten while the right nostril is running, when digestive fire is held to be strongest.
Shiva Svarodaya 1.102
Physical Exercise and Martial Arts in Pingala (Vyayama Yudha Svara)
Hard physical work, lifting, training and martial practice, is assigned to the same right-side phase. The rule is consistent: heat for effort.
Shiva Svarodaya 1.112
Ida as the Guardian of Sleep and Rejuvenation (Nidra Rakshaka)
Falling asleep with the left side dominant is said to give deeper, more restoring sleep. It is the piece of this advice that costs nothing to try.
Shiva Svarodaya 2.14
Lateral Recumbent Shift (Side-Lying Posture) (Parshva Shayana Svara)
The method for changing sides is posture: lying on one side opens the upper nostril within a few minutes. Almost every practical instruction in swara yoga comes back to this one lever.
Charaka Samhita, Sutrasthana 8
Taken together this is a single instruction repeated: do the heavy things on the warm side, the quiet things on the cool side, and change sides by lying down. Whether the physiology holds as stated is not something the texts can settle. The shape of the advice, eat and train while you are warm and rest when you are not, is not an eccentric one.