Many languages use one word for breath, spirit and animating principle, and the traditions behind them treat breathing as continuous with vitality. The convergence has observable causes.
Breathing is the visible sign of being alive
Before instruments, the most reliable external indication that a person was living was that they were breathing, and its cessation coincided with death.
A phenomenon that begins at birth and stops at death is naturally treated as the thing that makes the difference rather than as one process among many.
The linguistic overlap follows directly, and it appears in language families with no contact, which is what would be expected from a shared observation.
It sits between voluntary and involuntary control
Breathing continues without attention and can also be altered deliberately, which is unusual among bodily processes.
That dual status makes it the obvious point of access for anyone attempting to influence the body through the mind or the reverse.
Practice traditions across the world converged on breath regulation for this reason, without needing to share any theory about what was being regulated.
Deliberate breathing produces immediate effects
Changing rate and depth alters how a person feels within a short period, and the effects are consistent enough that anyone can verify them.
Slow breathing with extended exhalation is associated with measurable changes in heart rate variability, and rapid breathing produces sensations that are also reliable.
A practice with same-session effects is easy to transmit and hard to abandon, which explains why breath techniques persist in traditions that otherwise share nothing.
The concepts are not interchangeable
Terms rendered as vital energy in different traditions carry different theoretical commitments and sit inside different accounts of the body.
Translating them all with one English phrase flattens genuine differences, and comparative scholars generally retain the original terms for this reason.
The practices differ accordingly, and techniques taken from one system and inserted into another are not doing what they did in their original setting.
Vigorous techniques carry real cautions
Rapid or forceful breathing methods can produce dizziness, tingling, muscle spasm and fainting, and traditional manuals restrict who may attempt them and prescribe extended preparation first.
They are treated as contraindicated in a number of conditions, including some cardiovascular, neurological and respiratory ones, and during pregnancy within many teaching frameworks.
Anyone with a relevant medical condition should consult a clinician before undertaking intensive breath practice, and should learn such techniques from a qualified teacher rather than from written instructions alone.