Cell biology and proposed mechanisms
Oxidative preconditioning
Oxidative preconditioning is the proposal that repeated small, controlled doses of an oxidant train a cell's defences, so that a later and larger oxidative insult causes less damage. It is the central mechanistic hypothesis of ozone therapy, and it is supported mainly by cell and animal work.
Also called ozone oxidative preconditioning, controlled oxidative conditioning, controlled oxidative stress, calculated oxidative stress
The idea
The parent idea, ischaemic preconditioning, is well established in physiology: a brief, non-damaging challenge can make tissue more tolerant of a later, longer one. Oxidative preconditioning applies the same logic to oxidants: a controlled challenge activates Nrf2, Nrf2 raises production of superoxide dismutase, catalase and glutathione-related enzymes, and the cell then meets the next challenge better defended.
The research
Most of the work is in cell culture and in animals, with ozone given by routes other than a sauna. The founding paper is Ozone oxidative preconditioning: a protection against cellular damage by free radicals, Mediators of Inflammation (1998), a study in rats. The cell work is reviewed in The Role of Nrf2 in the Antioxidant Cellular Response to Medical Ozone Exposure, International Journal of Molecular Sciences (2019). Sagai and Bocci set out the hypothesis in Medical Gas Research (2011).
Why it matters here
It is the mechanism behind most explanations of how an ozone sauna session is proposed to work. It is a well-developed hypothesis with animal support by other delivery routes, and worth understanding as exactly that.