Therapeutic potential of intermittent hypoxia: a matter of dose - Navarrete-Opazo and Mitchell (2014)
Intermittent hypoxia (IH) has many therapeutic benefits; however, the benefits are dose dependent, and adverse side effects are observed from chronic hypoxia
The therapeutic range of IH is between 9-16% inspired O2, which roughly corresponds to blood oxygen saturations of 82-95% (altitudes of ~1500-5000 m)
3-15 episodes per day of IH in the above range elicits therapeutic benefits without harmful side effects
The Breathing Diabetic Summary
I would have never imagined that intermittent hypoxia (IH) could have so many benefits. When I first started practicing breath holds regularly, I did it mainly to boost performance (breath holds increase circulating red blood cells, increasing oxygen carrying capacity). However, this review study explains many other benefits to IH when done within certain limitations.
For practical application, the key message from this paper is that IH is therapeutic when blood oxygen saturation is between 82-95% and 3-15 cycles are performed per day. Enter Principle 3.
Let’s look at some of the therapeutic effects these authors found when reviewing relevant scientific papers.
The first benefit of IH is improved performance, something we are familiar with from the Oxygen Advantage. However, they then show that IH, when applied in the therapeutic range, is safe for and might even prevent hypertension. They provide evidence that IH leads to increased nitric oxide and reduced sympathetic nervous system activity, both of which lower blood pressure. Both of these mechanisms are also extremely important to diabetics.
Heart disease, one of the main causes of mortality in the world, and something diabetics suffer more from, also benefits from IH in the therapeutic range.
One of the most extraordinary benefits from IH was its positive effects on the immune system. The authors found that IH enhances the innate immune system and has an overall anti-inflammatory effect. These aspects of IH are clearly relevant to diabetics whose immune systems are compromised and who suffer from higher levels of inflammation. (See notes on IH and the immune system here.)
As if these benefits are not enough, they also found that IH lowers blood glucose and increases insulin sensitivity. (Are you practicing Principle 3 yet?!?)
I did not even come close to covering all of the beneficial aspects of IH. For example, they found improvements in memory, improvements in bone density, and decreases in depression symptoms, all from practicing IH in the therapeutic range.
To summarize, intermittent hypoxia sounds pretty amazing. For us, the main take home points are that it (1) increases innate immunity, (2) is anti-inflammatory, (3) decreases blood sugar, and (4) increases insulin sensitivity. So, one more time, are you practicing Principle 3 yet?
Abstract from Paper
Intermittent hypoxia (IH) has been the subject of considerable research in recent years, and triggers a bewildering array of both detrimental and beneficial effects in multiple physiological systems. Here, we review the extensive literature concerning IH and its impact on the respiratory, cardiovascular, immune, metabolic, bone, and nervous systems. One major goal is to define relevant IH characteristics leading to safe, protective, and/or therapeutic effects vs. pathogenesis. To understand the impact of IH, it is essential to define critical characteristics of the IH protocol under investigation, including potentially the severity of hypoxia within episodes, the duration of hypoxic episodes, the number of hypoxic episodes per day, the pattern of presentation across time (e.g., within vs. consecutive vs. alternating days), and the cumulative time of exposure. Not surprisingly, severe/chronic IH protocols tend to be pathogenic, whereas any beneficial effects are more likely to arise from modest/acute IH exposures. Features of the IH protocol most highly associated with beneficial vs. pathogenic outcomes include the level of hypoxemia within episodes and the number of episodes per day. Modest hypoxia (9–16% inspired O2) and low cycle numbers (3–15 episodes per day) most often lead to beneficial effects without pathology, whereas severe hypoxia (2–8% inspired O2) and more episodes per day (48 –2,400 episodes/day) elicit progressively greater pathology. Accumulating evidence suggests that “low dose” IH (modest hypoxia, few episodes) may be a simple, safe, and effective treatment with considerable therapeutic potential for multiple clinical disorders.
Angela Navarrete-Opazo and Gordon S. Mitchell, (2014) Therapeutic potential of intermittent hypoxia: a matter of dose, Am J Physiol Regul Integr Comp Physiol, 307: R1181–R1197, doi:10.1152/ajpregu.00208.2014.