Many forms of mild, intermittent stress produce an overall net benefit to cell and tissue function: low nutrient intake; heat; cold; excessive oxidative molecules; some toxins; and the topic of today's open access paper, hypoxia. When under stress, cells react with increased maintenance efforts aimed at removing damaged molecules and structures. If the stress is mild or of short duration, then the damage done it outweighed by the ongoing repair carried out. Work on the biochemistry of the beneficial response to calorie restriction suggests that autophagy is the most important of these processes, but there are others. In autophagy, molecules and structures are engulfed in an autophagosome and moved to a lysosome where they are broken down for recycling.
In the research noted here, scientists apply an intermittent hypoxia treatment to older patients for half a year and see a modest improvement in only some measures of metabolic health. Chronic inflammation and fat mass were reduced, though the effect size compares unfavorably with structured exercise programs, as is near always the case in these efforts to upregulate cellular maintenance processes. Additionally, a range of other health parameters remained unchanged, an outcome that definitely compares unfavorably with exercise, which tends to produce benefits across the board.
Oxygen is essential for human life, playing a determining role in aerobic respiration and cellular metabolism. A decrease in oxygen (hypoxia) could be deleterious for cellular adaptation and survival. In addition, sustained hypoxia contributes to functional decline during the aging process. Chronic exposure to severe hypoxia leads to an increased oxidative stress, vasoconstrictor activation, systemic inflammation, hypoxemia, pulmonary hypertension, and myocardial ischemia. Conversely, intermittent exposures to moderate hypoxia could have beneficial health effects in both healthy and diseased individuals.
Intermittent hypoxia (IH), defined as short alternating exposures to hypoxia and normoxia, can change body composition and health status with improved exercise tolerance, metabolism, and systemic arterial pressure. It has also been presented as a promising tool to beneficially impact bone metabolism. IH exposure allows modulating and stabilizing the hypoxia-inducible factor-1 alpha (HIF-1α), which is involved in the expression of factors related to angiogenesis, osteogenesis, lipolysis, and regulation of the inflammatory response.
Previous studies have suggested that IH could positively influence age-related alterations in older adults. The aim of this study was to evaluate the effect of 24 weeks of moderate intermittent hypoxia exposure on parameters related to body composition, inflammation, cardiovascular, and bone health in older adults. We hypothesized that IH intervention will have a positive effect on these health parameters. A total of 38 healthy older adults (aged 65-75 years) were divided into two groups: control group (C), and hypoxia group (H) that was subjected to an intermittent hypoxia exposure (at simulated altitude of 2500 m above sea level) during a 24-week period (3 days/week).
The results obtained have shown that IH exposure leads to beneficial effects on the health of the older adults. However, our initial hypothesis has only been partially fulfilled. After 24 weeks of intervention with IH, there has been a decrease in fat mass and C-reactive protein concentrations, as well as an improvement in blood biomarkers of bone remodeling, but no significant changes have been observed in bone mineral content and bone mineral density, nor in the metabolic and cardiovascular health parameters.