PURPOSE Adaptation to acutely intermittent hypoxic exposure appears to produce worthwhile enhancements in endurance performance, but the current 5-min duration of hypoxia and recovery intervals may not be optimal. METHODS Eighteen male competitive cyclists and triathletes were randomized to one of two intermittent-hypoxia groups, and nine similar athletes represented a control group. Athletes...

The effects of repeated short-term hypoxia on exercise tolerance in patients at risk for, or with mild COPD were investigated. Eighteen patients (10 males, 8 females; 33-72 years) were randomly assigned in a double-blind fashion to receive 15 sessions of intermittent hypoxia (FiO(2): 0.15-0.12) or normoxia within 3 weeks. Three weeks of intermittent hypoxia increased total haemoglobin mass (+4%...

Chronic intermittent or episodic hypoxia, as occurs during a number of disease states, can have devastating effects, and prolonged exposure to this hypoxia can result in cell injury or cell death. Indeed, intermittent hypoxia activates a number of signaling pathways that are involved in oxygen sensing, oxidative stress, metabolism, catecholamine biosynthesis, and immune responsiveness. The cumu...

Blood flow to the brain is highly regulated through an array of interacting cells and molecular signals, all impinging on the vasculature. Although many mechanisms influence cerebrovascular resistance and, thus, cerebral blood flow, 2 of the most powerful regulators are molecular oxygen and carbon dioxide. The impact of sustained hypoxia (decreases in arterial PO2) and hypercapnia (increases in...

Sleep apnea syndrome increases the risk of cardiovascular morbidity and mortality. We previously reported that intermittent hypoxia increases superoxide production in a manner dependent on nicotinamide adenine dinucleotide phosphate and accelerates adverse left ventricular (LV) remodeling. Recent studies have suggested that hydrogen (H(2)) may have an antioxidant effect by reducing hydroxyl rad...

The aim of this study was to provide information on heart rate and blood pressure responses during a 3-week intermittent hypoxia breathing program in COPD patients. Sixteen participants with COPD symptoms were randomly assigned to a hypoxia or control group and completed a 3-week intermittent hypoxia breathing program (five sessions per week, each consisting of three to five breathing cycles, e...

Hypoxia-inducible factor-1 (HIF-1) stabilization is a pivotal event in the response to hypoxic stress. A study in the December 15, 2006 issue of Cancer Research shows that HIF-1 stabilization occurs more robustly as a result of intermittent hypoxia compared with chronic hypoxia. The findings of this study suggest that intermittent hypoxia might influence the efficacy of radiotherapy by more str...