The aim of this study is to assess the effect of interval hypoxy-hyperoxic training (IHHT) on the arterial stiffness and elasticity of the liver tissue in patients with metabolic syndrome and on other components of the metabolic syndrome, and the possibility of their reversible recovery after training.

The study will included 60 patients with metabolic syndrome (alimentary obesity (large waist, that measures at least 89 centimeters for women, and 102 centimeters for men), high blood pressure (130/85 mm Hg or higher), dislipidemia (triglyceride level 150 mg/dL (1.7 mmol/L) or higher of this type of fat found in blood; reduced high-density lipoprotein (HDL) cholesterol less than 40 mg/dL (1.04 mmol/L) in men, or less than 50 mg/dL (1.3 mmol/L) in women of HDL cholesterol), elevated fasting blood sugar (100 mg/dL (5,6 mmol/L) or higher). All patients were random separated into two groups: trial (30 pers., who will undergo 15 procedures of the IHHT, 5 days a week for 3 weeks), and control (30 pers., who will undergo 15 placebo procedures simulating IHHT, 5 days a week for 3 weeks). Before and after procedures of IHHT all patients will undergo laboratory and instrumental examinations, wich include arterial stiffness measurement, making by Fukuda Denshi VS-100 VaSera, measurement of liver tissue elasticity and fibrosis, making by elastography on FibroScan (Echosense, XL-sensor), and laboratory analysis (lipid profile, fasting blood sugar, trimethylamin N-oxyde (TMAO), Toll-like receptors 4,7,9). After 6 month of IHHT all patients will undergo the same laboratory and instrumental examinations to assess the duration of the effect.

Inclusion Criteria:

• Patient's written informed consent.
• The presence of metabolic syndrome: as having three or more of the following traits, including traits you're taking medication to control:
• Large waist - A waistline that measures at least 35 inches (89 centimeters) for women and 40 inches (102 centimeters) for men;
• High triglyceride level - 150 milligrams per deciliter (mg/dL), or 1.7 millimoles per liter (mmol/L), or higher of this type of fat found in blood;
• Reduced "good" or HDL cholesterol - Less than 40 mg/dL (1.04 mmol/L) in men or less than 50 mg/dL (1.3 mmol/L) in women of high-density lipoprotein (HDL) cholesterol;
• Increased blood pressure - 130/85 millimeters of mercury (mm Hg) or higher;
• Elevated fasting blood sugar - 100 mg/dL (5.6 mmol/L) or higher.
• Must be able to come to the hospital 5 days per week, for 3 weeks.

Exclusion Criteria:

• Refusal from further participation in the study.
• Individual intolerance to hypoxia.
• Cirrhosis of the liver with liver failure class C according to the classification of Child-Pugh.
• Alcohol use 140 g / week or more for men, and 70 g / week or more for women.
• Patients with positive serological reactions to hepatitis B and C.
• Chronic kidney disease (GFR less than 30 ml / min / 1.73 m 2).
• Pregnancy, lactation.

Prohibition of local ethics committee