Intermittent hypoxia revisited: a promising non-pharmaceutical strategy to reduce cardio-metabolic risk factors?

The study aims to investigate the effects of moderate intermittent hypoxia (IH) on key cardio-metabolic risk factors in overweight and obese subjects. Six subjects were exposed to 10 sessions of moderate IH over 2 weeks (based on ; similar to 70 min per session). Measures were made of blood glucose (GLU) and lactate (La-); high (HDLc) and low-density lipoproteins (LDLc); triglycerides (TRG), systolic (SBP), and diastolic blood pressure (DBP); and cardiac autonomic indices [root mean square of successive R-R interval differences (RMSSD) and short-term fractal scaling exponent (DFA alpha 1)]. GLU decreased and La- increased following a single IH session (6.21 +/- 1.62 vs. 5.32 +/- 1.03 mmol L-1; p < 0.05; 1.14 +/- 0.21 vs. 1.47 +/- 0.22 mmol L-1), but no sustained change after 10 sessions of IH occurred (p > 0.05). Conversely, LDLc (3.00 +/- 0.68 vs. 2.51 +/- 0.60 mmol L-1; p < 0.05), LDLc/HDLc ratio (2.52 +/- 0.66 vs. 2.26 +/- 0.70 mmol L-1; p < 0.05), and SBP (118.6 +/- 13.3 vs. 109.6 +/- 11.3 mmHg; p < 0.05) were all significantly decreased after 10 sessions. A short course of recurrent IH appears to be a safe and effective non-pharmacological method of reducing key cardiovascular risk factors associated with metabolic disorders.