Cyclic hypobaric hypoxia improves markers of glucose metabolism in middle-aged men.

ABSTRACT

UNLABELLED Chronic hypoxia increases dependence on glucose in men and increases insulin sensitivity in men and women. Cyclic Variations in Altitude Conditioning (CVAC) is a novel technology that provides exposure to rapidly fluctuating cyclic hypobaric hypoxia (CHH). PURPOSE: To test the hypothesis that markers of glucose metabolism would change with CVAC CHH, two groups of middle-aged men were exposed to 10 weeks (40 min/day, 3 day/week) of either CHH or sham (SH) sessions. METHODS: CHH subjects (age 48 ± 6, weight 86 ± 12 kg, BMI 27.1 ± 3, n=11) experienced cyclic pressures simulating altitudes ranging from sea level to 3048 m (week 1) and progressing to 6096 m (by week 5 through week 10). SH subjects (age 50 ± 4, weight 89 ± 15 kg, BMI 27.5 ± 3, n=10) were exposed to slowly-fluctuating pressures up to 607 m (all subjects blinded to elevation). Physical function and blood markers of glucose metabolism were measured at baseline, 3, 6, and 10 weeks. RESULTS: Two CHH subjects were dropped from analysis for failure to progress past 3048 m (CHH n=9). Weight and physical activity remained stable for both groups. There was a group-by-time interaction in fasting glucose (CHH 96 ± 9 to 91 ± 7 mg/dL, SH 94 ± 7 to 97 ± 9 mg/dL, p<0.05). Reduction in plasma glucose response to oral glucose tolerance test [area under the curve] was greater in CHH compared to SH after 10 weeks of exposure (p<0.03). Neither group experienced changes in fasting insulin, insulin response during the OGTT, or changes in a timed walk test. CONCLUSION: Ten weeks of CVAC CHH exposure improves markers of glucose metabolism in middle-aged men at risk for metabolic syndrome.