Effects of Periodic Hypobaric and Hypoxic Environment Systems onPostprandial Hyperglycemia During Endurance Exercise and Calisthenics

Abstract

We developed a periodic pressure-controlling system to mimic a hypobaric hypoxic environment in a chamber. The characteristics of this system varied between decreased pressure at an altitude of 1,500 m for 180 seconds and increased pressure at an altitude of 0 m for 180 seconds. The present study aimed to determine the relationship between exercise in the periodic hypobaric hypoxic environment （PHHE） and physiological responses evaluated using an oral glucose tolerance test. This study included 2 groups of 13 （Experiment 1） and 8 （Experiment 2） healthy men, who provided written informed consent for participation in the study. All subjects performed an oral glucose tolerance test for 120 minutes and two exercise tests: endurance exercise （Experiment 1） and calisthenics （Experiment 2）．The endurance exercise test consisted of 40% maximal oxygen intake for 18 minutes. The calisthenics test included performance of 3 sets of squat exercises （10 squats/set）．We established three experimental conditions: exercise in PHHE system （periodic condition），at an altitude of 750 m （fixed condition），and at an altitude of 0 m （control condition）．In the periodic condition, the atmospheric pressure was changed periodically from 967 to 817 hPa （external pressure was 1,008 hPa）．In the fixed condition, the atmospheric pressure was fixed at 892 hPa. In the control condition, the atmospheric pressure was fixed at 1,008 hPa. Pulse rate （PR），systolic （SBP） and diastolic blood pressure （DBP），arterial oxygen saturation （SpO2），and blood glucose values were measured during the oral glucose tolerance test. Heart rate, SpO2, and the rating of perceived exertion （RPE） were measured during exercise in experiment 1. SpO2 was significantly lower in the periodic condition. PR, SBP, and DBP were significantly different among the 3 conditions. There were no significant differences in blood glucose values among the 3 conditions. During exercise, HR and RPE were not significantly different among the 3 conditions. In conclusion, glucose metabolism was not suppressed by exercise in the PHHE.