低酸素曝露によるエネルギー消費量の増加とエネルギー摂取量への影響なし：無酸素性低酸素症と正常酸素性低酸素症の比較

Extended exposure to hypobaric hypoxia at high altitude induces negative energy balance through elevations in resting metabolic rate (RMR) and decreases in energy intake. It is unknown if an overnight bout of normobaric hypoxic (NH) exposure at sea level induces similar changes in energy balance and associated mechanisms.

To determine the effects of a single overnight exposure to NH on RMR, heart rate variability (HRV), appetite, and energy intake compared to an overnight exposure to normobaric normoxia (NN) in normal-weight adults.

In this randomized, single-blind, sham-controlled, crossover study, twenty adults (22.7±1.7kg/m², 24.5±3.9y) slept 8h in a tent maintained at either ∼15% (∼2640m elevation) or ∼20% oxygen (∼305m elevation). The following morning, HRV was measured inside the tent using electrocardiography; RMR was measured outside the tent using indirect calorimetry; and energy intake and subjective appetite were assessed outside the tent with an ad-libitum breakfast buffet and visual analog scales, respectively.

Overnight peripheral oxygen saturation was lower in NH (mean±SD: 88.2±2.3%) compared to NN (96.2±0.9%; p-condition<0.0001). Root mean square of successive RR interval difference (RMSSD) and high frequency (HF) activity, markers of parasympathetic nervous system (PNS) activity, were lower following NH (47.7±19.5ms and 524±335ms², respectively) compared to NN (58.3±22.6ms, p-condition=0.034 and 748±476ms², p-condition=0.052, respectively). Heart rate was greater in NH (61.3±7.4 bpm) compared to NN (56.2±7.6 bpm; p-condition<0.0001). RMR was elevated in NH (1.07±0.18kcal/min) compared to NN (1.04±0.13kcal/min; p-condition=0.018). Appetite and energy intake did not differ between conditions (p-condition>0.05).

One-night exposure to NH reduced PNS activity, increased HR and RMR, and had no impact on energy intake or appetite when compared to NN exposure. This trial is registered at https://clinicaltrials.gov/ as NCT04151927.