Effects of hypoxic exercise on 24-hour glucose profile and substrate metabolism in overweight and obese men with impaired glucose metabolism

Am J Physiol Endocrinol Metab. 2023 Feb 1;324(2):E135-E143. doi: 10.1152/ajpendo.00230.2022. Epub 2022 Dec 21.

Abstract

Hypoxic exercise (HE) may have more pronounced effects on glucose homeostasis than exercise under normoxic conditions (NE), but effects on 24-h glucose profile and substrate utilization remain unclear. We investigated the effects of moderate-intensity HE compared with NE on 24-h glucose profile and substrate metabolism in overweight/obese individuals. Ten overweight/obese men with impaired glucose homeostasis participated in a randomized, single-blind, crossover trial. Participants performed moderate-intensity cycling exercise for 4 consecutive days under mild normobaric hypoxic ([Formula: see text]: 15%) or normoxic ([Formula: see text]: 21%) conditions at similar relative exercise intensity (2 × 30 min/day at 50% of maximal heart rate, with a ∼4-wk washout period. Twenty-four-hour glucose levels and systemic oxygen saturation ([Formula: see text]) were monitored throughout the study. At day 5, plasma metabolites and substrate oxidation were determined during a mixed-meal test under normoxic conditions. [Formula: see text] and absolute workload were lower (both P < 0.001), whereas heart rate was comparable during HE compared with NE. HE did not alter mean 24-h, daytime, and nighttime glucose concentrations, and measures of glycemic variability. However, the HE-induced decrease in [Formula: see text] was positively correlated with HE-induced improvements in mean 24-h (rs = 0.683, P = 0.042) and daytime (rs = 0.783, P = 0.013) glucose concentrations. HE at similar relative exercise intensity reduces [Formula: see text] and has comparable effects on mean 24-h glucose concentration and glycemic variability than NE in overweight/obese men with impaired glucose metabolism. Nevertheless, a more pronounced reduction in [Formula: see text] during HE was associated with lower 24-h glucose concentrations, suggesting that a marked hypoxic stimulus is needed to improve glucose homeostasis.NEW & NOTEWORTHY We demonstrate that hypoxic exercise at similar relative exercise intensity (i.e. lower absolute workload) reduces systemic oxygen saturation ([Formula: see text]) and has comparable effects on mean 24-h glucose concentrations and glycemic variability than normoxic exercise in men with overweight/obesity and impaired glucose metabolism. A more pronounced reduction in [Formula: see text] during hypoxic exercise, however, was associated with lower 24-h and daytime glucose concentrations. Our findings suggest that a marked hypoxic stimulus may improve glucose homeostasis.

Keywords: continuous glucose monitoring; exercise; glucose homeostasis; hypoxia; substrate metabolism.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Exercise / physiology
  • Glucose*
  • Humans
  • Hypoxia
  • Male
  • Obesity / metabolism
  • Overweight* / therapy
  • Oxygen Consumption
  • Single-Blind Method

Substances

  • Glucose