Effects of Aerobic Exercise Training in Hypoxia Versus Normoxia on Body Composition and Metabolic Health in Overweight and/or Obese Populations: an Updated Meta-Analysis.

Abstract

Background: While aerobic training is well-established for improving body composition and metabolic health in normoxia, its effectiveness in hypoxia remains unclear.

Objective: This meta-analysis examines whether aerobic training in hypoxia is more effective than in normoxia for improving body composition and metabolic health in overweight and/or obese individuals, and identifies optimal exercise prescription variables.

Methods: A search of five databases was conducted through 10 November 2024. Random-effects meta-analyses evaluated body composition (e.g., body mass and fat mass) and metabolic health markers (e.g., triglycerides and glucose). Subgroup analyses were performed based on hypoxic severity, hypoxic dose, exercise duration, frequency, session length, and age.

Results: Aerobic training in hypoxia resulted in greater reductions in body mass (mean difference [MD] = -0.90, 95% confidence interval [CI]: -1.80 to -0.01), triglycerides (MD = -10.78, 95% CI: -20.68 to -0.88), low-density lipoprotein cholesterol (MD = -3.74, 95% CI: -6.92 to -0.56, p < 0.05), and insulin resistance (MD = -0.22, 95% CI: -0.33 to -0.11) (all p < 0.05), with a trend towards larger fat mass loss (MD = -1.22, 95% CI: -2.59 to 0.15, p = 0.08). These benefits were more prominent in moderate hypoxia (inspired oxygen fraction [FiO₂] ≥ 15%), with hypoxic dose ≥ 55 km·h, in individuals < 40 years, and with protocols involving ≥ 4 days/week, ≥ 60-min sessions, and < 8 weeks of training.

Conclusion: Aerobic training in hypoxia is more effective than in normoxia for reducing body mass, fat mass, triglycerides, low-density lipoprotein cholesterol, and insulin resistance in overweight and/or obese individuals. These findings could help inform obesity management strategies using hypoxic training.