Effects of Aerobic Exercise Training in Hypoxia versus Normoxia on Body Composition and Metabolic Health in Overweight and/or Obese Population: An updated Meta-Analysis

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 inspired oxygen fraction (FiO ₂ ), 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 = -5.28, 95% CI: -8.75 to -1.81), 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 (FiO ₂  ≥ 15%), 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.