Normobaric Intermittent Hypoxia over 8 Months Does Not Reduce Body Weight and Metabolic Risk Factors – a Randomized, Single Blind, Placebo-Controlled Study in Normobaric Hypoxia and Normobaric Sham Hypoxia

OBJECTIVE Both a 1- to 4-week continuous or intermittent stay and moderate exercise in hypoxia versus normoxia can lead to weight loss. We examined the reproducibility and durability of added hypoxic exposure in a feasible health program of several months. METHODS 32 obese persons, randomly assigned to either a hypoxia (age 50.3 ± 10.3 years, BMI 37.9 ± 8.1 kg/m(²)) or a normoxia (age 52.4 ± 7.9 years, BMI 36.3 ± 4.0 kg/m(²)) group, completed 52 exercise sessions within 8 months. Participants exercised for 90 min (65-70% HR(peak)) either at a simulated altitude of 3,500 m or in normoxia, and rested for further 90 min at 4,500 m or normoxia. Before, after 5 weeks, after 3 months, and after the intervention, body composition and exercise capacity were determined. Risk markers (e.g., blood pressure, cholesterol) were measured before, after 3 months, and after the intervention period. RESULTS Body weight, BMI, waist and hip circumference, P(peak) and BP(sys) improved over time (p < 0.05) but without group difference. Fat mass reductions correlated with HDL changes (r = -0.427; p < 0.05) in the entire group. CONCLUSION Long-term, moderate intensity exercise and rest in hypoxia does not lead to higher reductions in body weight than normoxia alone. Therefore, for weight loss and metabolic markers hypoxic exposure does not add effects at least when stimuli (i.e., hypoxia dose, exercise intensity/duration) are unaltered throughout the intervention.