The Effect of Normobaric Hypoxic Confinement on Metabolism, Gut Hormones, and Body Composition.
To assess the effect of normobaric hypoxia on metabolism, gut hormones, and body composition, 11 normal weight, aerobically trained (O2peak: 60.6 ± 9.5 ml·kg(-1)·min(-1)) men (73.0 ± 7.7 kg; 23.7 ± 4.0 years, BMI 22.2 ± 2.4 kg·m(-2)) were confined to a normobaric (altitude ≃ 940 m) normoxic (NORMOXIA; PIO2 ≃ 133.2 mmHg) or normobaric hypoxic (HYPOXIA; PIO was reduced from 105.6 to 97.7 mmHg over 10 days) environment for 10 days in a randomized cross-over design. The wash-out period between confinements was 3 weeks. During each 10-day period, subjects avoided strenuous physical activity and were under continuous nutritional control. Before, and at the end of each exposure, subjects completed a meal tolerance test (MTT), during which blood glucose, insulin, GLP-1, ghrelin, peptide-YY, adrenaline, noradrenaline, leptin, and gastro-intestinal blood flow and appetite sensations were measured. There was no significant change in body weight in either of the confinements (NORMOXIA: -0.7 ± 0.2 kg; HYPOXIA: -0.9 ± 0.2 kg), but a significant increase in fat mass in NORMOXIA (0.23 ± 0.45 kg), but not in HYPOXIA (0.08 ± 0.08 kg). HYPOXIA confinement increased fasting noradrenaline and decreased energy intake, the latter most likely associated with increased fasting leptin. The majority of all other measured variables/responses were similar in NORMOXIA and HYPOXIA. To conclude, normobaric hypoxic confinement without exercise training results in negative energy balance due to primarily reduced energy intake.
Department of Automation, Biocybernetics and Robotics, Jožef Stefan InstituteLjubljana, Slovenia; Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada.
Igor B
IB
Mekjavic
Jožef Stefan International Postgraduate School Ljubljana, Slovenia.
Mojca
M
Amon
Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology Stockholm, Sweden.
Roger
R
Kölegård
Human Performance-Rehabilitation Laboratory, Faculty of Physical and Cultural Education, Hellenic Military University Vari, Greece.
Stylianos N
SN
Kounalakis
Metabolic Physiology Group, Faculty of Medicine and Health Sciences, University of Nottingham Queen's Medical Centre Nottingham, UK.
Liz
L
Simpson
Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology Stockholm, Sweden.
Ola
O
Eiken
Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology Stockholm, Sweden.
Michail E
ME
Keramidas
Metabolic Physiology Group, Faculty of Medicine and Health Sciences, University of Nottingham Queen's Medical Centre Nottingham, UK.
Ian A
IA
Macdonald
altitude; appetite; energy expenditure; hypoxia; metabolism