Women at altitude: energy requirement at 4,300 m

• Published in: Journal of applied physiology (1985) Vol. 88; no. 1; pp. 272 - 281
• Main Authors: Mawson, Jacinda T, Braun, Barry, Rock, Paul B, Moore, Lorna G, Mazzeo, Robert, Butterfield, Gail E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.01.2000; American Physiological Society
• Subjects: Adult; Altitude; Applied physiology; Basal Metabolism - physiology; Biological and medical sciences; Body Composition; Body Weight; Catecholamines - analysis; Energy Intake - physiology; Energy Metabolism - physiology; Female; Follicular Phase - physiology; Human physiology applied to population studies and life conditions. Human ecophysiology; Humans; Luteal Phase - physiology; Medical sciences; Menstruation; Metabolism; Nitrogen - analysis; Oxygen Consumption; Space life sciences; Time Factors; Transports. Aerospace. Diving. Altitude; Water-Electrolyte Balance; Weight control; Women; Human; Energy balance; High altitude; Energy metabolism; Menstrual cycle; Body weight; Environmental factor; Female; Basal metabolism; Adaptation
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.88.1.272

1  Palo Alto Veterans Affairs Health Care System, Palo Alto 94304; 2  Stanford University, Stanford, California 94305; 3  United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01460; 4  University of Colorado Health Sciences Center, Denver 80262; and 5  University of Colorado, Boulder, Colorado 80309 To test the hypotheses that prolonged exposure to moderately high altitude increases the energy requirement of adequately fed women and that the sole cause of the increase is an elevation in basal metabolic rate (BMR), we studied 16 healthy women [21.7   ± 0.5 (SD) yr; 167.4 ± 1.1 cm; 62.2 ± 1.0 kg]. Studies were conducted over 12 days at sea level (SL) and at 4,300 m [high altitude (HA)]. To test that menstrual cycle phase has an effect on energetics at HA, we monitored menstrual cycle in all women, and most women ( n  = 11) were studied in the same phase at SL and HA. Daily energy intake at HA was increased to respond to increases in BMR and to maintain body weight and body composition. Mean BMR for the group rose 6.9% above SL by day 3  at HA and fell to SL values by day 6.  Total energy requirement remained elevated 6% at HA [~670 kJ/day (160 kcal/day) above that at SL], but the small and transient increase in BMR could not explain all of this increase, giving rise to an apparent "energy requirement excess." The transient nature of the rise in BMR may have been due to the fitness level of the subjects. The response to altitude was not affected by menstrual cycle phase. The energy requirement excess is at present unexplained. basal metabolic rate; nitrogen balance; acclimatization; menstrual cycle; controlled diet; energy balance; weight control