Operation Everest. II: Nutrition and body composition

Rose, Madeleine S.; Houston, C. Stuart; Fulco, Charles S.; Coates, Geoffrey; Sutton, John R.; Cymerman, Allen

doi:10.1152/jappl.1988.65.6.2545

Cited by 190 publications

(170 citation statements)

References 0 publications

Supporting

Mentioning

157

Contrasting

Order By: Relevance

“…It is noteworthy that similar results were obtained in EDL muscle (data not shown). Thus, in agreement with previous studies (4,33), these data show that hypoxia also exerts a hypophagia-independent effect on skeletal muscle mass loss. Chronic hypoxia and the UPS.…”

Section: Resultssupporting

confidence: 93%

Downregulation of Akt/mammalian target of rapamycin pathway in skeletal muscle is associated with increased REDD1 expression in response to chronic hypoxia

Favier

Costes

Defour

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

103

114

View full text Add to dashboard Cite

Although it is well established that chronic hypoxia leads to an inexorable loss of skeletal muscle mass in healthy subjects, the underlying molecular mechanisms involved in this process are currently unknown. Skeletal muscle atrophy is also an important systemic consequence of chronic obstructive pulmonary disease (COPD), but the role of hypoxemia in this regulation is still debated. Our general aim was to determine the molecular mechanisms involved in the regulation of skeletal muscle mass after exposure to chronic hypoxia and to test the biological relevance of our findings into the clinical context of COPD. Expression of positive and negative regulators of skeletal muscle mass were explored 1) in the soleus muscle of rats exposed to severe hypoxia (6,300 m) for 3 wk and 2) in vastus lateralis muscle of nonhypoxemic and hypoxemic COPD patients. In rodents, we observed a marked inhibition of the mammalian target of rapamycin (mTOR) pathway together with a strong increase in regulated in development and DNA damage response 1 (REDD1) expression and in its association with 14-3-3, a mechanism known to downregulate the mTOR pathway. Importantly, REDD1 overexpression in vivo was sufficient to cause skeletal muscle fiber atrophy in normoxia. Finally, the comparative analysis of skeletal muscle in hypoxemic vs. nonhypoxemic COPD patients confirms that hypoxia causes an inhibition of the mTOR signaling pathway. We thus identify REDD1 as a negative regulator of skeletal muscle mass during chronic hypoxia. Translation of this fundamental knowledge into the clinical investigation of COPD shows the interest to develop therapeutic strategies aimed at inhibiting REDD1.

show abstract

Section: Resultssupporting

confidence: 93%

Downregulation of Akt/mammalian target of rapamycin pathway in skeletal muscle is associated with increased REDD1 expression in response to chronic hypoxia

Favier

Costes

Defour

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

103

114

View full text Add to dashboard Cite

show abstract

“…Everest represented the opportunity to further GH AUC (mg/l min) investigate the endocrine and metabolic responses to prolonged exposure to extreme HA hypobaric hypoxia in association with physical exercise such as that performed by elite climbers. A large variety of factors, including environmental conditions, have been found to influence the hormonal response to exercise at HA (22,23) such as reduced oxygen availability, hypohydration, and alterations in nutritional homeostasis (24)(25)(26).…”

Section: Discussionmentioning

confidence: 99%

Endocrine and metabolic responses to extreme altitude and physical exercise in climbers

Benso

Broglio

Aimaretti

et al. 2007

European Journal of Endocrinology

106

103

View full text Add to dashboard Cite

Context: Chronic hypoxia induces complex metabolic and endocrine adaptations. High-altitude (HA) exposure is a physiological model of hypoxia. Objective: To further investigate the endocrine and metabolic responses to extreme HA. Methods: We studied nine male elite climbers at sea level and at 5200 m after climbing Mt. Everest. Results: After 7 weeks at HA, body weight was reduced (P!0.05); regarding endocrine variables we observed: a) an increase of 2-h mean GH concentration (P!0.05) as well as of total IGF-I and IGF binding protein-3 levels (P!0.05 for both); b) a prolactin increase (P!0.05) coupled with testosterone decrease (P!0.01) and progesterone increase (P!0.05) without any change in estradiol levels: c) no change in cortisol, ACTH, and dehydroepiandrosterone sulfate (DHEAS) levels; d) an increase in free thyroxine (P!0.05) and free tri-iodothyronine (T 3 ) decrease (P!0.05) but no change in TSH levels; e) a plasma glucose decrease (P!0.05) without any change in insulin levels; f) an increase in mean free fatty acid levels (P!0.05); g) despite body weight loss, leptin levels showed non-significant trend toward decrease, while ghrelin levels did not change at all. Conclusions:The results of the present study in a unique experimental human model of maximal exposure to altitude and physical exercise demonstrate that extreme HA and strenuous physical exercise are coupled with specific endocrine adaptations. These include increased activity of the GH/IGF-I axis and a low T 3 syndrome but no change in ghrelin and leptin that was expected taking into account body weight decrease. These findings would contribute to better understanding human endocrine and metabolic physiology in hypoxic conditions. European Journal of Endocrinology 157 733-740

show abstract

“…28 This change in taste sensation may be a factor in high-altitude anorexia, a self-induced starvation. 42 Animals 77 and humans 78 lose body weight when exposed to high-altitude conditions, due to reduced daily food intake and perhaps other factors. One study 78 found that hypoxia was associated with an 8.9% reduction in initial body weight, with appetite suppression and decreased caloric intake lasting for several weeks (during the study), particularly due to a decrease in carbohydrate preference, despite access to ample varieties and quantities of highly palatable foods.…”

Section: Vision Hearing and Tastementioning

confidence: 99%

Cognitive performance, mood, and neurological status at high terrestrial elevation

Banderet¹,

Shukitt-Hale²

2002

PsycEXTRA Dataset

View full text Add to dashboard Cite

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. ABSTRACT (Maximum 200 words)Cognitive and psychomotor performance and mood states, including many critical behavioral functions such as sleep, memory, ■ reasoning, and vigilance, are significantly impaired by ascent to HTE higher than 3,000 m. Impairments in behavior caused by HTE can degrade military operations because the judgment and rate and accuracy of performance of military personnel can be affected. Such adverse effects have distinct and measurable time courses; onset of some effects is immediate (cognitive performance), whereas the onset of others is delayed (symptoms of AMS or adverse moods). The behavioral consequences of HTE are primarily dependent on the level of altitude, the duration of exposure the rate of ascent, an individual's state of physiological acclimation or acclimatization, characteristics of the task performed, and characteristics of the individual such as hypoxic sensitivity. Military history documents that the adverse effects induced by HTE need to be considered when military operations at altitude are planned and undertaken. Current research indicates that some performance decrements induced by ascent to extremely high mountains (e.g., Mount Everest, 8,848 m) may persist for a year or longer after return to lower elevations. Psychological, operational, and medical strategies have been employed to minimize these adverse effects. Psychological strategies often involve training and familiarization with the adverse effects that will be experienced at high altitude. Operational strategies include staging at intermediate altitudes, acclimatizing, and using supplemental oxygen from tanks of oxygen generators. Medical strategies often involve the use of medications to improve functioning at altitude and techniques to avoid complications. In most situations, multiple strategies are employed. The strategies now available and new developments to come will ensure that high-altitude military operations in the future will be less affected by adverse changes in cognitive and psychomotor performance and mood.14. SUBJECT TERMS high altitude, hypoxia, cognitive performance, moods, symptoms, time course of altitude effects, behavior NUMBER OF PAGES 3516. PRICE CODE

show abstract

Operation Everest. II: Nutrition and body composition

Cited by 190 publications

References 0 publications

Downregulation of Akt/mammalian target of rapamycin pathway in skeletal muscle is associated with increased REDD1 expression in response to chronic hypoxia

Downregulation of Akt/mammalian target of rapamycin pathway in skeletal muscle is associated with increased REDD1 expression in response to chronic hypoxia

Endocrine and metabolic responses to extreme altitude and physical exercise in climbers

Cognitive performance, mood, and neurological status at high terrestrial elevation

Contact Info

Product

Resources

About