View clinical trials related to High Altitude.
Filter by:To understand alterations in glycogen and molecular regulation of skeletal muscle glucose uptake, glycogen synthesis, and muscle protein recovery when consuming CHO (glucose) or CHO+PRO (glucose + whey) post-exercise during unacclimatized high altitude exposure, randomized crossover double blinded studies will be conducted in the hypobaric/hypoxic chamber at USARIEM Table 1. Briefly, the study consists of a 2 day baseline period at SL followed by two, 3 day trial periods (with the 3rd day being a testing day) at HA. The baseline is separated from trial 1 for a least a day, and trial 1 & 2 separated by at least 4 days. Volunteers will consume CHO (glucose) or CHO+PRO (glucose + whey) drinks post-exercise during unacclimatized high altitude exposure during the two trial periods. The order of the drinks will be randomized (using a random number generator such as randomizer.org) and kept by a study staff not directly involved in data collection to maintain blinding.
Apparent hypoxia-induced insulin insensitivity along with alterations in glucose kinetics suggests reduction in glucose uptake by the peripheral tissue is a primary factor contributing to reductions in exogenous glucose oxidation at HA. As such, the primary objective of this study is to determine the ability of an insulin sensitizer (Pioglitazone, PIO) to enhance exogenous glucose oxidation and metabolic clearance rate during metabolically-matched, steady-state exercise during acute HA exposure compared to placebo (PLA) in native lowlanders. Secondary objective of this study will be to assess the impact of PIO on markers of inflammation and iron status compared to PLA. This randomized crossover placebo control double blinded study will examine substrate oxidation and glucose kinetic responses to ingesting supplemental carbohydrate (glucose) during metabolically-matched, steady-state exercise with acute (~5 h) exposure to HA (460 mmHg, or 4300m, barometric pressure similar to Pike's Peak) after receiving PIO (HA+PIO), or after receiving a matched placebo (HA+PLA). Eight healthy, recreationally active males between the ages of 18-39 yrs will be required to complete this study. Following a 4 day glycogen normalization period receiving PIO or PLA daily, volunteers will complete two 80-min trials, performing metabolically-matched, steady-state aerobic (same absolute workload corresponding to ~55 ± 5% of V̇O2peak at HA) exercise on a treadmill, and consuming 145 g of glucose (1.8 g/min); one trial with HA+PIO and the other with HA+PLA. A dual glucose tracer (13C-glucose oral ingestion and [6,6-2H2]-glucose primed, continuous infusion) technique and indirect calorimetry will be used to selectively analyze endogenous and exogenous glucose oxidation, as well as glucose rate of appearance (Ra), disappearance (Rd) and metabolic clearance rate (MCR). Serial blood samples will be collected during each trial to assess endocrine and circulating substrate responses to exercise, carbohydrate, and hypoxia with or without PIO. All trials will occur at the same time of day in the USARIEM hypobaric/hypoxic chamber and be separated by a minimum 10-d washout period. The primary risks associated with this study include those associated with acute hypobaric hypoxia, exercise, and blood sampling.
High altitude (>2400 m) is associated with decreased atmosphere pressure leading to hypoxia which in turn impairs exercise capacity and causes acute mountain sickness (AMS). It is noted that adding CO2 might be beneficial to improve hypoxia and exercise performance at high altitude. However, no device is currently available that can supply a constant low dose of CO2 during free movement at high altitude. We have recently invented a portable device which is small and light enough for supplement of low dose CO2 during field exercise at high altitude.
The predictive value of the hypoxia altitude simulation test (HAST) or other baseline values to predict altitude-related adverse health effects (ARAHE) is not established. To address this gap, the main goals of this investigation will be 1) to evaluate the diagnostic accuracy of the HAST in identifying individuals that will experience ARAHE during altitude travel and 2) to establish prediction models incorporating other commonly assessed clinical characteristics either alone or in combination with the HAST as predictors of ARAHE in altitude travelers. Hypotheses: In lowlanders with COPD, a PaO2 <6.6 kPa or another cutoff of PaO2 or SpO2 at the end of the HAST, at rest or during exertion and/or clinical variables including symptoms, pulmonary function indices, 6-min walk distance (6MWD), either alone or combined to a multivariable model, will predict ARAHE during a sojourn of 2 days at 3100m with accuracy greater than chance
Congenital heart diseases are among the most common congenital anomalies and occur with an incidence of approximately 8ınd12 / 1,000 live births worldwide. This figure does not cover minor lesions such as bicuspid aortic valves and small atrial or ventricular septal defects. Most of these defects do not need treatment or treatment is needed after infancy. Other defects are severe and usually require early treatment in the neonatal period. Critical congenital heart disease is defined as structural heart defects that are associated with hypoxia in the neonatal period and have significant morbidity and mortality potential in early life. Critical congenital heart disease is estimated to be ~3 in 1000 live births. It is estimated that 50% of congenital heart diseases are detected by prenatal ultrasound. Even if a standard neonatal examination is performed, 13 to 55% of patients with critical congenital heart disease can be discharged from the hospital without being diagnosed. Screening of infants with non-invasive oxygen saturation measurement has been proposed as an adjunct to early detection of critical congenital heart disease. The American Academy of Pediatrics, the American Cardiology Foundation and the American Heart Association have targeted 7 specific lesions for the pulse oximetry screening protocol: truncus arteriosus, transposition of the great arteries, tricuspid atresia, tetralogy of Fallot, total pulmonary venous return anomaly, hypoplastic left heart syndrome and pulmonary atresia. The reference values of peripheral perfusion (PPI) index has been established for normal newborns between 1 and 120 h of age. Lower PPI values than 0.70 may indicate illness. Including cut-off values for PPI in pulse-oximetry screening for duct dependent congenital heart disease is a promising tool for improving the detection of critical congenital heart disease with duct-dependent systemic circulation. We aimed to investigate screening critical congenital heart disease and also to establish normal values of oxygen saturation and perfusion index at high altitude.
Recent studies have reported that oxidation of exogenous carbohydrate is reduced under acute hypobaric hypoxic (high altitude; HA) conditions compared to normoxia (sea level; SL) in native lowlanders. However, the mechanisms by which HA suppresses exogenous carbohydrate oxidation are not known. This study will seek to confirm that acute HA exposure decreases exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL, and explore if the mechanism inhibiting plasma glucose uptake is insulin dependent or independent.
Ibuprofen is often taken by travelers to high altitude to treat the symptoms of acute mountain sickness such as headache and malaise. However, the blunting of inflammation by ibuprofen may slow the process of acclimatization to altitude, which relies on mediators of inflammation for adjustments in breathing. The study randomizes healthy subjects to receive ibuprofen or placebo and then ascend to altitude (12,500 feet). Blood cytokines and non-invasive measurements of blood and tissue oxygen levels will be made for 48 hours at altitude. The hypothesis being tested is that subjects receiving ibuprofen will have lower blood and tissue oxygen levels after 48 hours at altitude than will placebo subjects.
This study is aimed to assess the efficacy of combined treatment with two antihypertensive agents (telmisartan and nifedipine) in subjects with mild hypertension exposed to high altitude.