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Total testosterone levels (A) and free testosterone levels (total testosterone/fasting sex hormone-binding globulin; B) for each group at SL and over the 21-day intervention period. Values are mean SE. P 0.05, significant from SL baseline (*), significant from ADQ ( ‡), and significant from HYPO ( §).
Source publication
High-altitude anorexia leads to a hormonal response pattern modulated by both hypoxia and caloric restriction (CR). The purpose of this study was to compare altitude-induced neuroendocrine changes with or without energy imbalance and to explore how energy sufficiency alters the endocrine acclimatization process. Twenty-six normal-weight, young men...
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Purpose
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Citations
... TSH concentration is one of the most sensitive indices of HPT axis function [37]. Studies have shown that the adrenal, thyroid, and gonadal axes are affected by increased altitude, and the HPT axis is altered to adapt to hypoxic conditions [38][39][40]. Under transient highaltitude exposure, such as mountaineering expeditions, Hackney found significantly lower TSH and FT3 concentrations among 15 mountain climbers who climbed Mount. ...
Background
Chinese topography appears a three-rung ladder-like distribution of decreasing elevation from northwest to southeast, which is divided by two sloping edges. Previous studies have reported that prevalence of thyroid diseases differed by altitude, and geographical factors were associated with thyroid disorders. To explore the association between three-rung ladder-like regions and thyroid disorders according to unique Chinese topographic features, we conducted an epidemiological cross-sectional study from 2015–2017 that covered all 31 mainland Chinese provinces.
Methods
A total of 78,470 participants aged ≥ 18 years from a nationally representative cross-sectional study were included. Serum thyroid peroxidase antibody, thyroglobulin antibody, and thyroid-stimulating hormone levels; urine iodine concentration; and thyroid volume were measured. The three-rung ladder-like distribution of decreasing elevation from northwest to southeast in China was categorized into three topographic groups according to elevation: first ladder, > 3000 m above sea level; second ladder, descending from 3000—500 m; and third ladder, descending from 500 m to sea level. The third ladder was further divided into groups A (500–100 m) and B (< 100 m). Associations between geographic factors and thyroid disorders were assessed using linear and binary logistic regression analyses.
Results
Participants in the first ladder group were associated with lower thyroid peroxidase (β = -4.69; P = 0.00), thyroglobulin antibody levels (β = -11.08; P = 0.01), and the largest thyroid volume (β = 1.74; P = 0.00), compared with the other groups. The second ladder group was associated with autoimmune thyroiditis (odds ratio = 1.30, 95% confidence interval [1.18–1.43]) and subclinical hypothyroidism (odds ratio = 0.61, 95%confidence interval [0.57–0.66]) (P < 0.05) compared with the first ladder group. Group A (third ladder) (500–100 m) was associated with thyroid nodules and subclinical hypothyroidism (P < 0.05). Furthermore, group B (< 100 m) was positively associated with autoimmune thyroiditis, thyroid peroxidase and thyroglobulin antibody positivity, and negatively associated with overt hypothyroidism, subclinical hypothyroidism, and goiter compared with the first ladder group(P < 0.05).
Conclusion
We are the first to investigate the association between different ladder regions and thyroid disorders according to unique Chinese topographic features. The prevalence of thyroid disorders varied among the three-rung ladder-like topography groups in China, with the exception of overt hyperthyroidism.
... In most studies there have been increased level of thyroid hormones at high altitude, although report suggest that TSH secretion is not modified but the mechanisms involved in this process are still unclear 52 . The insulin level is increased during elevated glucose circulation and it functions to suppress the hepatic glucose output. ...
When people are exposed to the extreme environmental conditions, such as high altitude where there is decrease in temperature and partial pressure of oxygen induces fatigue, insomnia, loss of appetite and increased cardiac output. Hence there is need to improve the appetite through the diet and digestion clout of the individual. In the present review paper the efficiency of digestion is compromised at high altitude is discussed. Also about, Hypoxia, resulting by decreased partial pressure of oxygen can be classified into acute hypoxia and chronic hypoxia
based on the exposure time. There is increased formation of reactive oxygen species due to less oxygen available in the air at high altitude which leads to oxidative stress. Lipid peroxidation caused by oxidative stress. Hypoxia
is mediated through hypoxia inducible factors which maintain oxygen haemostasis in the body. At high altitude diet
rich in carbohydrates have been found to be beneficial as it increases glucose metabolism. Requirement of nutrients such as vitamin A, vitamin E and vitamin C as well as micronutrients such as zinc, iron, selenium, copper and manganese will be required at high altitude. Hypoxia effect on the intestine leads to malabsorption and the lipid storage is stimulated and lipid catabolism is inhibited through β-oxidation.
... In most studies, thyroid hormone levels have been reported to rise at higher altitudes, but TSH secretion is unaffected, and the processes underlying this dissociation remain unknown (Barnholt et al., 2006). TSH levels remain stable, but higher levels of total and free fractions of T3 and T4 are consistent with most prior investigations, implying that moderate hyperthyroidism may be required to tolerate the severe conditions of high altitudes (Basu et al., 1995;Ramirez et al., 1995). ...
As the altitude increases, the partial pressure of oxygen decreases, leading to hypoxic conditions and ultimately disturbing body homeostasis and affecting neuroendocrine function in cattle. These physiological changes causes low conception rate, early embryonic death, low fertility, etc. in cattle and other livestock species. So far, cattle's reproductive health associated with high-altitude hypoxic conditions has rarely been studied with respect to reproductive physiology, endocrinology, and physio-biochemical perspective. Hence, this review discusses various physiological changes, hormonal disturbance, placenta development, haematological and biochemical changes etc. which are associated and affecting cattle's reproductive physiology.
... Research shows that it has excitatory effects on almost all tissues and has a certain correlation with energy metabolism (proteins, sugars, and fats), thermoregulation, tissue differentiation, and growth and development of bodies (Maria et al., 2019). Hypoxia at high altitudes leads to changes in thyroid function and structure (Naeije, 2010); however, the results of previous studies on the changes in TH caused by hypoxia are inconsistent (Rawal et al., 1993;Savourey et al., 2004;Barnholt et al., 2006). Thyroid function has been shown to be enhanced, weakened, or even unchanged, which is related to many factors such as the exposure mode of hypoxia, altitude, duration, and availability of altitude adaptive training. ...
High altitude pulmonary edema (HAPE) is a serious threat to the physical and mental health of people who quickly enter high plateaus, deserves more attention and in-depth research. In our study, through the detection of various physiological indexes and other phenotypes in a HAPE rat model, the HAPE group showed a significant decrease in oxygen partial pressure and oxygen saturation, and a significant increase in pulmonary artery pressure and lung tissue water content. The lung histomorphology showed characteristics such as pulmonary interstitial thickening and inflammatory cell infiltration. We applied quasi-targeted metabolomics to compare and analyze the components of metabolites in arterial–veinous blood in control rats and HAPE rats. Using kyoto Encyclopedia of Genes Genomes (KEGG) enrichment analysis and two machine algorithms, we speculate that after hypoxic stress and comparing arterial blood and venous blood products in rats, the metabolites were richer, indicating that normal physiological activities, such as metabolism and pulmonary circulationhad a greater impact after hypoxic stress; D-mannoseDOWN, oxidized glutathioneDOWN, glutathione disulfideDOWN, and dehydrocholic acidDOWN in arterial blood play key roles in predicting the occurrence of HAPE; in venous blood, L-leucineDOWN, L-thyroxineDOWN, and cis-4-hydroxy- D-prolineDOWN may have key roles, which can be considered biomarkers of HAPE. This result provides a new perspective for the further diagnosis and treatment of plateau disease and lays a strong foundation for further research.
... In high altitude areas, the hypoxia changes the level of thyroid hormones T3 & T4 (Alhawiti et al., 2018). Thus according to this research, high altitude places create hypoxia, which must be compensated for by mild hyperthyroidism (Barnholt et al., 2006). ...
... Similar reductions in blood T levels were noted following an 18-day stay at an altitude of 3500 m [48]. It has been suggested that negative energy balance may be an important factor responsible for reduced blood T levels at high altitudes [49]. Indeed, it was shown that, following 21 days of exposure to an altitude of 4300 m, blood T levels increased and remained elevated only in the group with a balanced and controlled diet. ...
The aim of this study was to analyze the effects of the "live high, train low" method (LH-TL) and intermittent hypoxic training (IHT) on testosterone (T) and cortisol (C) levels in cyclists. Thirty cyclists participated in the experiment. The LH-TL group (n = 10) was exposed to normobaric hypoxia (FiO2 = 16.3%) for 11-12 h a day and trained in normoxia for 3 weeks. In the IHT group (n = 10), participants followed the IHT routine three times a week for 3 weeks in normobaric hypoxia (FiO2 = 16.3%). The control group (N; n = 10) followed the same training protocol in normoxia. The LH-TL training was found to significantly increase (p < 0.05) T levels and the testosterone/cortisol (T/C) ratio during the experiment. The area under the curve (AUC) calculated for T levels over 4 weeks was significantly (p < 0.05) higher in the LH-TL group, by 25.6%, compared to the N group. The results also indicated a significant correlation (r = 0.53; p < 0.05) between AUC for T levels over 4 weeks and ∆ values of hemoglobin (HGB) in the LH-TL group. Overall, the findings show that LH-TL training at a moderate simulated altitude contributes to an increase in T levels and T/C ratio in athletes, which is a beneficial change stimulating anabolic processes and erythropoiesis.
... [18][19][20][72][73][74][75] An exception to this would be cases when there is considerable high altitude-related muscle wasting. 76,77 However, studies have shown that this muscular atrophy can be greatly limited by increased caloric intake, 78,79 which would prevent an atrophy-associated decline in MVC force with CH. It follows that neuromuscular fatigability studies involving single-joint isometric exercise, using the same relative exercise intensity (% MVC force) across SL, AH and CH, will most likely target the same absolute force (or joint torque). ...
... 136,137 Preservation of motoneurone excitability with CH may be due to increased sympathetic nervous system activity 138,139 that leads to greater circulating epinephrine and norepinephrine concentrations. 79,140,141 More excitable motoneurones would require less descending drive for a given muscle output, which would mitigate the functional consequence of any impairment to cortical drive. ...
Ascent to high altitude is accompanied by a reduction in partial pressure of inspired oxygen, which leads to interconnected adjustments within the neuromuscular system. This review describes the unique challenge that such an environment poses to neuromuscular fatigability (peripheral, central, and supraspinal) for individuals who normally reside near to sea level (< 1000 m; i.e., lowlanders) and for native highlanders, who represent the manifestation of high altitude-related heritable adaptations across millennia. Firstly, the effect of acute exposure to high altitude-related hypoxia on neuromuscular fatigability will be examined. Under these conditions, both supraspinal and peripheral fatigability are increased compared to sea level. The specific mechanisms contributing to impaired performance are dependent on the exercise paradigm and amount of muscle mass involved. Next, the effect of chronic exposure to high altitude (i.e., acclimatisation of ~7-28 days) will be considered. With acclimatisation, supraspinal fatigability is restored to sea level values, regardless of the amount of muscle mass involved, whereas peripheral fatigability remains greater than sea level except when exercise involves a small amount of muscle mass (e.g., knee extensors). Indeed, when whole-body exercise is involved, peripheral fatigability is not different to acute high-altitude exposure, due to competing positive (haematological and muscle metabolic) and negative (respiratory-mediated) effects of acclimatisation on neuromuscular performance. In the final section, we consider evolutionary adaptations of native highlanders (primarily Himalayans of Tibet and Nepal) that may account for their superior performance at altitude and lesser degree of neuromuscular fatigability compared to acclimatised lowlanders, for both single-joint and whole-body exercise.
... Consequently, ratios of LDL/HDL, cholesterol/HDL, and AIP, potential risk factors for coronary artery disease (CAD) were elevated for HA-D150. Both animal and human studies have reported that hypoxia increases plasma triglycerides by decreasing tissue uptake (Barnholt et al., 2006;Siques et al., 2014). Epidemiological studies have reported a high prevalence of hypercholesterolemia and low HDL levels for indigenous high land native populations of Peru (Mohanna et al., 2006), Chile (Santos et al., 2001), and Tibet (Sherpa et al., 2011). ...
Acute exposure to high altitude perturbs physiological parameters and induces an array of molecular changes in healthy lowlanders. However, activation of compensatory mechanisms and biological processes facilitates high altitude acclimatization. A large number of lowlanders stay at high altitude regions from weeks to months for work and professional commitments, and thus are vulnerable to altitude-associated disorders. Despite this, there is a scarcity of information for molecular changes associated with long-term stay at high altitudes. In the present study, we evaluated oxygen saturation (SpO2), heart rate (HR), and systolic and diastolic blood pressure (SBP and DBP) of lowlanders after short- (7 days, HA-D7) and long-term (3 months, HA-D150) stay at high altitudes, and used TMT-based proteomics studies to decipher plasma proteome alterations. We observed improvements in SpO2 levels after prolonged stay, while HR, SBP, and DBP remained elevated as compared with short-term stay. Plasma proteomics studies revealed higher levels of apolipoproteins APOB, APOCI, APOCIII, APOE, and APOL, and carbonic anhydrases (CA1 and CA2) during hypoxia exposure. Biological network analysis also identified profound alterations in lipoprotein-associated pathways like plasma lipoprotein assembly, VLDL clearance, chylomicron assembly, chylomicron remodeling, plasma lipoprotein clearance, and chylomicron clearance. In corroboration, lipid profiling revealed higher levels of total cholesterol (TC), triglycerides (TGs), low-density lipoprotein (LDL) for HA-D150 whereas high density lipoproteins (HDL) levels were lower as compared with HA-D7 and sea-level indicating dyslipidemia. We also observed higher levels of proinflammatory cytokines IL-6, TNFα, and CRP for HA-D150 along with oxidized LDL (oxLDL), suggesting vascular inflammation and proartherogenic propensity. These results demonstrate that long-term stay at high altitudes exacerbates dyslipidemia and associated disorders.
... In OSA, increased sympathetic nerve activity and catecholamines may occur as a result of repeated arousals or repeated oxygen desaturations [40]. In humans, exposure to high altitude hypoxia for a few days increases glucose and insulin concentrations together with increased plasma catecholamines and cortisol [36,41,42]. Moreover, OSA is reportedly associated with marked impairments in insulin sensitivity and disposition index (an integrated measure of pancreatic ß-cell function) independent of adiposity [9,43]. ...
Introduction
Obstructive sleep apnoea (OSA) is an underdiagnosed condition frequently associated with glycaemic control impairment in patients with type 2 diabetes.
Aim
To assess the relationship between glycometabolic parameters and OSA in obese non-diabetic subjects.
Methods
Ninety consecutive subjects (mean age 44.9 ± 12 years, mean BMI 42.1 ± 9 kg/m ² ) underwent polysomnography and a 2-h oral glucose tolerance test (OGTT).
Results
OSA was identified in 75% of subjects, with a higher prevalence of males compared to the group of subjects without OSA (62% vs 32%, p = 0.02). Patients with OSA had comparable BMI (42.8 kg/m ² vs 39.4 kg/m ² ), a higher average HbA1c (5.8% vs 5.4%, p < 0.001), plasma glucose at 120 min during OGTT (2 h-PG; 123 mg/dl vs 97 mg/dl, p = 0.009) and diastolic blood pressure (81.1 mmHg vs 76.2 mmHg, p = 0.046) than obese subjects without OSA. HbA1c and 2 h-PG were found to be correlated with the apnoea-hypopnoea index (AHI; r = 0.35 and r = 0.42, respectively) and with percent of sleep time with oxyhaemoglobin saturation < 90% (ST90; r = 0.44 and r = 0.39, respectively). Further, in a linear regression model, ST90 and AHI were found to be the main determinants of 2 h-PG ( β = 0.81, p < 0.01 and β = 0.75, p = 0.02, respectively) after controlling for age, sex, waist circumference, physical activity, and C-reactive protein. Similarly, ST90 and AHI persisted as independent determinants of HbA1c ( β = 0.01, p = 0.01 and β = 0.01, p = 0.01, respectively).
Conclusion
Beyond the traditional clinical parameters, the presence of a normal-high value of 2 h-PG and HbA1c should raise suspicion of the presence of OSA in obese subjects.
... It is reported that hypoxic environment exposure can increase tissue oxygen supply, capillary density (Lecoultre et al., 2010), regulate the synthesis rate of mitochondria in skeletal muscle (Zoll et al., 2006), and promote the secretion of hormones related to energy metabolism, thus activating fat metabolism (Barnholt et al., 2006). At present, the mechanism of increased energy consumption during hypoxia exposure has not been fully identified, but it is believed that one of the main reasons is the activation of sympathetic nervous system (Louis & Punjabi, 2009;Mawson et al., 2000). ...
Environmental and maternal exercise experienced even during the very earliest stages of life has the potential to cause developmental changes. The growing evidence demonstrated that diverse environmental stressors affect offspring in various aspects in early stage of life and can be transmitted directly or indirectly by both parental lines. The development of normobaric hypoxic environment facilities began in recent years after athletes born and trained at high altitude continued to update their records in sports competition, especially marathons and other endurance sports. Although a large number of studies have proved the effect of hypoxic training in the field of sports science and competition, the effectiveness of this training model on exercise performance/capacity and physiological variables is still controversial. Therefore, this study makes a brief review of the papers related to this scope and attempted to understand the potential mechanism of maternal exercise in hypoxic environment on exercise performance and reduction of metabolic risk factors.
