Austrian Moderate Altitude Studies (AMAS): benefits of exposure to moderate altitudes (1,500-2,500 m)

Effect of Altitude on Polycythemia Vera: Is it Necessary to Change Limits?

Serin, Istemi, Ahmet Unal, Arzu Dobral, Fatma Elif Eroglu, Erdem Ayik, Jale Oz Unal, Mehmet Barış Cengiz, Okan Kati, Toros Taskin, Vural Bastug, and Abdulkadir Karismaz. The effect of altitude on polycythemia vera: Is it necessary to change limits? High Alt Med Biol. 00:00-00, 2025. Background: Polycythemia vera (PV) is a myeloproliferative disease characterized by high hemoglobin/hematocrit levels accompanied by JAK2 mutations. In this study, we aimed to establish a new hemoglobin cut-off value for the diagnosis and further evaluation of PV, taking into account the altitude of the regions where patients reside. In addition, we sought to examine the impact of altitude on patients diagnosed with PV and secondary polycythemia (SP) within our case series. Methods: Patients living in Istanbul and Agri who were evaluated for PV at the hematology outpatient clinic of Istanbul and Agri Training and Research Hospitals between January 20, 2023, and January 20, 2024, were included in the study. The average altitude of the center of Agri is 1,630 m, while the center of Istanbul is 30 m. Results: The mean altitude of residence for individuals diagnosed with PV was 326 ± 259 m, whereas it was significantly higher at 1,065 ± 675 m in the SP subgroup (p < 0.001). However, in subgroup analyses of patients with PV and SP, altitude was not a significant factor influencing hemoglobin levels. Conclusions: Our study results did not support the use of different hemoglobin cut-off values or correction factors for further evaluation of PV in patients living at different altitudes. Our results might not be applicable to altitudes higher than those we examined.

Flying to high-altitude destinations

Every year millions of people fly to high-altitude destinations. They thereby expose themselves to specific high-altitude conditions. The hypoxic environment (low ambient oxygen availability) constitutes a major factor affecting health and well-being at high altitude. While the oxygen availability is already moderately reduced inside the aircraft cabin, this reduction becomes aggravated when leaving the plane at high-altitude destinations. Especially if not pre-acclimatized, the risk of suffering from high-altitude illnesses, e.g., acute mountain sickness, high-altitude cerebral or pulmonary edema, increases with the level of altitude. In addition, diminished oxygen availability impairs exercise tolerance, which not only limits physical activity at high altitude but may also provoke symptomatic exacerbation of pre-existing diseases. Moreover, the cold and dry ambient air and increased levels of solar radiation may contribute to adverse health effects at higher altitude. Thus, medical pre-examination and pre-flight advice, and proper preparation (pre-acclimatization, exercise training, and potentially adaptation of pharmacological regimes) are of utmost importance to reduce negative health impacts and frustrating travel experiences.

Are Suggested Hiking Times Accurate? A Validation of Hiking Time Estimations for Preventive Measures in Mountains

Background and Objectives: Accurate hiking time estimate is crucial for outdoor activity planning, especially in mountainous terrains. Traditional mountain signage and online platforms provide generalized hiking time recommendations, often lacking personalization. This study aims to evaluate the variability in hiking time estimates from different methods and assess the potential of a novel algorithm, MOVE, to enhance accuracy and safety. Materials and Methods: A cross-sectional analysis was conducted using data from 25 Italian loop trails selected via the Wikiloc platform, considering user-uploaded GPS data from at least 20 users per trail. Real-world hiking times were compared with estimations from Komoot, Outdooractive, mountain signage, and the MOVE algorithm, which incorporates individualized biological and trail characteristics. Results: Significant discrepancies were observed between actual hiking times and estimates from Komoot (ΔWK: -48.92 ± 57.16 min), Outdooractive (ΔWO: -69.13 ± 58.23 min), and mountain signage (ΔWS: -29.59 ± 59.90 min; all p < 0.001). In contrast, MOVE showed no statistically significant difference (ΔWM: -0.27 ± 65.72 min; p = 0.278), providing the most accurate predictions. Conclusions: Current hiking time estimation methods show substantial variability and inaccuracy, which may pose safety risks. MOVE demonstrated superior accuracy, offering personalized hiking time predictions based on user-specific data and trail characteristics. Integrating such advanced tools into outdoor activity planning could enhance safety and accessibility, particularly for individuals with chronic conditions. Further studies should explore integrating real-time health data to refine these tools.

Taste and Appetite at Altitude: A Comprehensive Review of Sensory and Hunger Modulation in High-Altitude Environments

Introduction: Individuals living or working at high altitudes typically experience altered taste perceptions and reduced appetite. These changes can lead to nutritional deficiencies, affecting the energy balance and body composition. Methods: We conducted a nonsystematic review of PubMed to explore these phenomena and expound on their findings to offer additional insights. Results: Changes in taste and perception are common and typically lead to loss of mass. There are limited practical solutions to mitigate these challenges. Discussion: Gradual acclimatization and tailored nutritional strategies are required to enhance health and performance in high-altitude environments. This review provides critical insights into the intersection of altitude, nutrition, and health.

Moderate altitude exposure impacts host fasting blood glucose and serum metabolome by regulation of the intestinal flora

Moderate altitude exposure has shown beneficial effects on diabetes incidence but the underlying mechanisms are not understood. Our study aimed to investigate how the human gut microbiome impacted the serum metabolome and associated with glucose homeostasis in healthy Chinese individuals upon moderate-altitude exposure. Faecal microbiome composition was assessed using shotgun metagenomic sequencing. Serum metabolome was acquired by untargeted metabolomics technology, and amino acids (AAs) and propionic acid in serum were quantified by targeted metabolomics technology. The results indicated that the moderate-altitude exposed individuals presented lowered fasting blood glucose (FBG) and propionic acid, increased circulating L-Glutamine but decreased L-Glutamate and L-Valine, which correlated with enriched Bacteroidetes and decreased Proteobacteria. Additionally, the silico causality associations among gut microbiota, serum metabolome and host FBG were analyzed by mediation analysis. It showed that increased Bacteroides ovatus (B. ovatus) and decreased Escherichia coli (E. coli) were identified as the main antagonistic species driving the association between L-Glutamate and FBG in silico causality. Furthermore, the high-fat diet (HFD) fed mice subjected to faecal microbiota transplantation (FMT) were applied to validate the cause-in-fact effects of gut microbiota on the beneficial glucose response. We found that microbiome in the moderate-altitude exposed donor could predict the extent of the FBG response in recipient mice, which showed lowered FBG, L-Glutamate and Firmicutes/Bacteroidetes ratio. Our findings suggest that moderate-altitude exposure targeting gut microbiota and circulating metabolome, may pave novel avenues to counter dysglycemia.

Long-Term Effects of Mountain Hiking vs. Forest Therapy on Physical and Mental Health of Couples: A Randomized Controlled Trial

BACKGROUND

Lifelong physical activity is related to longer health span, which is reflected at an individual level, and is of substantial socioeconomic relevance. Sedentary lifestyles, on the other hand, pose an increasingly major public health problem. In addition, the COVID-19 pandemic had a negative impact on activity levels and well-being. Previous research indicates that contact with nature might improve exercise levels as well as well-being.

METHODS

This randomized, controlled clinical trial (ANKER-study) investigated the effects of two types of nature-based therapies (forest therapy and mountain hiking) in couples (FTG: n = 23; HG: n = 22;) with a sedentary or inactive lifestyle on health-related quality of life, relationship quality and other psychological and physiological parameters.

RESULTS

The results of this study displayed that healthy and highly functioning women and men with sedentary lifestyles mentally benefit from contact with nature (quality of life, satisfaction with life, mood, internal and external health-related control beliefs). The gender-specific effect on women is most visible in the physiological outcomes (hemopoietic system, aerobic capacity, skeletal muscle mass and hydration) of mountain hiking. Men and women showed small improvements in blood pressure as a result of the interventions.

CONCLUSIONS

The ANKER-study provides a method for valid comparison of forest therapy interventions for the first time. Regarding the COVID-19 pandemic, the nature-based intervention presented could offer a multimodal contribution to maintaining a more active lifestyle, further contact with nature that affects peoples physical as well as mental health, and an improvement in social interaction.

Monitoring Physiological Performance over 4 Weeks Moderate Altitude Training in Elite Chinese Cross-Country Skiers: An Observational Study

The current observational study aimed to monitor the physiological performance over 4 weeks of living and training at a moderate altitude in elite Chinese cross-country skiers (8 males, mean age 20.83 ± 1.08 years). Lactate threshold, maximal oxygen uptake, blood, and body composition tests were performed at different time points to investigate the changes in physiological performance. The data were analysed by a one-way repeated measures ANOVA and a paired sample T-test between the test results. During the training camp, systematic load monitoring was carried out. Lactate threshold velocity, lactate threshold heart rate, and upper body muscle mass increased significantly (p < 0.01) after moderate altitude training. Maximum oxygen uptake was reduced compared to pre-tests (p < 0.05). Aerobic capacity parameters (maximal oxygen uptake, haemoglobin, red blood cell count) did not significantly increase after athletes returned to sea level (p > 0.05). These findings suggest that 4 weeks of moderate altitude training can significantly improve athletes’ lactate threshold and upper body muscle mass; no significant improvement in other aerobic capacity was seen. Exposure time, training load, and nutritional strategies should be thoroughly planned for optimal training of skiers at moderate altitudes.

Health Benefits of Residence at Moderate Altitude Do Not Reduce COVID-19 Mortality

Moderate altitude (1000−2000 m above sea level) residence is emerging as a protective factor from the mortality of various causes, including of cardiovascular diseases. Conversely, mortality from certain respiratory diseases is higher at these altitudes than in lowlands. These divergent outcomes could indicate either beneficial or detrimental effects of altitude on the mortality of COVID-19 that primarily infects the respiratory tract but results in multi-organ damage. Previous epidemiological data indeed suggest divergent outcomes of moderate to high altitude residence in various countries. Confounding factors, such as variations in the access to clinical facilities or selection biases of investigated populations, may contribute to the equivocation of these observations. We interrogated a dataset of the complete population of an Alpine country in the center of Europe with relatively similar testing and clinical support conditions across altitude-levels of residence (up to around 2000 m) to assess altitude-dependent mortality from COVID-19 throughout 2020. While a reduced all-cause mortality was confirmed for people living higher than 1000 m, no differences in the mortality from COVID-19 between the lowest and the highest altitude regions were observed for the overall population and the population older than 60 years as well. Conversely, COVID-19 mortality seems to have been reduced in the very old (>85 years) women at moderate altitudes.

Is altitude a determinant of the health benefits of nature exposure? A systematic review and meta-analysis

Introduction

Nature exposure is a widely accepted option for promoting public health owing to the recent surge of scientific evidence. However, the actual settings to facilitate this initiative is yet to be extensively reviewed. In this systematic review, we have aimed to provide an up-to-date summary of interventional studies investigating the psycho-physiological effects of forests and urban forests, including details on their physical settings, and investigate an effect-modifying role of altitude and summarize data on the magnitude and shape of the association.

Methods

A keyword search using five electronic academic databases (PubMed, Embase, PsycINFO, Web of Science, and Scopus) was conducted to identify relevant articles published in English from the inception year to the end of February 2022. The methodological quality was evaluated using the ROBINS-I or ROB2 tool, depending on the study design. Meta-regression and random effects model were jointly used to examine the relationship between altitude and health outcomes.

Results

We included 27 eligible studies and 31 cases extracted from 19 studies were used for the meta-analysis. In the meta-regression, we observed a non-linear association between altitude and psycho-physiological effects. Altitude had a positive quadratic association with anxiety (p < 0.000, adjusted R ² = 96.79%), depression (p < 0.000, adjusted R ² = 98.78%), and fatigue (p < 0.000, adjusted R ² = 64.74%) alleviating effects. Conversely, altitude demonstrated a negative non-linear association with the blood pressure-lowering effect (p = 0.009, adjusted R ² = 32.83%). Additionally, the thermal index (THI) and illuminance (lx) levels were significantly associated with effect sizes of psychological restoration.

Discussion

This review provides moderate-certainty evidence for an effect-modifying role of altitude. The meta-regression results suggested the optimal and minimal altitude ranges for psychological restoration and physiological relaxation, respectively. Despite some limitations, the study findings provide a significant basis for utilizing altitude, which is easily accessible and simple, to promote the health benefits of nature-based initiatives.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022310894, identifier: CRD42022310894.

Physiological and pathophysiological aspects of short-term middle-altitude adaptation in humans

The review presents up-to-date information on the physiological and pathophysiological aspects of short-term middle-altitude adaptation in healthy individuals and patients with various chronic diseases. Unlike acute mountain sickness, which develops going to ≥3000, the physiological aspects of human adaptation to 2000-2500 m remain insufficiently studied. However, these altitudes are the most visited among tourist groups and individually.

Physiological and pathophysiological aspects of short-term middle-altitude adaptation in humans

The review presents up-to-date information on the physiological and pathophysiological aspects of short-term middle-altitude adaptation in healthy individuals and patients with various chronic diseases. Unlike acute mountain sickness, which develops going to ≥3000, the physiological aspects of human adaptation to 2000-2500 m remain insufficiently studied. However, these altitudes are the most visited among tourist groups and individually.

Blood Pressure Changes While Hiking at Moderate Altitudes: A Prospective Cohort Study

Recreational hiking in the mountains is a common activity, whether for a single day or for several days in a row. We sought to measure blood pressure (BP) response during a 10-day trek at moderate-altitude elevation (6500-13,000 feet) and observe for uncontrolled hypertension and/or adverse cardiovascular outcomes. A total of 1279 adult participants completed an observational study of resting BP during a 10-day trek in the Sangre de Cristo mountains. Following initial recruitment, participants were issued a trail data card to record BP measurements at day 0 (basecamp), day 3, day 6 and day 9. BP was measured using a sphygmomanometer and auscultation. Demographic data, height, weight, home altitude, daily water and sports drink intake, existence of pre-arrival hypertension and BP medication class were also recorded. We observed a rise in mean blood pressure for the cohort during all exposures to moderate altitudes. The increases were greatest for individuals with pre-existing hypertension and/or obesity. There were no observed life-threatening cardiovascular events for participants. We conclude that for individuals with a modestly controlled blood pressure of 160/95 mmHg, hiking at a moderate altitude is a safe activity.

Characteristics of Victims of Fall-Related Accidents during Mountain Hiking

The study evaluated characteristics of non-fatal mountain hiking accidents caused by falls. Questionnaires were sent to mountain hikers who suffered a fall-related accident in Tyrol (Austria) during a 3-year period. The questionnaire included details of socio-demographic data, physical activity, medication intake, defective vision, breaks, fluid intake, level of fatigue, muscle soreness, use of backpacks, use of hiking sticks, and type of shoes. Data of 405 individuals (57% females and 43% males) were included in the analyses. Victims were 56 ± 15 years of age, had a body mass index of 24.8 ± 3.5, and indicated 4.2 ± 3.9 h/week regular physical activity. A defective vision was reported by 70% of the victims, breaks were frequent (in 80%), and alcohol intake was rare (4%) among the interviewed hikers. Subjective level of fatigue was low and only 5% reported muscle soreness. A backpack was carried by 83% of the victims and the average weight was higher in males compared to females. The majority (61%) of the victims wore ankle-height hiking shoes with a profiled sole. Victims of non-fatal falls in mountain hiking are older than the general population of mountain hikers and are often afflicted with defective vision.

A unifying conceptual framework of factors associated to cardiac vagal control

Cardiac vagal control (CVC) reflects the activity of the vagus nerve regulating cardiac functioning. CVC can be inferred via heart rate variability measurement, and it has been positively associated to a broad range of cognitive, emotional, social, and health outcomes. It could then be considered as an indicator for effective self-regulation, and given this role, one should understand the factors increasing and decreasing CVC. The aim of this paper is to review the broad range of factors influencing CVC, and to provide a unifying conceptual framework to integrate comprehensively those factors. The structure of the unifying conceptual framework is based on the theory of ecological rationality, while its functional aspects are based on the neurovisceral integration model. The structure of this framework distinguishes two broad areas of associations: person and environment, as this reflects adequately the role played by CVC regarding adaptation. The added value of this framework lies at different levels: theoretically, it allows integrating findings from a variety of scientific disciplines and refining the predictions of the neurovisceral integration model; methodologically, it helps identifying factors that increase and decrease CVC; and lastly at the applied level, it can play an important role for society regarding health policies and for the individual to empower one's flourishing.

Enhancing cardiac vagal activity: Factors of interest for sport psychology

Self-regulation plays a critical role in sport performance. An objective, psychophysiological marker of self-regulation is cardiac vagal activity, the activity of the vagus nerve regulating cardiac functioning. The aim of this paper is to provide an overview of factors influencing cardiac vagal activity, which can be useful for athletes. Specifically, we organize this overview in two main domains: personal factors and environmental factors. Among the personal factors, we discuss the behavioral strategies that can be used by athletes: nutrition, non-ingestive oral habits, water immersion, body temperature reduction, sleeping habits, relaxation methods, cognitive techniques, praying, music, and exercise. Among environmental factors, we discuss those linked to the social (i.e., contact with humans and animals) and physical (i.e., aromas, lights, sounds, temperature, outdoor, altitude) environment. Future research directions are given, as well as practical implications for athletes and coaches.

Short Vacation Improves Stress-Level and Well-Being in German-Speaking Middle-Managers-A Randomized Controlled Trial

Stress in the work place has a detrimental effect on people's health. Sufficient recovery is necessary to counteract severe chronic negative load reactions. Previous research has shown that vacationing for at least seven consecutive days provided an efficient recovery strategy. Yet, thus far, the effects of short vacations and the mode of vacation (whether at home or in a new environment) have rarely been studied. We investigated the immediate and long-term effects of a short vacation (four nights) on well-being and perceived stress and whether the mode of vacation impacted on these results. Data was obtained from 40 middle managers (67.5% men and 32.5% women). The intervention group (n = 20) spent a short vacation in a hotel outside their usual environment. The control group (n = 20) spent their vacation at home. Results indicated that one single short-term vacation, independent of the mode, has large, positive and immediate effects on perceived stress, recovery, strain, and well-being. Strain levels decreased to a greater extent in the intervention group compared to the control group. The effects can still be detected at 30 days (recovery) and 45 days (well-being and strain) post-vacation. Encouraging middle management employees to take short vacations seems to be an efficient health promotion strategy; environmental effects seem to play a minor role.

Fall-related accidents among hikers in the Austrian Alps: a 9-year retrospective study

Objective

To analyse the circumstances of fatal and non-fatal mountain hiking accidents caused by falls.

Methods

The study was designed as a retrospective analysis. Mountain hiking accidents caused by falls were documented during a 9-year period (2006–2014). After screening of all data for potential exclusion criteria the final sample size of 5368 accidents and 5665 victims was included into the analyses. Main outcome measures were details about accidents, victims, type of trail and surface.

Results

The annual number of accidents showed a continuous increase from 467 in 2006 to 700 in 2014. In total, 5.8% of all victims died during the 9-year period. 75.3% of the hikers fell during descent and 80.9% of the victims had their accident on a marked hiking trail or small path. The sex ratio for non-fatal accidents was 55% female and 45% male; for fatal accidents the female-to-male ratio was 28%:72%. Mean age of all victims was 52.5±17.5 years and victims of fatalities were about 5 years older compared with victims of non-fatal accidents (57.5±16.5 vs 52.2±17.5 years, P<0.01).

Conclusion

Descent is the most risky part for accidents caused by falls during mountain hiking. Male hikers are at greater risk for fatalities independent of age and this is associated with accidents occurring in pathless terrain. The death rate from falls was 6%. We recommend a critical self-assessment of the individual capabilities and mountain hiking skills and adequate planning of the hiking tours for mountain hikers.

A Randomized Crossover Trial on Acute Stress-Related Physiological Responses to Mountain Hiking

Green exercise, defined as physical activity in natural environments, might have positive effects on stress-related physiological measures. Little is known about the acute effects of green exercise bouts lasting longer than 60 min. Therefore, the aim of the present study was to analyze the acute effects of a three-hour green exercise intervention (mountain hiking) on stress-related physiological responses. Using a randomized crossover design, 42 healthy participants were exposed to three different conditions in a field-based experiment: outdoor mountain hiking, indoor treadmill walking, and sedentary control condition (three hours each). At baseline and at follow-up (five minutes after the condition), stress-related physiological responses (salivary cortisol, blood pressure, and heart rate variability) were measured. Salivary cortisol decreased in all conditions, but showed a larger decrease after both mountain hiking and treadmill walking compared to the sedentary control situation (partial η² = 0.10). No differences were found between mountain hiking and treadmill walking in salivary cortisol. In heart rate variability and blood pressure, changes from baseline to follow-up did not significantly differ between the three conditions. The results indicate that three hours of hiking indoors or outdoors elicits positive effects on salivary cortisol concentration. Environmental effects seem to play a minor role in salivary cortisol, blood pressure, and heart rate variability.

Prevalence of Mental Health Problems and Factors Associated with Psychological Distress in Mountain Exercisers: A Cross-Sectional Study in Austria

Knowledge about potential protective factors against mental health problems is highly needed. Regular physical activity (PA) in an outdoor environment, like mountain exercising, might reduce psychological distress. Therefore, the aims of the present study were to assess the prevalence of mental health problems in mountain exercisers and to detect factors associated with psychological distress. In a cross-sectional design, we collected self-reported data of 1,536 Austrian mountain exercisers. The prevalence of mental health problems and psychological distress (Kessler Psychological Distress Scale), the level of PA International Physical Activity Questionnaire, and affective valence during PA (Feeling Scale) were obtained. Stepwise multiple linear regression analysis was conducted to assess factors influencing psychological distress. The prevalence of mental health problems in Austrian mountain exercisers was 14%. Health-enhancing PA level and higher affective valence during PA were significantly associated with lower psychological distress. Minimal PA level was not significantly associated with lower psychological distress compared to inactive PA level. Marital status, education, alpine association membership, and body mass index did not show a significant influence on psychological distress. The prevalence of mental health problems seems to be lower in Austrian mountain exercisers compared to the European population. A health-enhancing PA level and affective valence increasing forms of PA were shown to be associated with lower psychological distress. Results might lead to interventional studies focusing on the potential of outdoor PA, e.g., mountain exercise, as an adjunct treatment in people at risk or with mental health problems.

Affective responses in mountain hiking-A randomized crossover trial focusing on differences between indoor and outdoor activity

INTRODUCTION

Affective responses during physical activity (PA) are important for engagement in PA programs and for adherence to a physically active lifestyle. Little is known about the affective responses to PA bouts lasting longer than 45 minutes. Therefore, the aims of the present study were to analyse acute effects on affective responses of a three-hour outdoor PA intervention (mountain hiking) compared to a sedentary control situation and to an indoor treadmill condition.

METHODS

Using a randomized crossover design, 42 healthy participants were randomly exposed to three different conditions: outdoor mountain hiking, indoor treadmill walking, and sedentary control situation (approximately three hours each). Measures included the Feeling Scale, Felt Arousal Scale and a Mood Survey Scale. Repeated measures ANOVAs were used to analyse differences between the conditions.

RESULTS

Compared to the control situation, the participants showed a significant increase in affective valence (d = 1.21, p < .001), activation (d = 0.81, p = .004), elation (d = 1.07, p < .001), and calmness (d = 0.84, p = .004), and a significant decrease in fatigue (d = -1.19, p < .001) and anxiety (d = -.79, p < .001) after mountain hiking. Outdoor mountain hiking showed significantly greater positive effects on affective valence, activation, and fatigue compared to indoor treadmill walking.

DISCUSSION

The results indicate that a three-hour PA intervention (mountain hiking) elicits higher positive and lower negative affective responses compared to a sedentary control situation and to an indoor PA condition. Outdoor mountain hiking can be recommended by health professionals as a form of PA with the potential to positively influence affective responses.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02853760. https://clinicaltrials.gov/. Date of registration: 08/02/2016 (retrospectively registered). Date of enrolment of the first participant to the trial: 05/01/2014.

Anti-diabetes effect of chronic intermittent hypobaric hypoxia through improving liver insulin resistance in diabetic rats

AIM

Cumulating evidence demonstrated that chronic intermittent hypobaric hypoxia (CIHH) had beneficial effects on the body. The present study was to investigate the anti-diabetes effect of CIHH in type-2 diabetic rats for the first time.

MAIN METHODS

Sprague-Dawley rats were randomly divided into 4 groups: control group (CON), diabetes mellitus group (DM, induced by high-fat diet combined with low-dose streptozotocin), CIHH treatment group (CIHH, simulated 5000-m altitude, 6h per day for 28 days), and diabetes mellitus plus CIHH treatment group (DM+CIHH). Histopathology of liver, systolic arterial blood pressure (SAP), blood biochemicals, glucose and insulin tolerance were determined. The expression of proteins associated with insulin signaling pathway as well as hypoxia induced factors were assayed.

KEY FINDINGS

Diabetic rats showed impaired glucose tolerance, dyslipidemia, hepatic steatosis and hepatic insulin resistance in addition to increased SAP. However, SAP, serum triglyceride and cholesterol were decreased, and hepatic steatosis and insulin resistance were improved in DM+CIHH rats. Furthermore, the protein expression of glucokinase (GCK), insulin receptor substrates (IRS-1 and IRS-2), and HIF1α were increased, while the expression of phosphoenolpyruvate carboxykinase (PEPCK), was markedly reduced in DM+CIHH rats.

SIGNIFICANCE

We conclude that CIHH treatment has anti-diabetes effects through ameliorating insulin resistance via hepatic HIF-insulin signaling pathway in type-2 diabetic rats.

Effect of weekly hiking on cardiovascular risk factors in the elderly

BACKGROUND

Hiking is one of the most popular activities among the elderly in Alpine regions. Due to the long-lasting, moderately intensive nature of this form of physical activity, hiking is generally considered to be beneficial to health. However, it is currently unclear whether once-weekly hiking--as commonly practiced at weekends--really does yield such positive effects in elderly persons aged 60 years and over.

OBJECTIVES

This study investigated the effect of a single weekly mountain hiking session on cardiovascular risk factors.

MATERIALS AND METHODS

A 9-month mountain hiking program was completed by 14 male (age 65.6 ± 2.7 years) and 10 female (age 66.2 ± 4.4 years) elderly participants. The program consisted of a single weekly hiking session with the goal of achieving a 500-m altitude increase within 3 h. Before and after the 9-month program, an electrocardiogram (ECG) was performed and blood pressure, glycated hemoglobin (HbA1c), high-density (HDL) and low-density lipoprotein (LDL) measurements were made.

RESULTS

The elderly participants showed a normal cardiovascular risk profile at the start of the investigation. The estimated net energy expenditure for one hiking session was approximately 521 ± 91 kcal. Over the 9-month period, no changes were found in any of the investigated parameters for the entire group. However, participants with untreated hypertension showed a reduced systolic blood pressure.

CONCLUSION

The present investigation showed that moderate-intensity activity only at weekends does not improve cardiovascular risk factors in elderly persons with a relatively normal cardiovascular risk profile. Conversely, elderly persons suffering from hypertension might profit from such a practice.

Alveolar-capillary adaptation to chronic hypoxia in the fatty lung

AIM

Obese diabetic (ZDF fa/fa) rats with genetic leptin resistance suffer chronic lipotoxicity associated with age-related lung restriction and abnormal alveolar ultrastructure. We hypothesized that these abnormalities impair adaptation to ambient hypoxia.

METHODS

Male fa/fa and lean (+/+) ZDF rats (4-months old) were exposed to 21 or 13% O2 for 3 weeks. Lung function was measured under anaesthesia. Lung tissue was assayed for DNA damage and ultrastructure measured by morphometry.

RESULTS

In normoxia, lung volume, compliance and diffusing capacity were lower, while blood flow was higher in fa/fa than +/+ rats. In hypoxia, fa/fa animals lost more weight, circulating hematocrit rose higher, and lung volume failed to increase compared to +/+. In fa/fa, the hypoxia-induced increase in post-mortem lung volume was attenuated (19%) vs. +/+ (39%). Alveolar ducts were 35% smaller in normoxia but enlarged twofold more in hypoxia compared to +/+. Hypoxia induced broad increases (90-100%) in the volumes and surface areas of alveolar septal components in +/+ lungs; these increases were moderately attenuated in fa/fa lungs (58-75%), especially that of type II epithelium volume (16 vs. 61% in +/+). In fa/fa compared to +/+ lungs, oxidative DNA damage was greater with increased hypoxia induced efflux of alveolar macrophages. Harmonic mean thickness of the diffusion barrier was higher, indicating higher structural resistance to gas transfer.

CONCLUSION

Chronic lipotoxicity impaired hypoxia-induced lung expansion and compensatory alveolar growth with disproportionate effect on resident alveolar progenitor cells. The moderate structural impairment was offset by physiological adaptation primarily via a higher hematocrit.

Inactivation of corticotropin-releasing hormone-induced insulinotropic role by high-altitude hypoxia

We have shown that hypoxia reduces plasma insulin, which correlates with corticotropin-releasing hormone (CRH) receptor 1 (CRHR1) in rats, but the mechanism remains unclear. Here, we report that hypobaric hypoxia at an altitude of 5,000 m for 8 h enhances rat plasma CRH, corticosterone, and glucose levels, whereas the plasma insulin and pancreatic ATP/ADP ratio is reduced. In islets cultured under normoxia, CRH stimulated insulin release in a glucose- and CRH-level-dependent manner by activating CRHR1 and thus the cAMP-dependent protein kinase pathway and calcium influx through L-type channels. In islets cultured under hypoxia, however, the insulinotropic effect of CRH was inactivated due to reduced ATP and cAMP and coincident loss of intracellular calcium oscillations. Serum and glucocorticoid-inducible kinase 1 (SGK1) also played an inhibitory role. In human volunteers rapidly ascended to 3,860 m, plasma CRH and glucose levels increased without a detectable change in plasma insulin. By contrast, volunteers with acute mountain sickness (AMS) exhibited a marked decrease in HOMA insulin sensitivity (HOMA-IS) and enhanced plasma CRH. In conclusion, hypoxia may attenuate the CRH-insulinotropic effect by reducing cellular ATP/ADP ratio, cAMP and calcium influx, and upregulated SGK1. Hypoxia may not affect HOMA-IS in healthy volunteers but reduces it in AMS volunteers.

Chronic intermittent high altitude exposure, occupation, and body mass index in workers of mining industry

The obesity and overweight rates in population exposed to chronic intermittent exposure to high altitudes are not well studied. The aim of the retrospective study was to evaluate whether there are differences in body mass index in different occupation groups working in intermittent shifts at mining industry at high altitude: 3800-4500 meters above sea level. Our study demonstrated that obesity and overweight are common in workers of high altitude mining industry exposed to chronic intermittent hypoxia. The obesity rate was lowest among miners as compared to blue- and white-collar employees (9.5% vs. 15.6% and 14.7%, p=0.013). Obesity and overweight were associated with older age, higher rates of increased blood pressure (8.79% and 5.72% vs. 1.92%), cholesterol (45.8% and 45.6% vs. 32.8%) and glucose (4.3% and 1.26% vs. 0.57%) levels as compared to normal body mass index category (p<0.0001 for all). There were differences in patterns of cholesterol and glucose levels in men and women employees according to occupation type. In conclusion, obesity and overweight rates are prevalent and associated with increase in blood pressure, cholesterol, and glucose levels in workers of mining industry exposed to intermittent high-altitude hypoxia. Therefore, assessment and monitoring of body mass index seems to be essential in those who live and work at high altitudes to supply the correct nutrition, modify risk factors, and prevent related disorders.

Effects of acute exposure to moderate altitude on vascular function, metabolism and systemic inflammation

Background

Travel to mountain areas is popular. However, the effects of acute exposure to moderate altitude on the cardiovascular system and metabolism are largely unknown.

Objectives

To investigate the effects of acute exposure to moderate altitude on vascular function, metabolism and systemic inflammation.

Methods

In 51 healthy male subjects with a mean (SD) age of 26.9 (9.3) years, oxygen saturation, blood pressure, heart rate, arterial stiffness, lipid profiles, low density lipoprotein (LDL) particle size, insulin resistance (HOMA-index), highly-sensitive C-reactive protein and pro-inflammatory cytokines were measured at 490 m (Zurich) and during two days at 2590 m, (Davos Jakobshorn, Switzerland) in randomized order. The largest differences in outcomes between the two altitudes are reported.

Results

Mean (SD) oxygen saturation was significantly lower at 2590 m, 91.0 (2.0)%, compared to 490 m, 96.0 (1.0)%, p<0.001. Mean blood pressure (mean difference +4.8 mmHg, p<0.001) and heart rate (mean difference +3.3 bpm, p<0.001) were significantly higher at 2590 m, compared to 490 m, but this was not associated with increased arterial stiffness. At 2590 m, lipid profiles improved (median difference triglycerides −0.14 mmol/l, p = 0.012, HDL +0.08 mmol/l, p<0.001, total cholesterol/HDL-ratio −0.25, p = 0.001), LDL particle size increased (median difference +0.45 nm, p = 0.048) and hsCRP decreased (median difference −0.18 mg/l, p = 0.024) compared to 490 m. No significant change in pro-inflammatory cytokines or insulin resistance was observed upon ascent to 2590 m.

Conclusions

Short-term stay at moderate altitude is associated with increased blood pressure and heart rate likely due to augmented sympathetic activity. Exposure to moderate altitude improves the lipid profile and systemic inflammation, but seems to have no significant effect on glucose metabolism.

Trial Registration

ClinicalTrials.gov NCT01130948

Does climate therapy at moderate altitudes improve pulmonary function in asthma patients? A systematic review

PURPOSE

Allergic bronchial asthma is one of the most common chronic diseases worldwide. For many years, the climate at moderate altitude has been used as an alternative therapy for patients suffering from bronchial asthma. The aim of such therapy is to reduce the medication dose and to improve the quality of life for each patient. The aim of our current work was to assess published data evaluating the effects of climate therapy at moderate altitude on the health status of patients with bronchial asthma. The health status is represented through surrogate parameters for the pulmonary function (forced expiratory volume in one second (FEV1)), bronchial hyperresponsiveness (PC20), and inflammation (total number of eosinophils, eosinophilic cationic protein, and exhaled nitric oxide).

METHODS

Our systematic review included randomized controlled trials (RCTs) and single-armed studies with adults and children participating. Included in our review were climate therapies occurring at moderate altitudes between 1,500 and 2,500 m and evaluation of patient FEV1 or PC20 values.

RESULTS

A literature research in MEDLINE and EMBASE identified three RCTs, two clinically controlled trials, and 15 single-armed studies. Analysis revealed a lack of evidence regarding the moderate altitude therapy arising from small sample sizes, deficits in documentation, and heterogeneous results. Most of the studies, however, showed a tendency for improvement of the analyzed parameters.

CONCLUSIONS

The currently available data do not allow for valid and generalizable recommendations with respect to moderate altitude therapy for patients with allergic bronchial asthma. There is a need for additional, qualitatively strong research including larger sample sizes and randomized, controlled trial design.

Chronic intermittent hypobaric hypoxia prevents cardiac dysfunction through enhancing antioxidation in fructose-fed rats

High-fructose intake induces metabolic syndrome and cardiac dysfunction. Chronic intermittent hypobaric hypoxia (CIHH) preserves cardiac function during ischemia. We hypothesized that CIHH restores the impaired cardiac function in fructose-fed rats. Sprague-Dawley rats were randomly subject to treatment with fructose (10% fructose in drinking water for 6 weeks), CIHH (simulated 5000 m altitude, 6 h/day for 6 weeks in a hypobaric chamber), and CIHH plus fructose groups. In addition to an increase in blood pressure, fructose feeding caused elevated serum levels of glucose, fasting insulin and insulin C peptide, triglyceride, cholesterol, and mass ratio of heart to body. CIHH treatment decreased the arterial blood pressure, serum levels of biochemical markers, and cardiac hypertrophy in fructose-fed rats. Furthermore, CIHH treatment improved the recovery of left ventricular function after ischemia-reperfusion procedure (30 min global no-flow ischemia followed by 60 min of reperfusion) in rats with or without fructose feeding. In addition, CIHH treatment caused a significant increase in superoxide dismutase (SOD) activity and decrease in malondialdehyde level in cardiac myocardium experiencing ischemia-reperfusion in control and fructose-fed rats. Collectively, these data suggest that CIHH improve impaired cardiac function in fructose-fed rats through enhancing antioxidation in the myocardium.