High-altitude Trekking Research Articles

Blood Glucose During High Altitude Trekking in Young Healthy Adults.

Reid, Ly-Anh, Jordan L Rees, Miranda Kimber, Marina James, Graeme M Purdy, Megan Smorschok, Lauren E Maier, Normand G. Boulé, Trevor A. Day, Margie H. Davenport, and Craig D. Steinback. Blood glucose during high altitude trekking in young healthy adults. High Alt Med Biol. 00:00-00, 2024. Introduction: High altitude trekking is becoming more popular and accessible to an increased number of people. Simultaneously, there is a worldwide rise in the prevalence of metabolic diseases. The purpose of this study was to examine the impact of a gradual trekking ascent to high altitude on continuous glucose monitoring outcomes including fasting, mean 24-hour, postprandial, and post-75 g modified oral glucose tolerance test. This study also investigated the relationship between physical activity intensity, high altitude, and glucose concentrations. Methods: Individuals (n = 9) from Alberta, Canada participated in a 2-week trek in the Khumbu Valley in Nepal, ascending by foot from 2,860 m to 5,300 m (∼65 km) over 10 days. A standardized 75 g oral glucose load was given to participants at four different altitudes (1,130 m, 3,440 m, 3,820 m, 5,160 m). Physical activity (Actigraph accelerometry) and interstitial glucose (iPro2, Medtronic) were measured continuously during the trek. Results: Fasting and mean 24-hour glucose concentrations were not different between altitudes. However, 2-hour post dinner glucose and 2-hour post lunch glucose, AUC concentrations were different between altitudes. The relationship between physical activity intensity and glucose was not influenced by increasing altitudes. Conclusion: Our findings suggest that glucose regulation is largely preserved at high altitude; however, inconsistency in our postprandial glucose concentrations at altitude warrants further investigation.

High Altitude Mountaineering after Lung Transplantation - Jebel Toubkal Peak 4167m

After successful lung transplantation, patients can potentially reach same strength and endurance as healthy individuals. Although high-altitude trekking has been reported after LuTX, data on the patient's physiological adaptation during prolonged exercise in a reduced oxygen environment remains scarce. In September 2019, 14 lung transplanted patients and their accompanying doctors, climbed Mount Jebel Toubkal (4167 m; 13 671 ft), the highest peak in North Africa, High Atlas, Morocco. Participants had regular cardiopulmonary exams (lung function, polysomnography, echocardiography) as well as blood sampling (capillary blood gasses, lactate, creatinine) throughout the expedition up to 3145 m (10 318 ft). Patients (♀: n=3 | ♂: n=11) had a median age of 42.1 years (24.8-65.2). Their underlying diagnoses were CF (n=10), Emphysema (n=2), IPF (n=1) and PH (n=1). Median time from LuTX to this expedition was 4.1 Years (1.7-17.6). Controls (♂: n=4) were 31.3 (29.3-46.7) years old. Over 7 days, participants hiked a distance of 81km (50.3 mi) with a cumulative elevation gain of 5496 m (18,031 ft.) vertical distance. Eleven Patients (78.6%) reached the summit whereas three patients had to abort because of altitude sickness (n=1 on day 1 at 2431m) or physical exhaustion (n=2 on day 3 at 3124m and day 6 at 3800m). Blood gas analysis and vital signs did not differ significantly between the patients and four healthy controls (pO2: 59.1 ±8.9 vs. 61.8 ±14.4 mmHg | pCO2: 29.8 ±1.5 vs. 29.8 ±0.5 mmHg | lactate 0.82 vs 0.83 mmol/l). Creatinine was significantly higher in transplanted patients (1.87 vs. 0.97 mg/dl; p=0.025). Although technically challenging, medical monitoring of lung transplanted patients is feasible during high altitude hiking. In carefully selected athletic LuTX patients, gas exchange and metabolism didn't differ compared to healthy adults.

High altitude trekking after lung transplantation: a prospective study using lung ultrasound to detect comets tails for interstitial pulmonary edema in lung transplant recipients and healthy volunteers.

The intensity of physical activity which can be tolerated after lung transplantation and the tolerance to prolonged exercise at high altitude are poorly investigated. Lung ultrasound comet tails have been used in the diagnosis of interstitial pulmonary edema and high pulmonary altitude edema. The aim was to assess the number of lung ultrasound comet tails and to monitor changes in the optic nerve sheath diameter (ONSD) during a climb to the top of Mount Kilimanjaro in 10 lung transplant recipients and 10 healthy controls at three different altitude levels: 1360, 3505, 4900m. Lung transplant recipients showed a constant increase in comet tail scores with altitude, whereas control subjects only showed an increase at the highest measurement point. Differences between groups (transplant versus control) reached significance only after the first ascend: 0.9 (95% CI: -0.41; 2.21) vs. 0.1 (95% CI: -0.12; 0.32) (P=0.2; 1360m), 2.33 (95% CI: 0.64; 4.02) vs. 0.3 (95% CI: -0.18; 0.78) (P=0.04; 3505m), and 4.11 (95% CI: 0.13; 0.34) vs. 2.9 (95% CI: 0.49; 5.31) (P=0.15; 4900m); ONSD increased significantly in both groups from 3.53 (95% CI: 0.34; 0.66) at 1360m to 4.11 (95% CI: 0.36; 0.71) at 4900m (P<0.05). Lungs of transplant recipients are able to adapt to altitude and capable of performing prolonged exercise at high altitude after slow ascend.

High-Altitude Illness Death Investigation.

High altitude illness (HAI) is the current accepted clinical term for a group of disorders including acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE), which occur in travelers visiting high-altitude locations. High-altitude illness is due to hypobaric hypoxia, is not associated with age or physical conditioning, and mild forms are easily treated. High-altitude cerebral edema and HAPE are medical emergencies that are fatal if not promptly treated and fortunately are uncommon. The cause of most high-altitude fatalities is not related to HAI and can be easily distinguished from HACE and HAPE; however, other causes of death may have symptoms and physical findings that overlap with HAI, making postmortem diagnosis challenging. Fatalities due to HAPE and HACE are diagnoses of exclusion. Medical examiners and coroners who work in jurisdictions with high-altitude locations should be aware of the risk factors, physiology, pathology, differential diagnosis, and classification of HAI to accurately recognize HAI as a cause of death. Medical examiners who do not work in jurisdictions with high-altitude locations may be asked to evaluate deaths that occur overseas associated with high-altitude trekking and mountaineering activities.

An Eye on Travel: An Overview of Travel-Related Ocular Complications

Travellers are at risk of a diverse range of environmental and infectious conditions, some of which may affect the eyes and lead to blindness in severe cases. Travel-related ocular infections include onchocerciasis, leishmaniasis, cysticercosis, trachoma, dengue, loiasis, and leptospirosis. The travel medicine adviser should also recognise other hazards encountered during travel which may adversely affect the eye. These include recreational activities such as high altitude trekking, bungee jumping, skiing, scuba diving, and sun exposure. There is a subset of travellers who have underlying eye conditions, which predispose them to complications during international travel, including angle-closure glaucoma, and expansion of intraocular gas from previous vitreoretinal surgery. Contact lens wearers have a greater risk of ocular infection and corneal erosion during travel, especially where hygiene standards are low. Despite the susceptibility of the eye to infection, traumatic injury and environmental damage during international travel, this topic is not frequently discussed in the context of pre-travel consultations. Travel medicine professionals should have a reasonable knowledge of the major ocular risks associated with travel overseas.

Type 1 Diabetes at High Altitude: Performance of Personal Insulin Pumps and Patient Metabolic Control.

High-altitude trekking can expose people to extreme environmental conditions, like low temperatures and hypobaric hypoxia. Such extreme conditions make it more difficult for people with type 1 diabetes mellitus (T1DM) to maintain glycemic control. Intensive blood glucose monitoring using either glucose meters or continuous systems is imperative in these cases. In this observational study, we report metabolic control of T1DM patients and the performance of various insulin pumps at high altitude. All 19 patients with T1DM included in this study participated in the final step of the "5000 meters above sugar level" initiative, which involved trekking Damavand Mountain to an altitude of 5670 meters above sea level. We found that all pump models worked well without any disruption and no cases of diabetes decompensation or severe hypoglycemia occurred. Therefore, healthy, physically fit, and experienced individuals with T1DM should not be discouraged from participating in mountain trekking activities, as modern personal insulin pumps work well at high altitudes.

Managing diabetes at high altitude: personal experience with support from a Multidisciplinary Physical Activity and Diabetes Clinic

ObjectivePhysical activity is important for well-being but can be challenging for people with diabetes. Data informing support of specialist activities such as climbing and high-altitude trekking are limited. A 42-year-old...

Gokyo Khumbu/Ama Dablam Trek 2012: effects of physical training and high-altitude exposure on oxidative metabolism, muscle composition, and metabolic cost of walking in women.

We investigated the effects of moderate-intensity training at low and high altitude on VO2 and QaO2 kinetics and on myosin heavy-chain expression (MyHC) in seven women (36.3 yy ± 7.1; 65.8 kg ± 11.7; 165 cm ± 8) who participated in two 12- to 14-day trekking expeditions at low (598 m) and high altitude (4132 m) separated by 4 months of recovery. Breath-by-breath VO2 and beat-by-beat QaO2 at the onset of moderate-intensity cycling exercise and energy cost of walking (Cw) were assessed before and after trekking. MyHC expression of vastus lateralis was evaluated before and after low-altitude and after high-altitude trekking; muscle fiber high-resolution respirography was performed at the beginning of the study and after high-altitude trekking. Mean response time of VO2 kinetics was faster (P = 0.002 and P = 0.001) and oxygen deficit was smaller (P = 0.001 and P = 0.0004) after low- and high-altitude trekking, whereas ˙ QaO2 kinetics and Cw did not change. Percentages of slow and fast isoforms of MyHC and mitochondrial mass were not affected by low- and high-altitude training. After training altitude, muscle fiber ADP-stimulated mitochondrial respiration was decreased as compared with the control condition (P = 0.016), whereas leak respiration was increased (P = 0.031), leading to a significant increase in the respiratory control ratio (P = 0.016). Although training did not significantly modify muscle phenotype, it induced beneficial adaptations of the oxygen transport-utilization systems witnessed by faster VO2 kinetics at exercise onset.

Functional Changes Induced by High Altitude Trekking

This paper is part of an ampler approach that aims at emphasizing the efficiency of outdoor activities for increasing the quality of life in persons of different age categories. Within our study, the opportunity of these activities introduced into the adult persons’ program of physical exercises is assessed through the functional alterations registered at the individual's body level, under the conditions of his participation in altitude trekking activities. At the same time, we think that an extension of the outdoor-type activities to the persons of any age will decisively improve the individual's degree of awareness about the importance of conserving the natural environment and, consequently, his involvement on this direction.

Blood Oxidative-Stress Markers During a High-Altitude Trek

Oxidative stress occurs as a result of altitude-induced hypobaric hypoxia and physical exercise. The effect of exercise on oxidative stress under hypobaric hypoxia is not well understood. To determine the effect of high-altitude exercise on blood oxidative stress. Nine male participants completed a 2-d trek up and down Mt Rainer, in North America, at a peak altitude of 4,393 m. Day 1 consisted of steady-pace climbing for 6.25 hr to a final elevation of 3,000 m. The 4,393-m summit was reached on Day 2 in approximately 5 hr. Climb-rest intervals varied but were consistent between participants, with approximately 14 hr of total time including rest periods. Blood samples were assayed for biomarkers of oxidative stress and antioxidant potential at the following time points: Pre (before the trek), 3Kup (at ascent to 3,000 m), 3Kdown (at 3,000 m on the descent), and Post (posttrek at base elevation). Blood serum variables included ferric-reducing antioxidant potential (FRAP), Trolox equivalent antioxidant capacity (TEAC), protein carbonyls (PC), and lipid hydroperoxides. Serum FRAP was elevated at 3Kup and 3Kdown compared with Pre and Post values (p = .004, 8% and 11% increase from Pre). Serum TEAC values were increased at 3Kdown and Post (p = .032, 10% and 18% increase from Pre). Serum PC were elevated at 3Kup and 3Kdown time points (p = .034, 194% and 138% increase from Pre), while lipid hydroperoxides were elevated Post only (p = .004, 257% increase from Pre). Findings indicate that high-altitude trekking is associated with increased blood oxidative stress.

Increased Insulin Requirements During Exercise at Very High Altitude in Type 1 Diabetes

OBJECTIVESafe, very high altitude trekking in subjects with type 1 diabetes requires understanding of glucose regulation at high altitude. We investigated insulin requirements, energy expenditure, and glucose levels at very high altitude in relation to acute mountain sickness (AMS) symptoms in individuals with type 1 diabetes.RESEARCH DESIGN AND METHODSEight individuals with complication-free type 1 diabetes took part in a 14-day expedition to Mount Meru (4,562 m) and Mount Kilimanjaro (5,895 m) in Tanzania. Daily insulin doses, glucose levels, energy expenditure, and AMS symptoms were determined. Also, energy expenditure and AMS symptoms were compared with a healthy control group.RESULTSWe found a positive relation between AMS symptoms and insulin requirements (r = 0.78; P = 0.041) and AMS symptoms and glucose levels (r = 0.86; P = 0.014) for Mount Kilimanjaro. Compared with sea level, insulin doses tended to decrease by 14.2% (19.7) (median [interquartile range]) (P = 0.41), whereas glucose levels remained stable up to 5,000 m altitude. However, at altitudes >5,000 m, insulin dose was unchanged (36.8 ± 17 vs. 37.6 ± 19.1 international units [mean ± SD] P = 0.75), but glucose levels (7.5 ± 0.6 vs. 9.5 ± 0.8 mmol/L [mean ± SD] P = 0.067) and AMS scores (1.3 ± 1.6 vs. 4.4 ± 4 points [mean ± SD] P = 0.091) tended to increase. Energy expenditure and AMS symptoms were comparable in both groups (P = 0.84).CONCLUSIONSOur data indicate that in complication-free individuals with type 1 diabetes, insulin requirements tend to increase during altitudes above 5,000 m despite high energy expenditure. This change may be explained, at least partly, by AMS.

Accuracy of Handheld Blood Glucose Meters at High Altitude

BackgroundDue to increasing numbers of people with diabetes taking part in extreme sports (e.g., high-altitude trekking), reliable handheld blood glucose meters (BGMs) are necessary. Accurate blood glucose measurement under extreme conditions is paramount for safe recreation at altitude. Prior studies reported bias in blood glucose measurements using different BGMs at high altitude. We hypothesized that glucose-oxidase based BGMs are more influenced by the lower atmospheric oxygen pressure at altitude than glucose dehydrogenase based BGMs.Methodology/Principal FindingsGlucose measurements at simulated altitude of nine BGMs (six glucose dehydrogenase and three glucose oxidase BGMs) were compared to glucose measurement on a similar BGM at sea level and to a laboratory glucose reference method. Venous blood samples of four different glucose levels were used. Moreover, two glucose oxidase and two glucose dehydrogenase based BGMs were evaluated at different altitudes on Mount Kilimanjaro. Accuracy criteria were set at a bias <15% from reference glucose (when >6.5 mmol/L) and <1 mmol/L from reference glucose (when <6.5 mmol/L). No significant difference was observed between measurements at simulated altitude and sea level for either glucose oxidase based BGMs or glucose dehydrogenase based BGMs as a group phenomenon. Two GDH based BGMs did not meet set performance criteria. Most BGMs are generally overestimating true glucose concentration at high altitude.ConclusionAt simulated high altitude all tested BGMs, including glucose oxidase based BGMs, did not show influence of low atmospheric oxygen pressure. All BGMs, except for two GDH based BGMs, performed within predefined criteria. At true high altitude one GDH based BGM had best precision and accuracy.

Energy Expenditure Measure By Portable Accelerometer During A High Altitude Trekking

Energy Expenditure Measure By Portable Accelerometer During A High Altitude Trekking

Delayed Acclimatization of the Ventilatory Threshold in Healthy Trekkers

To test the hypothesis that acclimatization to high altitude results in an improvement of the ventilatory threshold (VT). Eight lowlanders underwent cardiopulmonary exercise testing with a cycle ergometer to determine VT and peak oxygen uptake (Vo2peak) in Coventry, United Kingdom (altitude: 80 m), on arrival in leh, india (altitude: 3500 m), and after 12 days of acclimatization that included a 5-day high altitude trek up to 4770 m. Vo2peak fell on arrival at 3500 m and remained depressed at 12 days. VT was depressed on arrival at high altitude and was further depressed at 12 days. VT as a proportion of the Vo2peak was decreased on arrival at high altitude, and after acclimatization, this relationship was further decreased. Individuals who are sedentary or not participating in regular physical training appear to require a longer period of acclimatization than trained athletes. With the increasing numbers participating in high-altitude trekking and charity climbs of peaks, such as Mt. Kilimanjaro, this information has clinically significant practical implications for those leading or acting as medical advisors.

Pulmonary function parameters changes at different altitudes in healthy athletes.

Hypoxia and hypocapnia can cause broncho-constriction in human subjects, and this could have a bearing on performance at high altitude. The object of this study was to examine how pulmonary ventilatory functions during high-altitude trekking. This study is a cohort study on spirometric parameters at different altitudes. Fifty six healthy male volunteers from a university student population were enrolled in the study (ages 22.9+/-5.3 years). Pulmonary function was assessed with a Spirolab II in all participants before ascending at baseline (1150 meter), after ascending at different altitudes (2850, 4150 meter), and after descending at sea level during a 3-day trek in Sialan Mount. This study indicates that in an actual trek, ascending results in significant decrease in forced vital capacity (FVC). FVC significantly decreased with increasing altitude from baseline level and at the sea level it was significantly less than baseline level. Peak flow increased with increasing altitude from baseline (1150 m) to 2850 m and decreased with decreasing altitude (p<0.01). Maximal midexpiratory flow rate (FEF 25-75%) and forced expiratory volume in 1 second to forced expiratory volume ratio (FEV1.0%) significantly increased with increasing and decreasing altitude from baseline level (p<0.001). There was no significant change in FEV1. It could be concluded that changes in some pulmonary ventilatory parameters were proportional to the magnitude of change in altitude during a high-altitude trek. These changes are significant at the beginning of ascending.

Chronic Hypoxia, Physical Exercise and PSA: Correlation during High-Altitude Trekking (2004 K2 Expedition)

The aim of the present study was to identify the effects of physical exercise on PSA serum levels and the diagnostic validity of PSA in the screening of prostate cancer in subjects undergoing physical exercise during chronic hypoxia. The study was performed during trekking between 3,200 and 5,600 meters of altitude on K2 mountain for 26 days. Mean serum PSA values before and after exposure did not show significant difference due to physical exercise. These data indicate that physical exercise or mountain hypoxia do not affect the diagnostic validity of PSA.

Inca Trail porters: the health of local tourism employees as a challenge for travel medicine.

Trekking is an activity that forms part of the increasing adventure and outdoor tourism. High altitude trekking in the Himalayas or Andes has been popular for some time. For longer treks, porters are employed to carry necessary equipment. Porters' working conditions are unfortunate and subsequent health problems considerable. Although Himalayan porters have received some attention in the press and research literature, porters on the popular Inca Trail in Peru have been neglected. In light of the growing awareness of health problems of local tourism employees, the purpose of this study was to describe Inca Trail porters' working conditions and their reports on their related health status to provide baseline information for further research and strategies for improvement. For this descriptive study, 101 Inca Trail porters were interviewed (August/September 2001) using a structured interview schedule. Porters were between 17 and 68 years old; estimated body weight ranged from 50 kg to 76 kg. The usual portering job lasts for 4 days with 9 to 10 hours of carrying per day. Estimated weight of loads ranged from 20 kg to 45 kg. Major concerns were lack of fuel, clothes, shelter, and equipment but foremost the lack of sufficient food provisions. A third described their general health as poor or very poor and attributed this to work. Health complaints included respiratory infections, kidney problems, or rheumatism. Thirty-eight porters recalled injuries while on the trail and over 90% had fallen ill on the job with cold, "majurki," and stomach pain due to lack of food or cold food being named most often. Porters' demands for improvement included increased pay and appropriate and sufficient food. The porters' working conditions and subsequent health problems need to be addressed. A range of stakeholders is responsible for the porters' conditions and are in a position to improve current situations. Specific responsibility for health care lies with travel health professionals and local health authorities since the health of host communities has been acknowledged as an important area within travel medicine.

Hospitality Industry - REDEFINING Leisure And Recreation

We live in an age of cocooning: there is a tangible need to feel secure and pampered in a world of terrorism and uncertainty. The latest trend in travel is not high-altitude trekking or exploring remote and difficult reaches — it is the emergence of hotels as complete travel destinations. The accommodation industry is rising to the challenge, bolstering city hotels with extra facilities to fit the urban oasis template and creating resorts so complete it almost becomes redundant to go out.

High-Altitude trekking in the Himalayas increases the activity of circulating endothelial cells

Circulating endothelial progenitor cells (EPCs) are believed to contribute to vascular homeostasis; unfortunately, the response of EPCs in physiological conditions remains largely unknown. Herein we report our observations of a 44-year-old healthy subject after a trek in the Himalayas that support high-altitude hypoxia and exercise oxygen demands are strong stimuli for clonogenic endothelial cell activation and activity, as shown by the increase in the number of mature EPCs and in the endothelial colony-forming unit capacity. Both of these effects were completely reverted at sea level, 45 days after the subject's trek.

Noninvasive assessment of cerebral oxygenation during high altitude trekking in the Nepal Himalayas (2850–5600 m)

Mountain trekking is significantly increasing in popularity. Hypoxia seems to play a key role in the pathogenesis of acute mountain sickness (AMS). The purpose of this study was to investigate regional cerebral (rSO2) and peripheral (SaO2) oxygen saturation for the first time, during 22 days high altitude trekking (measurement points: 3450, 4450, 4750, 5050 and 2850 m) in the Khumbu region of Nepal with near infrared spectroscopy and pulse oximetry. We examined 17 healthy volunteers 19–65 years old (8 female, 9 male; mean age ± SD, 46.1 ± 13.1 years). RSO2 and SaO were significantly (p < 0.001, ANOVA, Tukey test) decreased at high altitudes (4450, 4750 and 50502m). The decrease in cerebral oxygen saturation was more pronounced at higher altitudes than in the periphery (rSO2/SaO = 0.56 at 5050 m). At higher altitudes (> 4450 m), two subjects showed reversible symptoms of AMS. The present data indicates that acute reduction in rSO2 values might be a primary cause of AMS, however, further studies and analysis are necessary to correlate our findings with cerebral symptom scores.