Energy expenditure during load carriage at high altitude

1981 ◽  
Vol 51 (1) ◽  
pp. 14-18 ◽  
Author(s):  
A. Cymerman ◽  
K. B. Pandolf ◽  
A. J. Young ◽  
J. T. Maher
Keyword(s):  
Energy Expenditure ◽  
High Altitude ◽  
Sea Level ◽  
Prediction Equation ◽  
Cycle Ergometer ◽  
Load Carriage ◽  
Metabolic Rates ◽  
Specific Exercise ◽  
Upper Limit ◽  
Predicted Values

To determine the applicability of a prediction equation for energy expenditure during load carriage at high altitude that was previously validated at sea level, oxygen uptake (Vo2) was determined in five young men at 4,300 m while they walked with backpack loads of 0, 15, and 30 kg at treadmill grades of 0,8, and 16% at 1.12 m.s-1 for 10 min. Mean +/- SE maximal Vo2, determined on the cycle ergometer, was 42.2 +/- 2.3 at sea level and 35.6 +/- 1.7 ml.kg-1 .min-1 at altitude. There were no significant differences in daily Vo2 at any specific exercise intensity on days 1, 5, and 9 of exposure, nor were there any differences in endurance times at the two most difficult exercise intensities. Endurance times for 15- and 30-kg loads at 16% grade were 7.3 and 4.2 min, respectively. Measured energy expenditure was compared with that predicted by the formula of Pandolf et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 43: 577–581, 1977) and found to be significantly different. The differences could be attributed to measurements at metabolic rates exceeding 730 W or 2.1 1.min-1 Vo2. These data indicate that the prediction equation can be used at altitude for exercise intensities not exceeding this upper limit. The observed deviations from predicted values at the high exercise intensities could possibly be attributed to the occurrence of appreciable oxygen deficits and the inability to achieve steady-state conditions.

AltitudeOmics: impaired pulmonary gas exchange efficiency and blunted ventilatory acclimatization in humans with patent foramen ovale after 16 days at 5,260 m

2015 ◽  
Vol 118 (9) ◽  
pp. 1100-1112 ◽  
Author(s):  
Jonathan E. Elliott ◽  
Steven S. Laurie ◽  
Julia P. Kern ◽  
Kara M. Beasley ◽  
Randall D. Goodman ◽  
...  
Keyword(s):  
Gas Exchange ◽  
High Altitude ◽  
Sea Level ◽  
Patent Foramen Ovale ◽  
Acute Mountain Sickness ◽  
Cycle Ergometer ◽  
Pulmonary Gas Exchange ◽  
Foramen Ovale ◽  
Ergometer Exercise ◽  
High Altitude Acclimatization

A patent foramen ovale (PFO), present in ∼40% of the general population, is a potential source of right-to-left shunt that can impair pulmonary gas exchange efficiency [i.e., increase the alveolar-to-arterial Po2 difference (A-aDO2)]. Prior studies investigating human acclimatization to high-altitude with A-aDO2 as a key parameter have not investigated differences between subjects with (PFO+) or without a PFO (PFO−). We hypothesized that in PFO+ subjects A-aDO2 would not improve (i.e., decrease) after acclimatization to high altitude compared with PFO− subjects. Twenty-one (11 PFO+) healthy sea-level residents were studied at rest and during cycle ergometer exercise at the highest iso-workload achieved at sea level (SL), after acute transport to 5,260 m (ALT1), and again at 5,260 m after 16 days of high-altitude acclimatization (ALT16). In contrast to PFO− subjects, PFO+ subjects had 1) no improvement in A-aDO2 at rest and during exercise at ALT16 compared with ALT1, 2) no significant increase in resting alveolar ventilation, or alveolar Po2, at ALT16 compared with ALT1, and consequently had 3) an increased arterial Pco2 and decreased arterial Po2 and arterial O2 saturation at rest at ALT16. Furthermore, PFO+ subjects had an increased incidence of acute mountain sickness (AMS) at ALT1 concomitant with significantly lower peripheral O2 saturation (SpO2). These data suggest that PFO+ subjects have increased susceptibility to AMS when not taking prophylactic treatments, that right-to-left shunt through a PFO impairs pulmonary gas exchange efficiency even after acclimatization to high altitude, and that PFO+ subjects have blunted ventilatory acclimatization after 16 days at altitude compared with PFO− subjects.

Effects of chronic hypoxia and exercise on plasma erythropoietin in high-altitude residents

1993 ◽  
Vol 74 (4) ◽  
pp. 1874-1878 ◽  
Author(s):  
W. Schmidt ◽  
H. Spielvogel ◽  
K. U. Eckardt ◽  
A. Quintela ◽  
R. Penaloza
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Cycle Ergometer ◽  
Control Group ◽  
Ergometer Exercise ◽  
High Altitude Natives ◽  
The Mean ◽  
The Relationship ◽  
Arterial Po2 ◽  
Level Group

The present study was performed to evaluate the effects of chronic inspiratory hypoxia and its combination with physical exercise on plasma erythropoietin concentration ([EPO]). Eight natives from the Bolivian Plateau were investigated at 3,600 m above sea level at rest as well as during and up to 48 h after exhaustive exercise (EE) and 60 min of submaximal (60%) cycle ergometer exercise (SE). Ten sea-level subjects were used as a control group for resting values. The mean resting plasma [EPO] of the high-altitude group (19.5 +/- 0.7 mU/ml) did not differ from that of the sea-level group (18.1 +/- 0.4 mU/ml) but was higher than would be expected from the relationship between [EPO] and hematocrit at sea level. Five hours after both types of exercise, [EPO] decreased by 2.1 +/- 0.8 (EE, P < 0.01) and 1.6 +/- 0.8 mU/ml (SE, P < 0.05); 48 h after SE, [EPO] increased by 2.6 +/- 0.9 mU/ml (P < 0.05). It is concluded that 1) high-altitude natives need relatively high [EPO] to maintain their high hematocrit and 2) exercise at low basal arterial PO2 does not directly increase plasma [EPO] in high-altitude residents but seems to exert suppressive effects.

scholarly journals Effect of losartan on performance and physiological responses to exercise at high altitude (5035 m)

2021 ◽  
Vol 7 (1) ◽  
pp. e000982
Author(s):  
Samuel J E Lucas ◽  
William L Malein ◽  
Owen D Thomas ◽  
Kimberly M Ashdown ◽  
Carla A Rue ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
High Altitude ◽  
Sea Level ◽  
Peak Power ◽  
Cycle Ergometer ◽  
Angiotensin Ii Receptor ◽  
Lung Water ◽  
Randomised Study ◽  
Exercise Induced ◽  
Double Blinded

ObjectiveAltitude-related and exercise-related elevations in blood pressure (BP) increase the likelihood of developing pulmonary hypertension and high-altitude illness during high-altitude sojourn. This study examined the antihypertensive effect and potential exercise benefit of the angiotensin II receptor antagonist losartan when taken at altitude.MethodsTwenty participants, paired for age and ACE genotype status, completed a double-blinded, randomised study, where participants took either losartan (100 mg/day) or placebo for 21 days prior to arrival at 5035 m (Whymper Hut, Mt Chimborazo, Ecuador). Participants completed a maximal exercise test on a supine cycle ergometer at sea level (4 weeks prior) and within 48 hours of arrival to 5035 m (10-day ascent). Power output, beat-to-beat BP, oxygen saturation (SpO2) and heart rate (HR) were recorded during exercise, with resting BP collected from daily medicals during ascent. Before and immediately following exercise at 5035 m, extravascular lung water prevalence was assessed with ultrasound (quantified via B-line count).ResultsAt altitude, peak power was reduced relative to sea level (p<0.01) in both groups (losartan vs placebo: down 100±29 vs 91±28 W, p=0.55), while SpO2 (70±6 vs 70±5%, p=0.96) and HR (146±21 vs 149±24 bpm, p=0.78) were similar between groups at peak power, as was the increase in systolic BP from rest to peak power (up 80±37 vs 69±33 mm Hg, p=0.56). Exercise increased B-line count (p<0.05), but not differently between groups (up 5±5 vs 8±10, p=0.44).ConclusionLosartan had no observable effect on resting or exercising BP, exercise-induced symptomology of pulmonary hypertension or performance at 5035 m.

Alveolar Pco2 oscillations and ventilation at sea level and at high altitude

2008 ◽  
Vol 104 (2) ◽  
pp. 404-415 ◽  
Author(s):  
D. J. Collier ◽  
A. H. Nickol ◽  
J. S. Milledge ◽  
H. J. A. van Ruiten ◽  
C. J. Collier ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Respiratory Control ◽  
Cycle Ergometer ◽  
Feedback Signal ◽  
Ventilatory Responses ◽  
Base Camp ◽  
Ventilatory Drive ◽  
The Face ◽  
End Tidal

This study examines the potential for a ventilatory drive, independent of mean Pco2, but depending instead on changes in Pco2 that occur during the respiratory cycle. This responsiveness is referred to here as “dynamic ventilatory sensitivity.” The normal, spontaneous, respiratory oscillations in alveolar Pco2 have been modified with inspiratory pulses approximating alveolar Pco2 concentrations, both at sea level and at high altitude (5,000 m, 16,400 ft.). All tests were conducted with subjects exercising on a cycle ergometer at 60 W. The pulses last about half the inspiratory duration and are timed to arrive in the alveoli during early or late inspiration. Differences in ventilation, which then occur in the face of similar end-tidal Pco2 values, are taken to result from dynamic ventilatory sensitivity. Highly significant ventilatory responses (early pulse response greater than late) occurred in hypoxia and normoxia at sea level and after more than 4 days at 5,000 m. The response at high altitude was eliminated by normalizing Po2 and was reduced or eliminated with acetazolamide. No response was present soon after arrival (<4 days) at base camp, 5,000 m, on either of two high-altitude expeditions (BMEME, 1994, and Kanchenjunga, 1998). The largest responses at 5,000 m were obtained in subjects returning from very high altitude (7,100–8,848 m). The present study confirms and extends previous investigations that suggest that alveolar Pco2 oscillations provide a feedback signal for respiratory control, independent of changes in mean Pco2, suggesting that natural Pco2 oscillations drive breathing in exercise.

scholarly journals Unchanged Cerebral Blood Flow and Oxidative Metabolism after Acclimatization to High Altitude

2002 ◽  
Vol 22 (1) ◽  
pp. 118-126 ◽  
Author(s):  
Kirsten Møller ◽  
Olaf B. Paulson ◽  
Tom F. Hornbein ◽  
Wil N. J. M. Colier ◽  
Anna S. Paulson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Reaction Time ◽  
High Altitude ◽  
Sea Level ◽  
Oxidative Metabolism ◽  
Arterial Oxygen ◽  
Metabolic Rates ◽  
Arterial Oxygen Content ◽  
Global Cerebral Blood Flow

The authors investigated the effect of acclimatization to high altitude on cerebral blood flow and oxidative metabolism at rest and during exercise. Nine healthy, native sea-level residents were studied 3 weeks after arrival at Chacaltaya, Bolivia (5,260 m) and after reacclimatization to sea level. Global cerebral blood flow at rest and during exercise on a bicycle ergometer was measured by the Kety-Schmidt technique. Cerebral metabolic rates of oxygen, glucose, and lactate were calculated by the Fick principle. Cerebral function was assessed by a computer-based measurement of reaction time. At high altitude at rest, arterial carbon dioxide tension, oxygen saturation, and oxygen tension were significantly reduced, and arterial oxygen content was increased because of an increase in hemoglobin concentration. Global cerebral blood flow was similar in the four conditions. Cerebral oxygen delivery and cerebral metabolic rates of oxygen and glucose also remained unchanged, whereas cerebral metabolic rates of lactate increased slightly but nonsignificantly at high altitude during exercise compared with high altitude at rest. Reaction time was unchanged. The data indicate that cerebral blood flow and oxidative metabolism are unaltered after high-altitude acclimatization from sea level, despite marked changes in breathing and other organ functions.

Multiple Sclerosis: Treadmill Versus Cycle Ergometry Maximal Exercise Test Responses

2020 ◽  
Vol 9 (3) ◽  
pp. 113-117
Author(s):  
Garett Griffith ◽  
Badeia Saed ◽  
Tracy Baynard
Keyword(s):  
Multiple Sclerosis ◽  
Aerobic Capacity ◽  
Work Capacity ◽  
Cross Sectional Study ◽  
Cycle Ergometer ◽  
Cycle Ergometry ◽  
Cross Sectional ◽  
Complete Test ◽  
Peak Aerobic Capacity ◽  
Predicted Values

ABSTRACT Background: Multiple sclerosis (MS) is an autoimmune disease that impacts the central nervous system. MS generally results in decreased mobility and work capacity. Our objective was to determine exercise testing responses on both a treadmill and cycle ergometer among individuals with MS who were able to ambulate freely. Methods: Twenty-six individuals with MS participated in a cross-sectional study (44 ± 11 years; body mass index 26.8 ± 6.2 kg·m−2; expanded disability scale score 3.1 ± 0.9), with 24 individuals with complete test data for both treadmill and cycle ergometry tests. Peak aerobic capacity (VO2peak) for both treadmill and cycle ergometry tests were measured with indirect calorimetry. Results: Participants safely completed both treadmill and cycle ergometry tests, and treadmill testing yielded higher values (26.7 ± 6.4 mL·kg−1·min−1) compared with cycle ergometry (23.7 ± 5.7 mL·kg−1·min−1), with values ~12% greater for treadmill. When comparing tests to their respected predicted values within modality, treadmill tests were 8% lower and cycle ergometry tests were 10% lower than predicted. Conclusions: While peak aerobic capacity was very low for this population, treadmill tests were still higher than cycle ergometry data, with this difference between modes being similar to that observed in healthy adult populations. Additional research is required to determine if these findings are impacted by participation in physical activity or regular exercise.

scholarly journals Effect of high altitude on human placental amino acid transport

2020 ◽  
Vol 128 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Owen. R. Vaughan ◽  
Fredrick Thompson ◽  
Ramón. A. Lorca ◽  
Colleen G. Julian ◽  
Theresa L. Powell ◽  
...  
Keyword(s):  
Birth Weight ◽  
Amino Acid ◽  
High Altitude ◽  
Sea Level ◽  
Amino Acid Transport ◽  
Acid Uptake ◽  
Acid Transport ◽  
Transport Capacity ◽  
System A ◽  
Low Altitude

Women residing at high altitudes deliver infants of lower birth weight than at sea level. Birth weight correlates with placental system A-mediated amino acid transport capacity, and severe environmental hypoxia reduces system A activity in isolated trophoblast and the mouse placenta. However, the effect of high altitude on human placental amino acid transport remains unknown. We hypothesized that microvillous membrane (MVM) system A and system L amino acid transporter activity is lower in placentas of women living at high altitude compared with low-altitude controls. Placentas were collected at term from healthy pregnant women residing at high altitude (HA; >2,500 m; n = 14) or low altitude (LA; <1,700 m; n = 14) following planned, unlabored cesarean section. Birth weight, but not placenta weight, was 13% lower in HA pregnancies (2.88 ± 0.11 kg) compared with LA (3.30 ± 0.07 kg, P < 0.01). MVM erythropoietin receptor abundance, determined by immunoblot, was greater in HA than in LA placentas, consistent with lower placental oxygen levels at HA. However, there was no effect of altitude on MVM system A or L activity, determined by Na+-dependent [14C]methylaminoisobutyric acid uptake and [3H]leucine uptake, respectively. MVM abundance of glucose transporters (GLUTs) 1 and 4 and basal membrane GLUT4 were also similar in LA and HA placentas. Low birth weights in the neonates of women residing at high altitude are not a consequence of reduced placental amino acid transport capacity. These observations are in general agreement with studies of IUGR babies at low altitude, in which MVM system A activity is downregulated only in growth-restricted babies with significant compromise. NEW & NOTEWORTHY Babies born at high altitude are smaller than at sea level. Birth weight is dependent on growth in utero and, in turn, placental nutrient transport. We determined amino acid transport capacity in placentas collected from women resident at low and high altitude. Altitude did not affect system A amino acid transport across the syncytiotrophoblast microvillous membrane, suggesting that impaired placental amino acid transport does not contribute to reduced birth weight in this high-altitude population.

Body water metabolism in high altitude natives during and after a stay at sea level

1981 ◽  
Vol 25 (1) ◽  
pp. 47-52 ◽  
Author(s):  
S. C. Jain ◽  
Jaya Bardhan ◽  
Y. V. Swamy ◽  
A. Grover ◽  
H. S. Nayar
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Body Water ◽  
Water Metabolism ◽  
High Altitude Natives

scholarly journals Seasonal and Altitudinal Prevalence of Fascioliasis in Buffalo in Eastern Nepal

2018 ◽  
Vol 4 ◽  
pp. 48-53
Author(s):  
Ramesh Prasad Sah ◽  
Hari Kumar Prasai ◽  
Jiban Shrestha ◽  
Md Hasanuzzaman Talukder ◽  
AKM Anisur Rahman ◽  
...  
Keyword(s):  
High Risk ◽  
High Altitude ◽  
Sea Level ◽  
Rainy Season ◽  
Meat Production ◽  
Parasitic Diseases ◽  
Sedimentation Technique ◽  
Risk Period ◽  
Pasture Contamination ◽  
Low Altitude

Buffalo is the most important livestock commodities for milk, meat production and several other multipurpose uses distributed densely from southern tarai to northern mid-hills in Nepal. Among several internal parasitic diseases fascioliasis is highly economic one caused by Fasciola in buffaloes. However, there are only few studies carried on prevalence of fascioliasis emphasizing buffaloes in relation to seasonal (summer and rainy, and winter) and altitudinal variations. Therefore, we examined prevalence of fascioliasis seasonally and vertically. For the purpose, we selected two districts of eastern Nepal and sampled from low altitude area known as Madhesha ranging from 175-200, Dhankuta from 800-1200 m, and Murtidhunga from 1800-2200 m elevation from the sea level, representing tarai, mid hills and high hills, respectively. Altogether from February 2013 to January 2014 at every two months interval we collected 798 fecal samples from buffaloes; 282 from Murtidhunga, 239 from Dhankuta and 277 from Madhesha. The samples were examined microscopically for the presence of Fasciola eggs using sedimentation technique. Results showed that overall prevalence of fascioliasis in buffaloes was 39.9% (319/798), ranging highest 42.6%in Madhesha followed by 39.7% in Murtidhunga and 37.2% in Dhankuta, respectively. The prevalence of fascioliasis was found to be significantly (p <0.05) high in winter (44.9%) comparing to rainy season (34.4%). The prevalence of fascioliasis in buffaloes was relatively higher in low altitude than high altitude, although it was not statistically significant (p <0.05). In our findings the female buffaloes showed higher prevalence for fascioliasis than in male. Since the fascioliasis in buffaloes is highly endemic, thus strategic deworming in high risk period is recommended along with measure to prevent pasture contamination with buffalo feces.

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