The Effect of Altitude on Peripheral Oxygen Levels and Heart Rate in Trained Acclimatized Individuals versus Untrained, Unacclimatized Individuals During a Climb of Mount Kilimanjaro

Abstract

BackgroundThe acute physiological response to increased altitude includes increased cardiac output, via increased heart rate with no change in stroke volume, for improved oxygen delivery to tissues. An inability to adapt to decreased oxygen availability can result in hypoxemia and thus, hypoxia. Acclimatizing after extended exposure to the environment results in a return of cardiac output to baseline by maintaining an elevated heart rate with a reduction in stroke volume. Both training duration and intensity can impact the changes in heart rate and oxygen saturation. A significant fraction of climbers who attempt to summit Mt. Kilimanjaro (5895 m) are unsuccessful, usually due to inability to adapt to altitude. We wished to determine whether the physiological adjustments during the climb of Mt. Kilimanjaro were related to training before the climb, and whether the physiological adjustments of climbing guides differed from those of guided climbers.MethodsAll subjects provided informed consent. Ten guided climbers (6 male, 4 female, ages 21 to 69) and five guides (male, ages 24 to 31) completed an 8‐day climb of Mt. Kilimanjaro. Each guided climber completed a survey assessing their training regimen leading up to the climb. Guided climbers were classified into four categories based upon the intensities of their training regimens. Heart rate (HR) and peripheral oxygen saturation (SpO2) were measured by pulse oximeter. Each data point was measured twice to ensure accuracy. Data was collected from guided climbers and guides before beginning the climb, as well as each morning and evening while resting at camp from climbing day one to day six (summit night). Correlations were assessed with Spearman's rho, and differences between groups were assessed with the Mann Whitney U test.ResultsThere was a significant correlation between training intensity and overall change in heart rate from day one to day six (rs= 0.918, p<.001) among the guided climbers, where those who trained harder before the climb increased their HR more during the climb. There was not a significant correlation between training intensity and decrease in oxygen saturation during the ascent (rs= □0.35, p>0.3). There was a significant difference in the change in heart rate from day one to day six in the guides compared to the guided climbers (median ΔHR=+9.0 bpm for guides versus +20.5 bpm for guided climbers, U=0, p<0.01). The change in oxygen saturation from day one to day six was not significantly different at the p<.05 level between guides and guided climbers (median ΔSpO2 =−9.0% for guides and −11.5% for guided climbers, U=9.5, 0.05<p<0.10).ConclusionThe intensity of training prior to summit attempt impacts the changes in heart rate in Mt. Kilimanjaro climbers. Climbers who completed a higher intensity training program had a greater change in heart rate, allowing them to complete the climb with less difficulty than untrained individuals. There was a significant difference between the changes in heart rate as altitude increases between mostly unacclimatized individuals (guided climbers) and highly acclimatized individuals (guides).Support or Funding InformationThe David A. Plastino Scholars ProgramThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.