Show simple item record Foss, Joshua 2015-11-19T16:15:43Z 2015-11-19T16:15:43Z 2015-11
dc.description.abstract Endurance performance at altitude is diminished as a consequence of the hypoxic environment. Timing the arrival at altitude prior to such a competition is an important consideration due to time-dependent changes as a result of acclimatization. While the time course of changes over the first few weeks of altitude exposure has been well documented, the changes seen within the first few hours of arrival have not been characterized. As a result, coaches and athletes employ varied arrival strategies in an attempt to maximize performance, notable arrival just prior to the competition or arrival the night before competition. Purpose: To compare cycling 20km time trial performance outcomes and related parameters at altitude after 2 hours and 14 hours of arrival at a simulated altitude of 2500m. Methods: Subjects performed a familiarization 20km time trial, followed every 7 days by a total of 3 overnight stays in an altitude tent. The three random, single-blinded interventions were as follows: 14 hours of hypoxia, 12 hours of normoxia and 2 hours of hypoxia, or 14 hours of normoxia. The two hypoxic trials were followed by a 20km time trial in hypoxia and the normoxic trial was followed by a 20km time trial in normoxia. Ventilatory acclimatization, sleep disturbances, and plasma volume decrements were also measured during the study. Results: No differences were observed in performance times between the two hypoxic trials. Average times to completion for each trial were: 2hr - 36:47 ± 0:47s, 14hr – 36:44 ± 0:50s, CTRL – 35:34 ± 0:39s. After 14 hours, plasma volume decreased by an average of 235 ml more than control, while an additional decrease over control of only 22ml occurred during the 2hr trial. V̇E/ V̇O2 values for each subsequent 4km were as follows: 34.4 ± 7.0, 33.4 ± 5.1, 33.8 ± 5.5, 32.9 ± 4.4, 35.9 ± 5.4 for the 2hr trial and 32.3 ± 6.1, 32.2 ± 5.8, 32.7 ± 5.3, 32.4 ± 5.2, 34.9 ± 5.6 for the 14hr trial, respectively (n.s. at any time point). Activity counts during sleep were 744.7 ± 30.2 for the 2hr trial and 740.9 ± 31.7 for the 14hr trial (n.s.). Conclusion: Differences in endurance exercise performance are not observed at altitude during the first 14 hours of arrival at altitude. While the some of the variables that would be expected to alter performance did show changes within this time frame (e.g. plasma volume loss), they were either not substantial enough to alter performance or acted to counter-balance each other, leaving performance variables equally affected by acute altitude exposure. en
dc.description.sponsorship A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Department of Kinesiology of the School of Public Health, Indiana University November 2015 en
dc.language.iso en_US en
dc.type Thesis en
dc.altmetrics.display false en

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