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Extreme Physiology and Medicine

, 3:8

First Online: 28 April 2014Received: 23 January 2014Accepted: 04 April 2014

Abstract

BackgroundThe purpose of this study was to determine whether cycling time trial TT performance differs between hypobaric hypoxia HH and normobaric hypoxia NH at the same ambient PO2 93 mmHg, 4,300-m altitude equivalent.

MethodsTwo groups of healthy fit men were matched on physical performance and demographic characteristics and completed a 720-kJ time trial on a cycle ergometer at sea level SL and following approximately 2 h of resting exposure to either HH n = 6, 20 ± 2 years, 75.2 ± 11.8 kg, mean ± SD or NH n = 6, 21 ± 3 years, 77.4 ± 8.8 kg. Volunteers were free to manually increase or decrease the work rate on the cycle ergometer. Heart rate HR, arterial oxygen saturation SaO2, and rating of perceived exertion RPE were collected every 5 min during the TT, and the mean was calculated.

ResultsBoth groups exhibited similar TT performance min at SL 73.9 ± 7.6 vs. 73.2 ± 8.2, but TT performance was longer P < 0.05 in HH 121.0 ± 12.1 compared to NH 99.5 ± 18.1. The percent decrement in TT performance from SL to HH 65.1 ± 23.6% was greater P < 0.05 than that from SL to NH 35.5 ± 13.7%. The mean exercise SaO2, HR, and RPE during the TT were not different in HH compared to NH.

ConclusionCycling time trial performance is impaired to a greater degree in HH versus NH at the same ambient PO2 equivalent to 4,300 m despite similar cardiorespiratory responses.

KeywordsEndurance performance Altitude Hypobaric hypoxia Resting ventilation Time trial performance AbbreviationsCOCardiac output

DBPDiastolic blood pressure

HHHypobaric hypoxia

HRHeart rate

HYPHypoxia

MAPMean arterial pressure

NHNormobaric hypoxia

PETCO2Partial pressure of end-tidal carbon dioxide

PETO2Partial pressure of end tidal oxygen

PIO2Inspired PO2

PO2Ambient PO2

PVPlasma volume

RPERating of perceived exertion

SaO2Arterial oxygen saturation

SBPSystolic blood pressure

SLSea level

TTTime trial

VEMinute ventilation

VE · VCO2-1Ventilatory equivalent for carbon dioxide

VE · VO2-1Ventilatory equivalent for oxygen

VCO2Carbon dioxide production

VO2Oxygen consumption

VO2peakPeak oxygen consumption.

Electronic supplementary materialThe online version of this article doi:10.1186-2046-7648-3-8 contains supplementary material, which is available to authorized users.

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Autor: Beth A Beidleman - Charles S Fulco - Janet E Staab - Sean P Andrew - Stephen R Muza

Fuente: https://link.springer.com/



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