Reproducibility of cardiorespiratory and performance responses to exercise in hypoxia
- Published
- Accepted
- Subject Areas
- Anatomy and Physiology
- Keywords
- Hypoxia, Exercise, time trial performance, reproducibility
- Copyright
- © 2016 Lee et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Reproducibility of cardiorespiratory and performance responses to exercise in hypoxia. PeerJ PrePrints 4:e1513v2 https://doi.org/10.7287/peerj.preprints.1513v2
Abstract
Background. Knowledge of the variance in physiological performance measures between repeated trials can inform whether familiarization sessions are necessary prior to intervention studies. The purpose of this study was to assess the reliability of cardiorespiratory and exercise performance measures during both steady state hypoxic exercise and a preloaded 16.1 km hypoxic time trial. Methods. Eighteen male participants (age, 22 ± 4 years; height, 1.77 ± 0.04 meters; body mass, 76.8 kg; estimated body fat and VO2peak = 3.50 ± 0.60 L.min-1) were divided into three groups. Reliability of responses (HR, SPO2 , VO2 , VCO2 , VE and respiratory exchange ratio; RER) to the HST (FIO2 0.14; 15 minutes rest, 60 minutes cycling at 50% normoxic VO2peak) was assessed across 3 repeat trials (HST 1, 2 and 3, n = 6). Reliability of the preloaded time trial (pTT; 15 min rest, 40 minutes cycling at 50% normoxic VO2peak, 16.1km time trial) was assessed across 3 repeat normoxic (N; FIO2 ≈ 0.21; n=6) and 3 repeat hypoxic (FIO2 ≈ 0.14; n = 6) trials. All exercise trials were undertaken at the same time of day, following exercise and dietary controls, 7 days apart. Results. Intra-class correlation coefficients (ICC’s) for mean and peak HR, SpO2 , VE , VO2 , VCO2 and blood lactate within each trial were improved from HST1 to HST2 (mean data: 0.99, 0.95, 0.75, 0.62, 0.70, 0.90; peak data: 0.98, 0.96, 0.64, 0.69, 0.74, 0.75) to HST2 and HST3 (ICC = 0.99, 0.97, 0.82, 0.85, 0.87 and 0.96 respectively). The reliability for time to pTT completion was improved following one trial, and the CV (test 2 vs. 3) was similar under normoxic (CV = 0.62) and hypoxic conditions (CV = 0.63). Conclusion. Cardiorespiratory responses to the HST were reproducible and the pTT performance time reliable in both normoxia and hypoxia. Since the reproducibility of the measurements in HST trials and reliability of pTT improved between the second and third trials, two familiarization visit are recommended prior to employing these protocols in future studies.
Author Comment
This is an update to the manuscript submitted to PeerJ for peer review. The article now focuses on the physiological and performance responses to repeated hypoxic tests, with the cellular markers removed in order to improve focus.