Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology
Abstract The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min st...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2022-11-01
|
| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-022-23698-5 |
| _version_ | 1798016835574038528 |
|---|---|
| author | Alejandro M. Rosales Robert J. Shute Walter S. Hailes Christopher W. Collins Brent C. Ruby Dustin R. Slivka |
| author_facet | Alejandro M. Rosales Robert J. Shute Walter S. Hailes Christopher W. Collins Brent C. Ruby Dustin R. Slivka |
| author_sort | Alejandro M. Rosales |
| collection | DOAJ |
| description | Abstract The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxygenated hemoglobin (O2Hb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.001). During exercise, brain O2Hb was lower at HH compared to NN (p = 0.007), trending similarly with NH (p = 0.066), but no difference between NN and NH (p = 0.158). During exercise, HR at NH (141 ± 4 beats·min−1) and HH (141 ± 3 beats·min−1) were higher than NN (127 ± 44 beats·min−1, p = 0.002), but not each other (p = 0.208). During exercise, stroke volume at HH (109.6 ± 4.1 mL·beat−1) was higher than NH (97.8 ± 3.3 mL·beat−1) and NN (99.8 ± 3.9 mL·beat−1, p ≤ 0.010) with no difference between NH and NN (p = 0.481). During exercise, cardiac output at NH (13.8 ± 0.6 L) and HH (15.5 ± 0.7 L) were higher than NN (12.6 ± 0.5 L, p ≤ 0.006) with HH also higher than NH (p = 0.001). During acute hypoxic stimuli, skeletal muscle maintains oxygenation whereas the brain does not. These differences may be mediated by environmentally specific cardiovascular compensation. Thus, caution is advised when equating NH and HH. |
| first_indexed | 2024-04-11T15:57:02Z |
| format | Article |
| id | doaj.art-a05ee6761e2b4c5a9f4aeef1bc0bc767 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-11T15:57:02Z |
| publishDate | 2022-11-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-a05ee6761e2b4c5a9f4aeef1bc0bc7672022-12-22T04:15:08ZengNature PortfolioScientific Reports2045-23222022-11-0112111010.1038/s41598-022-23698-5Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiologyAlejandro M. Rosales0Robert J. Shute1Walter S. Hailes2Christopher W. Collins3Brent C. Ruby4Dustin R. Slivka5School of Health and Kinesiology, University of Nebraska at OmahaSchool of Health and Kinesiology, University of Nebraska at OmahaMontana Center for Work Physiology and Exercise Metabolism, Department of Integrative Physiology and Athletic Training, University of MontanaSchool of Health and Kinesiology, University of Nebraska at OmahaMontana Center for Work Physiology and Exercise Metabolism, Department of Integrative Physiology and Athletic Training, University of MontanaSchool of Health and Kinesiology, University of Nebraska at OmahaAbstract The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxygenated hemoglobin (O2Hb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.001). During exercise, brain O2Hb was lower at HH compared to NN (p = 0.007), trending similarly with NH (p = 0.066), but no difference between NN and NH (p = 0.158). During exercise, HR at NH (141 ± 4 beats·min−1) and HH (141 ± 3 beats·min−1) were higher than NN (127 ± 44 beats·min−1, p = 0.002), but not each other (p = 0.208). During exercise, stroke volume at HH (109.6 ± 4.1 mL·beat−1) was higher than NH (97.8 ± 3.3 mL·beat−1) and NN (99.8 ± 3.9 mL·beat−1, p ≤ 0.010) with no difference between NH and NN (p = 0.481). During exercise, cardiac output at NH (13.8 ± 0.6 L) and HH (15.5 ± 0.7 L) were higher than NN (12.6 ± 0.5 L, p ≤ 0.006) with HH also higher than NH (p = 0.001). During acute hypoxic stimuli, skeletal muscle maintains oxygenation whereas the brain does not. These differences may be mediated by environmentally specific cardiovascular compensation. Thus, caution is advised when equating NH and HH.https://doi.org/10.1038/s41598-022-23698-5 |
| spellingShingle | Alejandro M. Rosales Robert J. Shute Walter S. Hailes Christopher W. Collins Brent C. Ruby Dustin R. Slivka Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology Scientific Reports |
| title | Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| title_full | Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| title_fullStr | Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| title_full_unstemmed | Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| title_short | Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| title_sort | independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology |
| url | https://doi.org/10.1038/s41598-022-23698-5 |
| work_keys_str_mv | AT alejandromrosales independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology AT robertjshute independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology AT waltershailes independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology AT christopherwcollins independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology AT brentcruby independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology AT dustinrslivka independenteffectsofacutenormobarichypoxiaandhypobarichypoxiaonhumanphysiology |