Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males
Abstract To assess the impact of thoracic load carriage on the physiological response to exercise in hypoxia. Healthy males (n = 12) completed 3 trials consisting of 45 min walking in the following conditions: (1) unloaded normoxia (UN; FIO2:20.93%); (2) unloaded hypoxia (UH; FIO2:~13.0%); and (3) l...
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Wiley
2025-01-01
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| Online Access: | https://doi.org/10.14814/phy2.70197 |
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| author | Daniel A. Baur Caroline M. Lassalle Stephanie P. Kurti |
| author_facet | Daniel A. Baur Caroline M. Lassalle Stephanie P. Kurti |
| author_sort | Daniel A. Baur |
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| description | Abstract To assess the impact of thoracic load carriage on the physiological response to exercise in hypoxia. Healthy males (n = 12) completed 3 trials consisting of 45 min walking in the following conditions: (1) unloaded normoxia (UN; FIO2:20.93%); (2) unloaded hypoxia (UH; FIO2:~13.0%); and (3) loaded hypoxia (LH; 29.5 kg; FIO2:~13.0%). Intensity was matched for absolute VO2 (2.0 ± 0.2 L·min−1) across conditions and relative VO2 (64.0 ± 2.6 %VO2max) across hypoxic conditions. With LH versus UH, there were increases in breathing frequency (5–11 breaths·min−1; p < 0.05) and decreases in tidal volume (10%–18%; p < 0.05) throughout exercise due to reductions in end inspiratory lung volumes (p < 0.05). Consequently, deadspace (11%–23%; p < 0.05) and minute ventilation (7%–11%; p < 0.05) were increased starting at 20 and 30 min, respectively. In addition, LH increased perceived exertion/dyspnea and induced inspiratory (~12%; p < 0.05 vs. UN) and expiratory (~10%; p < 0.05 vs. pre‐exercise) respiratory muscle fatigue. Expiratory flow limitation was present in 50% of subjects during LH. Cardiac output and muscle oxygenation were maintained during LH despite reduced stroke volume (6%–8%; p < 0.05). Finally, cerebral oxygenated/total hemoglobin were elevated in the LH condition versus UH starting at 15 min (p < 0.05). Thoracic load carriage increases physiological strain and interferes with the compensatory response to hypoxic exposure. |
| format | Article |
| id | doaj-art-f78a9c64b568486d98a51e2e9bb7fb8b |
| institution | Kabale University |
| issn | 2051-817X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Wiley |
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| series | Physiological Reports |
| spelling | doaj-art-f78a9c64b568486d98a51e2e9bb7fb8b2025-01-15T13:36:31ZengWileyPhysiological Reports2051-817X2025-01-01131n/an/a10.14814/phy2.70197Thoracic load carriage impairs the acute physiological response to hypoxia in healthy malesDaniel A. Baur0Caroline M. Lassalle1Stephanie P. Kurti2Department of Human Performance and Wellness Virginia Military Institute Lexington Virginia USADepartment of Human Performance and Wellness Virginia Military Institute Lexington Virginia USADepartment of Kinesiology James Madison University Harrisonburg Virginia USAAbstract To assess the impact of thoracic load carriage on the physiological response to exercise in hypoxia. Healthy males (n = 12) completed 3 trials consisting of 45 min walking in the following conditions: (1) unloaded normoxia (UN; FIO2:20.93%); (2) unloaded hypoxia (UH; FIO2:~13.0%); and (3) loaded hypoxia (LH; 29.5 kg; FIO2:~13.0%). Intensity was matched for absolute VO2 (2.0 ± 0.2 L·min−1) across conditions and relative VO2 (64.0 ± 2.6 %VO2max) across hypoxic conditions. With LH versus UH, there were increases in breathing frequency (5–11 breaths·min−1; p < 0.05) and decreases in tidal volume (10%–18%; p < 0.05) throughout exercise due to reductions in end inspiratory lung volumes (p < 0.05). Consequently, deadspace (11%–23%; p < 0.05) and minute ventilation (7%–11%; p < 0.05) were increased starting at 20 and 30 min, respectively. In addition, LH increased perceived exertion/dyspnea and induced inspiratory (~12%; p < 0.05 vs. UN) and expiratory (~10%; p < 0.05 vs. pre‐exercise) respiratory muscle fatigue. Expiratory flow limitation was present in 50% of subjects during LH. Cardiac output and muscle oxygenation were maintained during LH despite reduced stroke volume (6%–8%; p < 0.05). Finally, cerebral oxygenated/total hemoglobin were elevated in the LH condition versus UH starting at 15 min (p < 0.05). Thoracic load carriage increases physiological strain and interferes with the compensatory response to hypoxic exposure.https://doi.org/10.14814/phy2.70197altitudeexpiratory flow limitationhemodynamicsnear‐infrared spectroscopyrespiratory muscle fatigueventilation |
| spellingShingle | Daniel A. Baur Caroline M. Lassalle Stephanie P. Kurti Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males Physiological Reports altitude expiratory flow limitation hemodynamics near‐infrared spectroscopy respiratory muscle fatigue ventilation |
| title | Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| title_full | Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| title_fullStr | Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| title_full_unstemmed | Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| title_short | Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| title_sort | thoracic load carriage impairs the acute physiological response to hypoxia in healthy males |
| topic | altitude expiratory flow limitation hemodynamics near‐infrared spectroscopy respiratory muscle fatigue ventilation |
| url | https://doi.org/10.14814/phy2.70197 |
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